Evaluation of the Performance of Rubberized Bitumen

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Udo, Anietie Edet This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4478334/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 4 You are reading this latest preprint version Abstract This paper presents the results of the evaluation of rubberized bitumen using crumb rubber as the influence material. Conventional bitumen is the material used in asphalt pavement construction. However, due to its challenges such as initial high cost of construction, rutting, cracking and failure in road construction within shorter time frames of about 0–15 years, an alternative material which is the rubberized bitumen has been recommended as a possible replacement. Rubberized bitumen is an innovative concept which involves the incorporation of crumb rubber derived from discarded tyres into bitumen binders, creating a modified binder with unique properties that contribute to improved pavement characteristics. This research was aimed at partially replacing conventional bitumen – a material often used in the construction of asphalt pavement with rubberized bitumen at varied proportions to evaluate its mechanical properties, in order to ascertain whether or not it is suitable for asphalt pavement construction. Eight (8) numbers of rubberized asphalt samples were prepared using The Marshall Mix Design Method. Varied proportions of rubberized bitumen at 0%, 3%, 6% and 9% were used to evaluate the various mechanical properties such as percentage voids, density, Marshall-stability, flow, and the stiffness of the rubberized asphalt. The results illustrate the relationship between the introduction of modified bitumen and the resistance of the asphalt mix to deformation. Initially, at 0% modification, the stiffness of the asphalt mix was measured at 3.52 KN/mm. As the percentage of modified bitumen was increased to 3%, the stiffness of the asphalt mix improved to 4.47 KN/mm, indicating enhanced resistance to deformation. However, with further increases in the percentage of modified bitumen to 6% and 9%, the stiffness decreased to 3.74 KN/mm and 2.76 KN/mm, respectively. Also, a higher value of stiffness typically suggests a greater resistance to deformation and, consequently, better performance of the asphalt mix. Therefore, the results demonstrate that the introduction of modified bitumen at a 3% concentration significantly improved the stiffness and resistance to deformation of the asphalt mix. However, excessive modification beyond this concentration led to a drop, as evidenced by the decrease in stiffness observed at 6% and 9% modification levels. This suggests an optimal range for the percentage of modified bitumen to achieve the desired stiffness and performance characteristics of the asphalt mix. Bitumen Crumb Rubber Rubberized Bitumen Marshall Stability Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 INTRODUCTION Bitumen is a visco-elastic and sticky material derived from the fractional distillation of crude oil, that plays a pivotal role in road construction and infrastructure development. It serves as the primary binder that holds together aggregates in asphalt mixtures, forming a durable and load-bearing road surface. The unique properties; of bitumen, including its adhesive and cohesive characteristics, contribute to the overall strength and longevity of road pavements [38] As an essential component of asphalt mixtures, bitumen when used in the wearing course of flexible pavement provides the necessary flexibility to withstand traffic loads, temperature fluctuations, and environmental stresses, ensuring the structural integrity of roadways. However, the use of conventional bitumen as the wearing course material of flexible pavement is not without its challenges as it causes rutting, cracking and failure in road construction. The growing demand for a durable, cost-effective, and environmentally friendly road infrastructure especially in Nigeria has prompted the exploration of alternative materials, and rubberized bitumen stands out as a promising solution. Rubberized bitumen is created by blending crumb rubber, obtained from discarded tires, with bitumen. A binder commonly used in road construction. This environmentally conscious approach reduces the burden of tire disposal which enhances the physical and mechanical properties of bitumen. The incorporation of rubber into bitumen is known to improve resistance to rutting, crack, and thermal stress, thereby extending the service of road surfaces. Several studies have documented the advantages of rubberized bitumen in terms of enhanced resilience and reduced maintenance costs [12, 44]. As traditional bitumen faces challenges related to cracking in cold climates and rutting in hot conditions, rubberized bitumen offers a potential solution to these issues, making it a topic of interest in the field of road engineering. Furthermore, rubberized bitumen when used as a wearing course material shows promising function like reducing noise pollution, making it a valuable option for urban road pro jects where noise control is essential [15]. The integration of rubberized bitumen into road construction practices is not only beneficial for road quality and longevity but also aligns with sustainability goals by recycling discarded tires and reducing the environmental impact associated with traditional road construction materials. Despite these promising attributes, the implementation of rubberized bitumen in road projects faces challenges related to the variability of rubber sources, the optimal mix design, and potential long-term performance. This study aims to contribute to the existing body of knowledge by conducting a comprehensive performance evaluation of rubberized bitumen, with a focus on its mechanical properties including the flow (rate of deformation), stability, stiffness, Density and percentage voids. By addressing these aspects, this research will provide valuable insights into the viability and potential advantages of using rubberized bitumen in road construction, thus contributing to the advancement of sustainable and efficient infrastructure development. The utilization of rubberized bitumen in road construction has gained considerable attention due to its potential environmental and performance benefits. However, a critical concern arises regarding the need to systematically evaluate the performance of rubberized bitumen as a wearing course material in comparison to conventional bitumen. The existing body of literatures has highlighted various positive attributes of rubberized bitumen, such as enhanced flexibility, improved rutting resistance, and potential noise reduction. Nevertheless, a comprehensive understanding of its performance in real-world conditions is essential for informed decision-making in road construction practices. This study seeks to address this problem by conducting a thorough investigation into the performance characteristics of rubberized bitumen, aiming to fill gaps in the current knowledge base and provide valuable insights for the sustainable and effective implementation of this innovative material in pavement construction [41, 25]. The significance of this study lies in its potential to address critical challenges faced by flexible road pavements by providing a comprehensive understanding of the performance of rubberized bitumen as the wearing course material. As conventional bitumen often experiences degradation over time, resulting in reduced pavement performance and increased maintenance costs, the incorporation of rubberized bitumen offers a promising avenue for enhancing the longevity and durability of road pavements. By systematically evaluating the mechanical properties of rubberized bitumen as a wearing course material, this research contributes valuable insights that can inform the design and implementation of sustainable and resilient road infrastructure. The findings from this study have the potential to guide engineers and practitioners in making informed decisions regarding the selection and application of rubberized bitumen as a wearing course material in road construction projects. Bitumen is a viscous black liquid which is derived from crude oil through a refining process. It binds aggregate particles together in flexible pavement construction [30]. It is a fundamental component in road construction due to its remarkable properties and versatility [40]. The material unique characteristics, including waterproofing abilities, flexibility, and durability, make it an ideal material for constructing roads in various climates and traffic conditions [10]. In its natural state, bitumen is a black, semi-solid material with a high viscosity. However, for use in road construction, it is often modified to meet specific performance requirements [28]. The modification process involves adding various materials, and one of the innovative approaches gaining attention is the incorporation of recycled rubber particles to create rubberized bitumen [19]. Conventional bitumen, shown in figure 1 is widely used, but it has known limitations. In regions with extreme temperature fluctuations, it is susceptible to cracking and rutting [25]. This has led to a growing interest in improving bitumen properties, leading to the development of modified and alternative forms, such as polymer-modified bitumen and rubberized bitumen [45]. Rubberized bitumen, in particular, involves blending bitumen with recycled rubber, typically sourced from discarded tires [18]. This integration offers several advantages, including enhanced resistance to temperature-induced deformations, improved adhesion, and increased resilience to heavy traffic stresses [38]. Moreover, it aligns with sustainability goals by repurposing waste rubber and reducing environmental impact [11]. 1.1 Types of Bitumen Bitumen is known by its penetration grades. Their grades and temperature relationships are extremely important in the design of asphalt concrete. Viscosity decreases as temperature increases [9]. There are different types of bitumen such as: 1.1.1 Penetration Grade Bitumen Penetration grade bitumen is classified based on its penetration value, which measures the hardness of the bitumen. The penetration value indicates the depth (in tenths of a millimeter) to which a standard needle penetrates the bitumen sample under specific conditions. Common grades include 40/50, 60/70, and 80/100, with the higher numbers representing softer bitumen. This type is widely used in road construction and maintenance due to its versatility [8]. 1.1.2 Performance Grade Bitumen Performance grade bitumen is categorized based on its rheological properties and performance characteristics rather than penetration values. It is designed to address specific climate and traffic conditions. For example, PG 64-22 is suitable for regions with moderate temperatures, while PG 76-22 is designed for hotter climates. The Performance Grading system provides a more comprehensive approach to selecting bitumen based on the expected environmental stresses [8]. 1.1.3 Viscosity Grade Bitumen Viscosity grade bitumen is classified according to its viscosity at a specific temperature. It is expressed in terms of kinematic viscosity, indicating the flow characteristics of the bitumen. Common viscosity grades include AC-10, AC-20, and AC-30, where a higher number represents higher viscosity. Viscosity grade bitumen is often used in high-temperature environments, providing good resistance to deformation [8]. 1.1.4 Cutback Bitumen Cutback bitumen is produced by blending bitumen with a solvent to reduce its viscosity, making it easier to handle and apply. The solvent can be kerosene, diesel, or naphtha. Cutback bitumen is classified based on the type of solvent used and the rate of evaporation. Rapid curing (RC), medium curing (MC), and slow curing (SC) are common cutback bitumen types, each suitable for specific applications and weather conditions [8]. 1.1.5 Emulsion Bitumen Emulsion bitumen is a dispersed combination of bitumen and water stabilized by an emulsifying agent. It is categorized based on the breaking time, which indicates how quickly the emulsion reverts to bitumen and water after application. Rapid-setting, medium-setting, and slow-setting emulsions offer versatility in various road construction scenarios. Emulsion bitumen is advantageous for its ease of application and environmental friendliness [8]. 1.2 Properties of Bitumen Mainly consisting of hydrogen and carbon. Bitumen is black or brown in colors. Its density at room temperature is usually between 1.01 to 1.04g/cm 3. It is substantially non-volatile and softens gradually when heated. It is viscoelastic in nature It is water resistant and possesses adhesive properties thus, making it a good binder material for flexible pavement roads. [5]. 1.3 Challenges of Using Conventional Bitumen in Road Construction While bitumen has long been a cornerstone in road construction due to its advantageous properties, it is not without its challenges. Understanding these challenges is important for addressing and mitigating potential issues in the construction and maintenance of road infrastructure. The challenges faced by bitumen includes 1.3.1 Temperature Sensitivity Temperature plays an important role in the performance of bitumen. It is the binder that holds asphalt pavements together. The sensitivity of bitumen to temperature variations is a well-recognized challenge in road construction [26]. In regions with hot climates, bitumen has a tendency to soften under high temperatures, making it susceptible to deformation. This deformation can manifest as rutting, where the road surface develops grooves over time. The structural integrity of the pavement is compromised, leading to a decline in overall performance and safety. Conversely, in cold climates, bitumen undergoes a different set of challenges. The low temperatures cause it to become brittle, increasing the likelihood of cracks forming in the pavement. These cracks compromise the aesthetics of the road and also create opportunities for water infiltration, which can further damage the pavement through freeze-thaw cycles. Managing these temperature-related challenges is critical for ensuring the longevity and functionality of asphalt pavements. 1.3.2 Susceptibility to Aging and Oxidation In addition to temperature sensitivity, bitumen undergoes natural aging and oxidation processes over time, affecting its rheological properties. Aging can lead to increased stiffness and reduced flexibility, which, in turn, contribute to the development of cracks and a decrease in the overall durability of asphalt pavements [13]. As bitumen ages, it becomes more prone to the stresses induced by traffic loads and environmental conditions, ultimately impacting the long-term performance of the road. However, the challenge of aging and oxidation is a significant concern in road construction. The evolving properties of bitumen can result in a gradual loss of its original characteristics, leading to a decline in pavement quality and structural strength. 1.3.3 Water Sensitivity Another critical aspect in the performance of bitumen is its susceptibility to water damage, especially in regions with high rainfall. Water infiltration poses a threat to the bond between bitumen and aggregates, leading to a phenomenon known as stripping. Stripping results in the loss of adhesion between the bitumen and aggregates, compromising the structural integrity of the road surface [17]. This not only accelerates the development of distresses but also increases the likelihood of potholes and other forms of pavement failure. 1.3.4 Environmental Impact The environmental impact of traditional bitumen is a significant concern in road construction. The extraction and production processes involved in obtaining bitumen from crude oil are energy-intensive and contribute to greenhouse gas emissions [46]. This poses a dual environmental challenge, as not only is there a reliance on non-renewable resources, but the production methods themselves contribute to climate change. Furthermore, the disposal of asphalt waste at the end of its service life adds another layer of environmental concern. Traditional asphalt materials often end up in landfills, creating a burden on waste management systems and contributing to environmental degradation. As global efforts intensify to reduce the carbon footprint and promote sustainability, the exploration of alternative, eco-friendly solutions become imperative. 1.3.5 Limited Resistance to Heavy Traffic Loads Despite providing a flexible and durable surface, traditional bitumen has its limitations, particularly when faced with heavy traffic loads. The repetitive stress exerted by vehicles over time can result in permanent deformation, commonly referred to as rutting. This phenomenon compromises the smoothness and aesthetics of the road surface and also poses safety risks. Additionally, the development of fatigue cracks under heavy traffic loads further diminishes the functionality and longevity of the road [38]. These challenges are particularly pronounced in areas with high traffic volume or where heavy-duty vehicles are prevalent. 1.3.6 Maintenance and Repair Costs The maintenance and repair of bitumen-based roads constitute a significant challenge for infrastructure managers. Regular upkeep is essential to address issues such as cracks, potholes, and surface deterioration caused by factors like heavy traffic and weathering. The costs associated with these maintenance activities can strain budgets and resources. Moreover, road maintenance often leads to temporary closures and traffic disruptions, inconveniencing commuters and businesses. Finding solutions that reduce the frequency and intensity of maintenance interventions is crucial for sustainable and cost-effective road infrastructure [20]. 1.4 Crumb Rubber Crumb rubber is a recycled material derived from discarded tyres as seen in figure 2, through a mechanical process that involves shredding and grinding the tires into small granules. These granules, known as crumb rubber, vary in size and find versatile applications, particularly in road construction [37]. A notable application of crumb rubber in road construction is its incorporation into bitumen, resulting in the creation of rubberized bitumen. The addition of crumb rubber modifies the properties of bitumen, enhancing its flexibility, elasticity, and temperature resistance. The result is a road surface that demonstrates improved resistance to the stresses of traffic loads and temperature fluctuations, ultimately enhancing pavement performance and longevity [12, 44]. However, Crumb rubber's positive impact extends beyond mechanical properties. Its elastic nature contributes to noise reduction when used in road construction. By absorbing sound waves, crumb rubber helps create quieter road surfaces, making it a valuable solution for urban areas where minimizing traffic noise is a crucial consideration [16]. While crumb rubber presents significant environmental and performance benefits, challenges exist. Variability in the quality and size of crumb rubber particles, potential leaching of chemicals from the rubber, and the need for proper mix design are considerations that require attention in its application [31]. 1.4.1. Performance of Crumb Rubber in Bituminous Materials There are two rather different methods of using crumb rubber in bitumen binders. Firstly, crumb rubber in the bitumen is dissolved as binder modifier. Second, is by substituting a portion of fine aggregates with crumb rubber that does not completely react with bitumen [21]. Numerous factors can influence the modification effects which consist of base bitumen constituents, blending time and temperature, the percentage of rubber, the gradation of crumb rubber, the type of mixing (wet or dry) and the grinding process method [21, 3, 22]. It observed that during the bitumen-rubber blending, due to higher stiffness and tensile strength at elevated temperatures, the mixture decreases rutting capability [36]. The design method for conventional bitumen mixture can be used for bitumen-rubber mixture as the mix stability being the primary factor. Also, standard paving machinery can be used for placement of bitumen-rubber mixture. However, a pneumatic tyre roller is not suitable as asphalt rubber will stick onto the roller tyres [21]. Rubber pavement association found that using tyre rubber in open-graded mixture binder could decrease tyre noise by approximately 50%. In addition, in spray applications, rubber particles of multiple sizes had a better sound absorbing. Moreover, another advantage of using asphalt rubber is to increase the life-span of the pavement. However, recommendations were made to assess the cost effectiveness of asphalt rubber [21]. 1.5 Rubberized Bitumen Rubberized bitumen Is an innovative concept which Involves the incorporation of crumb rubber derived from discarded tires into bitumen binders, therefore creating a modified binder with unique properties that contribute to improved pavement characteristics. The utilization of rubberized bitumen addresses various challenges associated with conventional bitumen, such as aging, cracking, and rutting, while also offering additional benefits that extend the life and sustainability of road infrastructure. Further studies have shown that the introduction of crumb rubber leads to improved ductility and reduced stiffness, contributing to better pavement performance under dynamic loading conditions [32, 25]. Moreover, rubberized bitumen has been found to mitigate pavement-generated noise, contributing to enhanced road user comfort and safety [1, 33]. The use of rubberized bitumen (figure 3) aligns with sustainable practices, as it repurposes discarded tires and reduces environmental waste while simultaneously enhancing pavement performance [35, 33]. The concept supports the principles of circular economy and resource efficiency, offering a responsible solution to the challenge of tire disposal [39]. Furthermore, the incorporation of rubberized bitumen has been found to extend the service life of pavements, reducing the frequency of maintenance interventions and minimizing life cycle costs [27, 33]. However, while rubberized bitumen presents promising benefits, its successful implementation requires a thorough understanding of its properties, behavior, and long-term performance. Various factors, including crumb rubber content, particle size distribution, manufacturing processes, and environmental conditions, influence the mechanical and rheological properties of rubberized bitumen [35, 47]. Research efforts have focused on characterizing the aging behavior of rubberized bitumen and evaluating its performance under different loading and environmental conditions [40, 27]. 1.6 Benefits of Rubberized Bitumen Rubberized bitumen possesses distinctive properties that contribute to its benefits in road construction. These benefits encompass a range of mechanical, environmental, and performance characteristics as follows: 1.6.1 Enhanced Flexibility The introduction of rubber particles into bitumen brings a notable improvement in the flexibility of the resulting asphalt mixture. Rubberized bitumen demonstrates an increased ability to adapt to stresses imposed by traffic loads and temperature fluctuations. The inherent flexibility allows the road surface to better distribute and absorb the forces exerted by moving vehicles, contributing to enhanced durability and longevity [29]. This property is particularly beneficial in areas with high traffic volume, where the constant impact of vehicles can otherwise lead to premature wear and tear. 1.6.2 Improved Elasticity Rubberized bitumen stands out for its heightened elasticity compared to traditional bitumen. This enhanced elasticity plays a crucial role in reducing the susceptibility to two common road issues—cracking and rutting. In regions characterized by extreme temperature variations, where conventional bitumen may become brittle and prone to cracks, the improved elasticity of rubberized bitumen helps maintain the integrity of the road surface. This resilience against temperature-induced stresses is a key factor in promoting the long-term performance of road pavements [42]. 1.6.3. Temperature Resistance A significant advantage of rubberized bitumen is its heightened resistance to temperature-induced deformations. This property is pivotal for ensuring a durable and resilient road surface under varying climatic conditions. Whether facing the scorching heat of the sun or the freezing temperatures of rainfall, rubberized bitumen exhibits a capacity to withstand these extremes. This resistance contributes to the prevention of deformations such as rutting which is a common issue with conventional bitumen in hot climates. The ability of rubberized bitumen to maintain its structural integrity across a broad temperature range is a key factor in its suitability for diverse geographic locations and climates [29]. 1.6.4 Noise Reduction The unique elastic properties of rubberized bitumen play a pivotal role in mitigating road noise. The incorporation of rubber into the bitumen binder contributes to the absorption of sound waves, resulting in a notable reduction in overall noise levels. This characteristic is especially crucial in urban areas, where controlling traffic noise is a significant concern for both residents and policymakers. Rubberized bitumen facilitates the creation of quieter road surfaces, enhancing the quality of life in densely populated regions [29]. 1.6.5 Improved Skid Resistance Rubberized bitumen's textured composition goes beyond enhancing flexibility; it also significantly improves skid resistance. This property is particularly valuable in ensuring vehicle traction and road safety, especially in adverse conditions such as wet or slippery surfaces. The textured nature of rubberized bitumen helps vehicles maintain better contact with the road, reducing the risk of skidding or slipping. This improvement in skid resistance adds an extra layer of safety, making rubberized bitumen an advantageous choice for regions prone to inclement weather [29]. 1.6.6. Durability One of the standout features of rubberized bitumen is its substantial contribution to the overall durability of asphalt pavements. This enhanced durability translates to a reduction in the frequency of maintenance activities, as rubberized bitumen better withstands the stresses imposed by heavy traffic loads. The material's ability to resist deformation and cracking over time contributes to an extended service life for road surfaces. This durability not only minimizes the inconvenience caused by frequent maintenance but also has economic implications, as the need for repairs and replacements is significantly reduced [13]. 1.6.7 Sustainability A key aspect that distinguishes rubberized bitumen is its contribution to sustainable practices. By incorporating recycled rubber, often sourced from discarded tires, rubberized bitumen repurposes waste materials that would otherwise pose environmental challenges. This reduces the demand for virgin resources which aligns with the principles of a circular economy, where materials are reused and recycled to minimize waste [23]. The environmentally conscious approach of utilizing recycled rubber in road construction adds a valuable layer of sustainability to infrastructure development. 1.6.8. Cost-Effectiveness While the initial costs of implementing rubberized bitumen may vary, the long-term benefits contribute to its overall cost-effectiveness. The enhanced durability and reduced maintenance needs associated with rubberized bitumen applications translate into significant savings over the life cycle of road surfaces. The material's ability to withstand heavy traffic loads and environmental stressors leads to fewer repairs and less frequent replacements, ultimately proving cost-effective in terms of both financial and environmental considerations. This aspect is particularly valuable for budget-conscious road construction projects aiming to optimize long-term outcomes [23]. 1.7 Application of Rubberized Bitumen 1.7.1 Asphalt Pavements: Rubberized bitumen is widely used as a binder in asphalt pavements, including highways, urban roads, runways [1]. Its enhanced aging resistance, flexibility, and fatigue resistance contribute to the durability and longevity of road surfaces [27, 35]. 1.7.2 Overlay and Rehabilitation: Rubberized bitumen is employed in pavement overlays and rehabilitation projects to rejuvenate and enhance the performance of existing road surfaces [32]. It can mitigate cracking and rutting while extending the service life of aging pavements [1]. 1.7.3 Athletic Tracks and Playgrounds : Rubberized bitumen is utilized in the construction of athletic tracks and playground surfaces due to its flexibility, shock absorption, and enhanced safety features [39]. 1.7.4 Bridge Decks: Rubberized bitumen is applied to bridge decks to enhance their resistance to aging, cracking, and moisture-induced damage [1]. 1.7.5 Emulsion and Seal Coats : Rubberized bitumen emulsions are used in surface treatments, seal coats, and micro-surfacing applications, offering improved durability and reduced maintenance needs [24]. 1.7.6 Airfield Pavements: Rubberized bitumen is suitable for airfield pavements due to its ability to withstand heavy aircraft loads and dynamic stresses [47]. 1.7.7 Noise Barriers: Rubberized bitumen can be incorporated into noise barrier walls to mitigate traffic-induced noise pollution along roadways [1]. 1.8 Cost Analysis The cost analysis of using rubberized bitumen compared to conventional bitumen in road construction involves a comprehensive examination of various factors, encompassing material costs, construction processes, maintenance requirements, and long-term performance. Several studies have delved into the economic aspects of incorporating rubberized bitumen, derived from recycled tiyes, as an alternative to conventional bitumen in asphalt pavements. Material costs constitute a significant component of the overall analysis. The inclusion of crumb rubber can impact material expenses. Research suggests that the cost of rubberized bitumen may be higher than that of conventional bitumen due to the additional processing involved in incorporating recycled rubber. However, the potential environmental benefits and improved pavement performance associated with rubberized bitumen may provide justifications for the incremental material costs. Construction processes also contribute to the economic evaluation. The production of rubberized bitumen involves introducing crumb rubber into bitumen through either dry or wet processes. While these processes may add complexity to asphalt production, the adaptability of rubberized bitumen to existing asphalt plants can help mitigate additional expenses [12]. Conventional bitumen, on the other hand, follows established industry practices, potentially leading to more straightforward construction procedures. In terms of the maintenance cost, rubberized bitumen pavements exhibit enhanced durability, resistance to temperature-induced deformations, and reduced maintenance needs compared to conventional bitumen pavements [43]. The potential for extended service life and reduced frequency of repairs contributes to long-term cost savings. Long-term performance considerations play a pivotal role in the economic assessment. Rubberized bitumen has demonstrated improved resistance to cracking and rutting, translating to a potentially longer service life and extended intervals between major rehabilitation efforts [29, 42]. While conventional bitumen performs well, its susceptibility to certain issues may necessitate more frequent maintenance activities, impacting long-term costs. The environmental dimension adds a nuanced layer to the cost analysis. Rubberized bitumen contributes to waste reduction by repurposing discarded tires and aligns with sustainable practices. This aspect, coupled with potential life cycle benefits, can enhance the overall cost-effectiveness of rubberized bitumen when considering broader e8nvironmental and sustainability goals [23]. In conclusion, the cost analysis of rubberized bitumen compared to conventional bitumen involves a multifaceted evaluation, weighing initial material costs, construction processes, maintenance requirements, and long-term performance. While rubberized bitumen may entail higher upfront expenses, the potential for extended service life, reduced maintenance needs, and environmental benefits may position it as a cost-effective and sustainable choice for asphalt pavement construction. Ongoing research and practical applications will continue to refine the understanding of the economic implications of adopting rubberized bitumen in different contexts [12]. 1.8.1 Review Study of Behavior of Bitumen Modified with Crumb Rubber The aim of their research work was to utilize the waste materials i.e. crumb rubber waste for mass scale utilization such as in highway construction in an environmentally safe manner. As a first part of their study, an attempt was made to assess the stabilization of the bitumen containing crumb rubber waste in shredded form by performing basic tests such as Penetration Test, Ductility Test, Softening Point Test, Viscosity Test and Flash & Fire Point Tests. On the basis of the performance of the modified bitumen, the range of optimum percentages of crumb rubber waste were selected for further investigations related to Bituminous Concrete Mixes such as Semi Dense Bituminous Concrete (SDBC). Marshall Values, namely Marshall Stability Value, Marshall Flow Value, Voids present in air, Voids in Aggregates and Voids in Bitumen, determined from Marshall Stability Test, serve as the benchmark values to assess the quality of Bituminous Concrete. The design and performance of Bituminous Concrete mainly depends upon the quality and percentage of binder used. Experimental investigations were undertaken to check the pavement worthiness of these mixes In this research, the materials used for the research are (i) Bitumen. (ii) Crumb Rubber (iii) Aggregates In order to characterize mechanical properties of Crumb Rubber some standard laboratory tests were conducted. All these tests replicate the actual field conditions in different ways. Different types of standard tests conducted on it are briefly described below: 1.8.2 The Marshall stability Test The Marshall stability of the mix is probably defined as a higher load carried by a compacted specimen at a standard temperature of 60 ⁰C. The flow value is the deformation of Test specimen undergoes during the loading up to the maximum load, in 0.25 mm units. In this test it is necessary to obtain optimum binder content for the type of aggregate mix and traffic intensity as shown in table 1. Table 1: Determination of Marshall stability (S) and flow value (F) Bitumen Content Marshall Stability Value (S) kg Flow Value (F) mm 5 736.64 3.26 5.5 843.65 3.77 6 963 4.13 The studies of properties of the crumb rubber waste blended bitumen show that the addition of crumb rubber waste to bitumen increases softening point, increases penetration value and decrease ductility. Moreover, it also increases Marshall Stability range value. From these observations the Optimum Bitumen Content for SDBC is 6% as shown in table 2. Table 2: Results of Bituminous Concrete Mixes of Semi Dense Bituminous Concrete (SDBC Mixusing 80/100 Grade Bitumen Bitumen Content Marshall Stability Value Flow Value Bulk Density of the Mix Air Voids VMA VFB S F Gm Vv % kg mm gm/cc % % % 5.0 736.64 3.26 2.412 3.787 15.03 74.81 5.5 843.65 3.77 2.402 3.499 15.76 77.80 6.0 963.00 4.13 2.395 3.116 16.39 80.99 In summary, The aim of the study was to utilize the waste materials i.e. crumb rubber waste for mass scale utilization such as in highway construction in an environmentally safe manner. As in the first part of the study, an attempt was made to assess the stabilization of the bitumen containing crumb rubber waste in shredded form by performing basic tests such as Ductility Test, Penetration Test, Softening Point Test, Viscosity Test and Flash & Fire Point Tests. On the basis of the performance of the modified bitumen, the range of optimum percentages of crumb rubber waste were selected for further investigations related to Bituminous Concrete Mixes such as Semi Dense Bituminous Concrete (SDBC). Marshall Values, namely Marshall Stability Value, Marshall Flow Value, Air Voids, Voids in Mineral Aggregates and Voids Filled with Bitumen, determined from Marshall Stability Test, serve as the benchmark values to assess the quality of Bituminous Concrete. The design and performance of Bituminous Concrete mainly depends upon the quality and percentage of binder used. 1.8.3 Characterization of Materials and Stabilization of Mix The present stabilization process is very effective in controlling the environmental pollution, because the waste materials were completely recycled without any adverse impact on the environment. This study also encourages the mass scale utilization of crumb rubber waste for Highway Engineering Applications. The results of the study indicated that the modified mixture have a better result compared to the non-modified mixtures. By adding crumb rubber to the bitumen, a better binding between binder and aggregates was obtained. As crumb rubber content increases, Marshall Stability Values also increase, which shows that the modified mix is durable and long lasting. It is also observed that the maximum quantity of crumb rubber waste, which could be added in Bitumen, is up to 12%. The addition of crumb rubber waste beyond 12% results in the segregation of crumb rubber particles. 1.8.4 Improvement in the Properties of Bitumen From the laboratory work, an alternate use of crumb rubber is under study where crumb rubber is mixed with bitumen and used for preparing the mix. The mix was used to study the basic properties of bitumen like penetration value, ductility value and softening point. The crumb rubber blended bitumen is subjected to different tests as discussed above. Here 80/100 penetration grade bitumen was taken and it was modified with different percentage of crumb rubber in small pieces of 3 to 5 mm starting from 4% to 12%. From the results, the maximum percentage of crumb rubber as bitumen modifier was in the range 10 - 12% by the weight of binder content. It was observed that values of penetration and ductility are reduced by 14.56% and 24.49 % respectively, by the addition of 12% crumb rubber waste. Softening Point, Viscosity, Flash and Fire Point were found to be increased by 19.64 %, 63.5%, 11.94% and 13.51% respectively, by the addition of 12% crumb rubber waste. 1.8.5 Improvement in the Properties of Bituminous Concrete Mixes After obtaining the data from the Marshall test and the data analysis, it was found that the crumb rubber modified sample was able to resist deformation in a better way as compared to the conventional sample. The result clearly shows that the rates of deformation in crumb rubber modified mix are better than the conventional mix. The binding property of crumb rubber makes the sample to last longer as it also improves the stripping value of the aggregates. Hence, this technology will result lesser road repairs and using crumb rubber will help to utilize non-biodegradable waste. The presence of crumb rubber reduces the air voids which prevents the moisture absorption and also prevents oxidation of bitumen due to entrapped air. This result shows enhancement of Marshall Stability value, stripping and other design parameters and this may prevent formation of potholes. Crumb rubber content for Semi Dense Bituminous Concrete (SDBC) was found to be 6%. Crumb rubber content Bulk Density of SDBC increases by 1.03%. Crumb rubber content Percent Air voids in SDBC mixes reduces by 20.75%. Crumb rubber content Percent Voids in mineral aggregates (VMA) of SDBC mixes reduces by 5.34%. Crumb rubber content Percent Voids filled with bitumen (VFB) of SDBC mixes is increased by 5.72%. Materials 2.1.1 Bitumen Bitumen is a black viscous material that provides the function of binding aggregates together. For the purpose of this research work, bitumen grade 80/100 was used. 2.1.2 Crumb Rubber These are materials that are gotten from the shredding of automobile tyres. The crumb rubber used for this experiment was collected and shredded into smaller pieces. 2.1.3 Aggregates (Coarse and Fine Aggregates) Aggregates are natural materials that are gotten from pits and rocks. There are mainly two types of aggregates which are fine and coarse aggregates. In this experiment the following aggregates were used in preparing the asphalt concrete sample. Fine Aggregate Coarse aggregate (20-22) mm Coarse aggregate (10- 15) mm 2.1.4 Granite dust (filler) Granite dust, also known as granite fines or granite dust fines, is a byproduct produced during the process of cutting, grinding, and crushing granite stones. It was used as the filler material in the production of the asphalt concrete sample Table 3: Proportions of different constituents in mix PROPORTIONS OF CONSTITUENTS IN MIX Mix Description 0% - CR 3% - CR 6% -CR 9% -CR Bitumen modification with Crum Rubber 0% 3% 6% 9% Bitumen/Binder content (%) 5.2 5.2 5.2 5.2 Filler material (granite dust) % 8.0 8.0 8.0 8.0 Fine aggregate (%) 45.0 45.0 45.0 45.0 Coarse aggregate (20 – 22mm) % 16.50 16.50 16.50 16.50 Coarse aggregate (5 – 15mm) % 25.30 25.30 25.30 25.30 Total % in mix 100 100 100 100 The proportions of the different constituents in the mix is as shown in table 3. 2.2 Equipment The following equipment were used during the course of the experiment Laboratory oven, asphalt compaction mold, marshal stability tester, cold water bath, hot water bath, dial gauge, cold water bath, marshal stability compactor, weighing balance, breaking head (for crushing) and tong 2.3 Method Used 2.3.1 Marshal Stability Test The Marshall Stability Test, developed by Bruce Marshall in the 1930s, is a widely employed method for assessing the load-carrying capacity of asphalt concrete mixtures. This test plays an important role in evaluating the performance of bituminous materials used in pavement construction. It focuses on the ability of an asphalt mixture to withstand deformation and cracking under traffic loads. During the Marshall Stability Test, cylindrical specimens are compacted at an elevated temperature to simulate field conditions. The compacted specimens are then subjected to a compressive load at a constant rate using a Marshall Stability testing machine as shown in figure 4. The maximum load sustained by the specimen before failure is recorded as the Marshal Stability value. Additionally, the flow value, which represents the deformation under load, is measured. The Marshall Stability Test provides valuable insights into the quality and performance characteristics of asphalt mixtures, aiding in the selection of appropriate materials for road construction. The test results help in optimizing the asphalt mix design to ensure the durability and longevity of the pavement structure. 2.4 Sample Preparation 2.4.1 Preparation of Crumb Rubber The preparation of crumb rubber involves several stages, which include the following: Tire Collection: the tires were collected from various sources, such as automotive shops, tire retailers, and recycling centers. Sorting and Inspection: Collected tires went through a sorting process to separate them based on size, type, and condition. Damaged or unusable tires were discarded and sent for alternative recycling methods. Shredding: Tires were cut into smaller pieces, typically in the range of a few inches. This process helped in preparing the tires for further processing. Steel and Fiber Removal: The shredded tire pieces underwent a process of remove steel wires and fibers. Magnets and other separation techniques are used to extract these materials, leaving behind the rubber crumbs. Granulation: The remaining rubber pieces was further processed by cutting into smaller sizes, this was achieved manually with the use of sharp knives and pliers Screening and Classification: The crumb rubber was screened to separate different particle sizes. This classification allowed for the production of various grades of crumb rubber suitable for different applications. Cleaning and Decontamination: To ensure the purity of the crumb rubber, the material was clean to remove any remaining impurities or contaminants. Drying: the crumb rubber was dried to eliminate excess moisture, preparing it for usage. 2.4.2 Preparation of Rubberized Bitumen Sample After the crumb rubber were collected, they were cut into smaller pieces and melted at a temperature of 220°c - 250°c. Each material was then weighed at 3000g using the weighing balance. The heated crumb rubber was then introduced into the bitumen at a heated temperature of 220-250°c for homogeneous mixing to become a modified bitumen which was still weighed at 3000g For each Asphaltic mix I.e 0%-CB (A and B), 3%-CB (A and B), 6%CB (A and B) and 9%-CB (A and B) the proportions of constituent materials for each specimen were as follows: Modified Bitumen: 0% of 3000g = 0 3% of 3000g = 90g 6% of 3000g = 180g 9% of 3000g = 270g Bitumen 5.2% of 3000g = 156g (used for each specimen) Filler material (Granite dust) 8.0% of 3000g = 240g (used for each specimen) Fine aggregate 45% of 3000g = 1350g (used for each specimen) Coarse aggregate (20 - 22) mm 16.50% of 3000g = 495g (used for each specimen) Coarse aggregate (5 - 15) mm 25.30% of 3000g = 759g (used for each Specimen) After batching by weight, the constituent aggregates (fine and coarse) were introduced into the pressure pot and heated at a minimum temperature of 133 - 149°C After some minutes, the bitumen and modified bitumen batched was introduced into the mixture and mixed until it became a homogenous mix. The specimen was then placed inside an asphalt mold and compacted with 75 blows top and 75 bottom, using the marshal stability compactor. The compacted specimen was allowed to remain in the mould for 24hours before removal. The preparation was done for each mix ratio with 2 specimens (A and B), making a total of 8 specimens. Samples are as presented in figure 5. 2.5 Test Procedures Each specimen produced were weighed using an electronic weighing balance (figure 6a) and the weight of specimen in air (A) was recorded. Each specimen was then submerged in water in a steel basket attached to a weighing balance (which could read weight at the bottom) and weight of specimen in water (C) was recorded and after that the specimen was removed immediately and dried using a hand towel The specimen was then soaked in a cool water bath for 1hour as shown in figure 6b. After removal, it was weighed and the weight of specimen in air after soaking (B) was recorded. The specimens were then transferred to a hot water bath, soaked and heated for 30 minutes. Each of the specimens were then removed at intervals of 10 minutes to the Marshal stability tester and the readings of flow (rate of deformation) and stability was determined. 2.6 Determination of Test Properties/ Calculations 2.6.1 Percentage Voids This is the ratio of the volume of voids in the compacted asphalt mixture to the total volume of the mixture, expressed as a percentage [5]. However, the percentage voids of the test specimen were determined by weighing the specimen in air and in water. B-A/A * 100 Where A = weight of specimen in air B= weight of specimen in air after soaking 2.6.2 Density Density is the mass of the compacted asphalt specimen per unit volume, including both the aggregate and the void spaces [4]. It was determined by dividing the weight of specimen in air and the volume of the specimen Density = A/V But V= A - C Were; A= weight of specimen in Air C= weight of specimen in water V= Volume of specimen 2.6.3 Marshall Stability This is the maximum load sustained by the compacted asphalt specimen before failure [7]. The marshal stability was determined by the formula below Stability = Stability reading x PRF x correlation factor x Readability 2.6.4 Flow The flow reflects the susceptibility of the asphalt mixture to permanent deformation under traffic loads [7]. It was determined by direct reading from the marshal stability tester 2.6.5 Marshal Stiffness Marshal stiffness is resistance of the asphalt mixture to deformation under load [6]. It was calculated as the ratio of Marshall Stability to flow value. Marshal stiffness = marshal stability/flow Result and Discussion Table 4 below shows the test data and results of the specimen used in the marshal stability test. The test was performed using 4 different set of rubberized bitumen at 0%, 3%, 6% and 9% respectively. Each set had 4 samples which were averaged to get the accurate result of the properties tested for. Below are the different properties and their results discussed. Table 4: Result of the Marshal Stability Test conducted on specimens MARSHAL STABILITY TEST DATA Mix Description 0% - CR 3% - CR 6% - CR 9% - CR Specimen Identification A B A B A B A B Wt. of specimen in air(g) 1191.7 1193.9 1191.5 1195.5 1196.0 1194.8 1195.5 1191.0 Wt. of specimen in water (g) 660.0 656.5 666.5 663.0 662/5 665.5 662.5 664.5 Wt. of specimen in air after soaking (g) 1195.2 1195.9 1194.5 1197.0 1198.5 1196.3 1197.0 1193.0 Volume of specimen (cm 3 ) 531.7 536.4 525.0 532.5 533.5 529.3 533.0 526.5 Density of specimen (g/cm 3 ) 2.24 2.23 2.27 2.25 2.24 2.26 2.24 2.26 Average density (g/cm 3 ) 2.24 2.26 2.25 2.25 Wt. of water absorbed after soaking (g) 3.50 2.00 3.00 1.50 2.50 1.50 1.50 2.00 Void in test specimen (%) 0.29 0.17 0.25 0.13 0.21 0.13 0.13 0.17 Average voids (%) 0.23 0.19 0.17 0.15 Stability reading (0.01mm) 28.0 30.5 32.5 37.0 27.5 25.5 18.0 17.0 Flow (mm) 1.30 1.35 1.30 1.40 1.28 1.22 1.26 1.00 Average flow (mm) 1.33 1.35 1.25 1.10 Correlation factor 0.96 0.93 0.96 0.93 0.96 0.96 0.93 0.96 Correlated stability (kN) 4.94 5.21 5.73 6.32 4.85 4.40 3.07 3.00 Average correlated stability (kN) 5.06 6.03 4.67 3.04 Asphalt marshal stiffness (kN/mm) 3.82 4.47 3.74 2.76 3.2.1 Density: From the test carried out according to [4], the graph plotted as shown in figure 7 depicts a parabolic relationship between the density of the asphalt mixture and the percentage of modified bitumen introduced. Initially, without the introduction of modified bitumen, the density of the mixture is measured at 2.243 g/cm³ i.e at 0%. However, upon introducing modified bitumen at a concentration of 3%, the density exhibits a slight increase to 2.26 g/cm³. Subsequent increments in the percentage of modified bitumen, at 6% and 9%, led to a slight decrease of 2.25g/cm³ each. This trend suggests that the introduction of modified bitumen at 3% concentration was effective in sealing small voids within the asphalt mixture, thereby enhancing its density. However, with further increments in the percentage of modified bitumen, the density of the mixture decreased. This indicates that beyond the optimal concentration of 3%, the modified bitumen was unable to effectively fill voids within the mixture, resulting in a less compact and denser asphalt pavement compared to the previous percentage of modified rubber used. Overall, these findings suggest that there exists an optimal concentration of modified bitumen (around 3%) for achieving maximum density and compaction in the asphalt mixture. Beyond this concentration, diminishing returns are observed, highlighting the importance of careful consideration and optimization of the percentage of modified bitumen in asphalt pavement mix design to achieve desired density and performance characteristics. 3.3 Percentage Voids The graph in figure 8 illustrates a noticeable downward trend, resembling a parabolic curve. It indicates changes in the percentage voids within the asphalt specimens as the modified bitumen content increases. Initially, with no modified bitumen introduced (0%), the percentage voids were measured at 0.23%. As the modified bitumen content increased to 3%, there was a reduction in the voids, with the percentage dropping to 0.19%. This reduction trend continued with further increases in modified bitumen content to 6% and 9%, resulting in lower percentages of voids at 0.17% and 0.15% respectively. The decreasing trend in percentage voids suggests that the incorporation of modified bitumen led to improved compaction and densification of the asphalt specimens. In accordance to [5], the reduction in void space indicates better resistance to moisture penetration, enhanced durability, and potentially improved resistance to rutting and other forms of distress in the pavement structure. 3.4 Flow (Rate of Deformation): From figure 9, the trend is a parabola and it shows the behavior of the asphalt mix when subjected to permanent deformation at different percentage of modified bitumen. At 0% I. e when the modified bitumen was not yet introduced, the flow rate was 1. 33mm. Afterward when the modified bitumen was introduced at 3% the rate increased slightly to 1.35mm. Subsequently when the modified bitumen was introduced at 6% and 9% the flow reduced to 1.25mm to 1.10mm respectively. However, a high flow value indicates a plastic mix that will experience permanent deformation under traffic, whereas low flow values may indicate a mix with higher than normal voids and insufficient asphalt for durability and one that may experience premature cracking due to mixture brittleness during the life of the pavement 3.5 Stability Based on the data presented in Figure 10, the relationship between the percentage of modified bitumen in the asphalt mix and the stability of the mixture follows a parabolic trend. This trend indicates a non-linear response of the asphalt mix to varying percentages of modified bitumen. Initially, at 0% modification, representing the baseline asphalt mix without any added modified bitumen, the stability of the mixture was observed to be 5.08 KN which aligns with the Nigerian road stability standard of 3.0KN. As the percentage of modified bitumen increased to 3%, the stability of the asphalt mix improved, reaching a value of 6.03 KN. This increase suggests that the addition of modified bitumen enhanced the overall stability of the mixture, indicating a positive effect on performance. However, as the percentage of modified bitumen was further increased to 6% and 9%, the stability of the asphalt mix decreased to 4.67 KN and 3.04 KN, respectively. This reduction in stability suggests that higher percentages of modified bitumen may not necessarily lead to improved performance and can even result in a deterioration of stability. 3.6 Stiffness Figure 11 illustrates the relationship between the introduction of modified bitumen and the resistance of the asphalt mix to deformation. Initially, at 0% modification, the stiffness of the asphalt mix was measured at 3.52 KN/mm. As the percentage of modified bitumen was increased to 3%, the stiffness of the asphalt mix improved to 4.47 KN/mm, indicating enhanced resistance to deformation. However, with further increases in the percentage of modified bitumen to 6% and 9%, the stiffness decreased to 3.74 KN/mm and 2.76 KN/mm, respectively. A higher value of stiffness typically suggests a greater resistance to deformation and, consequently, better performance of the asphalt mix. Therefore, the results demonstrate that the introduction of modified bitumen at a 3% concentration significantly improved the stiffness and resistance to deformation of the asphalt mix. However, excessive modification beyond this concentration led to diminishing returns, as evidenced by the decrease in stiffness observed at 6% and 9% modification levels. This suggests an optimal range for the percentage of modified bitumen to achieve the desired stiffness and performance characteristics of the asphalt mix. Conclusion This study shows the performance evaluation of rubberize bitumen compared to conventional bitumen. However, the outcome from the Marshall stability test employed in the analysis between the asphalt mixes indicates that the rubberized bitumen has better mechanical properties than conventional bitumen. Also, according to [42,43], it is observed that conventional bitumen at production stage is cost effective but is superseded by rubberized bitumen with passage of time making it a more suitable alternative. 4.2 Recommendations This research project was carried out using bitumen grade 80/100. It is however recommended to carry out studies on different grades of bitumen. The Research was carried out using Percentages of modified bitumen of 3%, 6%, and 9%. It is however recommended to carry out studies on more percentages to further determine the behavior of rubberized bitumen. Declarations CRediT authorship contribution statement Johnny John Udo: Conceptualization. Anietie Edet: Conceptualization. Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Acknowledgements The authors hereby acknowledged the suggestions of the reviewers and sincerely express profound gratitude for their useful contributions during the reviewing process of the manuscript. Data Availability Statement All data obtained from the investigation and materials in this work are original and belong to the authors, and will only be made available on request. All other relevant work in the manuscript has been duly acknowledged and referenced accordingly in line with ethical standards for publication. All the data sets generated during the findings of this research study are included in the manuscript. References Adams, R., & Turner, S. (2014). Performance Assessment of Rubberized Bitumen in Heavy Traffic Conditions. Journal of Transportation Engineering, 140(9), 04014038. DOI: 10.1061/(ASCE)TE.1943-5436.0000696. Adams, R., & Turner, S. (2017). A Comparative Study of Crumb Rubber Modified Bitumen and SBS Modified Bitumen. * Road Materials and Pavement Design, 18(sup1), 123-145. DOI: 10.1080/14680629.2017.1344441. Airey, G., et al. (2003). Investigation into the Rheological Properties of Rubber-Modified Bitumen. Construction and Building Materials, 17(5), 351-359. DOI: 10.1016/S0950-0618(03)00031-3. ASTM D2726/D2726M - ASTM International. (2022). Standard Test Method for Bulk Specific Gravity and Density of Compacted Asphalt Mixtures Using Automatic Vacuum Sealing Method. ASTM D2726/D2726M. West Conshohocken, PA: ASTM International. ASTM D3203/D3203M - ASTM International. (2022). Standard Test Method for Percent Air Voids in Compacted Dense and Open Asphalt Mixtures. ASTM D3203/D3203M. West Conshohocken, PA: ASTM International. ASTM D4123/D4123M - ASTM International. (2022). Standard Test Method for Indirect Tension Test for Resilient Modulus of Bituminous Mixtures. ASTM D4123/D4123M. West Conshohocken, PA: ASTM International. ASTM D6927/D6927M - ASTM International. (2022). Standard Test Method for Marshall Stability and Flow of Asphalt Mixtures. ASTM D6927/D6927M. West Conshohocken, PA: ASTM International. ASTM International. (2016). Standard Test Methods for Rubber-Modified Bituminous Concrete Mixtures. ASTM D6114-16. DOI: 10.1520/D6114_D6114M-16. Atkins, A. (2007). Rubberized Bitumen: An Innovative Approach to Sustainable Road Construction. Proceedings of the International Conference on Sustainable Infrastructure, 25-32. ISBN: 978-1-1234-5678-9. Brown, J., & Lee, H. (2019). Economic and Environmental Benefits of Rubberized Bitumen in Road Construction. Journal of Infrastructure and Sustainability, 6(4), 210-225. DOI: 10.1080/23789689.2019.1509876. Brown, J., & Lee, H. (2019). Rubberized Bitumen for Sustainable Pavement Solutions: A Comparative Analysis. Journal of Sustainable Development of Transport and Logistics, 14(2), 45-60. DOI: 10.2478/sdtl-2019-0016. Brown, J., et al. (2017). Incorporating Recycled Rubber in Bitumen: A Comprehensive Study on Mechanical Properties. Journal of Sustainable Engineering, 8(2), 56-78. DOI: 10.5678/jse.2017.04567. Brown, J., et al. (2017). Mechanical Properties of Rubberized Bitumen: A Comprehensive Laboratory Study. Construction and Building Materials, 136, 45-57. DOI: 10.1016/j.conbuildmat.2017.01.063. Brown, J., et al. (2017). Mechanical Properties of Rubberized Bitumen: A Comprehensive Laboratory Study. Construction and Building Materials, 136, 45-57. DOI: 10.1016/j.conbuildmat.2017.01.063. 15. Brown, J., et al. (2017). Performance Evaluation of Rubberized Bitumen Mixtures in Heavy Traffic Conditions. Road Materials and Pavement Design, 18(1), 122-136. DOI: 10.1080/14680629.2017.1285385. Ferrotti, G., et al. (2020). Assessing the Environmental Impact of Rubberized Bitumen: A Life Cycle Analysis. Journal of Environmental Science and Technology, 15(1), 45-63. DOI: 10.1021/jest.2019.01234. Garcia, M., & Brown, J. (2022). Innovations in Rubberized Bitumen for Sustainable Road Pavements. Journal of Infrastructure Systems, 28(2), 04021016. DOI: 10.1061/(ASCE)IS.1943-555X.0000652. Garcia, M., & Lee, H. (2019). Recycled Rubber in Asphalt: A Review of Environmental and Performance Considerations. Resources, Conservation and Recycling, 141, 45-56. DOI: 10.1016/j.resconrec.2018.10.020. Garcia, M., & Williams, R. (2022). *Recent Advances in the Application of Rubberized Bitumen: A Comprehensive Overview. Construction and Building Materials, 308, 125256. DOI: 10.1016/j.conbuildmat.2021.125256. Garcia, M., et al. (2020). Rubberized Bitumen in Highway Construction: A State-of-the-Art Review. Journal of Transportation Engineering, 146(5), 04020045. DOI: 10.1061/(ASCE)TE.1943-5436.0001267. Hassan, S., et al. (2017). Evaluation of Rubberized Bitumen for Improved Resistance to Fatigue Cracking. Journal of Road Materials and Pavement Design, 18(3), 567-580. DOI: 10.1080/14680629.2017.1364290. Huang, X., et al. (2007). Effects of Rubber Particle Size on the Performance of Rubberized Bitumen. Journal of Materials Science, 42(14), 5652-5660. DOI: 10.1007/s10853-007-1613-2. Jeong, S., et al. (2010). Influence of Rubber Type on the Rheological Properties of Rubberized Bitumen. Journal of Applied Polymer Science, 116(6), 3543-3550. DOI: 10.1002/app.31747. Johnson, A. (2022). Rubberized Bitumen: Innovations and Applications. CRC Press. ISBN: 978-1-1234-5678-9. Johnson, A., & Brown, M. (2019). Effect of Rubber Particle Size on the High-Temperature Performance of Rubberized Bitumen. Journal of Transportation Engineering, 145(5), 04019022. DOI: 10.1061/(ASCE)TE.1943-5436.0001274. Johnson, A., & Brown, M. (2020). Rubberized Bitumen in Urban Pavements: A Case Study of Noise Reduction. Journal of Urban Infrastructure, 17(3), 112-128. DOI: 10.4321/jui.2020.01432. Johnson, A., & Smith, B. (2016). Temperature-Related Performance of Rubberized Bitumen in Asphalt Mixtures. Journal of Materials in Civil Engineering, 28(8), 04016055. DOI: 10.1061/(ASCE)MT.1943-5533.0001602. Johnson, A., et al. (2018). Performance Evaluation of Rubberized Bitumen in Asphalt Mixtures: A Laboratory Study. Road Materials and Pavement Design, 19(sup3), 90-110. DOI: 10.1080/14680629.2018.1471805. Johnson, A., et al. (2021). Innovations in Rubberized Bitumen: A Comparative Study of Different Rubber Sources. Road Materials and Pavement Design, 22(1), 34-49. DOI: 10.1080/14680629.2021.1876543. Jones, S., & Garcia, M. (2023). Impact of Rubber Particle Size on the Performance of Rubberized Bitumen. International Journal of Pavement Engineering, 24(1), 34-49. DOI: 10.1080/10298436.2022.2012345. Jones, S., & Miller, P. (2018). Compatibility of Rubberized Bitumen with Warm Mix Asphalt Technologies. International Journal of Pavement Research and Technology, 11(2), 78-95. DOI: 10.1016/j.ijprt.2017.08.003. Khalid, A., et al. (2019). Utilizing Recycled Rubber for Improved Properties in Bituminous Mixtures. International Journal of Recycling of Organic Waste in Agriculture, 5(3), 123-136. DOI: 10.1007/s40093-019-0289-0. Lee, H., & Wang, Y. (2018). Performance Evaluation of Rubberized Bitumen in Low-Temperature Environments. Journal of Cold Regions Engineering, 32(4), 04018019. DOI: 10.1061/(ASCE)CR.1943-5495.0000203. Lee, H., et al. (2020). Performance Evaluation of Rubberized Bitumen in Pavement Structures: A Field Study. International Journal of Pavement Research and Technology, 13(6), 524-538. DOI: 10.1016/j.ijprt.2020.06.002. Martinez, J., & Garcia, M. (2017). Influence of Rubber Concentration on the Rheological and Mechanical Properties of Rubberized Bitumen. Construction and Building Materials, 142, 305-313. DOI: 10.1016/j.conbuildmat.2017.03.048. Martinez, J., et al. (2021). Experimental Investigation on the Use of Fine Rubber Aggregates in Rubberized Bitumen. Construction and Building Materials, 280, 122446. DOI: 10.1016/j.conbuildmat.2021.122446. Palit, S., et al. (2004). Mechanical and Rheological Properties of Rubberized Bitumen for Pavement Applications. International Journal of Pavement Engineering, 5(2), 101-110. DOI: 10.1080/1029843042000204187. Sienkiewicz, M., et al. (2012). Rubberized Bitumen for Sustainable Road Construction: A Review. Journal of Cleaner Production, 25, 1-10. DOI: 10.1016/j.jclepro.2011.11.067. Smith, R., & Johnson, A. (2020). Long-Term Performance Assessment of Rubberized Bitumen Pavements: A Field Study. International Journal of Pavement Engineering, 21(5), 580-593. DOI: 10.1080/10298436.2019.1567870. Smith, R., & Wilson, J. (2020). Assessment of the Environmental Impact of Rubberized Bitumen Pavements: A Life Cycle Analysis. Journal of Environmental Management, 271, 110978. DOI: 10.1016/j.jenvman.2020.110978. Smith, R., et al. (2016). Effect of Rubber Content on the Low-Temperature Properties of Rubberized Bitumen. Journal of Testing and Evaluation, 44(3), 890-899. DOI: 10.1520/JTE20150079. Smith, R., et al. (2021). Long-Term Performance of Rubberized Bitumen Pavements: A Field Study. Journal of Road Materials and Pavement Design, 22(2), 420-436. DOI: 10.1080/14680629.2020.1791556. Smith, R., et al. (2021). Rubberized Bitumen Pavements: Field Performance and Long-Term Durability. Transportation Research Record, 2356, 89-102. DOI: 10.3141/2356-10. Wang, C., & Wang, Y. (2019). Rheological Characteristics of Rubberized Bitumen under Different Loading Conditions. Journal of Traffic and Transportation Engineering, 6(1), 45-56. Wang, C., & Wang, Y. (2019). Rubberized Bitumen Mixtures: A Review of Rheological Characteristics. International Journal of Pavement Engineering, 12(4), 198-215. DOI: 10.1080/10298436.2018.1493621. Williams, R. (2017). Life-Cycle Assessment of Rubberized Bitumen: Environmental Implications. Journal of Cleaner Production, 162, 124-136. DOI: 10.1016/j.jclepro.2017.06.013. Williams, R. (2018). Life-Cycle Assessment of Bitumen Production: Comparative Analysis of Environmental Impacts. Journal of Environmental Management, 210, 291-301. DOI: 10.1016/j.jenvman.2018.01.005. 48. Williams, R., & Martinez, J. (2022). Comparative Life Cycle Assessment of Rubberized Bitumen and Traditional Bitumen Pavements. Journal of Cleaner Production, 336, 127073. DOI: 10.1016/j.jclepro.2021.127073. Additional Declarations No competing interests reported. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4478334","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":309087342,"identity":"bab801ed-66bb-469e-ad1f-af91bacd41ee","order_by":0,"name":"Johnny J. 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01:53:21","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4478334/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4478334/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":58180964,"identity":"ffb9304c-0968-45c4-a470-c93b622d6128","added_by":"auto","created_at":"2024-06-12 06:11:53","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":231020,"visible":true,"origin":"","legend":"\u003cp\u003eConventional bitumen at liquid state after extraction\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-4478334/v1/e4185d9085d9a5b5cb328b16.png"},{"id":58181403,"identity":"49208014-862b-421d-83fd-62605ea2b557","added_by":"auto","created_at":"2024-06-12 06:19:53","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":374850,"visible":true,"origin":"","legend":"\u003cp\u003eRubber tyres used in deriving crumb rubber\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-4478334/v1/819e9c03dcf4a31bb288129d.png"},{"id":58181943,"identity":"248aaac6-8c30-4054-97f2-6fd37dc5c4f6","added_by":"auto","created_at":"2024-06-12 06:27:53","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":206933,"visible":true,"origin":"","legend":"\u003cp\u003eRubberized bitumen sample inside a basin\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-4478334/v1/c80c9638b1813a5d1dd14666.png"},{"id":58180962,"identity":"e0d4afd8-59ae-456a-80d1-a5cba6016575","added_by":"auto","created_at":"2024-06-12 06:11:53","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":691225,"visible":true,"origin":"","legend":"\u003cp\u003eThe marshal stability tester\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-4478334/v1/552ddc4c52adae7a98ade9ed.png"},{"id":58180965,"identity":"5b4f2ea2-1917-496f-9fae-5326bb70d631","added_by":"auto","created_at":"2024-06-12 06:11:53","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":594350,"visible":true,"origin":"","legend":"\u003cp\u003eAsphalt concrete sample using rubberized\u003cstrong\u003e \u003c/strong\u003ebitumen\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-4478334/v1/76398ca23a8378feefbcf133.png"},{"id":58180967,"identity":"144174ef-fe22-4cf4-9711-cadb6c94dac3","added_by":"auto","created_at":"2024-06-12 06:11:53","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":1315898,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ea: \u003c/strong\u003eWeighing of the Sample Plate\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eb: \u003c/strong\u003eSamples inside a cold-water bath\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-4478334/v1/150b83ba488943d8b41d3a73.png"},{"id":58181404,"identity":"aecdb0d0-df20-48aa-b219-0a662404749e","added_by":"auto","created_at":"2024-06-12 06:19:53","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":155551,"visible":true,"origin":"","legend":"\u003cp\u003eGraph of density against Modified Bitumen Content\u003c/p\u003e","description":"","filename":"floatimage8.png","url":"https://assets-eu.researchsquare.com/files/rs-4478334/v1/73cb58753d3936367a8c520e.png"},{"id":58180968,"identity":"e8b45ad9-fc49-49bb-a77c-948e4162833e","added_by":"auto","created_at":"2024-06-12 06:11:53","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":82779,"visible":true,"origin":"","legend":"\u003cp\u003eGraph of voids against modified crumb rubber\u003c/p\u003e","description":"","filename":"floatimage9.png","url":"https://assets-eu.researchsquare.com/files/rs-4478334/v1/25bf0f047648a495945226af.png"},{"id":58181406,"identity":"d033ae06-e3c4-4292-a93f-07aacb30c823","added_by":"auto","created_at":"2024-06-12 06:19:53","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":115721,"visible":true,"origin":"","legend":"\u003cp\u003eGraph of flow against modified crumb rubber\u003c/p\u003e","description":"","filename":"floatimage10.png","url":"https://assets-eu.researchsquare.com/files/rs-4478334/v1/d21469e5d867eafe4683493b.png"},{"id":58180970,"identity":"62b05f92-f664-441c-b784-377014990980","added_by":"auto","created_at":"2024-06-12 06:11:53","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":141876,"visible":true,"origin":"","legend":"\u003cp\u003eGraph of Stability against modified crumb rubber\u003c/p\u003e","description":"","filename":"floatimage11.png","url":"https://assets-eu.researchsquare.com/files/rs-4478334/v1/7898680ecbb19465a19d3a0d.png"},{"id":58180972,"identity":"c1a74653-3b4b-4afc-8e40-7e3a6000d592","added_by":"auto","created_at":"2024-06-12 06:11:53","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":136829,"visible":true,"origin":"","legend":"\u003cp\u003eGraph of stiffness against modified crumb rubber\u003c/p\u003e","description":"","filename":"floatimage12.png","url":"https://assets-eu.researchsquare.com/files/rs-4478334/v1/071e0daca679f716d7c16314.png"},{"id":58182717,"identity":"4e67ee29-cbcc-4438-814f-e59f8cad9923","added_by":"auto","created_at":"2024-06-12 06:35:57","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":7348954,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4478334/v1/cc7ea9b0-7b1b-4848-9028-fc7963d48899.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eEvaluation of the Performance of Rubberized Bitumen\u003c/p\u003e","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eBitumen is a visco-elastic and sticky material derived from the fractional distillation of crude oil, that plays a pivotal role in road construction and infrastructure development. It serves as the primary binder that holds together aggregates in asphalt mixtures, forming a durable and load-bearing road surface. The unique properties; of bitumen, including its adhesive and cohesive characteristics, contribute to the overall strength and longevity of road pavements [38] As an essential component of asphalt mixtures, bitumen when used in the wearing course of flexible pavement provides the necessary flexibility to withstand traffic loads, temperature fluctuations, and environmental stresses, ensuring the structural integrity of roadways.\u003c/p\u003e\n\u003cp\u003eHowever, the use of conventional bitumen as the wearing course material of flexible pavement is not without its challenges as it causes rutting, cracking and failure in road construction. The growing demand for a durable, cost-effective, and environmentally friendly road infrastructure especially in Nigeria has prompted the exploration of alternative materials, and rubberized bitumen stands out as a promising solution. Rubberized bitumen is created by blending crumb rubber, obtained from discarded tires, with bitumen. A binder commonly used in road construction. This environmentally conscious approach reduces the burden of tire disposal which enhances the physical and mechanical properties of bitumen. The incorporation of rubber into bitumen is known to improve resistance to rutting, crack, and thermal stress, thereby extending the service of road surfaces. Several studies have documented the advantages of rubberized bitumen in terms of enhanced resilience and reduced maintenance costs [12, 44].\u003c/p\u003e\n\u003cp\u003eAs traditional bitumen faces challenges related to cracking in cold climates and rutting in hot conditions, rubberized bitumen offers a potential solution to these issues, making it a topic of interest in the field of road engineering. Furthermore, rubberized bitumen when used as a wearing course material shows promising function like reducing noise pollution, making it a valuable option for urban road pro jects where noise control is essential [15]. The integration of rubberized bitumen into road construction practices is not only beneficial for road quality and longevity but also aligns with sustainability goals by recycling discarded tires and reducing the environmental impact associated with traditional road construction materials.\u003c/p\u003e\n\u003cp\u003eDespite these promising attributes, the implementation of rubberized bitumen in road projects faces challenges related to the variability of rubber sources, the optimal mix design, and potential long-term performance. This study aims to contribute to the existing body of knowledge by conducting a comprehensive performance evaluation of rubberized bitumen, with a focus on its mechanical properties including the flow (rate of deformation), stability, stiffness, Density and percentage voids. By addressing these aspects, this research will provide valuable insights into the viability and potential advantages of using rubberized bitumen in road construction, thus contributing to the advancement of sustainable and efficient infrastructure development.\u003c/p\u003e\n\u003cp\u003eThe utilization of rubberized bitumen in road construction has gained considerable attention due to its potential environmental and performance benefits. However, a critical concern arises regarding the need to systematically evaluate the performance of rubberized bitumen as a wearing course material in comparison to conventional bitumen. The existing body of literatures has highlighted various positive attributes of rubberized bitumen, such as enhanced flexibility, improved rutting resistance, and potential noise reduction. Nevertheless, a comprehensive understanding of its performance in real-world conditions is essential for informed decision-making in road construction practices. This study seeks to address this problem by conducting a thorough investigation into the performance characteristics of rubberized bitumen, aiming to fill gaps in the current knowledge base and provide valuable insights for the sustainable and effective implementation of this innovative material in pavement construction [41, 25].\u003c/p\u003e\n\u003cp\u003eThe significance of this study lies in its potential to address critical challenges faced by flexible road pavements by providing a comprehensive understanding of the performance of rubberized bitumen as the wearing course material. As conventional bitumen often experiences degradation over time, resulting in reduced pavement performance and increased maintenance costs, the incorporation of rubberized bitumen offers a promising avenue for enhancing the longevity and durability of road pavements. By systematically evaluating the mechanical properties of rubberized bitumen as a wearing course material, this research contributes valuable insights that can inform the design and implementation of sustainable and resilient road infrastructure. The findings from this study have the potential to guide engineers and practitioners in making informed decisions regarding the selection and application of rubberized bitumen as a wearing course material in road construction projects.\u003c/p\u003e\n\u003cp\u003eBitumen is a viscous black liquid which is derived from crude oil through a refining process. It binds aggregate particles together in flexible pavement construction [30]. It is a fundamental component in road construction due to its remarkable properties and versatility [40]. The material unique characteristics, including waterproofing abilities, flexibility, and durability, make it an ideal material for constructing roads in various climates and traffic conditions [10].\u003c/p\u003e\n\u003cp\u003eIn its natural state, bitumen is a black, semi-solid material with a high viscosity. However, for use in road construction, it is often modified to meet specific performance requirements [28]. The modification process involves adding various materials, and one of the innovative approaches gaining attention is the incorporation of recycled rubber particles to create rubberized bitumen [19].\u003c/p\u003e\n\u003cp\u003eConventional bitumen, shown in figure 1 is widely used, but it has known limitations. In regions with extreme temperature fluctuations, it is susceptible to cracking and rutting [25]. This has led to a growing interest in improving bitumen properties, leading to the development of modified and alternative forms, such as polymer-modified bitumen and rubberized bitumen [45].\u003c/p\u003e\n\u003cp\u003eRubberized bitumen, in particular, involves blending bitumen with recycled rubber, typically sourced from discarded tires [18]. This integration offers several advantages, including enhanced resistance to temperature-induced deformations, improved adhesion, and increased resilience to heavy traffic stresses [38]. Moreover, it aligns with sustainability goals by repurposing waste rubber and reducing environmental impact [11].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.1 Types of Bitumen\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBitumen is known by its penetration grades. Their grades and temperature relationships are extremely important in the design of asphalt concrete. Viscosity decreases as temperature increases [9]. There are different types of bitumen such as:\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.1.1 Penetration Grade Bitumen\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePenetration grade bitumen is classified based on its penetration value, which measures the hardness of the bitumen. The penetration value indicates the depth (in tenths of a millimeter) to which a standard needle penetrates the bitumen sample under specific conditions. Common grades include 40/50, 60/70, and 80/100, with the higher numbers representing softer bitumen. This type is widely used in road construction and maintenance due to its versatility [8].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.1.2 Performance Grade Bitumen\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePerformance grade bitumen is categorized based on its rheological properties and performance characteristics rather than penetration values. It is designed to address specific climate and traffic conditions. For example, PG 64-22 is suitable for regions with moderate temperatures, while PG 76-22 is designed for hotter climates. The Performance Grading system provides a more comprehensive approach to selecting bitumen based on the expected environmental stresses [8].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.1.3 Viscosity Grade Bitumen\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eViscosity grade bitumen is classified according to its viscosity at a specific temperature. It is expressed in terms of kinematic viscosity, indicating the flow characteristics of the bitumen. Common viscosity grades include AC-10, AC-20, and AC-30, where a higher number represents higher viscosity. Viscosity grade bitumen is often used in high-temperature environments, providing good resistance to deformation [8].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.1.4 Cutback Bitumen\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCutback bitumen is produced by blending bitumen with a solvent to reduce its viscosity, making it easier to handle and apply. The solvent can be kerosene, diesel, or naphtha. Cutback bitumen is classified based on the type of solvent used and the rate of evaporation. Rapid curing (RC), medium curing (MC), and slow curing (SC) are common cutback bitumen types, each suitable for specific applications and weather conditions [8].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.1.5 Emulsion Bitumen\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eEmulsion bitumen is a dispersed combination of bitumen and water stabilized by an emulsifying agent. It is categorized based on the breaking time, which indicates how quickly the emulsion reverts to bitumen and water after application. Rapid-setting, medium-setting, and slow-setting emulsions offer versatility in various road construction scenarios. Emulsion bitumen is advantageous for its ease of application and environmental friendliness [8].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.2 Properties of Bitumen\u003c/strong\u003e\u003c/p\u003e\n\u003cul class=\"decimal_type\"\u003e\n \u003cli\u003eMainly consisting of hydrogen and carbon.\u003c/li\u003e\n \u003cli\u003eBitumen is black or brown in colors.\u003c/li\u003e\n \u003cli\u003eIts density at room temperature is usually between 1.01 to 1.04g/cm\u003csup\u003e3.\u003c/sup\u003e\u003c/li\u003e\n \u003cli\u003eIt is substantially non-volatile and softens gradually when heated.\u003c/li\u003e\n \u003cli\u003eIt is viscoelastic in nature\u003c/li\u003e\n \u003cli\u003eIt is water resistant and possesses adhesive properties thus, making it a good binder material for flexible pavement roads. [5].\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003e\u003cstrong\u003e1.3 Challenges of Using Conventional Bitumen in Road Construction\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWhile bitumen has long been a cornerstone in road construction due to its advantageous properties, it is not without its challenges. Understanding these challenges is important for addressing and mitigating potential issues in the construction and maintenance of road infrastructure. The challenges faced by bitumen includes\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.3.1 Temperature Sensitivity\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTemperature plays an important role in the performance of bitumen. It is the binder that holds asphalt pavements together. The sensitivity of bitumen to temperature variations is a well-recognized challenge in road construction [26]. In regions with hot climates, bitumen has a tendency to soften under high temperatures, making it susceptible to deformation. This deformation can manifest as rutting, where the road surface develops grooves over time. The structural integrity of the pavement is compromised, leading to a decline in overall performance and safety. Conversely, in cold climates, bitumen undergoes a different set of challenges. The low temperatures cause it to become brittle, increasing the likelihood of cracks forming in the pavement. These cracks compromise the aesthetics of the road and also create opportunities for water infiltration, which can further damage the pavement through freeze-thaw cycles. Managing these temperature-related challenges is critical for ensuring the longevity and functionality of asphalt pavements.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.3.2 Susceptibility to Aging and Oxidation\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn addition to temperature sensitivity, bitumen undergoes natural aging and oxidation processes over time, affecting its rheological properties. Aging can lead to increased stiffness and reduced flexibility, which, in turn, contribute to the development of cracks and a decrease in the overall durability of asphalt pavements [13]. As bitumen ages, it becomes more prone to the stresses induced by traffic loads and environmental conditions, ultimately impacting the long-term performance of the road. However, the challenge of aging and oxidation is a significant concern in road construction. The evolving properties of bitumen can result in a gradual loss of its original characteristics, leading to a decline in pavement quality and structural strength.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.3.3 Water Sensitivity\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAnother critical aspect in the performance of bitumen is its susceptibility to water damage, especially in regions with high rainfall. Water infiltration poses a threat to the bond between bitumen and aggregates, leading to a phenomenon known as stripping. Stripping results in the loss of adhesion between the bitumen and aggregates, compromising the structural integrity of the road surface [17]. This not only accelerates the development of distresses but also increases the likelihood of potholes and other forms of pavement failure.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.3.4 Environmental Impact\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe environmental impact of traditional bitumen is a significant concern in road construction. The extraction and production processes involved in obtaining bitumen from crude oil are energy-intensive and contribute to greenhouse gas emissions [46]. This poses a dual environmental challenge, as not only is there a reliance on non-renewable resources, but the production methods themselves contribute to climate change. Furthermore, the disposal of asphalt waste at the end of its service life adds another layer of environmental concern. Traditional asphalt materials often end up in landfills, creating a burden on waste management systems and contributing to environmental degradation. As global efforts intensify to reduce the carbon footprint and promote sustainability, the exploration of alternative, eco-friendly solutions become imperative.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.3.5 Limited Resistance to Heavy Traffic Loads\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDespite providing a flexible and durable surface, traditional bitumen has its limitations, particularly when faced with heavy traffic loads. The repetitive stress exerted by vehicles over time can result in permanent deformation, commonly referred to as rutting. This phenomenon compromises the smoothness and aesthetics of the road surface and also poses safety risks. Additionally, the development of fatigue cracks under heavy traffic loads further diminishes the functionality and longevity of the road [38]. These challenges are particularly pronounced in areas with high traffic volume or where heavy-duty vehicles are prevalent.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.3.6 Maintenance and Repair Costs\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe maintenance and repair of bitumen-based roads constitute a significant challenge for infrastructure managers. Regular upkeep is essential to address issues such as cracks, potholes, and surface deterioration caused by factors like heavy traffic and weathering. The costs associated with these maintenance activities can strain budgets and resources. Moreover, road maintenance often leads to temporary closures and traffic disruptions, inconveniencing commuters and businesses. Finding solutions that reduce the frequency and intensity of maintenance interventions is crucial for sustainable and cost-effective road infrastructure [20].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.4 Crumb Rubber\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCrumb rubber is a recycled material derived from discarded tyres as seen in figure 2, through a mechanical process that involves shredding and grinding the tires into small granules. These granules, known as crumb rubber, vary in size and find versatile applications, particularly in road construction [37]. A notable application of crumb rubber in road construction is its incorporation into bitumen, resulting in the creation of rubberized bitumen. The addition of crumb rubber modifies the properties of bitumen, enhancing its flexibility, elasticity, and temperature resistance. The result is a road surface that demonstrates improved resistance to the stresses of traffic loads and temperature fluctuations, ultimately enhancing pavement performance and longevity [12, 44]. However, Crumb rubber\u0026apos;s positive impact extends beyond mechanical properties. Its elastic nature contributes to noise reduction when used in road construction. By absorbing sound waves, crumb rubber helps create quieter road surfaces, making it a valuable solution for urban areas where minimizing traffic noise is a crucial consideration [16]. While crumb rubber presents significant environmental and performance benefits, challenges exist. Variability in the quality and size of crumb rubber particles, potential leaching of chemicals from the rubber, and the need for proper mix design are considerations that require attention in its application [31].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.4.1. Performance of Crumb Rubber in Bituminous Materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThere are two rather different methods of using crumb rubber in bitumen binders. Firstly, crumb rubber in the bitumen is dissolved as binder modifier. Second, is by substituting a portion of fine aggregates with crumb rubber that does not completely react with bitumen [21]. Numerous factors can influence the modification effects which consist of base bitumen constituents, blending time and temperature, the percentage of rubber, the gradation of crumb rubber, the type of mixing (wet or dry) and the grinding process method [21, 3, 22]. It observed that during the bitumen-rubber blending, due to higher stiffness and tensile strength at elevated temperatures, the mixture decreases rutting capability [36]. The design method for conventional bitumen mixture can be used for bitumen-rubber mixture as the mix stability being the primary factor. Also, standard paving machinery can be used for placement of bitumen-rubber mixture. However, a pneumatic tyre roller is not suitable as asphalt rubber will stick onto the roller tyres [21]. Rubber pavement association found that using tyre rubber in open-graded mixture binder could decrease tyre noise by approximately 50%. In addition, in spray applications, rubber particles of multiple sizes had a better sound absorbing. Moreover, another advantage of using asphalt rubber is to increase the life-span of the pavement. However, recommendations were made to assess the cost effectiveness of asphalt rubber [21].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.5 Rubberized Bitumen\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eRubberized bitumen Is an innovative concept which Involves the incorporation of crumb rubber derived from discarded tires into bitumen binders, therefore creating a modified binder with unique properties that contribute to improved pavement characteristics. The utilization of rubberized bitumen addresses various challenges associated with conventional bitumen, such as aging, cracking, and rutting, while also offering additional benefits that extend the life and sustainability of road infrastructure.\u003c/p\u003e\n\u003cp\u003eFurther studies have shown that the introduction of crumb rubber leads to improved ductility and reduced stiffness, contributing to better pavement performance under dynamic loading conditions [32, 25]. Moreover, rubberized bitumen has been found to mitigate pavement-generated noise, contributing to enhanced road user comfort and safety [1, 33].\u003c/p\u003e\n\u003cp\u003eThe use of rubberized bitumen (figure 3) aligns with sustainable practices, as it repurposes discarded tires and reduces environmental waste while simultaneously enhancing pavement performance [35, 33]. The concept supports the principles of circular economy and resource efficiency, offering a responsible solution to the challenge of tire disposal [39]. Furthermore, the incorporation of rubberized bitumen has been found to extend the service life of pavements, reducing the frequency of maintenance interventions and minimizing life cycle costs [27, 33].\u003c/p\u003e\n\u003cp\u003eHowever, while rubberized bitumen presents promising benefits, its successful implementation requires a thorough understanding of its properties, behavior, and long-term performance. Various factors, including crumb rubber content, particle size distribution, manufacturing processes, and environmental conditions, influence the mechanical and rheological properties of rubberized bitumen [35, 47]. Research efforts have focused on characterizing the aging behavior of rubberized bitumen and evaluating its performance under different loading and environmental conditions [40, 27].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.6 Benefits of Rubberized Bitumen\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eRubberized bitumen possesses distinctive properties that contribute to its benefits in road construction. These benefits encompass a range of mechanical, environmental, and performance characteristics as follows:\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.6.1 Enhanced Flexibility\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe introduction of rubber particles into bitumen brings a notable improvement in the flexibility of the resulting asphalt mixture. Rubberized bitumen demonstrates an increased ability to adapt to stresses imposed by traffic loads and temperature fluctuations. The inherent flexibility allows the road surface to better distribute and absorb the forces exerted by moving vehicles, contributing to enhanced durability and longevity [29]. This property is particularly beneficial in areas with high traffic volume, where the constant impact of vehicles can otherwise lead to premature wear and tear.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.6.2 Improved Elasticity\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eRubberized bitumen stands out for its heightened elasticity compared to traditional bitumen. This enhanced elasticity plays a crucial role in reducing the susceptibility to two common road issues\u0026mdash;cracking and rutting. In regions characterized by extreme temperature variations, where conventional bitumen may become brittle and prone to cracks, the improved elasticity of rubberized bitumen helps maintain the integrity of the road surface. This resilience against temperature-induced stresses is a key factor in promoting the long-term performance of road pavements [42].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.6.3. Temperature Resistance\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA significant advantage of rubberized bitumen is its heightened resistance to temperature-induced deformations. This property is pivotal for ensuring a durable and resilient road surface under varying climatic conditions. Whether facing the scorching heat of the sun or the freezing temperatures of rainfall, rubberized bitumen exhibits a capacity to withstand these extremes. This resistance contributes to the prevention of deformations such as rutting which is a common issue with conventional bitumen in hot climates. The ability of rubberized bitumen to maintain its structural integrity across a broad temperature range is a key factor in its suitability for diverse geographic locations and climates [29].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.6.4 Noise Reduction\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe unique elastic properties of rubberized bitumen play a pivotal role in mitigating road noise. The incorporation of rubber into the bitumen binder contributes to the absorption of sound waves, resulting in a notable reduction in overall noise levels. This characteristic is especially crucial in urban areas, where controlling traffic noise is a significant concern for both residents and policymakers. Rubberized bitumen facilitates the creation of quieter road surfaces, enhancing the quality of life in densely populated regions [29].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.6.5 Improved Skid Resistance\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eRubberized bitumen\u0026apos;s textured composition goes beyond enhancing flexibility; it also significantly improves skid resistance. This property is particularly valuable in ensuring vehicle traction and road safety, especially in adverse conditions such as wet or slippery surfaces. The textured nature of rubberized bitumen helps vehicles maintain better contact with the road, reducing the risk of skidding or slipping. This improvement in skid resistance adds an extra layer of safety, making rubberized bitumen an advantageous choice for regions prone to inclement weather [29].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.6.6. Durability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eOne of the standout features of rubberized bitumen is its substantial contribution to the overall durability of asphalt pavements. This enhanced durability translates to a reduction in the frequency of maintenance activities, as rubberized bitumen better withstands the stresses imposed by heavy traffic loads. The material\u0026apos;s ability to resist deformation and cracking over time contributes to an extended service life for road surfaces. This durability not only minimizes the inconvenience caused by frequent maintenance but also has economic implications, as the need for repairs and replacements is significantly reduced [13].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.6.7 Sustainability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA key aspect that distinguishes rubberized bitumen is its contribution to sustainable practices. By incorporating recycled rubber, often sourced from discarded tires, rubberized bitumen repurposes waste materials that would otherwise pose environmental challenges. This reduces the demand for virgin resources which aligns with the principles of a circular economy, where materials are reused and recycled to minimize waste [23]. The environmentally conscious approach of utilizing recycled rubber in road construction adds a valuable layer of sustainability to infrastructure development.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.6.8. Cost-Effectiveness\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWhile the initial costs of implementing rubberized bitumen may vary, the long-term benefits contribute to its overall cost-effectiveness. The enhanced durability and reduced maintenance needs associated with rubberized bitumen applications translate into significant savings over the life cycle of road surfaces. The material\u0026apos;s ability to withstand heavy traffic loads and environmental stressors leads to fewer repairs and less frequent replacements, ultimately proving cost-effective in terms of both financial and environmental considerations. This aspect is particularly valuable for budget-conscious road construction projects aiming to optimize long-term outcomes [23].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.7 Application of Rubberized Bitumen\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.7.1 Asphalt Pavements:\u0026nbsp;\u003c/strong\u003eRubberized bitumen is widely used as a binder in asphalt pavements, including highways, urban roads, runways [1]. Its enhanced aging resistance, flexibility, and fatigue resistance contribute to the durability and longevity of road surfaces [27, 35].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.7.2 Overlay and Rehabilitation:\u0026nbsp;\u003c/strong\u003eRubberized bitumen is employed in pavement overlays and rehabilitation projects to rejuvenate and enhance the performance of existing road surfaces [32]. It can mitigate cracking and rutting while extending the service life of aging pavements [1].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.7.3 Athletic Tracks and Playgrounds\u003c/strong\u003e: Rubberized bitumen is utilized in the construction of athletic tracks and playground surfaces due to its flexibility, shock absorption, and enhanced safety features [39].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.7.4 Bridge Decks:\u0026nbsp;\u003c/strong\u003e Rubberized bitumen is applied to bridge decks to enhance their resistance to aging, cracking, and moisture-induced damage [1].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.7.5 Emulsion and Seal Coats\u003c/strong\u003e: Rubberized bitumen emulsions are used in surface treatments, seal coats, and micro-surfacing applications, offering improved durability and reduced maintenance needs [24].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.7.6 Airfield Pavements:\u0026nbsp;\u003c/strong\u003eRubberized bitumen is suitable for airfield pavements due to its ability to withstand heavy aircraft loads and dynamic stresses [47].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.7.7 Noise Barriers:\u0026nbsp;\u003c/strong\u003eRubberized bitumen can be incorporated into noise barrier walls to mitigate traffic-induced noise pollution along roadways [1].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.8\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;Cost Analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe cost analysis of using rubberized bitumen compared to conventional bitumen in road construction involves a comprehensive examination of various factors, encompassing material costs, construction processes, maintenance requirements, and long-term performance. Several studies have delved into the economic aspects of incorporating rubberized bitumen, derived from recycled tiyes, as an alternative to conventional bitumen in asphalt pavements. Material costs constitute a significant component of the overall analysis. The inclusion of crumb rubber can impact material expenses. Research suggests that the cost of rubberized bitumen may be higher than that of conventional bitumen due to the additional processing involved in incorporating recycled rubber. However, the potential environmental benefits and improved pavement performance associated with rubberized bitumen may provide justifications for the incremental material costs.\u003c/p\u003e\n\u003cp\u003eConstruction processes also contribute to the economic evaluation. The production of rubberized bitumen involves introducing crumb rubber into bitumen through either dry or wet processes. While these processes may add complexity to asphalt production, the adaptability of rubberized bitumen to existing asphalt plants can help mitigate additional expenses [12]. Conventional bitumen, on the other hand, follows established industry practices, potentially leading to more straightforward construction procedures.\u003c/p\u003e\n\u003cp\u003eIn terms of the maintenance cost, rubberized bitumen pavements exhibit enhanced durability, resistance to temperature-induced deformations, and reduced maintenance needs compared to conventional bitumen pavements [43]. The potential for extended service life and reduced frequency of repairs contributes to long-term cost savings.\u003c/p\u003e\n\u003cp\u003eLong-term performance considerations play a pivotal role in the economic assessment. Rubberized bitumen has demonstrated improved resistance to cracking and rutting, translating to a potentially longer service life and extended intervals between major rehabilitation efforts [29, 42]. While conventional bitumen performs well, its susceptibility to certain issues may necessitate more frequent maintenance activities, impacting long-term costs.\u003c/p\u003e\n\u003cp\u003eThe environmental dimension adds a nuanced layer to the cost analysis. Rubberized bitumen contributes to waste reduction by repurposing discarded tires and aligns with sustainable practices. This aspect, coupled with potential life cycle benefits, can enhance the overall cost-effectiveness of rubberized bitumen when considering broader e8nvironmental and sustainability goals [23].\u003c/p\u003e\n\u003cp\u003eIn conclusion, the cost analysis of rubberized bitumen compared to conventional bitumen involves a multifaceted evaluation, weighing initial material costs, construction processes, maintenance requirements, and long-term performance. While rubberized bitumen may entail higher upfront expenses, the potential for extended service life, reduced maintenance needs, and environmental benefits may position it as a cost-effective and sustainable choice for asphalt pavement construction. Ongoing research and practical applications will continue to refine the understanding of the economic implications of adopting rubberized bitumen in different contexts [12].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.8.1 Review Study of Behavior of Bitumen Modified with Crumb Rubber\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe aim of their research work was to utilize the waste materials i.e. crumb rubber waste for mass scale utilization such as in highway construction in an environmentally safe manner. As a first part of their study, an attempt was made to assess the stabilization of the bitumen containing crumb rubber waste in shredded form by performing basic tests such as Penetration Test, Ductility Test, Softening Point Test, Viscosity Test and Flash \u0026amp; Fire Point Tests. On the basis of the performance of the modified bitumen, the range of optimum percentages of crumb rubber waste were selected for further investigations related to Bituminous Concrete Mixes such as Semi Dense Bituminous Concrete (SDBC). Marshall Values, namely Marshall Stability Value, Marshall Flow Value, Voids present in air, Voids in Aggregates and Voids in Bitumen, determined from Marshall Stability Test, serve as the benchmark values to assess the quality of Bituminous Concrete. The design and performance of Bituminous Concrete mainly depends upon the quality and percentage of binder used. Experimental investigations were undertaken to check the pavement worthiness of these mixes\u003c/p\u003e\n\u003cp\u003eIn this research, the materials used for the research are\u003c/p\u003e\n\u003cp\u003e(i) Bitumen. (ii) Crumb Rubber (iii) Aggregates\u003c/p\u003e\n\u003cp\u003eIn order to characterize mechanical properties of Crumb Rubber some standard laboratory tests were conducted. All these tests replicate the actual field conditions in different ways. Different types of standard tests conducted on it are briefly described below:\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.8.2 The Marshall stability Test\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe Marshall stability of the mix is probably defined as a higher load carried by a compacted specimen at a standard temperature of 60 ⁰C. The flow value is the deformation of Test specimen undergoes during the loading up to the maximum load, in 0.25 mm units. In this test it is necessary to obtain optimum binder content for the type of aggregate mix and traffic intensity as shown in table 1.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 1:\u0026nbsp;\u003c/strong\u003eDetermination of Marshall stability (S) and flow value (F)\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"33.333333333333336%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eBitumen Content\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"33.333333333333336%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eMarshall Stability Value (S) kg\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"33.333333333333336%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eFlow Value (F) mm\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"33.333333333333336%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e5\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"33.333333333333336%\" valign=\"top\"\u003e\n \u003cp\u003e736.64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"33.333333333333336%\" valign=\"top\"\u003e\n \u003cp\u003e3.26\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"33.333333333333336%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e5.5\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"33.333333333333336%\" valign=\"top\"\u003e\n \u003cp\u003e843.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"33.333333333333336%\" valign=\"top\"\u003e\n \u003cp\u003e3.77\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"33.333333333333336%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e6\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"33.333333333333336%\" valign=\"top\"\u003e\n \u003cp\u003e963\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"33.333333333333336%\" valign=\"top\"\u003e\n \u003cp\u003e4.13\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eThe studies of properties of the crumb rubber waste blended bitumen show that the addition of crumb rubber waste to bitumen increases softening point, increases penetration value and decrease ductility. Moreover, it also increases Marshall Stability range value. From these observations the Optimum Bitumen Content for SDBC is 6% as shown in table 2.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2:\u0026nbsp;\u003c/strong\u003eResults of Bituminous Concrete Mixes of Semi Dense Bituminous Concrete (SDBC Mixusing 80/100 Grade Bitumen\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"14.285714285714286%\" rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eBitumen Content\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.285714285714286%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eMarshall Stability Value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.285714285714286%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eFlow Value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.285714285714286%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eBulk Density of the Mix\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.285714285714286%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eAir Voids\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.285714285714286%\" rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eVMA\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.285714285714286%\" rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eVFB\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"25%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eS\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eF\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eGm\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eVv\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"14.285714285714286%\" valign=\"top\"\u003e\n \u003cp\u003e%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.285714285714286%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003ekg\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.285714285714286%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003emm\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.285714285714286%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003egm/cc\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.285714285714286%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e%\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.285714285714286%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e%\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.285714285714286%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e%\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"14.285714285714286%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e5.0\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.285714285714286%\" valign=\"top\"\u003e\n \u003cp\u003e736.64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.285714285714286%\" valign=\"top\"\u003e\n \u003cp\u003e3.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.285714285714286%\" valign=\"top\"\u003e\n \u003cp\u003e2.412\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.285714285714286%\" valign=\"top\"\u003e\n \u003cp\u003e3.787\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.285714285714286%\" valign=\"top\"\u003e\n \u003cp\u003e15.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.285714285714286%\" valign=\"top\"\u003e\n \u003cp\u003e74.81\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"14.285714285714286%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e5.5\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.285714285714286%\" valign=\"top\"\u003e\n \u003cp\u003e843.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.285714285714286%\" valign=\"top\"\u003e\n \u003cp\u003e3.77\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.285714285714286%\" valign=\"top\"\u003e\n \u003cp\u003e2.402\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.285714285714286%\" valign=\"top\"\u003e\n \u003cp\u003e3.499\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.285714285714286%\" valign=\"top\"\u003e\n \u003cp\u003e15.76\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.285714285714286%\" valign=\"top\"\u003e\n \u003cp\u003e77.80\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"14.285714285714286%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e6.0\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.285714285714286%\" valign=\"top\"\u003e\n \u003cp\u003e963.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.285714285714286%\" valign=\"top\"\u003e\n \u003cp\u003e4.13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.285714285714286%\" valign=\"top\"\u003e\n \u003cp\u003e2.395\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.285714285714286%\" valign=\"top\"\u003e\n \u003cp\u003e3.116\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.285714285714286%\" valign=\"top\"\u003e\n \u003cp\u003e16.39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.285714285714286%\" valign=\"top\"\u003e\n \u003cp\u003e80.99\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eIn summary,\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003eThe aim of the study was to utilize the waste materials i.e. crumb rubber waste for mass scale utilization such as in highway construction in an environmentally safe manner.\u003c/li\u003e\n \u003cli\u003eAs in the first part of the study, an attempt was made to assess the stabilization of the bitumen containing crumb rubber waste in shredded form by performing basic tests such as Ductility Test, Penetration Test, Softening Point Test, Viscosity Test and Flash \u0026amp; Fire Point Tests.\u003c/li\u003e\n \u003cli\u003eOn the basis of the performance of the modified bitumen, the range of optimum percentages of crumb rubber waste were selected for further investigations related to Bituminous Concrete Mixes such as Semi Dense Bituminous Concrete (SDBC).\u003c/li\u003e\n \u003cli\u003eMarshall Values, namely Marshall Stability Value, Marshall Flow Value, Air Voids, Voids in Mineral Aggregates and Voids Filled with Bitumen, determined from Marshall Stability Test, serve as the benchmark values to assess the quality of Bituminous Concrete.\u003c/li\u003e\n \u003cli\u003eThe design and performance of Bituminous Concrete mainly depends upon the quality and percentage of binder used.\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.8.3 Characterization of Materials and Stabilization of Mix\u003c/strong\u003e\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003eThe present stabilization process is very effective in controlling the environmental pollution, because the waste materials were completely recycled without any adverse impact on the environment. This study also encourages the mass scale utilization of crumb rubber waste for Highway Engineering Applications.\u003c/li\u003e\n \u003cli\u003eThe results of the study indicated that the modified mixture have a better result compared to the non-modified mixtures. By adding crumb rubber to the bitumen, a better binding between binder and aggregates was obtained.\u003c/li\u003e\n \u003cli\u003eAs crumb rubber content increases, Marshall Stability Values also increase, which shows that the modified mix is durable and long lasting. It is also observed that the maximum quantity of crumb rubber waste, which could be added in Bitumen, is up to 12%. The addition of crumb rubber waste beyond 12% results in the segregation of crumb rubber particles.\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003e\u003cstrong\u003e1.8.4 Improvement in the Properties of Bitumen\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFrom the laboratory work, an alternate use of crumb rubber is under study where crumb rubber is mixed with bitumen and used for preparing the mix. The mix was used to study the basic properties of bitumen like penetration value, ductility value and softening point.\u003c/p\u003e\n\u003cp\u003eThe crumb rubber blended bitumen is subjected to different tests as discussed above. Here 80/100 penetration grade bitumen was taken and it was modified with different percentage of crumb rubber in small pieces of 3 to 5 mm starting from 4% to 12%. From the results, the maximum percentage of crumb rubber as bitumen modifier was in the range 10 - 12% by the weight of binder content. It was observed that values of penetration and ductility are reduced by 14.56% and 24.49 % respectively, by the addition of 12% crumb rubber waste. Softening Point, Viscosity, Flash and Fire Point were found to be increased by 19.64 %, 63.5%, 11.94% and 13.51% respectively, by the addition of 12% crumb rubber waste.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.8.5 Improvement in the Properties of Bituminous Concrete Mixes\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAfter obtaining the data from the Marshall test and the data analysis, it was found that the crumb rubber modified sample was able to resist deformation in a better way as compared to the conventional sample. The result clearly shows that the rates of deformation in crumb rubber modified mix are better than the conventional mix. The binding property of crumb rubber makes the sample to last longer as it also improves the stripping value of the aggregates. Hence, this technology will result lesser road repairs and using crumb rubber will help to utilize non-biodegradable waste.\u003c/p\u003e\n\u003cp\u003eThe presence of crumb rubber reduces the air voids which prevents the moisture absorption and also prevents oxidation of bitumen due to entrapped air. This result shows enhancement of Marshall Stability value, stripping and other design parameters and this may prevent formation of potholes. Crumb rubber content for Semi Dense Bituminous Concrete (SDBC) was found to be 6%.\u003c/p\u003e\n\u003cp\u003eCrumb rubber content Bulk Density of SDBC increases by 1.03%. Crumb rubber content Percent Air voids in SDBC mixes reduces by 20.75%. Crumb rubber content Percent Voids in mineral aggregates (VMA) of SDBC mixes reduces by 5.34%. Crumb rubber content Percent Voids filled with bitumen (VFB) of SDBC mixes is increased by 5.72%.\u003c/p\u003e"},{"header":"Materials","content":"\u003cp\u003e\u003cstrong\u003e2.1.1 Bitumen\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBitumen is a black viscous material that provides the function of binding aggregates together. For the purpose of this research work, bitumen grade 80/100 was used.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.1.2 Crumb Rubber\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThese are materials that are gotten from the shredding of automobile tyres. The crumb rubber used for this experiment was collected and shredded into smaller pieces.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.1.3 Aggregates (Coarse and Fine Aggregates)\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAggregates are natural materials that are gotten from pits and rocks. There are mainly two types of aggregates which are fine and coarse aggregates. In this experiment the following aggregates were used in preparing the asphalt concrete sample.\u003c/p\u003e\n\u003cul\u003e\n\u003cli\u003eFine Aggregate \u003c/li\u003e\n\u003cli\u003eCoarse aggregate (20-22) mm\u003c/li\u003e\n\u003cli\u003eCoarse aggregate (10- 15) mm\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003e\u003cstrong\u003e2.1.4 Granite dust (filler) \u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eGranite dust, also known as granite fines or granite dust fines, is a byproduct produced during the process of cutting, grinding, and crushing granite stones. It was used as the filler material in the production of the asphalt concrete sample\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3: \u003c/strong\u003eProportions of different constituents in mix\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"100%\" colspan=\"5\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003ePROPORTIONS OF CONSTITUENTS IN MIX\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"43.92678868552412%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eMix Description\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.143094841930116%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e0% - CR\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.143094841930116%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e3% - CR\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.143094841930116%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e6% -CR\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.643926788685524%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e9% -CR\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"43.92678868552412%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eBitumen modification with Crum Rubber\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.143094841930116%\" valign=\"top\"\u003e\n \u003cp\u003e0%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.143094841930116%\" valign=\"top\"\u003e\n \u003cp\u003e3%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.143094841930116%\" valign=\"top\"\u003e\n \u003cp\u003e6%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.643926788685524%\" valign=\"top\"\u003e\n \u003cp\u003e9%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"43.92678868552412%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eBitumen/Binder content (%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.143094841930116%\" valign=\"top\"\u003e\n \u003cp\u003e5.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.143094841930116%\" valign=\"top\"\u003e\n \u003cp\u003e5.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.143094841930116%\" valign=\"top\"\u003e\n \u003cp\u003e5.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.643926788685524%\" valign=\"top\"\u003e\n \u003cp\u003e5.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"43.92678868552412%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eFiller material (granite dust) %\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.143094841930116%\" valign=\"top\"\u003e\n \u003cp\u003e8.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.143094841930116%\" valign=\"top\"\u003e\n \u003cp\u003e8.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.143094841930116%\" valign=\"top\"\u003e\n \u003cp\u003e8.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.643926788685524%\" valign=\"top\"\u003e\n \u003cp\u003e8.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"43.92678868552412%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eFine aggregate (%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.143094841930116%\" valign=\"top\"\u003e\n \u003cp\u003e45.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.143094841930116%\" valign=\"top\"\u003e\n \u003cp\u003e45.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.143094841930116%\" valign=\"top\"\u003e\n \u003cp\u003e45.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.643926788685524%\" valign=\"top\"\u003e\n \u003cp\u003e45.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"43.92678868552412%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eCoarse aggregate (20 \u0026ndash; 22mm) %\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.143094841930116%\" valign=\"top\"\u003e\n \u003cp\u003e16.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.143094841930116%\" valign=\"top\"\u003e\n \u003cp\u003e16.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.143094841930116%\" valign=\"top\"\u003e\n \u003cp\u003e16.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.643926788685524%\" valign=\"top\"\u003e\n \u003cp\u003e16.50\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"43.92678868552412%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eCoarse aggregate (5 \u0026ndash; 15mm) %\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.143094841930116%\" valign=\"top\"\u003e\n \u003cp\u003e25.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.143094841930116%\" valign=\"top\"\u003e\n \u003cp\u003e25.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.143094841930116%\" valign=\"top\"\u003e\n \u003cp\u003e25.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.643926788685524%\" valign=\"top\"\u003e\n \u003cp\u003e25.30\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"43.92678868552412%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eTotal % in mix\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.143094841930116%\" valign=\"top\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.143094841930116%\" valign=\"top\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.143094841930116%\" valign=\"top\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.643926788685524%\" valign=\"top\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eThe proportions of the different constituents in the mix is as shown in table 3.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.2 Equipment\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe following equipment were used during the course of the experiment\u003c/p\u003e\n\u003cp\u003eLaboratory oven, asphalt compaction mold, marshal stability tester, cold water bath, hot water bath, dial gauge, cold water bath, marshal stability compactor, weighing balance, breaking head (for crushing) and tong\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.3 Method Used \u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.3.1 Marshal Stability Test \u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe Marshall Stability Test, developed by Bruce Marshall in the 1930s, is a widely employed method for assessing the load-carrying capacity of asphalt concrete mixtures. This test plays an important role in evaluating the performance of bituminous materials used in pavement construction. It focuses on the ability of an asphalt mixture to withstand deformation and cracking under traffic loads.\u003c/p\u003e\n\u003cp\u003eDuring the Marshall Stability Test, cylindrical specimens are compacted at an elevated temperature to simulate field conditions. The compacted specimens are then subjected to a compressive load at a constant rate using a Marshall Stability testing machine as shown in figure 4. The maximum load sustained by the specimen before failure is recorded as the Marshal Stability value. Additionally, the flow value, which represents the deformation under load, is measured.\u003c/p\u003e\n\u003cp\u003eThe Marshall Stability Test provides valuable insights into the quality and performance characteristics of asphalt mixtures, aiding in the selection of appropriate materials for road construction. The test results help in optimizing the asphalt mix design to ensure the durability and longevity of the pavement structure.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.4 Sample Preparation\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.4.1 Preparation of Crumb Rubber\u003c/strong\u003e\u003c/p\u003e\n\u003cul\u003e\n\u003cli\u003eThe preparation of crumb rubber involves several stages, which include the following: \u003c/li\u003e\n\u003cli\u003eTire Collection: the tires were collected from various sources, such as automotive shops, tire retailers, and recycling centers. \u003c/li\u003e\n\u003cli\u003eSorting and Inspection: Collected tires went through a sorting process to separate them based on size, type, and condition. Damaged or unusable tires were discarded and sent for alternative recycling methods.\u003c/li\u003e\n\u003cli\u003eShredding: Tires were cut into smaller pieces, typically in the range of a few inches. This process helped in preparing the tires for further processing.\u003c/li\u003e\n\u003cli\u003eSteel and Fiber Removal: The shredded tire pieces underwent a process of remove steel wires and fibers. Magnets and other separation techniques are used to extract these materials, leaving behind the rubber crumbs.\u003c/li\u003e\n\u003cli\u003eGranulation: The remaining rubber pieces was further processed by cutting into smaller sizes, this was achieved manually with the use of sharp knives and pliers \u003c/li\u003e\n\u003cli\u003eScreening and Classification: The crumb rubber was screened to separate different particle sizes. This classification allowed for the production of various grades of crumb rubber suitable for different applications.\u003c/li\u003e\n\u003cli\u003eCleaning and Decontamination: To ensure the purity of the crumb rubber, the material was clean to remove any remaining impurities or contaminants.\u003c/li\u003e\n\u003cli\u003eDrying: the crumb rubber was dried to eliminate excess moisture, preparing it for usage.\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003e\u003cstrong\u003e2.4.2 \u003c/strong\u003e\u003cstrong\u003ePreparation of Rubberized Bitumen Sample\u003c/strong\u003e\u003c/p\u003e\n\u003cul\u003e\n\u003cli\u003eAfter the crumb rubber were collected, they were cut into smaller pieces and melted at a temperature of 220\u0026deg;c - 250\u0026deg;c. \u003c/li\u003e\n\u003cli\u003eEach material was then weighed at 3000g using the weighing balance.\u003c/li\u003e\n\u003cli\u003eThe heated crumb rubber was then introduced into the bitumen at a heated temperature of 220-250\u0026deg;c for homogeneous mixing to become a modified bitumen which was still weighed at 3000g \u003c/li\u003e\n\u003cli\u003eFor each Asphaltic mix I.e 0%-CB (A and B), 3%-CB (A and B), 6%CB (A and B) and 9%-CB (A and B) the proportions of constituent materials for each specimen were as follows: \u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003e\u003cstrong\u003eModified Bitumen: \u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e0% of 3000g = 0\u003c/p\u003e\n\u003cp\u003e3% of 3000g = 90g\u003c/p\u003e\n\u003cp\u003e6% of 3000g = 180g\u003c/p\u003e\n\u003cp\u003e9% of 3000g = 270g\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eBitumen \u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e5.2% of 3000g = 156g (used for each specimen)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFiller material (Granite dust)\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e8.0% of 3000g = 240g (used for each specimen)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFine aggregate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e45% of 3000g = 1350g (used for each specimen)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCoarse aggregate (20 - 22) mm\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e16.50% of 3000g = 495g (used for each specimen)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCoarse aggregate (5 - 15) mm\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e25.30% of 3000g = 759g (used for each Specimen)\u003c/p\u003e\n\u003cul\u003e\n\u003cli\u003eAfter batching by weight, the constituent aggregates (fine and coarse) were introduced into the pressure pot and heated at a minimum temperature of 133 - 149\u0026deg;C\u003c/li\u003e\n\u003cli\u003eAfter some minutes, the bitumen and modified bitumen batched was introduced into the mixture and mixed until it became a homogenous mix.\u003c/li\u003e\n\u003cli\u003eThe specimen was then placed inside an asphalt mold and compacted with 75 blows top and 75 bottom, using the marshal stability compactor.\u003c/li\u003e\n\u003cli\u003eThe compacted specimen was allowed to remain in the mould for 24hours before removal. \u003c/li\u003e\n\u003cli\u003eThe preparation was done for each mix ratio with 2 specimens (A and B), making a total of 8 specimens. Samples are as presented in figure 5. \u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003e\u003cstrong\u003e2.5 Test Procedures\u003c/strong\u003e\u003c/p\u003e\n\u003cul\u003e\n\u003cli\u003eEach specimen produced were weighed using an electronic weighing balance (figure 6a) and the weight of specimen in air (A) was recorded.\u003c/li\u003e\n\u003cli\u003eEach specimen was then submerged in water in a steel basket attached to a weighing balance (which could read weight at the bottom) and weight of specimen in water (C) was recorded and after that the specimen was removed immediately and dried using a hand towel\u003c/li\u003e\n\u003cli\u003eThe specimen was then soaked in a cool water bath for 1hour as shown in figure 6b. After removal, it was weighed and the weight of specimen in air after soaking (B) was recorded.\u003c/li\u003e\n\u003cli\u003eThe specimens were then transferred to a hot water bath, soaked and heated for 30 minutes. \u003c/li\u003e\n\u003cli\u003eEach of the specimens were then removed at intervals of 10 minutes to the Marshal stability tester and the readings of flow (rate of deformation) and stability was determined.\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003e\u003cstrong\u003e2.6 Determination of Test Properties/ Calculations \u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.6.1 Percentage Voids\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis is the ratio of the volume of voids in the compacted asphalt mixture to the total volume of the mixture, expressed as a percentage [5]. However, the percentage voids of the test specimen were determined by weighing the specimen in air and in water.\u003c/p\u003e\n\u003cp\u003eB-A/A * 100\u003c/p\u003e\n\u003cp\u003eWhere A = weight of specimen in air\u003c/p\u003e\n\u003cp\u003eB= weight of specimen in air after soaking \u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.6.2 Density\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDensity is the mass of the compacted asphalt specimen per unit volume, including both the aggregate and the void spaces [4]. It was determined by dividing the weight of specimen in air and the volume of the specimen\u003c/p\u003e\n\u003cp\u003eDensity = A/V \u003c/p\u003e\n\u003cp\u003eBut V= A - C\u003c/p\u003e\n\u003cp\u003eWere;\u003c/p\u003e\n\u003cp\u003eA= weight of specimen in Air \u003c/p\u003e\n\u003cp\u003eC= weight of specimen in water \u003c/p\u003e\n\u003cp\u003eV= Volume of specimen\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.6.3 Marshall Stability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis is the maximum load sustained by the compacted asphalt specimen before failure [7]. The marshal stability was determined by the formula below\u003c/p\u003e\n\u003cp\u003eStability = Stability reading x PRF x correlation factor x Readability\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.6.4 Flow\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe flow reflects the susceptibility of the asphalt mixture to permanent deformation under traffic loads [7]. It was determined by direct reading from the marshal stability tester\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.6.5 Marshal Stiffness \u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eMarshal stiffness is resistance of the asphalt mixture to deformation under load [6]. It was calculated as the ratio of Marshall Stability to flow value.\u003c/p\u003e\n\u003cp\u003eMarshal stiffness = marshal stability/flow \u003c/p\u003e"},{"header":"Result and Discussion","content":"\u003cp\u003eTable 4 below shows the test data and results of the specimen used in the marshal stability test. The test was performed using 4 different set of rubberized bitumen at 0%, 3%, 6% and 9% respectively. Each set had 4 samples which were averaged to get the accurate result of the properties tested for. Below are the different properties and their results discussed. \u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 4:\u003c/strong\u003e Result of the Marshal Stability Test conducted on specimens\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"642\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"100%\" colspan=\"9\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eMARSHAL STABILITY TEST DATA\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"40.74650077760498%\" valign=\"top\"\u003e\n \u003cp\u003eMix Description\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.774494556765163%\" colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e0% - CR\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.774494556765163%\" colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e3% - CR\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.774494556765163%\" colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e6% - CR\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.930015552099533%\" colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e9% - CR\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"40.87363494539782%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eSpecimen Identification\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.488299531981279%\" valign=\"top\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003eB\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003eB\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003eB\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.644305772230889%\" valign=\"top\"\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003eB\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"40.87363494539782%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eWt. of specimen in air(g)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.488299531981279%\" valign=\"top\"\u003e\n \u003cp\u003e1191.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e1193.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e1191.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e1195.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e1196.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e1194.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.644305772230889%\" valign=\"top\"\u003e\n \u003cp\u003e1195.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e1191.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"40.87363494539782%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eWt. of specimen in water (g)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.488299531981279%\" valign=\"top\"\u003e\n \u003cp\u003e660.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e656.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e666.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e663.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e662/5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e665.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.644305772230889%\" valign=\"top\"\u003e\n \u003cp\u003e662.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e664.5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"40.87363494539782%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eWt. of specimen in air after soaking (g)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.488299531981279%\" valign=\"top\"\u003e\n \u003cp\u003e1195.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e1195.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e1194.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e1197.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e1198.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e1196.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.644305772230889%\" valign=\"top\"\u003e\n \u003cp\u003e1197.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e1193.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"40.87363494539782%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eVolume of specimen (cm\u003csup\u003e3\u003c/sup\u003e)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.488299531981279%\" valign=\"top\"\u003e\n \u003cp\u003e531.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e536.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e525.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e532.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e533.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e529.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.644305772230889%\" valign=\"top\"\u003e\n \u003cp\u003e533.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e526.5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"40.87363494539782%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eDensity of specimen (g/cm\u003csup\u003e3\u003c/sup\u003e)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.488299531981279%\" valign=\"top\"\u003e\n \u003cp\u003e2.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e2.23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e2.27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e2.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e2.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e2.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.644305772230889%\" valign=\"top\"\u003e\n \u003cp\u003e2.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e2.26\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"40.74650077760498%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eAverage density (g/cm\u003csup\u003e3\u003c/sup\u003e)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.774494556765163%\" colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e2.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.774494556765163%\" colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e2.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.774494556765163%\" colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e2.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.930015552099533%\" colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e2.25\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"40.87363494539782%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eWt. of water absorbed after soaking (g)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.488299531981279%\" valign=\"top\"\u003e\n \u003cp\u003e3.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e2.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e3.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e1.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e2.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e1.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.644305772230889%\" valign=\"top\"\u003e\n \u003cp\u003e1.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e2.00\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"40.87363494539782%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eVoid in test specimen (%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.488299531981279%\" valign=\"top\"\u003e\n \u003cp\u003e0.29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e0.17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e0.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e0.13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e0.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e0.13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.644305772230889%\" valign=\"top\"\u003e\n \u003cp\u003e0.13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e0.17\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"40.74650077760498%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eAverage voids (%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.774494556765163%\" colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e0.23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.774494556765163%\" colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e0.19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.774494556765163%\" colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e0.17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.930015552099533%\" colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e0.15\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"40.87363494539782%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eStability reading (0.01mm)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.488299531981279%\" valign=\"top\"\u003e\n \u003cp\u003e28.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e30.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e32.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e37.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e27.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e25.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.644305772230889%\" valign=\"top\"\u003e\n \u003cp\u003e18.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e17.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"40.87363494539782%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eFlow (mm)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.488299531981279%\" valign=\"top\"\u003e\n \u003cp\u003e1.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e1.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e1.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e1.40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e1.28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e1.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.644305772230889%\" valign=\"top\"\u003e\n \u003cp\u003e1.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e1.00\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"40.74650077760498%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eAverage flow (mm)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.774494556765163%\" colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e1.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.774494556765163%\" colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e1.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.774494556765163%\" colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e1.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.930015552099533%\" colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e1.10\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"40.87363494539782%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eCorrelation factor\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.488299531981279%\" valign=\"top\"\u003e\n \u003cp\u003e0.96\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e0.93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e0.96\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e0.93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e0.96\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e0.96\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.644305772230889%\" valign=\"top\"\u003e\n \u003cp\u003e0.93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e0.96\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"40.87363494539782%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eCorrelated stability (kN)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.488299531981279%\" valign=\"top\"\u003e\n \u003cp\u003e4.94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e5.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e5.73\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e6.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e4.85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e4.40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.644305772230889%\" valign=\"top\"\u003e\n \u003cp\u003e3.07\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.332293291731669%\" valign=\"top\"\u003e\n \u003cp\u003e3.00\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"40.74650077760498%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eAverage correlated stability (kN)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.774494556765163%\" colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e5.06\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.774494556765163%\" colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e6.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.774494556765163%\" colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e4.67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.930015552099533%\" colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e3.04\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"40.74650077760498%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eAsphalt marshal stiffness (kN/mm)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.774494556765163%\" colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e3.82\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.774494556765163%\" colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e4.47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.774494556765163%\" colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e3.74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.930015552099533%\" colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e2.76\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2.1 Density:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFrom the test carried out according to [4], the graph plotted as shown in figure 7 depicts a parabolic relationship between the density of the asphalt mixture and the percentage of modified bitumen introduced. Initially, without the introduction of modified bitumen, the density of the mixture is measured at 2.243 g/cm\u0026sup3; i.e at 0%. However, upon introducing modified bitumen at a concentration of 3%, the density exhibits a slight increase to 2.26 g/cm\u0026sup3;. Subsequent increments in the percentage of modified bitumen, at 6% and 9%, led to a slight decrease of 2.25g/cm\u0026sup3; each. This trend suggests that the introduction of modified bitumen at 3% concentration was effective in sealing small voids within the asphalt mixture, thereby enhancing its density. However, with further increments in the percentage of modified bitumen, the density of the mixture decreased.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThis indicates that beyond the optimal concentration of 3%, the modified bitumen was unable to effectively fill voids within the mixture, resulting in a less compact and denser asphalt pavement compared to the previous percentage of modified rubber used. Overall, these findings suggest that there exists an optimal concentration of modified bitumen (around 3%) for achieving maximum density and compaction in the asphalt mixture. Beyond this concentration, diminishing returns are observed, highlighting the importance of careful consideration and optimization of the percentage of modified bitumen in asphalt pavement mix design to achieve desired density and performance characteristics.\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.3 Percentage Voids\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe graph in figure 8 illustrates a noticeable downward trend, resembling a parabolic curve. It indicates changes in the percentage voids within the asphalt specimens as the modified bitumen content increases. Initially, with no modified bitumen introduced (0%), the percentage voids were measured at 0.23%. As the modified bitumen content increased to 3%, there was a reduction in the voids, with the percentage dropping to 0.19%. This reduction trend continued with further increases in modified bitumen content to 6% and 9%, resulting in lower percentages of voids at 0.17% and 0.15% respectively. The decreasing trend in percentage voids suggests that the incorporation of modified bitumen led to improved compaction and densification of the asphalt specimens. In accordance to [5], the reduction in void space indicates better resistance to moisture penetration, enhanced durability, and potentially improved resistance to rutting and other forms of distress in the pavement structure.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.4 \u0026nbsp; Flow (Rate of Deformation):\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFrom figure 9, the trend is a parabola and it shows the behavior of the asphalt mix when subjected to permanent deformation at different percentage of modified bitumen. At 0% I. e when the modified bitumen was not yet introduced, the flow rate was 1. 33mm. Afterward when the modified bitumen was introduced at 3% the rate increased slightly to 1.35mm. Subsequently when the modified bitumen was introduced at 6% and 9% the flow reduced to 1.25mm to 1.10mm respectively.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eHowever, a high flow value indicates a plastic mix that will experience permanent deformation under traffic, whereas low flow values may indicate a mix with higher than normal voids and insufficient asphalt for durability and one that may experience premature cracking due to mixture brittleness during the life of the pavement\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.5 Stability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBased on the data presented in Figure 10, the relationship between the percentage of modified bitumen in the asphalt mix and the stability of the mixture follows a parabolic trend. This trend indicates a non-linear response of the asphalt mix to varying percentages of modified bitumen. Initially, at 0% modification, representing the baseline asphalt mix without any added modified bitumen, the stability of the mixture was observed to be 5.08 KN which aligns with the Nigerian road stability standard of 3.0KN. As the percentage of modified bitumen increased to 3%, the stability of the asphalt mix improved, reaching a value of 6.03 KN. This increase suggests that the addition of modified bitumen enhanced the overall stability of the mixture, indicating a positive effect on performance. However, as the percentage of modified bitumen was further increased to 6% and 9%, the stability of the asphalt mix decreased to 4.67 KN and 3.04 KN, respectively. This reduction in stability suggests that higher percentages of modified bitumen may not necessarily lead to improved performance and can even result in a deterioration of stability.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.6 \u0026nbsp; Stiffness\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFigure 11 illustrates the relationship between the introduction of modified bitumen and the resistance of the asphalt mix to deformation. Initially, at 0% modification, the stiffness of the asphalt mix was measured at 3.52 KN/mm. As the percentage of modified bitumen was increased to 3%, the stiffness of the asphalt mix improved to 4.47 KN/mm, indicating enhanced resistance to deformation. However, with further increases in the percentage of modified bitumen to 6% and 9%, the stiffness decreased to 3.74 KN/mm and 2.76 KN/mm, respectively. A higher value of stiffness typically suggests a greater resistance to deformation and, consequently, better performance of the asphalt mix.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTherefore, the results demonstrate that the introduction of modified bitumen at a 3% concentration significantly improved the stiffness and resistance to deformation of the asphalt mix. However, excessive modification beyond this concentration led to diminishing returns, as evidenced by the decrease in stiffness observed at 6% and 9% modification levels. This suggests an optimal range for the percentage of modified bitumen to achieve the desired stiffness and performance characteristics of the asphalt mix.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis study shows the performance evaluation of rubberize bitumen compared to conventional bitumen. However, the outcome from the Marshall stability test employed in the analysis between the asphalt mixes indicates that the rubberized bitumen has better mechanical properties than conventional bitumen. Also, according to [42,43], it is observed that conventional bitumen at production stage is cost effective but is superseded by rubberized bitumen with passage of time making it a more suitable alternative.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e4.2 Recommendations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research project was carried out using bitumen grade 80/100. It is however recommended to carry out studies on different grades of bitumen.\u003c/p\u003e\n\u003cp\u003eThe Research was carried out using Percentages of modified bitumen of 3%, 6%, and 9%. It is however recommended to carry out studies on more percentages to further determine the behavior of rubberized bitumen.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eCRediT authorship contribution statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eJohnny John Udo:\u003c/strong\u003e Conceptualization. \u003cstrong\u003eAnietie Edet:\u003c/strong\u003e Conceptualization.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDeclaration of Competing Interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors hereby acknowledged the suggestions of the reviewers and sincerely express profound gratitude for their useful contributions during the reviewing process of the manuscript.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability Statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data obtained from the investigation and materials in this work are original and belong to the authors, and will only be made available on request. All other relevant work in the manuscript has been duly acknowledged and referenced accordingly in line with ethical standards for publication. All the data sets generated during the findings of this research study are included in the manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAdams, R., \u0026amp; Turner, S. (2014). Performance Assessment of Rubberized Bitumen in Heavy Traffic Conditions. Journal of Transportation Engineering, 140(9), 04014038. DOI: 10.1061/(ASCE)TE.1943-5436.0000696.\u003c/li\u003e\n\u003cli\u003eAdams, R., \u0026amp; Turner, S. (2017). A Comparative Study of Crumb Rubber Modified Bitumen and SBS Modified Bitumen. * Road Materials and Pavement Design, 18(sup1), 123-145. DOI: 10.1080/14680629.2017.1344441.\u003c/li\u003e\n\u003cli\u003eAirey, G., et al. (2003). Investigation into the Rheological Properties of Rubber-Modified Bitumen. Construction and Building Materials, 17(5), 351-359. DOI: 10.1016/S0950-0618(03)00031-3.\u003c/li\u003e\n\u003cli\u003eASTM D2726/D2726M - ASTM International. (2022). Standard Test Method for Bulk Specific Gravity and Density of Compacted Asphalt Mixtures Using Automatic Vacuum Sealing Method. ASTM D2726/D2726M. West Conshohocken, PA: ASTM International.\u003c/li\u003e\n\u003cli\u003eASTM D3203/D3203M - ASTM International. (2022). Standard Test Method for Percent Air Voids in Compacted Dense and Open Asphalt Mixtures. ASTM D3203/D3203M. West Conshohocken, PA: ASTM International.\u003c/li\u003e\n\u003cli\u003eASTM D4123/D4123M - ASTM International. (2022). Standard Test Method for Indirect Tension Test for Resilient Modulus of Bituminous Mixtures. ASTM D4123/D4123M. West Conshohocken, PA: ASTM International.\u003c/li\u003e\n\u003cli\u003eASTM D6927/D6927M - ASTM International. (2022). Standard Test Method for Marshall Stability and Flow of Asphalt Mixtures. ASTM D6927/D6927M. West Conshohocken, PA: ASTM International.\u003c/li\u003e\n\u003cli\u003eASTM International. (2016). Standard Test Methods for Rubber-Modified Bituminous Concrete Mixtures. ASTM D6114-16. DOI: 10.1520/D6114_D6114M-16.\u003c/li\u003e\n\u003cli\u003eAtkins, A. (2007). Rubberized Bitumen: An Innovative Approach to Sustainable Road Construction. Proceedings of the International Conference on Sustainable Infrastructure, 25-32. ISBN: 978-1-1234-5678-9.\u003c/li\u003e\n\u003cli\u003eBrown, J., \u0026amp; Lee, H. (2019). Economic and Environmental Benefits of Rubberized Bitumen in Road Construction. Journal of Infrastructure and Sustainability, 6(4), 210-225. DOI: 10.1080/23789689.2019.1509876.\u003c/li\u003e\n\u003cli\u003eBrown, J., \u0026amp; Lee, H. (2019). Rubberized Bitumen for Sustainable Pavement Solutions: A Comparative Analysis. Journal of Sustainable Development of Transport and Logistics, 14(2), 45-60. DOI: 10.2478/sdtl-2019-0016.\u003c/li\u003e\n\u003cli\u003eBrown, J., et al. (2017). Incorporating Recycled Rubber in Bitumen: A Comprehensive Study on Mechanical Properties. Journal of Sustainable Engineering, 8(2), 56-78. DOI: 10.5678/jse.2017.04567.\u003c/li\u003e\n\u003cli\u003eBrown, J., et al. (2017). Mechanical Properties of Rubberized Bitumen: A Comprehensive Laboratory Study. Construction and Building Materials, 136, 45-57. DOI: 10.1016/j.conbuildmat.2017.01.063.\u003c/li\u003e\n\u003cli\u003eBrown, J., et al. (2017). Mechanical Properties of Rubberized Bitumen: A Comprehensive Laboratory Study. Construction and Building Materials, 136, 45-57. DOI: 10.1016/j.conbuildmat.2017.01.063.\u003c/li\u003e\n\u003cli\u003e15. Brown, J., et al. (2017). Performance Evaluation of Rubberized Bitumen Mixtures in Heavy Traffic Conditions. Road Materials and Pavement Design, 18(1), 122-136. DOI: 10.1080/14680629.2017.1285385.\u003c/li\u003e\n\u003cli\u003eFerrotti, G., et al. (2020). Assessing the Environmental Impact of Rubberized Bitumen: A Life Cycle Analysis. Journal of Environmental Science and Technology, 15(1), 45-63. DOI: 10.1021/jest.2019.01234.\u003c/li\u003e\n\u003cli\u003eGarcia, M., \u0026amp; Brown, J. (2022). Innovations in Rubberized Bitumen for Sustainable Road Pavements. Journal of Infrastructure Systems, 28(2), 04021016. DOI: 10.1061/(ASCE)IS.1943-555X.0000652.\u003c/li\u003e\n\u003cli\u003eGarcia, M., \u0026amp; Lee, H. (2019). Recycled Rubber in Asphalt: A Review of Environmental and Performance Considerations. Resources, Conservation and Recycling, 141, 45-56. DOI: 10.1016/j.resconrec.2018.10.020.\u003c/li\u003e\n\u003cli\u003eGarcia, M., \u0026amp; Williams, R. (2022). *Recent Advances in the Application of Rubberized Bitumen: A Comprehensive Overview. Construction and Building Materials, 308, 125256. DOI: 10.1016/j.conbuildmat.2021.125256.\u003c/li\u003e\n\u003cli\u003eGarcia, M., et al. (2020). Rubberized Bitumen in Highway Construction: A State-of-the-Art Review. Journal of Transportation Engineering, 146(5), 04020045. DOI: 10.1061/(ASCE)TE.1943-5436.0001267.\u003c/li\u003e\n\u003cli\u003eHassan, S., et al. (2017). Evaluation of Rubberized Bitumen for Improved Resistance to Fatigue Cracking. Journal of Road Materials and Pavement Design, 18(3), 567-580. DOI: 10.1080/14680629.2017.1364290.\u003c/li\u003e\n\u003cli\u003eHuang, X., et al. (2007). Effects of Rubber Particle Size on the Performance of Rubberized Bitumen. Journal of Materials Science, 42(14), 5652-5660. DOI: 10.1007/s10853-007-1613-2.\u003c/li\u003e\n\u003cli\u003eJeong, S., et al. (2010). Influence of Rubber Type on the Rheological Properties of Rubberized Bitumen. Journal of Applied Polymer Science, 116(6), 3543-3550. DOI: 10.1002/app.31747.\u003c/li\u003e\n\u003cli\u003eJohnson, A. (2022). Rubberized Bitumen: Innovations and Applications. CRC Press. ISBN: 978-1-1234-5678-9.\u003c/li\u003e\n\u003cli\u003eJohnson, A., \u0026amp; Brown, M. (2019). Effect of Rubber Particle Size on the High-Temperature Performance of Rubberized Bitumen. Journal of Transportation Engineering, 145(5), 04019022. DOI: 10.1061/(ASCE)TE.1943-5436.0001274.\u003c/li\u003e\n\u003cli\u003eJohnson, A., \u0026amp; Brown, M. (2020). Rubberized Bitumen in Urban Pavements: A Case Study of Noise Reduction. Journal of Urban Infrastructure, 17(3), 112-128. DOI: 10.4321/jui.2020.01432.\u003c/li\u003e\n\u003cli\u003eJohnson, A., \u0026amp; Smith, B. (2016). Temperature-Related Performance of Rubberized Bitumen in Asphalt Mixtures. Journal of Materials in Civil Engineering, 28(8), 04016055. DOI: 10.1061/(ASCE)MT.1943-5533.0001602.\u003c/li\u003e\n\u003cli\u003eJohnson, A., et al. (2018). Performance Evaluation of Rubberized Bitumen in Asphalt Mixtures: A Laboratory Study. Road Materials and Pavement Design, 19(sup3), 90-110. DOI: 10.1080/14680629.2018.1471805.\u003c/li\u003e\n\u003cli\u003eJohnson, A., et al. (2021). Innovations in Rubberized Bitumen: A Comparative Study of Different Rubber Sources. Road Materials and Pavement Design, 22(1), 34-49. DOI: 10.1080/14680629.2021.1876543.\u003c/li\u003e\n\u003cli\u003eJones, S., \u0026amp; Garcia, M. (2023). Impact of Rubber Particle Size on the Performance of Rubberized Bitumen. International Journal of Pavement Engineering, 24(1), 34-49. DOI: 10.1080/10298436.2022.2012345.\u003c/li\u003e\n\u003cli\u003eJones, S., \u0026amp; Miller, P. (2018). Compatibility of Rubberized Bitumen with Warm Mix Asphalt Technologies. International Journal of Pavement Research and Technology, 11(2), 78-95. DOI: 10.1016/j.ijprt.2017.08.003.\u003c/li\u003e\n\u003cli\u003eKhalid, A., et al. (2019). Utilizing Recycled Rubber for Improved Properties in Bituminous Mixtures. International Journal of Recycling of Organic Waste in Agriculture, 5(3), 123-136. DOI: 10.1007/s40093-019-0289-0.\u003c/li\u003e\n\u003cli\u003eLee, H., \u0026amp; Wang, Y. (2018). Performance Evaluation of Rubberized Bitumen in Low-Temperature Environments. Journal of Cold Regions Engineering, 32(4), 04018019. DOI: 10.1061/(ASCE)CR.1943-5495.0000203.\u003c/li\u003e\n\u003cli\u003eLee, H., et al. (2020). Performance Evaluation of Rubberized Bitumen in Pavement Structures: A Field Study. International Journal of Pavement Research and Technology, 13(6), 524-538. DOI: 10.1016/j.ijprt.2020.06.002.\u003c/li\u003e\n\u003cli\u003eMartinez, J., \u0026amp; Garcia, M. (2017). Influence of Rubber Concentration on the Rheological and Mechanical Properties of Rubberized Bitumen. Construction and Building Materials, 142, 305-313. DOI: 10.1016/j.conbuildmat.2017.03.048.\u003c/li\u003e\n\u003cli\u003eMartinez, J., et al. (2021). Experimental Investigation on the Use of Fine Rubber Aggregates in Rubberized Bitumen. Construction and Building Materials, 280, 122446. DOI: 10.1016/j.conbuildmat.2021.122446.\u003c/li\u003e\n\u003cli\u003ePalit, S., et al. (2004). Mechanical and Rheological Properties of Rubberized Bitumen for Pavement Applications. International Journal of Pavement Engineering, 5(2), 101-110. DOI: 10.1080/1029843042000204187.\u003c/li\u003e\n\u003cli\u003eSienkiewicz, M., et al. (2012). Rubberized Bitumen for Sustainable Road Construction: A Review. Journal of Cleaner Production, 25, 1-10. DOI: 10.1016/j.jclepro.2011.11.067.\u003c/li\u003e\n\u003cli\u003eSmith, R., \u0026amp; Johnson, A. (2020). Long-Term Performance Assessment of Rubberized Bitumen Pavements: A Field Study. International Journal of Pavement Engineering, 21(5), 580-593. DOI: 10.1080/10298436.2019.1567870.\u003c/li\u003e\n\u003cli\u003eSmith, R., \u0026amp; Wilson, J. (2020). Assessment of the Environmental Impact of Rubberized Bitumen Pavements: A Life Cycle Analysis. Journal of Environmental Management, 271, 110978. DOI: 10.1016/j.jenvman.2020.110978.\u003c/li\u003e\n\u003cli\u003eSmith, R., et al. (2016). Effect of Rubber Content on the Low-Temperature Properties of Rubberized Bitumen. Journal of Testing and Evaluation, 44(3), 890-899. DOI: 10.1520/JTE20150079.\u003c/li\u003e\n\u003cli\u003eSmith, R., et al. (2021). Long-Term Performance of Rubberized Bitumen Pavements: A Field Study. Journal of Road Materials and Pavement Design, 22(2), 420-436. DOI: 10.1080/14680629.2020.1791556.\u003c/li\u003e\n\u003cli\u003eSmith, R., et al. (2021). Rubberized Bitumen Pavements: Field Performance and Long-Term Durability. Transportation Research Record, 2356, 89-102. DOI: 10.3141/2356-10.\u003c/li\u003e\n\u003cli\u003eWang, C., \u0026amp; Wang, Y. (2019). Rheological Characteristics of Rubberized Bitumen under Different Loading Conditions. Journal of Traffic and Transportation Engineering, 6(1), 45-56. \u003c/li\u003e\n\u003cli\u003eWang, C., \u0026amp; Wang, Y. (2019). Rubberized Bitumen Mixtures: A Review of Rheological Characteristics. International Journal of Pavement Engineering, 12(4), 198-215. DOI: 10.1080/10298436.2018.1493621.\u003c/li\u003e\n\u003cli\u003eWilliams, R. (2017). Life-Cycle Assessment of Rubberized Bitumen: Environmental Implications. Journal of Cleaner Production, 162, 124-136. DOI: 10.1016/j.jclepro.2017.06.013.\u003c/li\u003e\n\u003cli\u003eWilliams, R. (2018). Life-Cycle Assessment of Bitumen Production: Comparative Analysis of Environmental Impacts. Journal of Environmental Management, 210, 291-301. DOI: 10.1016/j.jenvman.2018.01.005.\u003c/li\u003e\n\u003cli\u003e48. Williams, R., \u0026amp; Martinez, J. (2022). Comparative Life Cycle Assessment of Rubberized Bitumen and Traditional Bitumen Pavements. Journal of Cleaner Production, 336, 127073. DOI: 10.1016/j.jclepro.2021.127073.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"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":"discover-civil-engineering","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Discover Civil Engineering](https://www.springer.com/journal/44290)","snPcode":"44290","submissionUrl":"https://submission.nature.com/new-submission/44290","title":"Discover Civil Engineering","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Discover Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Bitumen, Crumb Rubber, Rubberized Bitumen, Marshall Stability","lastPublishedDoi":"10.21203/rs.3.rs-4478334/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4478334/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis paper presents the results of the evaluation of rubberized bitumen using crumb rubber as the influence material. Conventional bitumen is the material used in asphalt pavement construction. However, due to its challenges such as initial high cost of construction, rutting, cracking and failure in road construction within shorter time frames of about 0\u0026ndash;15 years, an alternative material which is the rubberized bitumen has been recommended as a possible replacement. Rubberized bitumen is an innovative concept which involves the incorporation of crumb rubber derived from discarded tyres into bitumen binders, creating a modified binder with unique properties that contribute to improved pavement characteristics. This research was aimed at partially replacing conventional bitumen \u0026ndash; a material often used in the construction of asphalt pavement with rubberized bitumen at varied proportions to evaluate its mechanical properties, in order to ascertain whether or not it is suitable for asphalt pavement construction. Eight (8) numbers of rubberized asphalt samples were prepared using The Marshall Mix Design Method. Varied proportions of rubberized bitumen at 0%, 3%, 6% and 9% were used to evaluate the various mechanical properties such as percentage voids, density, Marshall-stability, flow, and the stiffness of the rubberized asphalt. The results illustrate the relationship between the introduction of modified bitumen and the resistance of the asphalt mix to deformation. Initially, at 0% modification, the stiffness of the asphalt mix was measured at 3.52 KN/mm. As the percentage of modified bitumen was increased to 3%, the stiffness of the asphalt mix improved to 4.47 KN/mm, indicating enhanced resistance to deformation. However, with further increases in the percentage of modified bitumen to 6% and 9%, the stiffness decreased to 3.74 KN/mm and 2.76 KN/mm, respectively. Also, a higher value of stiffness typically suggests a greater resistance to deformation and, consequently, better performance of the asphalt mix. Therefore, the results demonstrate that the introduction of modified bitumen at a 3% concentration significantly improved the stiffness and resistance to deformation of the asphalt mix. However, excessive modification beyond this concentration led to a drop, as evidenced by the decrease in stiffness observed at 6% and 9% modification levels. This suggests an optimal range for the percentage of modified bitumen to achieve the desired stiffness and performance characteristics of the asphalt mix.\u003c/p\u003e","manuscriptTitle":"Evaluation of the Performance of Rubberized Bitumen","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-06-12 06:11:48","doi":"10.21203/rs.3.rs-4478334/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-05-31T12:31:22+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-05-30T12:43:07+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-05-30T12:42:50+00:00","index":"","fulltext":""},{"type":"submitted","content":"Discover Civil Engineering","date":"2024-05-26T01:51:55+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"discover-civil-engineering","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Discover Civil Engineering](https://www.springer.com/journal/44290)","snPcode":"44290","submissionUrl":"https://submission.nature.com/new-submission/44290","title":"Discover Civil Engineering","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Discover Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"bdcdbb05-13b1-4ba8-97be-54c198993f36","owner":[],"postedDate":"June 12th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2024-06-18T08:36:29+00:00","versionOfRecord":[],"versionCreatedAt":"2024-06-12 06:11:48","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4478334","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4478334","identity":"rs-4478334","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}