A scoping review of methodological approaches to measure circularity in asphalt mixtures

A scoping review of methodological approaches to measure circularity in asphalt mixtures | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Short Report A scoping review of methodological approaches to measure circularity in asphalt mixtures Osires de Medeiros Melo Neto, Ahmed Mohammad Youssef, Ibrahim Elnaml, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7794357/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract The transition from a linear to a circular economy in pavement engineering requires consistent methodologies to assess material reuse and sustainability. Asphalt mixtures containing recycled materials are key to reducing environmental impacts and improving resource efficiency, yet no standardized method exists to quantify circularity. This scoping review, following PRISMA-ScR guidelines, systematically mapped methodologies used to measure circularity in asphalt mixtures. A comprehensive search was conducted in April 2025 across Web of Science, Scopus, SciELO, and Google Scholar, without limits on year, language, or publication status. Two independent reviewers screened studies and extracted data, with inter-rater reliability assessed using the Kappa statistic. Of 173 records retrieved, 10 met the inclusion criteria. These studies, conducted mainly in Europe, South America, and Asia (2019–2025), applied indices such as the Material Circularity Index (MCI), Environmental Sustainability and Circularity Indicator (ESCi), and related metrics. Most methods focused on recycled content or material flow, potentially overestimating circularity. None provided an integrated assessment combining structural, environmental, and economic dimensions. The findings reveal a lack of methodological standardization that limits comparability and practical application. This review emphasizes the need for harmonized, multi-criteria approaches linking mechanical performance, cost, and environmental externalities to advance sustainable, circular pavement infrastructure. Asphalt Mixtures Circular Economy Circularity Index Recycling Standardization Sustainability Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 1. Introduction The conventional economic paradigm is grounded in a linear logic of extraction, production, consumption, and disposal, in which natural resources are used only once and goods, often still functional, are frequently discarded, intensifying waste generation [ 1 ]. Although this model prioritizes short-term cost reduction, it overlooks the reintegration of materials into the production cycle and disregards sustainability principles, leading to cumulative and long-lasting environmental impacts [ 2 ]. In contrast, the concept of circularity has gained prominence as a key strategy for restructuring more sustainable production systems, as it addresses critical challenges such as resource limitations, increasing waste generation, and escalating environmental degradation [ 3 , 4 ]. Given the significant environmental impacts caused by historically inefficient models of natural resource management [ 5 ], the adoption of the circular economy (CE) has been incorporated as a strategic guideline in the European Union’s public policies [ 6 ]. The specialized literature indicates that CE supports the transition toward sustainable development [ 7 ] by promoting the optimized use of resources through practices such as reduction, reuse, recycling, and recovery throughout production and consumption cycles [ 8 , 9 ]. Following the 26th United Nations Climate Change Conference (COP 26), several countries began implementing strategies aimed at achieving carbon neutrality [ 10 ]. In this context, the construction sector stands out as one of the main emitters of carbon dioxide, accounting for more than one-third of global emissions, thus making it a top priority in international climate mitigation policies ([ 11 ]. The progressive incorporation of recycled materials represents a strategic measure to enhance the technical, economic, and environmental efficiency of construction inputs, including those used in pavement applications. This practice contributes to the conservation of natural resources, the reduction of solid waste disposal, and the transition toward sustainable production models. Such an approach aligns with the principles of the circular economy by breaking away from the traditional linear logic that still prevails in the paving industry [ 11 , 12 ]. The promotion of a more sustainable and resilient road infrastructure system can be achieved through the reuse of asphalt materials, a practice that contributes to emission reductions, natural resource conservation, and lower operational costs [ 13 – 16 ]. Asphalt pavements, over their service life, undergo aging and structural deterioration due to cyclic vehicle loading, exposure to ultraviolet radiation, and the action of rainwater. Under these conditions, interventions such as milling and maintenance become necessary, resulting in the generation of large volumes of milled material, known as Reclaimed Asphalt Pavement (RAP) [ 17 ]. The reuse of RAP has been widely recognized for offering substantial benefits from both economic and environmental perspectives [ 18 , 19 ]. Several studies have employed warm mix asphalt technologies in combination with RAP to reconfigure the granular structure of asphalt mixtures, as well as to incorporate industrial solid wastes, such as fly ash and desulfurization ash, as partial replacements for cement in cementitious grouting materials, achieving significant reductions in energy consumption and pollutant emissions [ 20 – 24 ]. In this context, there is a growing incentive, both from the scientific community and public decision-makers, to use waste materials in road pavement construction as a strategy to promote circularity in the sector. However, this practice still raises important concerns, particularly regarding the measurement of circularity in these products after the incorporation of recycled materials. Despite the progress made, there is still no methodological consensus or standardized guidelines capable of accurately quantifying the degree of circularity in recycled pavements, which limits the systematic evaluation of their environmental and economic impacts. A scoping review is a well-established methodology for investigating the scientific literature on a given topic, allowing for the systematic mapping of academic output with a focus on identifying the breadth, diversity, and characteristics of existing research [ 25 – 27 ]. This approach aims to synthesize and disseminate available findings while also highlighting unexplored knowledge gaps. Although it shares the methodological rigor of systematic reviews regarding transparency and reproducibility of procedures, a scoping review does not aim to critically assess the quality of the included evidence [ 28 ]. Currently, there are significant gaps in the literature regarding the use of scoping reviews to explore the application of circular economy principles in asphalt mixtures. An exploratory search conducted in the Scopus database in early March 2025 using the descriptor “scoping review” revealed that only 4.91% of the retrieved documents were related to the field of engineering, while 4.13% were associated with environmental science. When the search was refined using the terms (“scoping review” AND “asphalt mixture”), only one scientific article was found—published in November 2023 in the journal Sustainable Production and Consumption, entitled “v” [ 29 ]. An identical result was obtained using the combination of descriptors (“scoping review” AND “asphalt mixture” AND “circular economy”). Therefore, it becomes essential to conduct a comprehensive investigation that examines and maps the methodologies applied in quantifying circularity in asphalt mixtures. This mapping enables a critical analysis of the most established methods as well as those providing more rigorous assessments of circularity feasibility in these mixtures. Consequently, such a study will serve as a foundation for the development of a new circularity index specific to recycled asphalt mixtures. Thus, the objective of this scoping review was to identify the methodologies and tools used to measure the circularity of asphalt mixtures. Unlike narrative reviews, which provide broad and often subjective syntheses, and systematic reviews, which critically appraise the quality of evidence to answer narrowly defined questions, a scoping review offers a distinct contribution by mapping the extent, diversity, and methodological approaches of the available literature. This perspective is particularly valuable for emerging topics such as circularity in asphalt mixtures, where the heterogeneity of methods and the absence of standardized indices demand a comprehensive overview to identify gaps, clarify conceptual boundaries, and inform future research and practice. 2. Methodology Fig. 1 illustrates the flowchart of the scoping review conducted on the circularity index in pavements. This study aimed to identify the methodologies and tools used to measure circularity in pavements through a scoping review. To this end, the PRISMA protocol (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) was adopted as the methodological approach, given that it promotes transparency and enhances the quality of reviews, including scoping reviews. PRISMA consists of a structured guide composed of a checklist and a flowchart, whose purpose is to standardize the preparation of reviews and ensure the replicability of investigative processes by the scientific community. The PRISMA extension for scoping reviews is a 22-item checklist covering all aspects of the manuscript [30]. The literature search was conducted in early April 2025 using internationally recognized academic databases, such as Web of Science (Clarivate), Scopus (Elsevier/ScienceDirect), SciELO, and Google Scholar. The search strategy employed terms related to the measurement of circularity within the pavement context, considering synonyms commonly used in the field, such as (“asphalt mix” OR “asphalt” OR “asphalt materials” OR “asphalt pavement” OR “asphalt binder” OR “asphalt concrete”) AND (“circularity index” OR “material circularity index”). No restrictions were applied regarding year, language, or publication status. Eligibility criteria were clearly defined as follows: Inclusion criteria: peer-reviewed articles or gray literature that investigated asphalt mixtures in the context of circular economy; studies explicitly addressing methods, indices, or tools for measuring circularity; and publications providing sufficient methodological detail for data extraction. Exclusion criteria: duplicate records; studies not related to asphalt mixtures or circular economy; publications without an accessible abstract or full text; articles focusing exclusively on environmental or mechanical performance without any reference to circularity indicators; and non-scientific documents such as editorials, opinion pieces, or technical notes. During the study selection and data extraction phases, two trained reviewers independently conducted the screening. Titles and abstracts were examined against the eligibility criteria, and when the information was insufficient, full texts were retrieved for assessment. Disagreements were resolved by a third reviewer. Inter-rater agreement was measured using the Kappa statistic. Data extraction was performed using Microsoft Excel and included: author and year of publication, country of study, objectives, data collection instruments, main findings, sample characteristics (type of asphalt mixture and materials used), and the circularity assessment method adopted. Data synthesis was then conducted to map and compare the methodologies applied to evaluate circularity in asphalt mixtures. 3. Results A scoping review was conducted with the objective of mapping the methods available in the literature for quantifying the circularity index in the context of asphalt pavement engineering. The initial search retrieved 173 articles, of which 7 were excluded due to duplication. After screening titles and abstracts, 146 studies were discarded for not meeting the inclusion criteria. These inclusion criteria considered, among other aspects, the nature of the article, the availability of the abstract, relevance to the topic of interest, measurement of circularity, and evaluation of pavement circularity. Subsequently, eligibility criteria were applied, involving verification of article availability, sample analysis (asphalt or pavement), investigation or measurement of circularity, and inclusion or exclusion of other materials. Based on these criteria, articles were then included or excluded from the analysis. Among the 20 articles selected for full-text reading, 7 were excluded due to differing objectives, and 3 were excluded because they were not scientific articles. After applying the eligibility criteria, 10 studies were included in the synthesis. The article selection process is illustrated in the PRISMA diagram shown in Fig. 2 . The main characteristics of the analyzed studies are summarized in Tables 1 , 2 , and 3 . The reviewed publications span the period from 2019 to 2025, without a defined temporal restriction, and were predominantly conducted in the Netherlands, Switzerland, Finland, Brazil, Italy, China, and Iran. This pattern indicates that research on circularity in the context of asphalt pavement has been concentrated in the last six years. Moreover, it is observed that the studies primarily focus on the European continent, with emphasis on the Netherlands, Switzerland, Finland, and Italy, followed by South America (Brazil) and Asia (Iran and China). These data suggest a growing mobilization of researchers in these regions in pursuit of solutions for more sustainable pavements, especially regarding the integration of residual materials within the circular economy. The agreement between reviewers regarding article inclusion and exclusion during the screening and eligibility process was assessed using the Kappa coefficient (K) (Eq. 1 ), resulting in K = 0.83, indicating a high level of agreement among the evaluators. $$\:K=\frac{{Probability}_{observed}-{Probability}_{chance\:}}{1-{Probability}_{chance}}$$ 1 The studies analyzed in the scoping review reveal a diversity of approaches for measuring circularity in asphalt mixtures, reflecting advances in the development of specific indices to assess the sustainability of asphalt materials. However, a detailed comparative analysis of the methods highlights strengths and limitations that affect the applicability of these indices both in academic research and practical pavement management. The articles employ different strategies for quantifying circularity, highlighting the Material Circularity Index (MCI) and its variations, as well as complementary indicators such as the Environmental Sustainability and Circularity Indicator (ESCi). The MCI has been applied to various materials, based on the methodology of the Ellen MacArthur Foundation and adapted for asphalt mixtures [ 31 , 32 ]. The ESCi, in turn, integrates life cycle assessment (LCA) with circularity, providing a more comprehensive analysis of the environmental and structural impacts of the mixtures [ 33 ]. The reviewed publications span the period from 2019 to 2025, with an increasing concentration in recent years. Figure 3 (a) summarizes the annual distribution of included studies, highlighting the recent consolidation of the topic within pavement engineering. To complement the annual distribution, Fig. 3 (b) presents the cumulative growth of included studies between 2019 and 2025, illustrating the progressive consolidation of research on circularity in asphalt mixtures. Tables 1 , 2 , and 3 demonstrate that the adopted methods differ in weighting criteria, considered variables, and levels of applicability. Some studies incorporate environmental indicators such as carbon footprint and energy efficiency [ 34 , 35 ], while others prioritize residual material flow and mechanical resistance as the basis for defining circularity [ 36 , 37 ]. Although combining these factors is essential for a holistic analysis, the lack of methodological standardization hinders comparability among studies and the replicability of indices across different geographical and climatic contexts. (a) Table 1 Characteristics of articles 1 to 3 included in the scoping review Analysis Criteria Articles Evaluated Article 1 Article 2 Article 3 Article Title Metrics for minimising environmental impacts while maximising circularity in biobased products: The case of lignin-based asphalt Viability of recycled asphalt mixtures with soybean oil sludge fatty acid Optimizing recycled asphalt mixtures with zeolite, cottonseed oil, and varied RAP content for enhanced performance and circular economy impact Authors/Year Corona et al. [ 34 ] de Medeiros Melo Neto et al. [ 36 ] da Costa et al. [ 32 ] Journal Journal of Cleaner Production Construction and Building Materials Case Studies in Construction Materials Name and Concept of the Circularity Index Material Circularity Index (MCI) and New Biogenic Carbon Storage Indicators (BCS100 and c-BCS) Material Circularity Index (MCI) Applied to Recycled Asphalt Mixtures with Fatty Acids from Soybean Oil Sludge Circularity Index for Recycled Asphalt Mixtures (MCIMAR), including methodological adaptations Main Objective Evaluate the Circularity and Sustainability of Lignin-Based Asphalt Compared to Conventional Bitumen-Based Asphalt To evaluate the technical, economic, and environmental feasibility of recycled asphalt mixtures containing 40% RAP and fatty acid from soybean oil sludge as a rejuvenating agent Evaluate the optimization of recycled asphalt mixtures with zeolite, cotton oil, and varying RAP contents for mechanical performance and impact on the circular economy Theoretical Basis Based on the Principles of Circular Economy and the Life Cycle Assessment (LCA) Methodology Based on the circular economy, using the MCI index Based on the principles of the circular economy, using MCIMAR Application Sector Developed for Application in Asphalt Materials, Especially Bio-Based Asphalts Pavement engineering, especially for recycled asphalt mixtures with sustainable rejuvenating agents Pavement Engineering, Especially for Recycled Asphalt Mixtures with Sustainable Additives Considered Indicators Material Circularity Index (MCI), BCS100, and c-BCS, as well as Environmental Impacts (GWP, Resource Depletion) Material Circularity Index (MCI), mechanical strength, fatigue performance, and permanent deformation MCIMAR, Mechanical Strength (Indirect Tensile Strength, Indirect Tensile Fatigue, Permanent Deformation, Cantabro Abrasion, Moisture-Induced Damage) Calculation Method Use of the MCI to Measure Material Circularity and Two New Indicators to Assess Biogenic Carbon Storage Use of the MCI according to the Ellen MacArthur Foundation methodology, adapted by Mantalovas and Di Mino (2019) for asphalt mixtures Enhancement of MCIMAR with an Extended Utility Factor, Including Additional Parameters Such as Moisture Resistance and Abrasion Weighting Criteria The indicators consider material recirculation, use of renewable raw materials, and biogenic carbon storage Factors such as recycled material fraction, recycling process efficiency, fatigue resistance, and permanent deformation Based on Mechanical and Environmental Variables, Considering Structural Performance and Recycling Efficiency of Materials Units of Measurement Values Expressed in kg C/m², kg CO₂/m²/year, and Dimensionless Units for MCI Values expressed in load cycles (fatigue and permanent deformation) and dimensionless units for MCI Values Expressed in Load Cycles, Strength in MPa, and Dimensionless Indices for MCIMAR Data Sources Experimental Data Collected from Lignin Refineries and Asphalt Producers Laboratory tests conducted with mixtures containing 40% RAP and rejuvenating agent Laboratory Tests with Mixtures Containing Different Contents of RAP, Cotton Oil, and Zeolite Data Scope Covers the Entire Life Cycle, from Raw Material Production to the Final Disposal of Asphalt Laboratory analyses of recycled asphalt mixtures with different compositions, considering mechanical strength and environmental impact Experimental Analyses of Recycled Mixtures in the Laboratory, Assessing Strength, Durability, and Circularity Data Limitations Challenges in Modeling Biogenic Carbon Storage and Accounting for Material Recycling Need for validation under real-world application conditions and analysis of long-term impact Need for Full-Scale Validation and Assessment of Environmental Impacts Throughout the Life Cycle Evaluated Materials or Technologies Comparison Between Conventional Asphalt Mixtures and Mixtures Containing Lignin as a Partial Substitute for Bitumen Recycled asphalt mixtures with 40% RAP and soybean oil sludge fatty acids as rejuvenator (3% and 5%) Recycled Asphalt Mixtures with Different RAP Contents (15%, 25%, 33%) and Incorporation of Cotton Oil (4%, 6%, 10%) or Zeolite (0.3%) Application Scale Tested in Simulations and Laboratory Experimental Studies, with Prospects for Industrial-Scale Application Application in laboratory tests, with potential for scaling up to field studies Laboratory Tests with Potential for Application in Large-Scale Sustainable Pavement Projects Obtained Results Lignin-Based Asphalt Exhibited Higher Circularity and Better Biogenic Carbon Storage, but with Some Technical Limitations The recycled mixtures exhibited higher circularity and better performance in fatigue and permanent deformation compared to the conventional mixture The Mixtures Containing 0.3% Zeolite and 25% RAP Showed Better Mechanical and Environmental Performance Environmental Impacts Assessment of Carbon Emissions, Energy Consumption, and Climate Change Impacts (GWP) Reduction in virgin material consumption, decreased disposal of asphalt waste, and potential reduction of carbon footprint Reduction in the Use of Virgin Aggregates, Lower Disposal of Asphalt Waste, and Potential Reduction of the Carbon Footprint Social and Economic Aspects The article mentions life cycle costs and environmental impacts but does not directly address social benefits Economic analysis demonstrated the feasibility of using the rejuvenating agent without increasing costs The Study Discusses Economic Feasibility, Highlighting the Possibility of Cost Reduction Without Compromising Mechanical Performance Sustainability Limitations Does not consider social and economic impacts in depth, focusing more on environmental aspects There remains a need for further studies on long-term durability and indirect environmental impacts The Study Does Not Address Social Impacts in Detail, Focusing Primarily on Environmental and Economic Aspects Experimental Validation Results Validated with Experimental Data and Simulations Based on Previous Studies Results validated through laboratory mechanical tests and modeling based on established methodologies Laboratory Tests with Statistical Analysis, Including Comparison Among Different Compositions of Recycled Mixtures Reproducibility The Methodology Can Be Replicated for Different Types of Bio-Based Asphalt Mixtures The methodology can be replicated for different asphalt mixtures and rejuvenator contents Methodology Replicable for Other Recycled Asphalt Mixtures with Additive Variations Comparative Studies Comparison with Conventional Asphalts and Other Circular Economy Studies Comparison between conventional and recycled asphalt mixtures, highlighting the benefits of incorporating RAP and fatty acids from soybean oil sludge Comparison Between Recycled and Conventional Mixtures with Different Compositions and Additive Contents Mentioned Gaps Need for Further Validation under Real Conditions and Improvement of Recycling Methods Need for additional studies on the long-term effects of the rejuvenator and validation at real scale Need for Further Full-Scale Studies to Evaluate Long-Term Durability and Performance Future Recommendations Suggestions to Optimize Circularity and Reduce Costs Through New Production Processes Explore real-scale application and evaluate environmental impacts under actual traffic conditions Explore Industrial Applications and Validate the Effectiveness of the Approach in Different Geographic and Environmental Contexts Specificity to Asphalts The indices address specific characteristics such as durability, adhesion, and volumetric stability Approach focused on recycled asphalt mixtures and analysis of material circularity Circularity Index Specifically Adapted for Recycled Asphalt Mixtures Adaptation Potential It Can Be Adapted for Different Recycled Asphalt Mixtures, with Methodological Adjustments Potential adaptation for different asphalt mixtures and other types of sustainable rejuvenators It Can Be Adapted to Different Recycled Mixture Formulations Depending on Local Conditions Normative Requirements The index partially complies with technical standards but requires adjustments to become more applicable in the industry There is currently no specific normative standardization for this type of rejuvenator The Methodology Is Not Yet Fully Aligned with Current Standards but Shows Potential for Future Standardization Application Complexity The method presents practical challenges due to the need for specific data collection and detailed calculations Relatively simple laboratory process, but requires adjustments for large-scale implementation The Method Requires Detailed Calculations and Several Specific Laboratory Tests, but It Is Feasible for Practical Applications Associated Costs Implementation Requires Investments in Laboratory Testing and Life Cycle Analyses Production costs similar to conventional mixtures, with no economic impact Relatively Low Implementation Cost, Especially Compared to Conventional Mixtures Interpretable Results The results are useful for decision-making but may be complex for professionals without experience in the field The results provide clear insights into the feasibility of using the rejuvenator and its impacts on the circularity of asphalt mixtures The Results Allow a Clear Assessment of the Technical and Environmental Feasibility of the Studied Mixtures Table 2 Characteristics of articles 4 to 6 included in the scoping review Analysis Criteria Articles Evaluated Article 4 Article 5 Article 6 Article Title The Sustainability of Reclaimed Asphalt as a Resource for Road Pavement Management through a Circular Economic Model Integrating Circularity in the Sustainability Assessment of Asphalt Mixtures Circular Economy as an Environmental Management Mechanism: Use of RAP in Asphalt Surfacing Layers Authors/Year Mantalovas e Di Mino [ 31 ] Mantalovas e Di Mino [ 33 ] Mendes et al. [ 38 ] Journal Sustainability Sustainability Revista Brasileira de Gestão Ambiental e Sustentabilidade Name and Concept of the Circularity Index Material Circularity Indicator (MCI) Applied to Reclaimed Asphalt (RA) Within a Circular Economy Model Environmental Sustainability and Circularity Indicator (ESCi), desenvolvido para avaliar a circularidade e sustentabilidade ambiental de misturas asfálticas Material Circularity Indicator (MCI) Applied to Reclaimed Asphalt Pavement (RAP) as an Indicator of Circular Economy in Pavement Engineering Main Objective Evaluate the Sustainability of Recycled Asphalt as a Resource for Road Pavement Management Within a Circular Economy Model To Develop and Apply a Composite Indicator (ESCi) That Simultaneously Assesses the Circularity and Environmental Impacts of Recycled Asphalt Mixtures with Varying RAP Contents To Analyze the Potential of the Circular Economy as an Environmental Management Tool in Pavement Engineering, with a Focus on the Reuse of RAP in Asphalt Surfacing Layers Theoretical Basis Based on the Principles of the Circular Economy and the Ellen MacArthur Foundation’s Methodology for MCI Quantification Based on the Principles of Circular Economy and Life Cycle Assessment (LCA), Using the Material Circularity Indicator (MCI) Adapted for Asphalt Mixtures Based on the Concepts of the Circular Economy and the Methodology of the Material Circularity Indicator (MCI), Adapted for Asphalt Mixtures Application Sector Pavement Engineering with a Focus on the Reuse of Milled Asphalt in Recycled Asphalt Mixtures Pavement Engineering with a Focus on Sustainability and Material Reuse in Recycled Asphalt Mixtures Pavement Engineering with a Focus on Environmental Management and Optimization of Recycled Material Reuse Considered Indicators Material Circularity Indicator (MCI), Milled Asphalt Recycling Rates, Reuse Process Efficiency, and Environmental Impacts ESCi, Material Circularity Indicator (MCI), Environmental Impact via LCA, and Mechanical Resistance of the Mixtures (Fatigue and Permanent Deformation) Material Circularity Indicator (MCI), Mechanical Performance (Fatigue and Permanent Deformation), and Environmental Impact of Pavement Recycling Calculation Method Application of the MCI Framework Considering Recycling Efficiency, Virgin Material Demand, and Waste Generation ESCi Is Calculated as a Weighted Combination of the Mixture’s Environmental Impacts and Its Circularity, Using Combined LCA and MCI Metrics The MCI is determined based on the Ellen MacArthur Foundation methodology, as adapted by Mantalovas and Di Mino (2019) for asphalt mixtures Weighting Criteria Use of Variables Such as Recycling Rates, Recycled Material Utilization, and Waste Minimization Across the Life Cycle Consideration of Environmental Sustainability and Circularity, Integrating the Mechanical Performance of the Mixtures for Final Quantification Use of variables such as recycled feedstock fraction, recycling efficiency, and mechanical performance of asphalt mixtures Units of Measurement MCI Expressed in Dimensionless Values, Along with Tonnes for Quantifying Available and Utilized RA Values Expressed in ESCi (Dimensionless Index), MCI, Load Cycles (Fatigue and Permanent Deformation), and Normalized Environmental Impacts Values expressed in tons of recycled material and dimensionless indices for circularity quantification Data Sources Data Sourced from the European Asphalt Pavement Association (EAPA) and Case Studies Applied to the Italian Road Network Case Studies with Asphalt Mixtures Containing 0%, 30%, 60%, and 90% RAP, Evaluated through LCA and Laboratory Testing Systematic literature review based on studies published between 2018 and 2022 on RAP and circular economy in pavement engineering Data Scope European-Level Analysis Considering Recycling and Reuse Rates of Milled Asphalt Across Different Regions Laboratory Analysis of Recycled Mixtures, Including Evaluation of Mechanical Performance and Associated Environmental Impacts Analysis of case studies on asphalt mixtures containing different RAP contents and their relationship with circularity and mechanical performance Data Limitations Need to Improve Regional Data on Recycling Process Efficiency and Associated Environmental Impacts Need for Full-Scale Validation to Assess Long-Term Impacts and Structural Performance in Different Climatic Contexts Lack of methodological standardization among the reviewed studies, hindering direct comparisons between different approaches Evaluated Materials or Technologies Recycled Asphalt Mixtures Containing Different RAP Contents and Analysis of Their Circularity Within a Sustainable Economic Model Recycled Asphalt Mixtures with Different RAP Contents and Analysis of the Feasibility of Circular Economy in the Road Sector Asphalt mixtures with different RAP contents, without the use of rejuvenating agents Application Scale Case Study Applied to the Italian Highway Network, with Potential for Replication in Other European Regions Case Study in Italy with Potential for Replication in Different Regions and Road Networks Theoretical application based on case studies, with potential for implementation in real-world road infrastructure projects Obtained Results The Base Layers Showed the Highest Circularity Indexes, Indicating Greater Feasibility for RAP Reuse ESCi Demonstrated that Mixtures with 60% and 90% RAP Have Higher Circularity and Lower Environmental Impact than Conventional Ones Mixtures containing up to 60% RAP demonstrated better mechanical performance and circularity, while mixtures with 90% showed lower fatigue resistance Environmental Impacts Reduction in the Need for Virgin Materials, Lower Waste Generation, and Potential to Reduce the Carbon Footprint of the Pavement Sector Reduction in the Need for Virgin Aggregates, Lower Carbon Footprint, and Optimization of Resource Use Reduction in the need for virgin aggregates, lower disposal of asphalt waste, and decreased carbon footprint of the road sector Social and Economic Aspects The Analysis Suggests Material Savings and the Financial Feasibility of Reclaimed Asphalt Reuse The Analysis Suggests Economic Feasibility of RAP Incorporation Without Compromising the Structural Quality of the Mixtures The study suggests that the adoption of RAP can reduce operational costs and promote greater sustainability in the paving sector Sustainability Limitations Challenges Related to the Quality of Recycled Materials and the Adaptation of Standards to Allow Greater RAP Incorporation Issues Related to the Mechanical Strength of Mixtures with High RAP Content Still Require Further Investigation The mechanical performance of mixtures with high RAP content may be compromised, requiring adjustments in the formulations Experimental Validation Modeling Based on Market Data and Case Studies, Without Direct Laboratory Experimentation Laboratory Tests on Fatigue and Permanent Deformation, Validated by ISO Standards and Established Methodologies The reviewed studies presented laboratory validation through fatigue and permanent deformation tests Reproducibility The Methodology Can Be Replicated for Different Road Networks by Adjusting Regional Production and Recycling Parameters The Methodology Can Be Replicated in Different Regions and Contexts by Adjusting Parameters as Needed The methodology can be replicated in different paving contexts, depending on local regulations Comparative Studies Comparison Between Current Recycling Practices and Optimized Scenarios for the Circularity of Reclaimed Asphalt Comparison Between Conventional and Recycled Mixtures, Demonstrating Environmental and Economic Gains Comparison between conventional and recycled mixtures, highlighting the advantages and challenges of RAP incorporation Mentioned Gaps Lack of Standardization for Quantifying Circularity in Asphalt Mixtures and the Need for Full-Scale Validation Need for Specific Regulatory Guidelines to Promote the Large-Scale Use of Recycled Asphalt Mixtures Need for field studies for large-scale validation and greater standardization in circularity assessment methodology Future Recommendations Development of Regulatory Guidelines to Increase RAP Reuse Rates and Optimize Recycling Processes Expansion of Research to Field Evaluations and Revision of Standards to Allow Greater Incorporation of RAP Development of specific regulations for RAP incorporation and improvement of circularity quantification methodologies Specificity to Asphalts Methodology Specifically Developed for Asphalt Mixtures, with a Focus on the Circular Economy Methodology Specifically Developed for Asphalt Mixtures, Considering Environmental and Mechanical Impacts Methodology applied exclusively to recycled asphalt mixtures, considering both environmental and mechanical impacts Adaptation Potential Potential Adaptation for Different Types of Recycled Mixtures and Distinct Regional Contexts Potential Adaptation to Different Formulations and Adjustments According to Regional Availability of Recyclable Materials It can be adapted to different regions and climatic conditions, depending on RAP availability and local regulatory guidelines Normative Requirements Currently, There Are No Standardized Guidelines for the Incorporation of High RAP Contents in Asphalt Mixtures Absence of Standardized Guidelines for High RAP Content, but the Study Suggests Directions for Regulation Lack of standardized guidelines for quantifying the circularity of asphalt mixtures containing RAP Application Complexity The Method Requires Detailed Modeling and the Collection of Specific Data, but Shows Potential for Practical Implementation The Method Requires Detailed Calculations but Can Be Integrated into Existing Sustainability Assessment Processes The method requires detailed calculations and mechanical performance data but can be applied with specific adaptations Associated Costs Adaptation Costs of Production Processes May Be Offset by Savings in Virgin Materials Optimizing Material Use Can Reduce Costs Without Compromising the Quality and Durability of the Mixtures The use of RAP can reduce production costs, but it requires investment in technology to optimize the recycling process Interpretable Results The Results Provide a Clear Insight into the Feasibility of Using RA within a Circular Economic Model The Results Allow a Clear and Quantitative Assessment of the Technical and Environmental Feasibility of the Studied Mixtures The results provide a clear assessment of the technical and environmental feasibility of incorporating RAP into asphalt mixtures Table 3 Characteristics of articles 7 to 10 included in the scoping review Analysis Criteria Articles Evaluated Article 7 Article 8 Article 9 Article 10 Article Title Viability of Asphalt Mixtures with Iron Ore Tailings as a Partial Substitute for Fine Aggregate Development of a Circular Economy Index for a Pavement Management System Utilizing Steelmaking By-Products for Pavement Deicing: A Sustainable Waste Management Approach in Circular Economy A multifaceted purpose-oriented approach to evaluate material circularity index for rejuvenated recycled asphalt mixtures Authors/Year de Moraes et al. [ 37 ] Wasiq and Golroo [ 35 ] Zhang et al. [ 39 ] Gholami et al. [ 40 ] Journal Transportation Research Record International Journal of Pavement Research and Technology Waste and Biomass Valorization Scientific Reports Name and Concept of the Circularity Index Material Circularity Indicator (MCI) applied to asphalt mixtures with iron ore tailings Universal Circular Economy Index for Pavement (UCEIP) – proposes an integrated assessment of environmental impacts, operational costs, and structural performance Material Circularity Index (MCI) Material Circularity Index (MCI) Main Objective To evaluate the technical, economic, and environmental feasibility of partially replacing fine aggregate with iron ore tailings (IoT) in hot mix asphalt Develop a circular economy index for a Pavement Management System (PMS) Evaluate the potential of the static magnetic properties and microwave absorption of steel slag (SS), iron slag (IS), and limestone using a vibrating sample magnetometer (VSM) and a vector network analyzer (VNA), aiming to verify their feasibility for enhancing the deicing performance of asphalt mixtures through mechanical analyses, cost-benefit assessment, and circularity evaluation Evaluate the impact of different mechanical properties, testing procedures, and environmental and economic factors on the calculation of the Material Circularity Index (MCI) Theoretical Basis Based on circular economy principles, using the Material Circularity Indicator (MCI) and economic feasibility analysis through Net Present Value (NPV) Based on the principles of circular economy applied to roadway infrastructure, employing concepts of sustainability, life cycle assessment (LCA), and pavement management Based on the circular economy principles, using the Material Circularity Index (MCI) Based on the principles of the circular economy and the Material Circularity Index (MCI) Application Sector Pavement engineering, particularly for sustainable asphalt mixtures incorporating mining waste Roadway infrastructure and pavement management systems Pavement engineering, especially for asphalt mixtures containing industrial by-products (iron slag and steel slag) Developed for application in rejuvenated recycled asphalt mixtures Considered Indicators Material Circularity Indicator (MCI), mechanical performance (fatigue resistance, permanent deformation), solar reflectance, and environmental impact Proportion of recycled materials, operational costs, CO₂ emissions, and structural performance of asphalt mixtures Material Circularity Index (MCI) Material Circularity Index (MCI) Calculation Method Application of the MCI based on the Ellen MacArthur Foundation methodology, adapted for asphalt mixtures containing iron ore tailings Multicriteria evaluation model based on the weighting of environmental, economic, and technical factors Use of the Material Circularity Indicator (MCI) according to the methodology proposed by the Ellen MacArthur Foundation, adapted by Mantalovas and Di Mino (2019) for asphalt mixtures Use of the Material Circularity Index (MCI) to measure material circularity, considering variations in the determination of the utility factor, including carbon footprint (CO₂) and cost per ton of asphalt mixture Weighting Criteria Consideration of structural performance, material recycling efficiency, and environmental impacts of the partial replacement of aggregates with mineral tailings Each factor is assigned a weight based on its relative importance within the pavement management system Factors such as recycled material fraction, recycling process efficiency, indirect tensile strength, moisture damage, and permanent deformation The adopted indicators consider the RAP fraction, recycling process efficiency, mechanical performance data, CO₂ emissions, and cost per ton of asphalt mixture Units of Measurement Values expressed in load cycles (fatigue and permanent deformation), albedo (%), and dimensionless index for MCI Tons of recycled material per kilometer of roadway, cost per kilometer, CO₂ emissions per kilometer, structural performance measured by resilience modulus and fatigue The values were expressed according to the type of mechanical test adopted for calculating the utility factor, and dimensionless units were used for the MCI Values were expressed according to the type of mechanical test adopted for the calculation of the utility factor, with CO₂ emissions reported in kg/t, costs in USD/t of asphalt mixture, and the MCI represented by dimensionless values Data Sources Laboratory tests conducted on asphalt mixtures containing different proportions of iron ore tailings (7.5%, 10%, and 12.5%) Environmental databases, case studies, and academic literature on pavement management Laboratory tests were conducted on mixtures containing 25%, 50%, 75%, and 100% steel and iron slag as a replacement for limestone Laboratory tests on asphalt mixtures containing 35%, 50%, and 65% RAP, incorporating a rejuvenating agent, supplemented by secondary data from technical literature related to costs and CO₂ emissions Data Scope Laboratory evaluation considering mechanical strength, solar reflectance, and economic and environmental impacts for different asphalt mixture compositions Historical data and modeling applied to different pavement scenarios Laboratory analyses of asphalt mixtures with different compositions, considering mechanical strength, costs, and environmental impact Laboratory analyses of recycled asphalt mixtures with varying compositions, considering mechanical resistance parameters, production cost, and environmental impact Data Limitations Need for full-scale validation and long-term assessment of mixture durability and thermal stability impacts Requirement for a large volume of operational and environmental data for robust application of the index There is a need for validation under real application conditions, long-term impact assessment, and inclusion of fatigue life testing in the determination of the utility factor The absence of an evaluation of the practical effectiveness of the proposed index is noted, as well as the lack of technical justification for the selection of the tests used to determine the utility factor, which undermines the methodological robustness and limits the applicability of the index across different design and analysis scenarios. Furthermore, the comparison based solely on cost per ton may lead to biased interpretations, since recycled mixtures often exhibit lower unit costs due to reduced use of virgin materials and, potentially, lower CO₂ emissions. However, this approach disregards the influence of the mixture’s mechanistic performance on the structural design of the pavement, which defines the layer thicknesses and, consequently, the total amount of material employed Evaluated Materials or Technologies Asphalt mixtures containing iron ore tailings as a partial substitute for fine aggregate, with proportions of 7.5%, 10%, and 12.5% Asphalt mixtures with varying RAP contents and different levels of sustainable additive incorporation Asphalt mixtures with 25%, 50%, 75%, and 100% steel and iron slag as aggregate replacement Recycled asphalt mixtures with RAP contents of 0%, 35%, 50%, and 65%, incorporating a rejuvenating agent Application Scale Laboratory tests with potential for scale-up to field trials and implementation in sustainable pavement projects Application in urban and highway pavement management systems Applied in laboratory tests, with potential for expansion to field studies Applied in laboratory tests, with potential for extension to field studies Obtained Results The mixture with 12.5% IoT exhibited superior mechanical performance, higher circularity, and a reduction of 2.9°C in the pavement surface temperature Demonstrates that the application of circular economy concepts can optimize pavement management by reducing costs and environmental impacts The asphalt mixture containing 50% steel slag (SS) exhibited the highest circularity, while the mixture with 75% iron slag (IS) showed a circularity level comparable to that of the conventional mixture The mixture containing 50% RAP consistently exhibited the best performance across various analyzed scenarios, particularly under climatic variations and when multiple performance criteria were considered simultaneously, with MCI values ranging from 0.38 to 0.83. Conversely, the mixture with 65% RAP demonstrated superior performance in contexts where economic and environmental aspects were prioritized, especially at moderate to low temperatures Environmental Impacts Reduction in the consumption of virgin aggregates, decreased disposal of mining tailings, and potential mitigation of the urban heat island effect Reduction of CO₂ emissions, decreased extraction of virgin materials, and extended service life of highways Asphalt mixtures incorporating steel slag (SS) tend to exhibit higher circularity than those containing iron slag (IS) Reduction in the consumption of virgin materials, decreased disposal of asphalt waste, and reduction of the carbon footprint Social and Economic Aspects Economic analysis showed that the use of IoT can reduce production costs without compromising the structural quality of asphalt mixtures Lower maintenance costs and greater operational efficiency in pavement management Economic analysis demonstrated the feasibility of using steel and iron slags in the production of asphalt mixtures The article presents production cost estimates per ton of asphalt mixture based on secondary data from the literature. However, it does not include cost analyses in realistic project scenarios, considering the variation in pavement layer thickness according to the mixture type. This omission does not reflect the actual asphalt demand, since thickness determines the material demand per kilometer of roadway, directly impacting total paving costs Sustainability Limitations Although it presents environmental and economic benefits, the long-term durability and potential regional variations in the composition of the tailings need to be better evaluated Challenges in collecting comprehensive data and the need for methodological standardization Further studies are still required on long-term durability and environmental impacts, particularly concerning CO₂ emissions and the determination of the Material Circularity Index (MCI) based on fatigue life data of the material It does not consider social impacts, focusing instead on environmental and economic aspects Experimental Validation Laboratory tests validated through ANOVA and statistical significance analysis of mechanical parameters No direct experimental validation was conducted, as the model is based on theoretical analyses and computational modeling Results validated through laboratory mechanical testing and modeling based on established methodologies Results validated through laboratory mechanical tests and modeling based on established methodologies Reproducibility The methodology can be replicated for other asphalt mixtures by adjusting the proportions of IoT according to regional availability Requires adaptation of parameters for different geographical contexts and data availability The methodology can be replicated for different asphalt mixtures containing metallic residues The methodology can be replicated for different asphalt mixtures and rejuvenator contents Comparative Studies Comparison between conventional asphalt mixtures and those containing different proportions of IoT, highlighting improvements in mechanical performance and sustainability Comparison with traditional sustainability assessment methodologies in pavement engineering Comparison between conventional asphalt mixtures and those containing steel and iron slag Comparison between conventional and recycled asphalt mixtures, highlighting the benefits of incorporating high RAP contents Mentioned Gaps Need for full-scale studies to evaluate long-term impacts and optimize the incorporation processes of tailings in asphalt production Need to simplify the index for application in locations with limited data availability Need for additional studies on the long-term effects of steel and iron slag, determination of the Material Circularity Index (MCI) using fatigue life data, and validation at full scale The need for careful selection of performance parameters and testing methods, since the choice of dynamic creep test procedures has been shown to significantly impact the MCI values Future Recommendations Explore large-scale feasibility and develop regulatory guidelines for the use of mining tailings in asphalt pavement Explore the implementation of the index in real PMS systems and validate the results through field studies Evaluate the circularity of asphalt mixtures containing steel and iron slag through an integrated index incorporating cost and environmental impact dimensions Further investigation is required on the impact of different types and dosages of rejuvenators, as well as variations in asphalt mixture compositions, alongside exploration of alternative methods to determine the optimal rejuvenator content within the context of the MCI framework Specificity to Asphalts Methodology specifically developed for hot asphalt mixtures, considering mechanical performance and environmental aspects Focused on flexible pavements, with potential for adaptation to other roadway infrastructures Abordagem direcionada para misturas asfálticas com resíduos metálicos Approach focused on recycled asphalt mixtures and analysis of material circularity Adaptation Potential It can be adapted for different types of mineral tailings and asphalt mixtures, depending on local geological and climatic conditions Possible adaptation to different climatic conditions and regulations Approach focused on asphalt mixtures containing metallic waste It can be adapted for different recycled asphalt mixtures, with adjustments in the determination of the utility factor Normative Requirements There is currently no standardized regulation for the use of iron ore tailings in asphalt mixtures, but the study suggests potential directions for future regulatory development There is still no specific regulation for the application of the index There is currently no specific regulatory standard for this type of asphalt mixture There is currently no specific regulatory standard for this type of asphalt mixture Application Complexity The process requires adjustments in the formulation and characterization of IoT but can be integrated into conventional asphalt production with adaptations The method requires the integration of multiple factors and extensive data collection Relatively simple process in the laboratory, but requires adjustments for large-scale implementation This is a relatively simple process at the laboratory scale; however, its large-scale application requires methodological adaptations that consider real project and execution scenarios Associated Costs The transportation cost of IoT may be a limiting factor, but the reduction in the use of natural aggregates provides economic compensation Costs vary depending on data availability and the need for additional laboratory testing Production costs of asphalt mixtures containing iron slag are lower than those of the other evaluated asphalt mixtures Recycled asphalt mixtures exhibited lower production costs compared to conventional asphalt mixtures Interpretable Results The results provide clear information on technical and environmental feasibility, enabling practical application in sustainable pavement projects The index provides a holistic view of circularity but may require training for proper interpretation The results provide information on the technical, economic, and circularity feasibility of using steel and iron slags in asphalt mixtures The results provide clear insights into the feasibility of using RAP and rejuvenator, as well as their impacts on the circularity of asphalt mixtures 4. Discussions 4.1. Contributions of Existing Indices The reviewed indices provide significant contributions to the assessment of circularity in pavement engineering. Studies such as those by Mantalovas and Di Mino [ 33 ] and Costa et al. [ 32 ] demonstrate that including factors like fatigue resistance, indirect tensile strength, moisture-induced damage, and permanent deformation enables a more technical evaluation of the durability of recycled mixtures. The use of RAP and additives, such as cottonseed oil and zeolite, resulted in increased circularity and improved mechanical performance, as reported in the studies by de Medeiros Melo Neto et al. [ 36 ] and Mendes et al. [ 38 ]. The ESCi stands out for its flexibility, as it can be adjusted to accommodate different compositions and recycling rates, broadening its applicability across different contexts. Figure 4 depicts the frequency of methodologies applied across the included studies, evidencing the predominance of MCI-based approaches relative to ESCi, MCIMAR, and UCEIP. This heterogeneous landscape reinforces the lack of standardization and motivates comparative mapping rather than ranking. 4.2. Limitations in Methodological Application Despite advances, the methods analyzed present limitations that hinder their practical implementation by infrastructure managers. Indices such as ICMMAR and ESCi require extensive mechanical and environmental tests, which may be difficult to apply in contexts without advanced laboratory infrastructure. The studies also employ varied criteria and scales to define circularity, complicating standardization and large-scale adoption. Moreover, there is no regulatory framework to guide circularity quantification in pavements, restricting these indices mainly to academic use [ 38 ]. 4.3. Challenges of High RAP Content Evidence suggests that mixtures with high RAP contents (≥ 90%) may exhibit reduced fatigue resistance, compromising durability [ 31 , 33 , 36 , 38 ]. This reinforces the need to balance environmental gains with mechanical performance. Most studies rely on laboratory data and simulations without validation under real traffic conditions, which limits applicability in practice. 4.4. Methodological Gaps in MCI Applications Several studies applied the MCI but introduced methodological variations. For instance, Zhang et al. [ 39 ] reproduced MCI calculations while neglecting fatigue life data, which is critical for durability assessment. Gholami et al. [ 40 ] advanced the methodology by including production costs and CO₂ emissions, but the lack of practical validation and the reliance on unconventional tests reduce its applicability in real-world pavement management. Furthermore, analyses based solely on cost per ton or CO₂ emissions may yield misleading results if mechanistic performance is not incorporated, since layer thickness directly influences both cost and environmental impact. 4.5. Toward an Integrated Circularity Index The comparative analysis reveals that circularity assessment in asphalt mixtures has evolved by integrating environmental, mechanical, and economic indicators. However, the lack of methodological standardization limits comparability and practical use. Future approaches should develop integrated indices that combine MCI, production costs, and environmental indicators without complex modeling. Tools such as the National Pavement Design Method (MeDiNa) may support more accurate evaluations of structural efficiency in recycled mixtures. The conceptual mapping in Fig. 5 clarifies how each index articulates the technical, environmental, and economic dimensions of circularity. While MCI and MCIMAR emphasize technical and environmental aspects, ESCi incorporates additional environmental breadth with partial economic integration, and UCEIP attempts a broader, system-level coupling. This visualization supports a scoping perspective focused on breadth and comparability rather than hierarchy. Furthermore, the asymmetry revealed by this mapping underscores that most indices still privilege technical and environmental dimensions, with only limited or emerging incorporation of economic criteria. Such imbalance highlights the absence of a standardized framework capable of equally addressing all three dimensions, restricting comparability across studies and practical applicability in pavement management. Therefore, the integration of technical durability, environmental impact, and economic feasibility remains an unmet challenge and represents a crucial direction for future methodological development. 4.6. Practical Implications and Future Directions To reconcile technical rigor with practical feasibility, future indices should: (i) minimize laboratory testing to essential structural and environmental parameters; (ii) employ accessible environmental indicators, such as carbon footprint per ton of mixture and virgin aggregate reduction; and (iii) integrate economic and social aspects to capture financial feasibility and broader sustainability impacts. Such an approach would balance analytical robustness and operational simplicity, enabling direct application in road infrastructure management while supporting the transition toward circular economy principles. 5. Conclusions This scoping review on methodologies employed for measuring circularity in asphalt mixtures led to the following conclusions: (i) The circularity of recycled asphalt mixtures depends on more than the simple incorporation of residual materials, requiring integrated consideration of structural performance, economic feasibility, and environmental impacts. (ii) Evaluating the recycled material fraction in isolation may lead to overestimation of circularity, reinforcing the need for multidimensional approaches that combine technical, economic, and environmental parameters. (iii) Ten studies addressing circularity indices in pavements were identified; however, they presented heterogeneous approaches and did not establish a standardized framework that consistently balances technical, economic, and environmental dimensions in an integrated way. The methodological mapping conducted highlights persistent gaps in circularity assessment and underscores the absence of standardized methods that incorporate technical, environmental, and economic aspects simultaneously. Establishing such standards is essential to guide evidence-based decision-making in pavement engineering and to align infrastructure practices with the principles of the circular economy. Declarations Competing Interests The authors have no relevant financial or non-financial interests to disclose. Funding The authors declare that no funds, grants, or other support were received during the preparation of this manuscript. Author Contribution Osires de Medeiros Melo Neto: Conceptualization, Project administration, Methodology, Investigation, Data Curation, Writing - Original Draft. Ahmed Mohammad Youssef: Data Curation, Writing - Original Draft, Writing - Review & Editing. Ibrahim Elnaml: Writing - Review & Editing. Lara Pereira Tavares Mendes: Data Curation, Writing - Original Draft, Writing - Review & Editing. Ingridy Minervina Silva: Writing - Original Draft, Writing - Review & Editing. Leda Christiane de Figueiredo Lopes Lucena: Conceptualization, Supervision, Project administration. Luciana de Figueiredo Lopes Lucena: Conceptualization, Supervision, Project administration. Acknowledgement The authors express their gratitude for the financial support received from the Paraíba State Research Support Foundation (FAPESQ), the National Council for Scientific and Technological Development (CNPq), and the Coordination for the Improvement of Higher Education Personnel (CAPES) through research grants. Data Availability The datasets used or analyzed during the current study are available from the corresponding author upon reasonable request. References Esposito M, Tse T, Soufani K. Introducing a Circular Economy: New Thinking with New Managerial and Policy Implications. Calif Manag Rev. 2018;60:5–19. https://doi.org/10.1177/0008125618764691 . Paletta A, Leal Filho W, Balogun A-L, et al. Barriers and challenges to plastics valorisation in the context of a circular economy: Case studies from Italy. J Clean Prod. 2019;241:118149. https://doi.org/10.1016/j.jclepro.2019.118149 . Vegter D, van Hillegersberg J, Olthaar M. Performance Measurement Systems for Circular Supply Chain Management: Current State of Development. Sustainability. 2021;13:12082. https://doi.org/10.3390/su132112082 . Kopeinig J, Kriechbaum KA, Köberl J, Zsifkovits H. Supply chain circularity composite index: Measuring the closed-loopedness of material flows. Sustainable Prod Consum. 2025. https://doi.org/10.1016/j.spc.2025.07.005 . Panel United Nations Environment Programme International Resource. (2011) Decoupling Natural Resource Use and Environmental Impacts from Economic Growth. UNEP/Earthprint. European Commission. (2019) Sustainable Products in a circular economy—Towards an EU product policy framework contributing to the circular economy. Geissdoerfer M, Savaget P, Bocken NMP, Hultink EJ. The Circular Economy – A new sustainability paradigm? J Clean Prod. 2017;143:757–68. https://doi.org/10.1016/j.jclepro.2016.12.048 . Kirchherr J, Reike D, Hekkert M. Conceptualizing the circular economy: An analysis of 114 definitions. Resources. Conserv Recycling. 2017;127:221–32. https://doi.org/10.1016/j.resconrec.2017.09.005 . Vellesalu A, Hjelmgren D, Lind F. Circular product development from a multi-level perspective: Adaptations in business networks. Ind Mark Manage. 2025;128:88–100. https://doi.org/10.1016/j.indmarman.2025.03.011 . Kwok T. (2022) Challenge of Net-Zero Carbon Construction and Measurement of Energy Consumption and Carbon Emission Reduction to Climate Change, Economy and Job Growths in Hong Kong and Australia. Wang Y, Pan W. Evaluating the carbon emissions of Hong Kong’s building sector from the life cycle perspective. Build Environ. 2024;265:111975. https://doi.org/10.1016/j.buildenv.2024.111975 . Liu Y, Loo BPY. Circular economy application in construction: An evaluation of modular integrated construction (MiC) lifecycle assessments. J Building Eng. 2025;111:113306. https://doi.org/10.1016/j.jobe.2025.113306 . Abdy C, Zhang Y, Wang J, et al. Pyrolysis of polyolefin plastic waste and potential applications in asphalt road construction: A technical review. Resour Conserv Recycl. 2022;180:106213. https://doi.org/10.1016/j.resconrec.2022.106213 . Guo J, Ali S, Xu M. Recycling is not enough to make the world a greener place: Prospects for the circular economy. Green Carbon. 2023;1:150–3. https://doi.org/10.1016/j.greenca.2023.10.006 . Xu T, Lv Q, Sheng G, et al. Evolving patterns and drivers of waste plastic trade in key global economies. Resour Conserv Recycl. 2024;206:107606. https://doi.org/10.1016/j.resconrec.2024.107606 . Mohd Satar MKI, Hainin MR, Yaacob H, et al. Advancing circular economy in road construction: Mechanical performance of second-cycle reclaimed asphalt pavement (R2AP). Clean Waste Syst. 2025;10:100249. https://doi.org/10.1016/j.clwas.2025.100249 . Freire AC, Correia E, Neves J, et al. Structural Pavement Rehabilitation with Recycled Materials in a Circular Economy Approach. In: Tutumluer E, Nazarian S, Al-Qadi I, Qamhia IIA, editors. Advances in Transportation Geotechnics IV. Cham: Springer International Publishing; 2022. pp. 293–304. Calabi-Floody A, Letelier V, Valdes G, Sanchez-Alonso E. Promoting the Circular Economy of Concrete Through Innovation in Asphalt Pavements. IOP Conf Ser: Earth Environ Sci. 2020;503:012018. https://doi.org/10.1088/1755-1315/503/1/012018 . Moura CFN, Loureiro CDA, Silva HMRD, et al. Optimizing steel slag and reclaimed asphalt incorporation in hot mix asphalt: From lab validation to full-scale application towards circular economy. Constr Build Mater. 2025;490:142561. https://doi.org/10.1016/j.conbuildmat.2025.142561 . Zhao W, Yang Q. Performance characterization and life cycle assessment of semi-flexible pavement after composite modification of cement-based grouting materials by desulfurization ash, fly ash, and rubber powder. Constr Build Mater. 2022;359:129549. https://doi.org/10.1016/j.conbuildmat.2022.129549 . Zhao W, Yang Q. Life cycle assessment and multi-index performance evaluation of semi-flexible pavement after composite modification by using fly ash, rubber particles, warm mixing asphalt and recycled asphalt pavement. Constr Build Mater. 2023;364:129945. https://doi.org/10.1016/j.conbuildmat.2022.129945 . Zhao W, Yang Q. Design and performance evaluation of a new green pavement: 100% recycled asphalt pavement and 100% industrial solid waste. J Clean Prod. 2023;421:138483. https://doi.org/10.1016/j.jclepro.2023.138483 . Zhao W, Yang Q. Life-cycle assessment of sustainable pavement based on the coordinated application of recycled asphalt pavement and solid waste: Environment and economy. J Clean Prod. 2024;434:140203. https://doi.org/10.1016/j.jclepro.2023.140203 . Zhao W, Qian G, Yang Q. Sustainable pavement design: A comprehensive study on incorporating 100% recycled asphalt pavement and utilizing 100% industrial solid waste. Constr Build Mater. 2025;462:139972. https://doi.org/10.1016/j.conbuildmat.2025.139972 . Arksey H, O’Malley L. Scoping studies: towards a methodological framework. Int J Soc Res Methodol. 2005;8:19–32. https://doi.org/10.1080/1364557032000119616 . Peters MDJ, Godfrey CM, Khalil H, et al. Guidance for conducting systematic scoping reviews. Int J Evid Based Healthc. 2015;13:141–6. https://doi.org/10.1097/XEB.0000000000000050 . Munn Z, Peters MDJ, Stern C, et al. Systematic review or scoping review? Guidance for authors when choosing between a systematic or scoping review approach. BMC Med Res Methodol. 2018;18:143. https://doi.org/10.1186/s12874-018-0611-x . Armstrong R, Hall BJ, Doyle J, Waters E. Cochrane Update. Scoping the scope of a cochrane review. J Public Health (Oxf). 2011;33:147–50. https://doi.org/10.1093/pubmed/fdr015 . Muñoz S, Hosseini MR, Crawford RH. Exploring the environmental assessment of circular economy in the construction industry: A scoping review. Sustainable Prod Consum. 2023;42:196–210. https://doi.org/10.1016/j.spc.2023.09.022 . Peters MDJ, Marnie C, Tricco AC, et al. Updated methodological guidance for the conduct of scoping reviews. JBI Evid Synthesis. 2020;18:2119. https://doi.org/10.11124/JBIES-20-00167 . Mantalovas K, Di Mino G. The Sustainability of Reclaimed Asphalt as a Resource for Road Pavement Management through a Circular Economic Model. Sustainability. 2019;11:2234. https://doi.org/10.3390/su11082234 . da Costa LF, de Medeiros Melo Neto O, de Macêdo ALF, et al. Optimizing recycled asphalt mixtures with zeolite, cottonseed oil, and varied RAP content for enhanced performance and circular economy impact. Case Stud Constr Mater. 2024;20:e02707. https://doi.org/10.1016/j.cscm.2023.e02707 . Mantalovas K, Di Mino G. Integrating Circularity in the Sustainability Assessment of Asphalt Mixtures. Sustainability. 2020;12:594. https://doi.org/10.3390/su12020594 . Corona B, Hoefnagels R, Vural Gürsel I, et al. Metrics for minimising environmental impacts while maximising circularity in biobased products: The case of lignin-based asphalt. J Clean Prod. 2022;379:134829. https://doi.org/10.1016/j.jclepro.2022.134829 . Wasiq S, Golroo A. Development of a Circular Economy Index for a Pavement Management System. Int J Pavement Res Technol. 2024;17:1327–39. https://doi.org/10.1007/s42947-023-00304-z . de Medeiros Melo Neto O, Minervina Silva I, de Figueiredo Lopes Lucena LC, et al. Viability of recycled asphalt mixtures with soybean oil sludge fatty acid. Constr Build Mater. 2022;349:128728. https://doi.org/10.1016/j.conbuildmat.2022.128728 . de Moraes TMRP, Neto O, de MM, Lucena AE, de FL, et al. Viability of Asphalt Mixtures with Iron Ore Tailings as a Partial Substitute for Fine Aggregate. Transp Res Rec. 2023;03611981231176289. https://doi.org/10.1177/03611981231176289 . Mendes LPT, Bezerra ALR, de Souza MCR, et al. Economia circular como mecanismo de gestão ambiental: utilização de RAP em camadas de revestimento asfáltico. Revista Brasileira de Gestao Ambiental e Sustentabilidade. 2023;10:151–69. https://doi.org/10.21438/rbgas(2023)102411 . Zhang F, Jia M, Kong L et al. (2025) Utilizing Steelmaking By-Products for Pavement Deicing: A Sustainable Waste Management Approach in Circular Economy. Waste Biomass Valor. https://doi.org/10.1007/s12649-025-02917-w Gholami M, Khodaii A, Hajikarimi P. A multifaceted purpose-oriented approach to evaluate material circularity index for rejuvenated recycled asphalt mixtures. Sci Rep. 2025;15:12213. https://doi.org/10.1038/s41598-025-96749-2 . Statements & Declarations Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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1","display":"","copyAsset":false,"role":"figure","size":16561,"visible":true,"origin":"","legend":"\u003cp\u003eFlowchart of the scoping review\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7794357/v1/b1cc56484694c59da8ce97fc.png"},{"id":93020148,"identity":"e0d8a73f-ab64-4ab5-a1c8-f93a75ccced4","added_by":"auto","created_at":"2025-10-08 08:39:37","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":102922,"visible":true,"origin":"","legend":"\u003cp\u003ePRISMA flowchart illustrating the study selection process for the scoping review\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7794357/v1/34356d811518bd04dcfef766.png"},{"id":93020142,"identity":"c64b5189-bd5e-4584-baec-43d765e9a8e4","added_by":"auto","created_at":"2025-10-08 08:39:36","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":152854,"visible":true,"origin":"","legend":"\u003cp\u003eTemporal distribution of the included studies: \u003cstrong\u003e(a)\u003c/strong\u003eNumber of studies published annually between 2019 and 2025, \u003cstrong\u003e(b)\u003c/strong\u003eCumulative growth of publications in the same period.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-7794357/v1/426695f924b987437628564b.png"},{"id":93020137,"identity":"ba7d29ad-0b1f-44d1-9730-8c7361ae5471","added_by":"auto","created_at":"2025-10-08 08:39:35","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":72016,"visible":true,"origin":"","legend":"\u003cp\u003eMethodologies used to evaluate circularity\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-7794357/v1/98b638eff22a14c1dcc840ad.png"},{"id":93021009,"identity":"8a6f240b-df25-4dd5-a1c3-5bd00e8ec22c","added_by":"auto","created_at":"2025-10-08 08:47:38","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":29689,"visible":true,"origin":"","legend":"\u003cp\u003eConceptual integration of dimensions by index\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-7794357/v1/2e4144612f72d9023763f3f2.png"},{"id":93025263,"identity":"c968a089-9c22-4432-96da-97f23b7273ad","added_by":"auto","created_at":"2025-10-08 09:23:22","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2515266,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7794357/v1/0df3462d-978b-45ff-8e16-ab473ebead0a.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"A scoping review of methodological approaches to measure circularity in asphalt mixtures","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eThe conventional economic paradigm is grounded in a linear logic of extraction, production, consumption, and disposal, in which natural resources are used only once and goods, often still functional, are frequently discarded, intensifying waste generation [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Although this model prioritizes short-term cost reduction, it overlooks the reintegration of materials into the production cycle and disregards sustainability principles, leading to cumulative and long-lasting environmental impacts [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. In contrast, the concept of circularity has gained prominence as a key strategy for restructuring more sustainable production systems, as it addresses critical challenges such as resource limitations, increasing waste generation, and escalating environmental degradation [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eGiven the significant environmental impacts caused by historically inefficient models of natural resource management [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e], the adoption of the circular economy (CE) has been incorporated as a strategic guideline in the European Union\u0026rsquo;s public policies [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. The specialized literature indicates that CE supports the transition toward sustainable development [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] by promoting the optimized use of resources through practices such as reduction, reuse, recycling, and recovery throughout production and consumption cycles [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eFollowing the 26th United Nations Climate Change Conference (COP 26), several countries began implementing strategies aimed at achieving carbon neutrality [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. In this context, the construction sector stands out as one of the main emitters of carbon dioxide, accounting for more than one-third of global emissions, thus making it a top priority in international climate mitigation policies ([\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. The progressive incorporation of recycled materials represents a strategic measure to enhance the technical, economic, and environmental efficiency of construction inputs, including those used in pavement applications. This practice contributes to the conservation of natural resources, the reduction of solid waste disposal, and the transition toward sustainable production models. Such an approach aligns with the principles of the circular economy by breaking away from the traditional linear logic that still prevails in the paving industry [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe promotion of a more sustainable and resilient road infrastructure system can be achieved through the reuse of asphalt materials, a practice that contributes to emission reductions, natural resource conservation, and lower operational costs [\u003cspan additionalcitationids=\"CR14 CR15\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Asphalt pavements, over their service life, undergo aging and structural deterioration due to cyclic vehicle loading, exposure to ultraviolet radiation, and the action of rainwater. Under these conditions, interventions such as milling and maintenance become necessary, resulting in the generation of large volumes of milled material, known as Reclaimed Asphalt Pavement (RAP) [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. The reuse of RAP has been widely recognized for offering substantial benefits from both economic and environmental perspectives [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eSeveral studies have employed warm mix asphalt technologies in combination with RAP to reconfigure the granular structure of asphalt mixtures, as well as to incorporate industrial solid wastes, such as fly ash and desulfurization ash, as partial replacements for cement in cementitious grouting materials, achieving significant reductions in energy consumption and pollutant emissions [\u003cspan additionalcitationids=\"CR21 CR22 CR23\" citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. In this context, there is a growing incentive, both from the scientific community and public decision-makers, to use waste materials in road pavement construction as a strategy to promote circularity in the sector. However, this practice still raises important concerns, particularly regarding the measurement of circularity in these products after the incorporation of recycled materials. Despite the progress made, there is still no methodological consensus or standardized guidelines capable of accurately quantifying the degree of circularity in recycled pavements, which limits the systematic evaluation of their environmental and economic impacts.\u003c/p\u003e\u003cp\u003eA scoping review is a well-established methodology for investigating the scientific literature on a given topic, allowing for the systematic mapping of academic output with a focus on identifying the breadth, diversity, and characteristics of existing research [\u003cspan additionalcitationids=\"CR26\" citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. This approach aims to synthesize and disseminate available findings while also highlighting unexplored knowledge gaps. Although it shares the methodological rigor of systematic reviews regarding transparency and reproducibility of procedures, a scoping review does not aim to critically assess the quality of the included evidence [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eCurrently, there are significant gaps in the literature regarding the use of scoping reviews to explore the application of circular economy principles in asphalt mixtures. An exploratory search conducted in the Scopus database in early March 2025 using the descriptor \u0026ldquo;scoping review\u0026rdquo; revealed that only 4.91% of the retrieved documents were related to the field of engineering, while 4.13% were associated with environmental science. When the search was refined using the terms (\u0026ldquo;scoping review\u0026rdquo; AND \u0026ldquo;asphalt mixture\u0026rdquo;), only one scientific article was found\u0026mdash;published in November 2023 in the journal Sustainable Production and Consumption, entitled \u0026ldquo;v\u0026rdquo; [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. An identical result was obtained using the combination of descriptors (\u0026ldquo;scoping review\u0026rdquo; AND \u0026ldquo;asphalt mixture\u0026rdquo; AND \u0026ldquo;circular economy\u0026rdquo;).\u003c/p\u003e\u003cp\u003eTherefore, it becomes essential to conduct a comprehensive investigation that examines and maps the methodologies applied in quantifying circularity in asphalt mixtures. This mapping enables a critical analysis of the most established methods as well as those providing more rigorous assessments of circularity feasibility in these mixtures. Consequently, such a study will serve as a foundation for the development of a new circularity index specific to recycled asphalt mixtures. Thus, the objective of this scoping review was to identify the methodologies and tools used to measure the circularity of asphalt mixtures.\u003c/p\u003e\u003cp\u003eUnlike narrative reviews, which provide broad and often subjective syntheses, and systematic reviews, which critically appraise the quality of evidence to answer narrowly defined questions, a scoping review offers a distinct contribution by mapping the extent, diversity, and methodological approaches of the available literature. This perspective is particularly valuable for emerging topics such as circularity in asphalt mixtures, where the heterogeneity of methods and the absence of standardized indices demand a comprehensive overview to identify gaps, clarify conceptual boundaries, and inform future research and practice.\u003c/p\u003e"},{"header":"2. Methodology","content":"\u003cp\u003eFig. 1 illustrates the flowchart of the scoping review conducted on the circularity index in pavements. This study aimed to identify the methodologies and tools used to measure circularity in pavements through a scoping review. To this end, the PRISMA protocol (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) was adopted as the methodological approach, given that it promotes transparency and enhances the quality of reviews, including scoping reviews. PRISMA consists of a structured guide composed of a checklist and a flowchart, whose purpose is to standardize the preparation of reviews and ensure the replicability of investigative processes by the scientific community. The PRISMA extension for scoping reviews is a 22-item checklist covering all aspects of the manuscript [30]. The literature search was conducted in early April 2025 using internationally recognized academic databases, such as Web of Science (Clarivate), Scopus (Elsevier/ScienceDirect), SciELO, and Google Scholar.\u003c/p\u003e\n\u003cp\u003eThe search strategy employed terms related to the measurement of circularity within the pavement context, considering synonyms commonly used in the field, such as (\u0026ldquo;asphalt mix\u0026rdquo; OR \u0026ldquo;asphalt\u0026rdquo; OR \u0026ldquo;asphalt materials\u0026rdquo; OR \u0026ldquo;asphalt pavement\u0026rdquo; OR \u0026ldquo;asphalt binder\u0026rdquo; OR \u0026ldquo;asphalt concrete\u0026rdquo;) AND (\u0026ldquo;circularity index\u0026rdquo; OR \u0026ldquo;material circularity index\u0026rdquo;). No restrictions were applied regarding year, language, or publication status.\u003c/p\u003e\n\u003cp\u003eEligibility criteria were clearly defined as follows:\u003c/p\u003e\n\u003col style=\"list-style-type: lower-roman;\"\u003e\n \u003cli\u003eInclusion criteria: peer-reviewed articles or gray literature that investigated asphalt mixtures in the context of circular economy; studies explicitly addressing methods, indices, or tools for measuring circularity; and publications providing sufficient methodological detail for data extraction.\u003c/li\u003e\n \u003cli\u003eExclusion criteria: duplicate records; studies not related to asphalt mixtures or circular economy; publications without an accessible abstract or full text; articles focusing exclusively on environmental or mechanical performance without any reference to circularity indicators; and non-scientific documents such as editorials, opinion pieces, or technical notes.\u003c/li\u003e\n\u003c/ol\u003e\n\u003cp\u003eDuring the study selection and data extraction phases, two trained reviewers independently conducted the screening. Titles and abstracts were examined against the eligibility criteria, and when the information was insufficient, full texts were retrieved for assessment. Disagreements were resolved by a third reviewer. Inter-rater agreement was measured using the Kappa statistic.\u003c/p\u003e\n\u003cp\u003eData extraction was performed using Microsoft Excel and included: author and year of publication, country of study, objectives, data collection instruments, main findings, sample characteristics (type of asphalt mixture and materials used), and the circularity assessment method adopted. Data synthesis was then conducted to map and compare the methodologies applied to evaluate circularity in asphalt mixtures.\u003c/p\u003e"},{"header":"3. Results","content":"\u003cp\u003eA scoping review was conducted with the objective of mapping the methods available in the literature for quantifying the circularity index in the context of asphalt pavement engineering. The initial search retrieved 173 articles, of which 7 were excluded due to duplication. After screening titles and abstracts, 146 studies were discarded for not meeting the inclusion criteria. These inclusion criteria considered, among other aspects, the nature of the article, the availability of the abstract, relevance to the topic of interest, measurement of circularity, and evaluation of pavement circularity. Subsequently, eligibility criteria were applied, involving verification of article availability, sample analysis (asphalt or pavement), investigation or measurement of circularity, and inclusion or exclusion of other materials. Based on these criteria, articles were then included or excluded from the analysis.\u003c/p\u003e\u003cp\u003eAmong the 20 articles selected for full-text reading, 7 were excluded due to differing objectives, and 3 were excluded because they were not scientific articles. After applying the eligibility criteria, 10 studies were included in the synthesis. The article selection process is illustrated in the PRISMA diagram shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e\u003cp\u003eThe main characteristics of the analyzed studies are summarized in Tables\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, \u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, and \u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. The reviewed publications span the period from 2019 to 2025, without a defined temporal restriction, and were predominantly conducted in the Netherlands, Switzerland, Finland, Brazil, Italy, China, and Iran. This pattern indicates that research on circularity in the context of asphalt pavement has been concentrated in the last six years. Moreover, it is observed that the studies primarily focus on the European continent, with emphasis on the Netherlands, Switzerland, Finland, and Italy, followed by South America (Brazil) and Asia (Iran and China). These data suggest a growing mobilization of researchers in these regions in pursuit of solutions for more sustainable pavements, especially regarding the integration of residual materials within the circular economy. The agreement between reviewers regarding article inclusion and exclusion during the screening and eligibility process was assessed using the Kappa coefficient (K) (Eq.\u0026nbsp;\u003cspan refid=\"Equ1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), resulting in K\u0026thinsp;=\u0026thinsp;0.83, indicating a high level of agreement among the evaluators.\u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ1\" name=\"EquationSource\"\u003e\n$$\\:K=\\frac{{Probability}_{observed}-{Probability}_{chance\\:}}{1-{Probability}_{chance}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e1\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThe studies analyzed in the scoping review reveal a diversity of approaches for measuring circularity in asphalt mixtures, reflecting advances in the development of specific indices to assess the sustainability of asphalt materials. However, a detailed comparative analysis of the methods highlights strengths and limitations that affect the applicability of these indices both in academic research and practical pavement management.\u003c/p\u003e\u003cp\u003eThe articles employ different strategies for quantifying circularity, highlighting the Material Circularity Index (MCI) and its variations, as well as complementary indicators such as the Environmental Sustainability and Circularity Indicator (ESCi). The MCI has been applied to various materials, based on the methodology of the Ellen MacArthur Foundation and adapted for asphalt mixtures [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. The ESCi, in turn, integrates life cycle assessment (LCA) with circularity, providing a more comprehensive analysis of the environmental and structural impacts of the mixtures [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe reviewed publications span the period from 2019 to 2025, with an increasing concentration in recent years. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e (a) summarizes the annual distribution of included studies, highlighting the recent consolidation of the topic within pavement engineering. To complement the annual distribution, Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e (b) presents the cumulative growth of included studies between 2019 and 2025, illustrating the progressive consolidation of research on circularity in asphalt mixtures.\u003c/p\u003e\u003cp\u003eTables\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, \u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, and \u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e demonstrate that the adopted methods differ in weighting criteria, considered variables, and levels of applicability. Some studies incorporate environmental indicators such as carbon footprint and energy efficiency [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e], while others prioritize residual material flow and mechanical resistance as the basis for defining circularity [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e, \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. Although combining these factors is essential for a holistic analysis, the lack of methodological standardization hinders comparability among studies and the replicability of indices across different geographical and climatic contexts.\u003c/p\u003e\u003cp\u003e\u003cb\u003e(a)\u003c/b\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eCharacteristics of articles 1 to 3 included in the scoping review\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eAnalysis Criteria\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e\u003cp\u003eArticles Evaluated\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eArticle 1\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eArticle 2\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eArticle 3\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eArticle Title\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMetrics for minimising environmental impacts while maximising circularity in biobased products: The case of lignin-based asphalt\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eViability of recycled asphalt mixtures with soybean oil sludge fatty acid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eOptimizing recycled asphalt mixtures with zeolite, cottonseed oil, and varied RAP content for enhanced performance and circular economy impact\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eAuthors/Year\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCorona et al. [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ede Medeiros Melo Neto et al. [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eda Costa et al. [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eJournal\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eJournal of Cleaner Production\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eConstruction and Building Materials\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eCase Studies in Construction Materials\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eName and Concept of the Circularity Index\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMaterial Circularity Index (MCI) and New Biogenic Carbon Storage Indicators (BCS100 and c-BCS)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eMaterial Circularity Index (MCI) Applied to Recycled Asphalt Mixtures with Fatty Acids from Soybean Oil Sludge\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eCircularity Index for Recycled Asphalt Mixtures (MCIMAR), including methodological adaptations\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eMain Objective\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eEvaluate the Circularity and Sustainability of Lignin-Based Asphalt Compared to Conventional Bitumen-Based Asphalt\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eTo evaluate the technical, economic, and environmental feasibility of recycled asphalt mixtures containing 40% RAP and fatty acid from soybean oil sludge as a rejuvenating agent\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eEvaluate the optimization of recycled asphalt mixtures with zeolite, cotton oil, and varying RAP contents for mechanical performance and impact on the circular economy\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eTheoretical Basis\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eBased on the Principles of Circular Economy and the Life Cycle Assessment (LCA) Methodology\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eBased on the circular economy, using the MCI index\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eBased on the principles of the circular economy, using MCIMAR\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eApplication Sector\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDeveloped for Application in Asphalt Materials, Especially Bio-Based Asphalts\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePavement engineering, especially for recycled asphalt mixtures with sustainable rejuvenating agents\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003ePavement Engineering, Especially for Recycled Asphalt Mixtures with Sustainable Additives\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eConsidered Indicators\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMaterial Circularity Index (MCI), BCS100, and c-BCS, as well as Environmental Impacts (GWP, Resource Depletion)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eMaterial Circularity Index (MCI), mechanical strength, fatigue performance, and permanent deformation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMCIMAR, Mechanical Strength (Indirect Tensile Strength, Indirect Tensile Fatigue, Permanent Deformation, Cantabro Abrasion, Moisture-Induced Damage)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eCalculation Method\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eUse of the MCI to Measure Material Circularity and Two New Indicators to Assess Biogenic Carbon Storage\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eUse of the MCI according to the Ellen MacArthur Foundation methodology, adapted by Mantalovas and Di Mino (2019) for asphalt mixtures\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eEnhancement of MCIMAR with an Extended Utility Factor, Including Additional Parameters Such as Moisture Resistance and Abrasion\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eWeighting Criteria\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eThe indicators consider material recirculation, use of renewable raw materials, and biogenic carbon storage\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eFactors such as recycled material fraction, recycling process efficiency, fatigue resistance, and permanent deformation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eBased on Mechanical and Environmental Variables, Considering Structural Performance and Recycling Efficiency of Materials\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eUnits of Measurement\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eValues Expressed in kg C/m\u0026sup2;, kg CO₂/m\u0026sup2;/year, and Dimensionless Units for MCI\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eValues expressed in load cycles (fatigue and permanent deformation) and dimensionless units for MCI\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eValues Expressed in Load Cycles, Strength in MPa, and Dimensionless Indices for MCIMAR\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eData Sources\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eExperimental Data Collected from Lignin Refineries and Asphalt Producers\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eLaboratory tests conducted with mixtures containing 40% RAP and rejuvenating agent\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eLaboratory Tests with Mixtures Containing Different Contents of RAP, Cotton Oil, and Zeolite\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eData Scope\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCovers the Entire Life Cycle, from Raw Material Production to the Final Disposal of Asphalt\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eLaboratory analyses of recycled asphalt mixtures with different compositions, considering mechanical strength and environmental impact\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eExperimental Analyses of Recycled Mixtures in the Laboratory, Assessing Strength, Durability, and Circularity\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eData Limitations\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eChallenges in Modeling Biogenic Carbon Storage and Accounting for Material Recycling\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNeed for validation under real-world application conditions and analysis of long-term impact\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eNeed for Full-Scale Validation and Assessment of Environmental Impacts Throughout the Life Cycle\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eEvaluated Materials or Technologies\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eComparison Between Conventional Asphalt Mixtures and Mixtures Containing Lignin as a Partial Substitute for Bitumen\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eRecycled asphalt mixtures with 40% RAP and soybean oil sludge fatty acids as rejuvenator (3% and 5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eRecycled Asphalt Mixtures with Different RAP Contents (15%, 25%, 33%) and Incorporation of Cotton Oil (4%, 6%, 10%) or Zeolite (0.3%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eApplication Scale\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eTested in Simulations and Laboratory Experimental Studies, with Prospects for Industrial-Scale Application\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eApplication in laboratory tests, with potential for scaling up to field studies\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eLaboratory Tests with Potential for Application in Large-Scale Sustainable Pavement Projects\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eObtained Results\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLignin-Based Asphalt Exhibited Higher Circularity and Better Biogenic Carbon Storage, but with Some Technical Limitations\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eThe recycled mixtures exhibited higher circularity and better performance in fatigue and permanent deformation compared to the conventional mixture\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eThe Mixtures Containing 0.3% Zeolite and 25% RAP Showed Better Mechanical and Environmental Performance\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eEnvironmental Impacts\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAssessment of Carbon Emissions, Energy Consumption, and Climate Change Impacts (GWP)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eReduction in virgin material consumption, decreased disposal of asphalt waste, and potential reduction of carbon footprint\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eReduction in the Use of Virgin Aggregates, Lower Disposal of Asphalt Waste, and Potential Reduction of the Carbon Footprint\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eSocial and Economic Aspects\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eThe article mentions life cycle costs and environmental impacts but does not directly address social benefits\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eEconomic analysis demonstrated the feasibility of using the rejuvenating agent without increasing costs\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eThe Study Discusses Economic Feasibility, Highlighting the Possibility of Cost Reduction Without Compromising Mechanical Performance\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eSustainability Limitations\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDoes not consider social and economic impacts in depth, focusing more on environmental aspects\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eThere remains a need for further studies on long-term durability and indirect environmental impacts\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eThe Study Does Not Address Social Impacts in Detail, Focusing Primarily on Environmental and Economic Aspects\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eExperimental Validation\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eResults Validated with Experimental Data and Simulations Based on Previous Studies\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eResults validated through laboratory mechanical tests and modeling based on established methodologies\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eLaboratory Tests with Statistical Analysis, Including Comparison Among Different Compositions of Recycled Mixtures\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eReproducibility\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eThe Methodology Can Be Replicated for Different Types of Bio-Based Asphalt Mixtures\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eThe methodology can be replicated for different asphalt mixtures and rejuvenator contents\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMethodology Replicable for Other Recycled Asphalt Mixtures with Additive Variations\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eComparative Studies\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eComparison with Conventional Asphalts and Other Circular Economy Studies\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eComparison between conventional and recycled asphalt mixtures, highlighting the benefits of incorporating RAP and fatty acids from soybean oil sludge\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eComparison Between Recycled and Conventional Mixtures with Different Compositions and Additive Contents\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eMentioned Gaps\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNeed for Further Validation under Real Conditions and Improvement of Recycling Methods\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNeed for additional studies on the long-term effects of the rejuvenator and validation at real scale\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eNeed for Further Full-Scale Studies to Evaluate Long-Term Durability and Performance\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eFuture Recommendations\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSuggestions to Optimize Circularity and Reduce Costs Through New Production Processes\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eExplore real-scale application and evaluate environmental impacts under actual traffic conditions\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eExplore Industrial Applications and Validate the Effectiveness of the Approach in Different Geographic and Environmental Contexts\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eSpecificity to Asphalts\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eThe indices address specific characteristics such as durability, adhesion, and volumetric stability\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eApproach focused on recycled asphalt mixtures and analysis of material circularity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eCircularity Index Specifically Adapted for Recycled Asphalt Mixtures\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eAdaptation Potential\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eIt Can Be Adapted for Different Recycled Asphalt Mixtures, with Methodological Adjustments\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePotential adaptation for different asphalt mixtures and other types of sustainable rejuvenators\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eIt Can Be Adapted to Different Recycled Mixture Formulations Depending on Local Conditions\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eNormative Requirements\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eThe index partially complies with technical standards but requires adjustments to become more applicable in the industry\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eThere is currently no specific normative standardization for this type of rejuvenator\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eThe Methodology Is Not Yet Fully Aligned with Current Standards but Shows Potential for Future Standardization\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eApplication Complexity\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eThe method presents practical challenges due to the need for specific data collection and detailed calculations\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eRelatively simple laboratory process, but requires adjustments for large-scale implementation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eThe Method Requires Detailed Calculations and Several Specific Laboratory Tests, but It Is Feasible for Practical Applications\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eAssociated Costs\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eImplementation Requires Investments in Laboratory Testing and Life Cycle Analyses\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eProduction costs similar to conventional mixtures, with no economic impact\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eRelatively Low Implementation Cost, Especially Compared to Conventional Mixtures\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eInterpretable Results\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eThe results are useful for decision-making but may be complex for professionals without experience in the field\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eThe results provide clear insights into the feasibility of using the rejuvenator and its impacts on the circularity of asphalt mixtures\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eThe Results Allow a Clear Assessment of the Technical and Environmental Feasibility of the Studied Mixtures\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eCharacteristics of articles 4 to 6 included in the scoping review\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eAnalysis Criteria\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e\u003cp\u003eArticles Evaluated\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eArticle 4\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eArticle 5\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eArticle 6\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eArticle Title\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eThe Sustainability of Reclaimed Asphalt as a Resource for Road Pavement Management through a Circular Economic Model\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eIntegrating Circularity in the Sustainability Assessment of Asphalt Mixtures\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eCircular Economy as an Environmental Management Mechanism: Use of RAP in Asphalt Surfacing Layers\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eAuthors/Year\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMantalovas e Di Mino [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eMantalovas e Di Mino [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMendes et al. [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eJournal\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSustainability\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eSustainability\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eRevista Brasileira de Gest\u0026atilde;o Ambiental e Sustentabilidade\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eName and Concept of the Circularity Index\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMaterial Circularity Indicator (MCI) Applied to Reclaimed Asphalt (RA) Within a Circular Economy Model\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eEnvironmental Sustainability and Circularity Indicator (ESCi), desenvolvido para avaliar a circularidade e sustentabilidade ambiental de misturas asf\u0026aacute;lticas\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMaterial Circularity Indicator (MCI) Applied to Reclaimed Asphalt Pavement (RAP) as an Indicator of Circular Economy in Pavement Engineering\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eMain Objective\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eEvaluate the Sustainability of Recycled Asphalt as a Resource for Road Pavement Management Within a Circular Economy Model\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eTo Develop and Apply a Composite Indicator (ESCi) That Simultaneously Assesses the Circularity and Environmental Impacts of Recycled Asphalt Mixtures with Varying RAP Contents\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eTo Analyze the Potential of the Circular Economy as an Environmental Management Tool in Pavement Engineering, with a Focus on the Reuse of RAP in Asphalt Surfacing Layers\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eTheoretical Basis\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eBased on the Principles of the Circular Economy and the Ellen MacArthur Foundation\u0026rsquo;s Methodology for MCI Quantification\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eBased on the Principles of Circular Economy and Life Cycle Assessment (LCA), Using the Material Circularity Indicator (MCI) Adapted for Asphalt Mixtures\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eBased on the Concepts of the Circular Economy and the Methodology of the Material Circularity Indicator (MCI), Adapted for Asphalt Mixtures\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eApplication Sector\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePavement Engineering with a Focus on the Reuse of Milled Asphalt in Recycled Asphalt Mixtures\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePavement Engineering with a Focus on Sustainability and Material Reuse in Recycled Asphalt Mixtures\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003ePavement Engineering with a Focus on Environmental Management and Optimization of Recycled Material Reuse\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eConsidered Indicators\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMaterial Circularity Indicator (MCI), Milled Asphalt Recycling Rates, Reuse Process Efficiency, and Environmental Impacts\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eESCi, Material Circularity Indicator (MCI), Environmental Impact via LCA, and Mechanical Resistance of the Mixtures (Fatigue and Permanent Deformation)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMaterial Circularity Indicator (MCI), Mechanical Performance (Fatigue and Permanent Deformation), and Environmental Impact of Pavement Recycling\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eCalculation Method\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eApplication of the MCI Framework Considering Recycling Efficiency, Virgin Material Demand, and Waste Generation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eESCi Is Calculated as a Weighted Combination of the Mixture\u0026rsquo;s Environmental Impacts and Its Circularity, Using Combined LCA and MCI Metrics\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eThe MCI is determined based on the Ellen MacArthur Foundation methodology, as adapted by Mantalovas and Di Mino (2019) for asphalt mixtures\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eWeighting Criteria\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eUse of Variables Such as Recycling Rates, Recycled Material Utilization, and Waste Minimization Across the Life Cycle\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eConsideration of Environmental Sustainability and Circularity, Integrating the Mechanical Performance of the Mixtures for Final Quantification\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eUse of variables such as recycled feedstock fraction, recycling efficiency, and mechanical performance of asphalt mixtures\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eUnits of Measurement\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMCI Expressed in Dimensionless Values, Along with Tonnes for Quantifying Available and Utilized RA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eValues Expressed in ESCi (Dimensionless Index), MCI, Load Cycles (Fatigue and Permanent Deformation), and Normalized Environmental Impacts\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eValues expressed in tons of recycled material and dimensionless indices for circularity quantification\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eData Sources\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eData Sourced from the European Asphalt Pavement Association (EAPA) and Case Studies Applied to the Italian Road Network\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eCase Studies with Asphalt Mixtures Containing 0%, 30%, 60%, and 90% RAP, Evaluated through LCA and Laboratory Testing\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eSystematic literature review based on studies published between 2018 and 2022 on RAP and circular economy in pavement engineering\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eData Scope\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eEuropean-Level Analysis Considering Recycling and Reuse Rates of Milled Asphalt Across Different Regions\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eLaboratory Analysis of Recycled Mixtures, Including Evaluation of Mechanical Performance and Associated Environmental Impacts\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eAnalysis of case studies on asphalt mixtures containing different RAP contents and their relationship with circularity and mechanical performance\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eData Limitations\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNeed to Improve Regional Data on Recycling Process Efficiency and Associated Environmental Impacts\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNeed for Full-Scale Validation to Assess Long-Term Impacts and Structural Performance in Different Climatic Contexts\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eLack of methodological standardization among the reviewed studies, hindering direct comparisons between different approaches\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eEvaluated Materials or Technologies\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRecycled Asphalt Mixtures Containing Different RAP Contents and Analysis of Their Circularity Within a Sustainable Economic Model\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eRecycled Asphalt Mixtures with Different RAP Contents and Analysis of the Feasibility of Circular Economy in the Road Sector\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eAsphalt mixtures with different RAP contents, without the use of rejuvenating agents\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eApplication Scale\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCase Study Applied to the Italian Highway Network, with Potential for Replication in Other European Regions\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eCase Study in Italy with Potential for Replication in Different Regions and Road Networks\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eTheoretical application based on case studies, with potential for implementation in real-world road infrastructure projects\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eObtained Results\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eThe Base Layers Showed the Highest Circularity Indexes, Indicating Greater Feasibility for RAP Reuse\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eESCi Demonstrated that Mixtures with 60% and 90% RAP Have Higher Circularity and Lower Environmental Impact than Conventional Ones\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMixtures containing up to 60% RAP demonstrated better mechanical performance and circularity, while mixtures with 90% showed lower fatigue resistance\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eEnvironmental Impacts\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eReduction in the Need for Virgin Materials, Lower Waste Generation, and Potential to Reduce the Carbon Footprint of the Pavement Sector\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eReduction in the Need for Virgin Aggregates, Lower Carbon Footprint, and Optimization of Resource Use\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eReduction in the need for virgin aggregates, lower disposal of asphalt waste, and decreased carbon footprint of the road sector\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eSocial and Economic Aspects\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eThe Analysis Suggests Material Savings and the Financial Feasibility of Reclaimed Asphalt Reuse\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eThe Analysis Suggests Economic Feasibility of RAP Incorporation Without Compromising the Structural Quality of the Mixtures\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eThe study suggests that the adoption of RAP can reduce operational costs and promote greater sustainability in the paving sector\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eSustainability Limitations\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eChallenges Related to the Quality of Recycled Materials and the Adaptation of Standards to Allow Greater RAP Incorporation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eIssues Related to the Mechanical Strength of Mixtures with High RAP Content Still Require Further Investigation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eThe mechanical performance of mixtures with high RAP content may be compromised, requiring adjustments in the formulations\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eExperimental Validation\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eModeling Based on Market Data and Case Studies, Without Direct Laboratory Experimentation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eLaboratory Tests on Fatigue and Permanent Deformation, Validated by ISO Standards and Established Methodologies\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eThe reviewed studies presented laboratory validation through fatigue and permanent deformation tests\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eReproducibility\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eThe Methodology Can Be Replicated for Different Road Networks by Adjusting Regional Production and Recycling Parameters\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eThe Methodology Can Be Replicated in Different Regions and Contexts by Adjusting Parameters as Needed\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eThe methodology can be replicated in different paving contexts, depending on local regulations\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eComparative Studies\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eComparison Between Current Recycling Practices and Optimized Scenarios for the Circularity of Reclaimed Asphalt\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eComparison Between Conventional and Recycled Mixtures, Demonstrating Environmental and Economic Gains\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eComparison between conventional and recycled mixtures, highlighting the advantages and challenges of RAP incorporation\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eMentioned Gaps\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLack of Standardization for Quantifying Circularity in Asphalt Mixtures and the Need for Full-Scale Validation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNeed for Specific Regulatory Guidelines to Promote the Large-Scale Use of Recycled Asphalt Mixtures\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eNeed for field studies for large-scale validation and greater standardization in circularity assessment methodology\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eFuture Recommendations\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDevelopment of Regulatory Guidelines to Increase RAP Reuse Rates and Optimize Recycling Processes\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eExpansion of Research to Field Evaluations and Revision of Standards to Allow Greater Incorporation of RAP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eDevelopment of specific regulations for RAP incorporation and improvement of circularity quantification methodologies\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eSpecificity to Asphalts\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMethodology Specifically Developed for Asphalt Mixtures, with a Focus on the Circular Economy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eMethodology Specifically Developed for Asphalt Mixtures, Considering Environmental and Mechanical Impacts\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMethodology applied exclusively to recycled asphalt mixtures, considering both environmental and mechanical impacts\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eAdaptation Potential\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePotential Adaptation for Different Types of Recycled Mixtures and Distinct Regional Contexts\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePotential Adaptation to Different Formulations and Adjustments According to Regional Availability of Recyclable Materials\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eIt can be adapted to different regions and climatic conditions, depending on RAP availability and local regulatory guidelines\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eNormative Requirements\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCurrently, There Are No Standardized Guidelines for the Incorporation of High RAP Contents in Asphalt Mixtures\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eAbsence of Standardized Guidelines for High RAP Content, but the Study Suggests Directions for Regulation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eLack of standardized guidelines for quantifying the circularity of asphalt mixtures containing RAP\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eApplication Complexity\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eThe Method Requires Detailed Modeling and the Collection of Specific Data, but Shows Potential for Practical Implementation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eThe Method Requires Detailed Calculations but Can Be Integrated into Existing Sustainability Assessment Processes\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eThe method requires detailed calculations and mechanical performance data but can be applied with specific adaptations\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eAssociated Costs\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAdaptation Costs of Production Processes May Be Offset by Savings in Virgin Materials\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eOptimizing Material Use Can Reduce Costs Without Compromising the Quality and Durability of the Mixtures\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eThe use of RAP can reduce production costs, but it requires investment in technology to optimize the recycling process\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eInterpretable Results\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eThe Results Provide a Clear Insight into the Feasibility of Using RA within a Circular Economic Model\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eThe Results Allow a Clear and Quantitative Assessment of the Technical and Environmental Feasibility of the Studied Mixtures\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eThe results provide a clear assessment of the technical and environmental feasibility of incorporating RAP into asphalt mixtures\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eCharacteristics of articles 7 to 10 included in the scoping review\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eAnalysis Criteria\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"4\" nameend=\"c5\" namest=\"c2\"\u003e\u003cp\u003eArticles Evaluated\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eArticle 7\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eArticle 8\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eArticle 9\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eArticle 10\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eArticle Title\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eViability of Asphalt Mixtures with Iron Ore Tailings as a Partial Substitute for Fine Aggregate\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eDevelopment of a Circular Economy Index for a Pavement Management System\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eUtilizing Steelmaking By-Products for Pavement Deicing: A Sustainable Waste Management Approach in Circular Economy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eA multifaceted purpose-oriented approach to evaluate material circularity index for rejuvenated recycled asphalt mixtures\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eAuthors/Year\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ede Moraes et al. [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eWasiq and Golroo [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eZhang et al. [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eGholami et al. [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e]\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eJournal\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eTransportation Research Record\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eInternational Journal of Pavement Research and Technology\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eWaste and Biomass Valorization\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eScientific Reports\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eName and Concept of the Circularity Index\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMaterial Circularity Indicator (MCI) applied to asphalt mixtures with iron ore tailings\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eUniversal Circular Economy Index for Pavement (UCEIP) \u0026ndash; proposes an integrated assessment of environmental impacts, operational costs, and structural performance\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMaterial Circularity Index (MCI)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eMaterial Circularity Index (MCI)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eMain Objective\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eTo evaluate the technical, economic, and environmental feasibility of partially replacing fine aggregate with iron ore tailings (IoT) in hot mix asphalt\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eDevelop a circular economy index for a Pavement Management System (PMS)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eEvaluate the potential of the static magnetic properties and microwave absorption of steel slag (SS), iron slag (IS), and limestone using a vibrating sample magnetometer (VSM) and a vector network analyzer (VNA), aiming to verify their feasibility for enhancing the deicing performance of asphalt mixtures through mechanical analyses, cost-benefit assessment, and circularity evaluation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eEvaluate the impact of different mechanical properties, testing procedures, and environmental and economic factors on the calculation of the Material Circularity Index (MCI)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eTheoretical Basis\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eBased on circular economy principles, using the Material Circularity Indicator (MCI) and economic feasibility analysis through Net Present Value (NPV)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eBased on the principles of circular economy applied to roadway infrastructure, employing concepts of sustainability, life cycle assessment (LCA), and pavement management\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eBased on the circular economy principles, using the Material Circularity Index (MCI)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eBased on the principles of the circular economy and the Material Circularity Index (MCI)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eApplication Sector\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePavement engineering, particularly for sustainable asphalt mixtures incorporating mining waste\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eRoadway infrastructure and pavement management systems\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003ePavement engineering, especially for asphalt mixtures containing industrial by-products (iron slag and steel slag)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eDeveloped for application in rejuvenated recycled asphalt mixtures\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eConsidered Indicators\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMaterial Circularity Indicator (MCI), mechanical performance (fatigue resistance, permanent deformation), solar reflectance, and environmental impact\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eProportion of recycled materials, operational costs, CO₂ emissions, and structural performance of asphalt mixtures\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMaterial Circularity Index (MCI)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eMaterial Circularity Index (MCI)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eCalculation Method\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eApplication of the MCI based on the Ellen MacArthur Foundation methodology, adapted for asphalt mixtures containing iron ore tailings\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eMulticriteria evaluation model based on the weighting of environmental, economic, and technical factors\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eUse of the Material Circularity Indicator (MCI) according to the methodology proposed by the Ellen MacArthur Foundation, adapted by Mantalovas and Di Mino (2019) for asphalt mixtures\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eUse of the Material Circularity Index (MCI) to measure material circularity, considering variations in the determination of the utility factor, including carbon footprint (CO₂) and cost per ton of asphalt mixture\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eWeighting Criteria\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eConsideration of structural performance, material recycling efficiency, and environmental impacts of the partial replacement of aggregates with mineral tailings\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eEach factor is assigned a weight based on its relative importance within the pavement management system\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eFactors such as recycled material fraction, recycling process efficiency, indirect tensile strength, moisture damage, and permanent deformation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eThe adopted indicators consider the RAP fraction, recycling process efficiency, mechanical performance data, CO₂ emissions, and cost per ton of asphalt mixture\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eUnits of Measurement\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eValues expressed in load cycles (fatigue and permanent deformation), albedo (%), and dimensionless index for MCI\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eTons of recycled material per kilometer of roadway, cost per kilometer, CO₂ emissions per kilometer, structural performance measured by resilience modulus and fatigue\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eThe values were expressed according to the type of mechanical test adopted for calculating the utility factor, and dimensionless units were used for the MCI\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eValues were expressed according to the type of mechanical test adopted for the calculation of the utility factor, with CO₂ emissions reported in kg/t, costs in USD/t of asphalt mixture, and the MCI represented by dimensionless values\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eData Sources\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLaboratory tests conducted on asphalt mixtures containing different proportions of iron ore tailings (7.5%, 10%, and 12.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eEnvironmental databases, case studies, and academic literature on pavement management\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eLaboratory tests were conducted on mixtures containing 25%, 50%, 75%, and 100% steel and iron slag as a replacement for limestone\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eLaboratory tests on asphalt mixtures containing 35%, 50%, and 65% RAP, incorporating a rejuvenating agent, supplemented by secondary data from technical literature related to costs and CO₂ emissions\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eData Scope\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLaboratory evaluation considering mechanical strength, solar reflectance, and economic and environmental impacts for different asphalt mixture compositions\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eHistorical data and modeling applied to different pavement scenarios\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eLaboratory analyses of asphalt mixtures with different compositions, considering mechanical strength, costs, and environmental impact\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eLaboratory analyses of recycled asphalt mixtures with varying compositions, considering mechanical resistance parameters, production cost, and environmental impact\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eData Limitations\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNeed for full-scale validation and long-term assessment of mixture durability and thermal stability impacts\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eRequirement for a large volume of operational and environmental data for robust application of the index\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eThere is a need for validation under real application conditions, long-term impact assessment, and inclusion of fatigue life testing in the determination of the utility factor\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eThe absence of an evaluation of the practical effectiveness of the proposed index is noted, as well as the lack of technical justification for the selection of the tests used to determine the utility factor, which undermines the methodological robustness and limits the applicability of the index across different design and analysis scenarios. Furthermore, the comparison based solely on cost per ton may lead to biased interpretations, since recycled mixtures often exhibit lower unit costs due to reduced use of virgin materials and, potentially, lower CO₂ emissions. However, this approach disregards the influence of the mixture\u0026rsquo;s mechanistic performance on the structural design of the pavement, which defines the layer thicknesses and, consequently, the total amount of material employed\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eEvaluated Materials or Technologies\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAsphalt mixtures containing iron ore tailings as a partial substitute for fine aggregate, with proportions of 7.5%, 10%, and 12.5%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eAsphalt mixtures with varying RAP contents and different levels of sustainable additive incorporation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eAsphalt mixtures with 25%, 50%, 75%, and 100% steel and iron slag as aggregate replacement\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eRecycled asphalt mixtures with RAP contents of 0%, 35%, 50%, and 65%, incorporating a rejuvenating agent\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eApplication Scale\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLaboratory tests with potential for scale-up to field trials and implementation in sustainable pavement projects\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eApplication in urban and highway pavement management systems\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eApplied in laboratory tests, with potential for expansion to field studies\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eApplied in laboratory tests, with potential for extension to field studies\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eObtained Results\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eThe mixture with 12.5% IoT exhibited superior mechanical performance, higher circularity, and a reduction of 2.9\u0026deg;C in the pavement surface temperature\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eDemonstrates that the application of circular economy concepts can optimize pavement management by reducing costs and environmental impacts\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eThe asphalt mixture containing 50% steel slag (SS) exhibited the highest circularity, while the mixture with 75% iron slag (IS) showed a circularity level comparable to that of the conventional mixture\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eThe mixture containing 50% RAP consistently exhibited the best performance across various analyzed scenarios, particularly under climatic variations and when multiple performance criteria were considered simultaneously, with MCI values ranging from 0.38 to 0.83. Conversely, the mixture with 65% RAP demonstrated superior performance in contexts where economic and environmental aspects were prioritized, especially at moderate to low temperatures\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eEnvironmental Impacts\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eReduction in the consumption of virgin aggregates, decreased disposal of mining tailings, and potential mitigation of the urban heat island effect\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eReduction of CO₂ emissions, decreased extraction of virgin materials, and extended service life of highways\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eAsphalt mixtures incorporating steel slag (SS) tend to exhibit higher circularity than those containing iron slag (IS)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eReduction in the consumption of virgin materials, decreased disposal of asphalt waste, and reduction of the carbon footprint\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eSocial and Economic Aspects\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eEconomic analysis showed that the use of IoT can reduce production costs without compromising the structural quality of asphalt mixtures\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eLower maintenance costs and greater operational efficiency in pavement management\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eEconomic analysis demonstrated the feasibility of using steel and iron slags in the production of asphalt mixtures\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eThe article presents production cost estimates per ton of asphalt mixture based on secondary data from the literature. However, it does not include cost analyses in realistic project scenarios, considering the variation in pavement layer thickness according to the mixture type. This omission does not reflect the actual asphalt demand, since thickness determines the material demand per kilometer of roadway, directly impacting total paving costs\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eSustainability Limitations\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAlthough it presents environmental and economic benefits, the long-term durability and potential regional variations in the composition of the tailings need to be better evaluated\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eChallenges in collecting comprehensive data and the need for methodological standardization\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eFurther studies are still required on long-term durability and environmental impacts, particularly concerning CO₂ emissions and the determination of the Material Circularity Index (MCI) based on fatigue life data of the material\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eIt does not consider social impacts, focusing instead on environmental and economic aspects\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eExperimental Validation\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLaboratory tests validated through ANOVA and statistical significance analysis of mechanical parameters\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNo direct experimental validation was conducted, as the model is based on theoretical analyses and computational modeling\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eResults validated through laboratory mechanical testing and modeling based on established methodologies\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eResults validated through laboratory mechanical tests and modeling based on established methodologies\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eReproducibility\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eThe methodology can be replicated for other asphalt mixtures by adjusting the proportions of IoT according to regional availability\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eRequires adaptation of parameters for different geographical contexts and data availability\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eThe methodology can be replicated for different asphalt mixtures containing metallic residues\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eThe methodology can be replicated for different asphalt mixtures and rejuvenator contents\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eComparative Studies\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eComparison between conventional asphalt mixtures and those containing different proportions of IoT, highlighting improvements in mechanical performance and sustainability\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eComparison with traditional sustainability assessment methodologies in pavement engineering\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eComparison between conventional asphalt mixtures and those containing steel and iron slag\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eComparison between conventional and recycled asphalt mixtures, highlighting the benefits of incorporating high RAP contents\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eMentioned Gaps\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNeed for full-scale studies to evaluate long-term impacts and optimize the incorporation processes of tailings in asphalt production\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNeed to simplify the index for application in locations with limited data availability\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eNeed for additional studies on the long-term effects of steel and iron slag, determination of the Material Circularity Index (MCI) using fatigue life data, and validation at full scale\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eThe need for careful selection of performance parameters and testing methods, since the choice of dynamic creep test procedures has been shown to significantly impact the MCI values\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eFuture Recommendations\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eExplore large-scale feasibility and develop regulatory guidelines for the use of mining tailings in asphalt pavement\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eExplore the implementation of the index in real PMS systems and validate the results through field studies\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eEvaluate the circularity of asphalt mixtures containing steel and iron slag through an integrated index incorporating cost and environmental impact dimensions\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eFurther investigation is required on the impact of different types and dosages of rejuvenators, as well as variations in asphalt mixture compositions, alongside exploration of alternative methods to determine the optimal rejuvenator content within the context of the MCI framework\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eSpecificity to Asphalts\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMethodology specifically developed for hot asphalt mixtures, considering mechanical performance and environmental aspects\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eFocused on flexible pavements, with potential for adaptation to other roadway infrastructures\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eAbordagem direcionada para misturas asf\u0026aacute;lticas com res\u0026iacute;duos met\u0026aacute;licos\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eApproach focused on recycled asphalt mixtures and analysis of material circularity\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eAdaptation Potential\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eIt can be adapted for different types of mineral tailings and asphalt mixtures, depending on local geological and climatic conditions\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePossible adaptation to different climatic conditions and regulations\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eApproach focused on asphalt mixtures containing metallic waste\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eIt can be adapted for different recycled asphalt mixtures, with adjustments in the determination of the utility factor\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eNormative Requirements\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eThere is currently no standardized regulation for the use of iron ore tailings in asphalt mixtures, but the study suggests potential directions for future regulatory development\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eThere is still no specific regulation for the application of the index\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eThere is currently no specific regulatory standard for this type of asphalt mixture\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eThere is currently no specific regulatory standard for this type of asphalt mixture\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eApplication Complexity\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eThe process requires adjustments in the formulation and characterization of IoT but can be integrated into conventional asphalt production with adaptations\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eThe method requires the integration of multiple factors and extensive data collection\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eRelatively simple process in the laboratory, but requires adjustments for large-scale implementation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eThis is a relatively simple process at the laboratory scale; however, its large-scale application requires methodological adaptations that consider real project and execution scenarios\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eAssociated Costs\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eThe transportation cost of IoT may be a limiting factor, but the reduction in the use of natural aggregates provides economic compensation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eCosts vary depending on data availability and the need for additional laboratory testing\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eProduction costs of asphalt mixtures containing iron slag are lower than those of the other evaluated asphalt mixtures\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eRecycled asphalt mixtures exhibited lower production costs compared to conventional asphalt mixtures\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eInterpretable Results\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eThe results provide clear information on technical and environmental feasibility, enabling practical application in sustainable pavement projects\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eThe index provides a holistic view of circularity but may require training for proper interpretation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eThe results provide information on the technical, economic, and circularity feasibility of using steel and iron slags in asphalt mixtures\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eThe results provide clear insights into the feasibility of using RAP and rejuvenator, as well as their impacts on the circularity of asphalt mixtures\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"4. Discussions","content":"\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\u003ch2\u003e4.1. Contributions of Existing Indices\u003c/h2\u003e\u003cp\u003eThe reviewed indices provide significant contributions to the assessment of circularity in pavement engineering. Studies such as those by Mantalovas and Di Mino [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e] and Costa et al. [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e] demonstrate that including factors like fatigue resistance, indirect tensile strength, moisture-induced damage, and permanent deformation enables a more technical evaluation of the durability of recycled mixtures. The use of RAP and additives, such as cottonseed oil and zeolite, resulted in increased circularity and improved mechanical performance, as reported in the studies by de Medeiros Melo Neto et al. [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e] and Mendes et al. [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]. The ESCi stands out for its flexibility, as it can be adjusted to accommodate different compositions and recycling rates, broadening its applicability across different contexts.\u003c/p\u003e\u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e depicts the frequency of methodologies applied across the included studies, evidencing the predominance of MCI-based approaches relative to ESCi, MCIMAR, and UCEIP. This heterogeneous landscape reinforces the lack of standardization and motivates comparative mapping rather than ranking.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\u003ch2\u003e4.2. Limitations in Methodological Application\u003c/h2\u003e\u003cp\u003eDespite advances, the methods analyzed present limitations that hinder their practical implementation by infrastructure managers. Indices such as ICMMAR and ESCi require extensive mechanical and environmental tests, which may be difficult to apply in contexts without advanced laboratory infrastructure. The studies also employ varied criteria and scales to define circularity, complicating standardization and large-scale adoption. Moreover, there is no regulatory framework to guide circularity quantification in pavements, restricting these indices mainly to academic use [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e].\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\u003ch2\u003e4.3. Challenges of High RAP Content\u003c/h2\u003e\u003cp\u003eEvidence suggests that mixtures with high RAP contents (\u0026ge;\u0026thinsp;90%) may exhibit reduced fatigue resistance, compromising durability [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]. This reinforces the need to balance environmental gains with mechanical performance. Most studies rely on laboratory data and simulations without validation under real traffic conditions, which limits applicability in practice.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003e4.4. Methodological Gaps in MCI Applications\u003c/h2\u003e\u003cp\u003eSeveral studies applied the MCI but introduced methodological variations. For instance, Zhang et al. [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e] reproduced MCI calculations while neglecting fatigue life data, which is critical for durability assessment. Gholami et al. [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e] advanced the methodology by including production costs and CO₂ emissions, but the lack of practical validation and the reliance on unconventional tests reduce its applicability in real-world pavement management. Furthermore, analyses based solely on cost per ton or CO₂ emissions may yield misleading results if mechanistic performance is not incorporated, since layer thickness directly influences both cost and environmental impact.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\u003ch2\u003e4.5. Toward an Integrated Circularity Index\u003c/h2\u003e\u003cp\u003eThe comparative analysis reveals that circularity assessment in asphalt mixtures has evolved by integrating environmental, mechanical, and economic indicators. However, the lack of methodological standardization limits comparability and practical use. Future approaches should develop integrated indices that combine MCI, production costs, and environmental indicators without complex modeling. Tools such as the National Pavement Design Method (MeDiNa) may support more accurate evaluations of structural efficiency in recycled mixtures.\u003c/p\u003e\u003cp\u003eThe conceptual mapping in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e clarifies how each index articulates the technical, environmental, and economic dimensions of circularity. While MCI and MCIMAR emphasize technical and environmental aspects, ESCi incorporates additional environmental breadth with partial economic integration, and UCEIP attempts a broader, system-level coupling. This visualization supports a scoping perspective focused on breadth and comparability rather than hierarchy. Furthermore, the asymmetry revealed by this mapping underscores that most indices still privilege technical and environmental dimensions, with only limited or emerging incorporation of economic criteria. Such imbalance highlights the absence of a standardized framework capable of equally addressing all three dimensions, restricting comparability across studies and practical applicability in pavement management. Therefore, the integration of technical durability, environmental impact, and economic feasibility remains an unmet challenge and represents a crucial direction for future methodological development.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e\u003ch2\u003e4.6. Practical Implications and Future Directions\u003c/h2\u003e\u003cp\u003eTo reconcile technical rigor with practical feasibility, future indices should: (i) minimize laboratory testing to essential structural and environmental parameters; (ii) employ accessible environmental indicators, such as carbon footprint per ton of mixture and virgin aggregate reduction; and (iii) integrate economic and social aspects to capture financial feasibility and broader sustainability impacts. Such an approach would balance analytical robustness and operational simplicity, enabling direct application in road infrastructure management while supporting the transition toward circular economy principles.\u003c/p\u003e\u003c/div\u003e"},{"header":"5. Conclusions","content":"\u003cp\u003eThis scoping review on methodologies employed for measuring circularity in asphalt mixtures led to the following conclusions:\u003c/p\u003e\n\u003cp\u003e(i) The circularity of recycled asphalt mixtures depends on more than the simple incorporation of residual materials, requiring integrated consideration of structural performance, economic feasibility, and environmental impacts.\u003c/p\u003e\n\u003cp\u003e(ii) Evaluating the recycled material fraction in isolation may lead to overestimation of circularity, reinforcing the need for multidimensional approaches that combine technical, economic, and environmental parameters.\u003c/p\u003e\n\u003cp\u003e(iii) Ten studies addressing circularity indices in pavements were identified; however, they presented heterogeneous approaches and did not establish a standardized framework that consistently balances technical, economic, and environmental dimensions in an integrated way.\u003c/p\u003e\n\u003cp\u003eThe methodological mapping conducted highlights persistent gaps in circularity assessment and underscores the absence of standardized methods that incorporate technical, environmental, and economic aspects simultaneously. Establishing such standards is essential to guide evidence-based decision-making in pavement engineering and to align infrastructure practices with the principles of the circular economy.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003ch2\u003eCompeting Interests\u003c/h2\u003e\u003cp\u003eThe authors have no relevant financial or non-financial interests to disclose.\u003c/p\u003e\u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e\u003cp\u003eThe authors declare that no funds, grants, or other support were received during the preparation of this manuscript.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eOsires de Medeiros Melo Neto: Conceptualization, Project administration, Methodology, Investigation, Data Curation, Writing - Original Draft. Ahmed Mohammad Youssef: Data Curation, Writing - Original Draft, Writing - Review \u0026amp; Editing. Ibrahim Elnaml: Writing - Review \u0026amp; Editing. Lara Pereira Tavares Mendes: Data Curation, Writing - Original Draft, Writing - Review \u0026amp; Editing. Ingridy Minervina Silva: Writing - Original Draft, Writing - Review \u0026amp; Editing. Leda Christiane de Figueiredo Lopes Lucena: Conceptualization, Supervision, Project administration. Luciana de Figueiredo Lopes Lucena: Conceptualization, Supervision, Project administration.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eThe authors express their gratitude for the financial support received from the Para\u0026iacute;ba State Research Support Foundation (FAPESQ), the National Council for Scientific and Technological Development (CNPq), and the Coordination for the Improvement of Higher Education Personnel (CAPES) through research grants.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe datasets used or analyzed during the current study are available from the corresponding author upon reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eEsposito M, Tse T, Soufani K. Introducing a Circular Economy: New Thinking with New Managerial and Policy Implications. Calif Manag Rev. 2018;60:5\u0026ndash;19. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1177/0008125618764691\u003c/span\u003e\u003cspan address=\"10.1177/0008125618764691\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePaletta A, Leal Filho W, Balogun A-L, et al. Barriers and challenges to plastics valorisation in the context of a circular economy: Case studies from Italy. J Clean Prod. 2019;241:118149. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jclepro.2019.118149\u003c/span\u003e\u003cspan address=\"10.1016/j.jclepro.2019.118149\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eVegter D, van Hillegersberg J, Olthaar M. Performance Measurement Systems for Circular Supply Chain Management: Current State of Development. Sustainability. 2021;13:12082. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3390/su132112082\u003c/span\u003e\u003cspan address=\"10.3390/su132112082\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKopeinig J, Kriechbaum KA, K\u0026ouml;berl J, Zsifkovits H. Supply chain circularity composite index: Measuring the closed-loopedness of material flows. Sustainable Prod Consum. 2025. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.spc.2025.07.005\u003c/span\u003e\u003cspan address=\"10.1016/j.spc.2025.07.005\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePanel United Nations Environment Programme International Resource. (2011) Decoupling Natural Resource Use and Environmental Impacts from Economic Growth. UNEP/Earthprint.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eEuropean Commission. (2019) Sustainable Products in a circular economy\u0026mdash;Towards an EU product policy framework contributing to the circular economy.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGeissdoerfer M, Savaget P, Bocken NMP, Hultink EJ. The Circular Economy \u0026ndash; A new sustainability paradigm? J Clean Prod. 2017;143:757\u0026ndash;68. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jclepro.2016.12.048\u003c/span\u003e\u003cspan address=\"10.1016/j.jclepro.2016.12.048\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKirchherr J, Reike D, Hekkert M. Conceptualizing the circular economy: An analysis of 114 definitions. Resources. Conserv Recycling. 2017;127:221\u0026ndash;32. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.resconrec.2017.09.005\u003c/span\u003e\u003cspan address=\"10.1016/j.resconrec.2017.09.005\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eVellesalu A, Hjelmgren D, Lind F. Circular product development from a multi-level perspective: Adaptations in business networks. Ind Mark Manage. 2025;128:88\u0026ndash;100. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.indmarman.2025.03.011\u003c/span\u003e\u003cspan address=\"10.1016/j.indmarman.2025.03.011\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKwok T. (2022) Challenge of Net-Zero Carbon Construction and Measurement of Energy Consumption and Carbon Emission Reduction to Climate Change, Economy and Job Growths in Hong Kong and Australia.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWang Y, Pan W. Evaluating the carbon emissions of Hong Kong\u0026rsquo;s building sector from the life cycle perspective. Build Environ. 2024;265:111975. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.buildenv.2024.111975\u003c/span\u003e\u003cspan address=\"10.1016/j.buildenv.2024.111975\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLiu Y, Loo BPY. Circular economy application in construction: An evaluation of modular integrated construction (MiC) lifecycle assessments. J Building Eng. 2025;111:113306. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jobe.2025.113306\u003c/span\u003e\u003cspan address=\"10.1016/j.jobe.2025.113306\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAbdy C, Zhang Y, Wang J, et al. Pyrolysis of polyolefin plastic waste and potential applications in asphalt road construction: A technical review. Resour Conserv Recycl. 2022;180:106213. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.resconrec.2022.106213\u003c/span\u003e\u003cspan address=\"10.1016/j.resconrec.2022.106213\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGuo J, Ali S, Xu M. Recycling is not enough to make the world a greener place: Prospects for the circular economy. Green Carbon. 2023;1:150\u0026ndash;3. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.greenca.2023.10.006\u003c/span\u003e\u003cspan address=\"10.1016/j.greenca.2023.10.006\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eXu T, Lv Q, Sheng G, et al. Evolving patterns and drivers of waste plastic trade in key global economies. Resour Conserv Recycl. 2024;206:107606. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.resconrec.2024.107606\u003c/span\u003e\u003cspan address=\"10.1016/j.resconrec.2024.107606\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMohd Satar MKI, Hainin MR, Yaacob H, et al. Advancing circular economy in road construction: Mechanical performance of second-cycle reclaimed asphalt pavement (R2AP). Clean Waste Syst. 2025;10:100249. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.clwas.2025.100249\u003c/span\u003e\u003cspan address=\"10.1016/j.clwas.2025.100249\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFreire AC, Correia E, Neves J, et al. Structural Pavement Rehabilitation with Recycled Materials in a Circular Economy Approach. In: Tutumluer E, Nazarian S, Al-Qadi I, Qamhia IIA, editors. Advances in Transportation Geotechnics IV. Cham: Springer International Publishing; 2022. pp. 293\u0026ndash;304.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCalabi-Floody A, Letelier V, Valdes G, Sanchez-Alonso E. Promoting the Circular Economy of Concrete Through Innovation in Asphalt Pavements. IOP Conf Ser: Earth Environ Sci. 2020;503:012018. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1088/1755-1315/503/1/012018\u003c/span\u003e\u003cspan address=\"10.1088/1755-1315/503/1/012018\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMoura CFN, Loureiro CDA, Silva HMRD, et al. Optimizing steel slag and reclaimed asphalt incorporation in hot mix asphalt: From lab validation to full-scale application towards circular economy. Constr Build Mater. 2025;490:142561. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.conbuildmat.2025.142561\u003c/span\u003e\u003cspan address=\"10.1016/j.conbuildmat.2025.142561\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZhao W, Yang Q. Performance characterization and life cycle assessment of semi-flexible pavement after composite modification of cement-based grouting materials by desulfurization ash, fly ash, and rubber powder. Constr Build Mater. 2022;359:129549. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.conbuildmat.2022.129549\u003c/span\u003e\u003cspan address=\"10.1016/j.conbuildmat.2022.129549\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZhao W, Yang Q. Life cycle assessment and multi-index performance evaluation of semi-flexible pavement after composite modification by using fly ash, rubber particles, warm mixing asphalt and recycled asphalt pavement. Constr Build Mater. 2023;364:129945. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.conbuildmat.2022.129945\u003c/span\u003e\u003cspan address=\"10.1016/j.conbuildmat.2022.129945\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZhao W, Yang Q. Design and performance evaluation of a new green pavement: 100% recycled asphalt pavement and 100% industrial solid waste. J Clean Prod. 2023;421:138483. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jclepro.2023.138483\u003c/span\u003e\u003cspan address=\"10.1016/j.jclepro.2023.138483\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZhao W, Yang Q. Life-cycle assessment of sustainable pavement based on the coordinated application of recycled asphalt pavement and solid waste: Environment and economy. J Clean Prod. 2024;434:140203. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jclepro.2023.140203\u003c/span\u003e\u003cspan address=\"10.1016/j.jclepro.2023.140203\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZhao W, Qian G, Yang Q. Sustainable pavement design: A comprehensive study on incorporating 100% recycled asphalt pavement and utilizing 100% industrial solid waste. Constr Build Mater. 2025;462:139972. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.conbuildmat.2025.139972\u003c/span\u003e\u003cspan address=\"10.1016/j.conbuildmat.2025.139972\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eArksey H, O\u0026rsquo;Malley L. Scoping studies: towards a methodological framework. Int J Soc Res Methodol. 2005;8:19\u0026ndash;32. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1080/1364557032000119616\u003c/span\u003e\u003cspan address=\"10.1080/1364557032000119616\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePeters MDJ, Godfrey CM, Khalil H, et al. Guidance for conducting systematic scoping reviews. Int J Evid Based Healthc. 2015;13:141\u0026ndash;6. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/XEB.0000000000000050\u003c/span\u003e\u003cspan address=\"10.1097/XEB.0000000000000050\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMunn Z, Peters MDJ, Stern C, et al. Systematic review or scoping review? Guidance for authors when choosing between a systematic or scoping review approach. BMC Med Res Methodol. 2018;18:143. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1186/s12874-018-0611-x\u003c/span\u003e\u003cspan address=\"10.1186/s12874-018-0611-x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eArmstrong R, Hall BJ, Doyle J, Waters E. Cochrane Update. Scoping the scope of a cochrane review. J Public Health (Oxf). 2011;33:147\u0026ndash;50. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1093/pubmed/fdr015\u003c/span\u003e\u003cspan address=\"10.1093/pubmed/fdr015\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMu\u0026ntilde;oz S, Hosseini MR, Crawford RH. Exploring the environmental assessment of circular economy in the construction industry: A scoping review. Sustainable Prod Consum. 2023;42:196\u0026ndash;210. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.spc.2023.09.022\u003c/span\u003e\u003cspan address=\"10.1016/j.spc.2023.09.022\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePeters MDJ, Marnie C, Tricco AC, et al. Updated methodological guidance for the conduct of scoping reviews. JBI Evid Synthesis. 2020;18:2119. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.11124/JBIES-20-00167\u003c/span\u003e\u003cspan address=\"10.11124/JBIES-20-00167\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMantalovas K, Di Mino G. The Sustainability of Reclaimed Asphalt as a Resource for Road Pavement Management through a Circular Economic Model. Sustainability. 2019;11:2234. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3390/su11082234\u003c/span\u003e\u003cspan address=\"10.3390/su11082234\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eda Costa LF, de Medeiros Melo Neto O, de Mac\u0026ecirc;do ALF, et al. Optimizing recycled asphalt mixtures with zeolite, cottonseed oil, and varied RAP content for enhanced performance and circular economy impact. Case Stud Constr Mater. 2024;20:e02707. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.cscm.2023.e02707\u003c/span\u003e\u003cspan address=\"10.1016/j.cscm.2023.e02707\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMantalovas K, Di Mino G. Integrating Circularity in the Sustainability Assessment of Asphalt Mixtures. Sustainability. 2020;12:594. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3390/su12020594\u003c/span\u003e\u003cspan address=\"10.3390/su12020594\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCorona B, Hoefnagels R, Vural G\u0026uuml;rsel I, et al. Metrics for minimising environmental impacts while maximising circularity in biobased products: The case of lignin-based asphalt. J Clean Prod. 2022;379:134829. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jclepro.2022.134829\u003c/span\u003e\u003cspan address=\"10.1016/j.jclepro.2022.134829\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWasiq S, Golroo A. Development of a Circular Economy Index for a Pavement Management System. Int J Pavement Res Technol. 2024;17:1327\u0026ndash;39. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s42947-023-00304-z\u003c/span\u003e\u003cspan address=\"10.1007/s42947-023-00304-z\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ede Medeiros Melo Neto O, Minervina Silva I, de Figueiredo Lopes Lucena LC, et al. Viability of recycled asphalt mixtures with soybean oil sludge fatty acid. Constr Build Mater. 2022;349:128728. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.conbuildmat.2022.128728\u003c/span\u003e\u003cspan address=\"10.1016/j.conbuildmat.2022.128728\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ede Moraes TMRP, Neto O, de MM, Lucena AE, de FL, et al. Viability of Asphalt Mixtures with Iron Ore Tailings as a Partial Substitute for Fine Aggregate. Transp Res Rec. 2023;03611981231176289. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1177/03611981231176289\u003c/span\u003e\u003cspan address=\"10.1177/03611981231176289\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMendes LPT, Bezerra ALR, de Souza MCR, et al. Economia circular como mecanismo de gest\u0026atilde;o ambiental: utiliza\u0026ccedil;\u0026atilde;o de RAP em camadas de revestimento asf\u0026aacute;ltico. Revista Brasileira de Gestao Ambiental e Sustentabilidade. 2023;10:151\u0026ndash;69. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.21438/rbgas(2023)102411\u003c/span\u003e\u003cspan address=\"10.21438/rbgas(2023)102411\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZhang F, Jia M, Kong L et al. (2025) Utilizing Steelmaking By-Products for Pavement Deicing: A Sustainable Waste Management Approach in Circular Economy. Waste Biomass Valor. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s12649-025-02917-w\u003c/span\u003e\u003cspan address=\"10.1007/s12649-025-02917-w\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGholami M, Khodaii A, Hajikarimi P. A multifaceted purpose-oriented approach to evaluate material circularity index for rejuvenated recycled asphalt mixtures. Sci Rep. 2025;15:12213. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1038/s41598-025-96749-2\u003c/span\u003e\u003cspan address=\"10.1038/s41598-025-96749-2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eStatements \u0026amp; Declarations\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Asphalt Mixtures, Circular Economy, Circularity Index, Recycling, Standardization, Sustainability","lastPublishedDoi":"10.21203/rs.3.rs-7794357/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7794357/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe transition from a linear to a circular economy in pavement engineering requires consistent methodologies to assess material reuse and sustainability. Asphalt mixtures containing recycled materials are key to reducing environmental impacts and improving resource efficiency, yet no standardized method exists to quantify circularity. This scoping review, following PRISMA-ScR guidelines, systematically mapped methodologies used to measure circularity in asphalt mixtures. A comprehensive search was conducted in April 2025 across Web of Science, Scopus, SciELO, and Google Scholar, without limits on year, language, or publication status. Two independent reviewers screened studies and extracted data, with inter-rater reliability assessed using the Kappa statistic. Of 173 records retrieved, 10 met the inclusion criteria. These studies, conducted mainly in Europe, South America, and Asia (2019\u0026ndash;2025), applied indices such as the Material Circularity Index (MCI), Environmental Sustainability and Circularity Indicator (ESCi), and related metrics. Most methods focused on recycled content or material flow, potentially overestimating circularity. None provided an integrated assessment combining structural, environmental, and economic dimensions. The findings reveal a lack of methodological standardization that limits comparability and practical application. This review emphasizes the need for harmonized, multi-criteria approaches linking mechanical performance, cost, and environmental externalities to advance sustainable, circular pavement infrastructure.\u003c/p\u003e","manuscriptTitle":"A scoping review of methodological approaches to measure circularity in asphalt mixtures","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-08 08:38:50","doi":"10.21203/rs.3.rs-7794357/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"54fe25d9-bc75-4f40-90ff-8d49f6619345","owner":[],"postedDate":"October 8th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-10-08T09:23:11+00:00","versionOfRecord":[],"versionCreatedAt":"2025-10-08 08:38:50","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7794357","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7794357","identity":"rs-7794357","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}