Performance Evaluation of Crumb Rubber and Basalt Fiber Modified Asphalt Mixes for Sustainable Flexible Pavements

Performance Evaluation of Crumb Rubber and Basalt Fiber Modified Asphalt Mixes for Sustainable Flexible Pavements | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Performance Evaluation of Crumb Rubber and Basalt Fiber Modified Asphalt Mixes for Sustainable Flexible Pavements Yash Bodade, Sumit Shetty, Ashutosh Verma, Om Tekale, Sahil Ilapate, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7695110/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract This study explores the enhancement of asphalt mixtures for flexible pavements by incorporating crumb rubber (CR) at varying percentages and basalt fiber (BF) as a reinforcing agent. The research focuses on modifying bitumen using the wet process, with bitumen content adjusted from 4% to 6%, and evaluates the performance of the resulting asphalt mixtures. The investigation aims to improve the mechanical properties and durability of pavement materials under diverse environmental conditions. The methodology involves preparing Marshall specimens and conducting a series of standard tests to assess the modified bitumen and asphalt mixes. The findings reveal significant improvements in stability and load-bearing capacity with increasing CR and BF percentages, achieving up to 23.1% enhancement in strength. Additionally, the study observes a notable increase in workability and density, reaching up to 1.5% improvement, while addressing air void reduction by up to 18.9%. These enhancements suggest potential for sustainable pavement solutions, though further optimization is indicated to meet stringent durability standards. The research contributes to the development of eco-friendly asphalt materials, utilizing waste rubber and fiber reinforcement, offering insights for future pavement design and construction practices. Asphalt Pavements Crumb Rubber Basalt Fiber Flexible Pavements Sustainable Construction Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Figure 15 Figure 16 1. Introduction In India, the construction sector faces challenges due to highly variable climatic conditions, diverse terrains, and mixed traffic patterns, which elevate the demand on road infrastructure. These factors increase stress on traditional bitumen and bituminous concrete layers, making them prone to rutting, fatigue cracking, deformations, pothole formation, and wear-and-tear issues. To address these challenges and improve the resilience of flexible pavements, it is essential to enhance bitumen and its mixtures through the incorporation of specialized additives, known as bitumen enhancers (Sinha, 2009 ). Various enhancement methods and materials are utilized, including polyethylene (PE), ethylene vinyl acetate (EVA), ethylene butyl acrylate (EBA), ethylene-methyl-acrylate (EMA), styrene-isoprene-styrene (SIS), styrene-butadiene-styrene (SBS), styrene-butadiene rubber (SBR), natural rubber (NR), and crumb rubber modifiers. (Koti Marg & Puram, n.d.) (IS 15462 ( 2004 ) - Polymer and Rubber Modified Bitumen , 2004) 1.1 Basalt Fiber: The durability of pavement is influenced by multiple factors that affect the quality of service provided by road networks. Consequently, research into advanced asphalt materials has become a critical focus in road engineering. The integration of fibers into asphalt has emerged as an effective strategy to boost the performance of asphalt blends. Studies have demonstrated that Basalt Fiber-reinforced Asphalt Mixture (BFAM) exhibits excellent rheological properties under high temperatures (Zhang et al., 2017 ), enhances resistance to permanent deformation(Celauro & Praticò, 2018 ), enhances resistance to permanent deformation(Kong et al., 2022 ) and strengthens fatigue endurance. Studies have highlighted that basalt fiber exhibits limited asphalt absorption, which can lead to poor adhesion of unbound asphalt within the mixture. This phenomenon contributes to pavement bleeding, a deterioration process where unbound asphalt migrates to the surface due to pressure gradients or thermal softening (Krishnan & Rao, n.d.). Consequently, insufficient asphalt absorption by the fibers may trigger bleeding on road surfaces, reducing skid resistance and compromising traffic safety. Previous research has identified factors such as aggregate properties, asphalt binder characteristics, traffic loads, climate, and environmental conditions as contributors to bleeding in asphalt mixtures (Krishnan & Rao, n.d.). This work targets bleeding in basalt fiber-reinforced asphalt mixtures through the use of SEM to examine microstructure and validate phenomena. ECF indicates 9.09% improvement in pavement performance, with the addition of mixed lignin and basalt fibers lowering bleeding by 16.7%. Bleeding is a result of the smooth surface of basalt fibers, low energy, and high expansive voids that bring about bonding problems. The addition of mixed fibers provides reinforcement and presents a suitable solution (Chen et al., 2023 ). Orthogonal analysis was utilized in this research to examine the reinforcement of asphalt mastic using basalt fiber, focusing on fiber concentration, filler-to-asphalt proportions, and asphalt viscosity impacts. Fuzzy Comprehensive Evaluation (FCE) identified optimal ratios for both gap-graded and dense-graded asphalt blends at viscosity levels of 2%, 1.0, 0.7 Pa·s, and 3%, 1.8, 1.1 Pa·s, respectively. Flocculated basalt fiber (FBF) outperformed other fibers, enhancing tensile strength and rheological properties, with the rutting resistance factor improving by over fourfold. The tensile fracture energy of FBF asphalt mastic was three times higher than that of standard mastic, though bundled basalt fiber (BBF) requires pre-breaking due to limited reinforcement efficacy (Shi et al., 2023 ). Studies indicate basalt fiber reinforced asphalt mixtures (BFRAM) exhibit a critical stress intensity factor decreasing and then increasing with an increase in M at medium and low temperatures. Basalt fiber reduces this factor at temperatures of 20°C but increases fracture energy at these temperatures. It optimizes reinforcement for mixed mode fractures, with the generalized maximum tangential stress (GMTS) criterion predicting fracture initiating angles, and a linear empirical fracture criterion efficiently examining mixed modes (Guo et al., 2021 ). Incorporating basalt fiber (BF) improves asphalt mixture and pavement quality. Studies responded to the paucity of data on BF's high-temperature performance through the use of AC-13, SMA-13, and SUP-13 mixtures with dynamic creep, modulus, penetration, and wheel tracking tests. Results indicate BF enhances dynamic stability, penetration strength, modulus index, and flow number, lowering rutting deformation. Dynamic stability follows a polynomial correlation with these parameters, which facilitates high-temperature performance estimation(Jiu et al., 2023 ). From the literature realted to basalt fibers, it is an eco-friendly and cost-effective inorganic fiber, offers high tensile strength, chemical stability, and resistance to thermal variations, corrosion, alkalis, and acids. Literature confirms that basalt fiber asphalt concrete outperforms both conventional asphalt concrete and other fiber-reinforced asphalt concretes in terms of high- and low-temperature performance, water stability, and fatigue resistance, significantly enhancing the pavement properties of asphalt mixtures. As a result, basalt fiber has been widely adopted to improve the mechanical stability of asphalt concrete. Research has determined that the optimal asphalt content for SBS-modified asphalt mixtures with basalt fiber contents of 0.00%, 0.15%, 0.25%, and 0.35% is 4.90%, 5.05%, 5.15%, and 5.20%, respectively. The fiber’s irregular distribution forms a three-dimensional network structure within the mixture. Experimental studies further established that the ideal basalt fiber weight content for optimal performance is 0.3%. 1.2 Crumb Rubber: The disposal of rubber waste is a growing concern, with 60% of waste tyres discarded in urban and rural sites, causing air and aesthetic pollution, health issues, and environmental harm. Crumb rubber, made by grinding distressed tyres into small pieces, is increasingly used in road construction in developing countries, following technical, economic, and ecological guidelines. In India, millions of tons of rubber waste are generated annually, prompting authorities to study its use in highway construction to address pollution and disposal challenges. Using waste tyres in road building reduces the need for natural rocks, mitigates global warming, and improves financial outcomes. The aggregate form of waste tyres mixes well with bitumen, making it a sustainable material for nationwide road construction (Sharma & Singh, 2018 ). The normal procedure included adding modifiers to bitumen for enhancing its strength and extending mix durability while simultaneously reducing global waste tire amounts. Crumb rubber represents auto scrap tire recycling products that consolidate rubber materials from natural sources with both synthetic and carbon black elements. Steel elements and tire lacing remove during recycling until tire rubber remains with either granular or milled-cracked structure. A scrap tire is reduced to small pieces of 1mm to 0.075mm using a crack mill equipped with mechanical blades. The bitumen paving mix receives scrap tire rubber through two fundamental methods known as wet process and dry process. Crumb rubber undergoes the wet process where it receives addition to pure bitumen at temperatures of 180°C to 200°C (Rana Magar, 2014 ). In brief, the mechanical properties of asphalt pavement can be enhanced with the addition of basalt fiber to an asphalt mixture to improve the high-temperature resistance, cracking resistance, and fatigue resistance. Otherwise, its low asphalt absorption can lead to bleeding issues, which can affect the pavement skid resistance. Crumb Rubber: From waste tires, it is an eco-friendly choice to enhance elasticity, durability, and long-term sustainability in asphalt with a positive impact on waste product disposal issues. In this study, asphalt modification using crumb rubber and basalt fiber will be applied for enhancements of performance, durability, and sustainability of pavements. In this study, these materials will be integrated to attain the best mechanical characteristics of flexible pavements while assisting the environment. A set of laboratory tests such as Penetration Test, Softening Point Test, Viscosity Test, Ductility Test, Marshall Test were employed to analyse the appropriate properties of basalt fiber asphalt for various structural types. The basalt fiber-reinforced asphalt mix shows good performance particularly when it still experiences bleeding that would compromise road safety but not passenger comfort. 2 Methodology 2.1 Material 2.1.1 Bitumen Many people make the mistake of calling bitumen from petroleum the same thing as tar. Both bitumen and coal tar appear to be black and sticky substances yet maintain different origins and chemical structures as well as fundamental characteristics. Coal tar emerges as a waste product from the heating process of coal at high temperatures during gas and coke manufacturing. Petroleum bitumen fulfilled the role of binding agent in road asphalt in the first part of the twentieth century until producers substituted 70 percent asphalt with 30 percent bituminous mix components. For Highway Department a combination of VG10 grade bitumen and passageway level 60–70 is utilized while tests must be performed at 160 C heating level with room temperature maintenance before measuring the bitumen's consistency, degree, thickness and temperature. The 60/70 penetration-grade bitumen utilized in this research shows its main physical along with chemical characteristics in the following list. These characteristics ensure its compatibility with crumb rubber and basalt fiber modifications, enhancing the performance of the flexible pavement mix. The physical properties for VG10 grade bitumen shows in table no. 1. Table No. 1 Properties of 60/70 Penetration-Grade Bitumen (VG10) Sr. No. Name of Property Range as per IS Standard IS Code Reference Result 1 Penetration (0.1mm) 60–70 IS 1203( IS 1201 to 1220 (1978): Methods for Testing Tar and Bituminous Materials , 1978) 65 2 Softening Point (°C) 40–55 IS 1205( IS 1201 to 1220 (1978): Methods for Testing Tar and Bituminous Materials , 1978) 48 3 Ductility (cm) ≥ 75 IS 1208( IS 1201 to 1220 (1978): Methods for Testing Tar and Bituminous Materials , 1978) 80 4 Absolute Viscosity (Poise) 800–1200 IS 1206 (Part 2)( IS 1201 to 1220 (1978): Methods for Testing Tar and Bituminous Materials , 1978) 1000 5 Specific Gravity ≥ 0.99 IS 1202( IS 1201 to 1220 (1978): Methods for Testing Tar and Bituminous Materials , 1978) 1.02 2.1.2 Aggregate Ag Aggregates are the primary strength foundation for road structures, forming the base material in construction. Sourced from natural glacial deposits or mines, mineral aggregates for bituminous mixes are processed or used unprocessed to create concrete. Processing enhances their performance quality. Replacing natural aggregates with industrial byproducts like steel slag, blast furnace slag, and fly ash can improve mixed product performance. Aggregates, constituting over 90% of mixture weight, provide the main force-bearing and strength properties. Controlled quality and physical property management are essential for quality pavements. Mixtures were prepared using limestone quarry dust, 10 mm crushed aggregate, and 20 mm graded aggregate in specific proportions with bitumen. 2.1.3 Crumbed Rubber Crumb rubber, derived from recycled waste tires, is incorporated into bitumen as a sustainable modifier to enhance the mechanical properties and durability of flexible pavements while addressing environmental concerns related to tire disposal. Waste tires, composed primarily of natural rubber, synthetic rubber (e.g., styrene-butadiene rubber), and reinforcing agents like carbon black, exhibit excellent physical properties such as high elasticity, tensile strength, and resistance to abrasion and fatigue. These characteristics make crumb rubber a promising additive for improving bitumen’s performance, particularly in reducing temperature susceptibility and enhancing overall pavement resilience. In India, where millions of tons of rubber waste are generated annually, utilizing this material in road construction offers both economic and ecological benefits by minimizing landfill use and pollution. The current study, crumb rubber was sourced from a local tire recycling facility, where discarded automotive tires were processed to remove steel and fabric components, leaving a granular rubber product. The crumb rubber was produced via the crack mill process, yielding particle sizes ranging from 0.075 mm to 1 mm, as this range ensures effective dispersion and interaction with bitumen (Das, 2015 ). The crumb rubber with a particle size of 0.1 mm was used, and the physical and chemical properties of crumb rubber are presented in Table no. 2 & Table no. 3. Table No. 2 Physical Properties of Crumb Rubber ( Rangaraj & Mukesh, 2020 ) Properties Range Specific Gravity 0.52–1.2 Bulk Density 524–1273 kg/m 3 Table No. 3 Chemical Properties of Crumb Rubber ( Rangaraj & Mukesh, 2020 ) Chemical Properties Percentage [%] SBR 48 Carbon black 47 Extender oil 1.9 Stearic acid 0.5 Accelerator 0.7 2.1.4 Basalt Fiber As shown in Fig. 1, this study used 6 mm long short-chopped basalt fibres. The graph shows the technical criteria of Basalt Fibre Chopped Strand (Hayael Aerospace India Private Limited, 2024 ). Every parameter follows set criteria. With a density of 2.65 g/cm³, a length of 6 mm, and a diameter of 13 µm, the fibres show a golden-brown colouration. Non-flammable, they show significant oil absorption (78%), outstanding tensile strength (2365 MPa), and noteworthy heat resistance (91% strength retention). Every test outcome qualifies; therefore, the material is fit for use on bituminous pavements. Fig. No. 1 Basalt Fiber Table No. 4 Technical Data Sheet Basalt Fiber Chopped Strand (Hayael Aerospace India Private Limited, 2024 ) Sr. No. Content and Requirements of Tested Items Results Individual Judgment 1 Appearance Golden Brown Qualified 2 Appearance qualified rate ≥ 90% Yes Qualified 3 Density (g/cm³): 2.6–2.8 2.65 Qualified 4 Nominal length (mm): 3–15 6 Qualified 5 Nominal diameter (µm): 7–25 13 Qualified 6 Oil absorption rate: ≥50% 78 Qualified 7 Flammability Cannot be ignited by open fire Qualified 8 Content of combustible materials: 0.1–1.0% 0.52 Qualified 9 Content of water ≤ 0.2% 0.003 Qualified 10 Tensile strength (MPa): ≥1200 2365 Qualified 11 Elasticity modulus (GPa): ≥75 93.4 Qualified 12 Elongation at break ≤ 3.1% 2.9 Qualified 13 Property of heat resistance, Retention rate of strength at break ≥ 85% 91 Qualified 2.2 Sample Preparation In this study, crumb rubber is used as a partial replacement for bitumen at varying proportions of 0%, 2%, 4%, 6%, and 8% by weight. For the Marshall Stability Test, a combination of crumb rubber (0%, 2%, 4%, 6%, and 8%) and basalt fiber (0%, 0.2%, 0.4%, 0.6%, and 0.8%) is used to evaluate the performance characteristics of the modified asphalt mixtures. The aim is to determine the optimal mix ratio that provides enhanced stability, durability, and resistance to deformation. 3. Result and Discussion The present study worked to assess the performance characteristics of asphalt mix material as it used CR to replace bitumen in quantities between 0% and 8% by weight while adding BF from 0% to 0.8% by weight of the entire mix for the Marshall Stability Test. The study determined the crumb rubber modified bitumen properties through four assessments: Penetration Tests and Softening Point, Ductility, and Viscosity Tests. This part presents and examines solutions to identify the mix ratio that maximizes stability alongside durability and deformation resistance based on the stated objectives. A discussion about the modified bitumen properties begins the section while presenting the Marshall Stability Test results of the asphalt mixtures. 3.1 Penetration Test The Penetration Test was conducted to assess the consistency of bitumen modified with crumb rubber at 0%, 2%, 4%, 6%, and 8% by weight, following IS:1203–1978( IS 1201 to 1220 (1978): Methods for Testing Tar and Bituminous Materials , 1978). The results are presented in Fig. 2, which plots penetration values (in mm) against crumb rubber content. Fig. No. 2 Penetration test on Bitumen with the % addition of Penetration decreased from 70.7 mm (0% CR) to 65.1 mm (8% CR), a 7.9% reduction, indicating that crumb rubber stiffens the bitumen. This trend contrasts with (Rangaraj & Mukesh, 2020 )who reported an increase from 70 mm (0%) to 94 mm (10%), peaking at 99 mm (15%). The stiffening effect suggests improved resistance to deformation at high temperatures, reducing rutting risk in hot climates. For VG30 bitumen, IRC: SP:53-2010 specifies a penetration range of 50–70 mm. The value at 8% CR (65.1 mm) falls within this range, making it suitable for high-traffic roads in warm regions. However, the reduced flexibility may increase brittleness at low temperatures, which warrants further investigation for cold climate applications. 3.2 Softening Point The Softening Point Test was conducted as per IS:1205–1978( IS 1201 to 1220 (1978): Methods for Testing Tar and Bituminous Materials , 1978). The results in Fig. 3 show that the softening point increased from 47°C (0% CR) to 51.9°C (8% CR), indicating improved thermal stability with crumb rubber addition. This trend enhances resistance to deformation at higher temperatures. All modified mixes meet the IRC: SP:53-2010 requirement of a minimum 47°C, making them suitable for high-temperature regions. Fig. No. 3 Bitumen softening test result 3.3 Viscosity Test The Viscosity Test was performed as per IS:1205–1978( IS 1201 to 1220 (1978): Methods for Testing Tar and Bituminous Materials , 1978) to evaluate the flow characteristics of bitumen modified with crumb rubber at 0%, 2%, 4%, 6%, and 8% by weight. The results, presented in Fig. 4, indicate a gradual decrease in viscosity from 90°C (0% CR) to 86.1°C (8% CR), corresponding to a reduction of approximately 4.3%. This decrease suggests that the addition of crumb rubber reduces the flow resistance of the bitumen, enhancing its workability during mixing and compaction processes. However, lower viscosity could potentially affect the binder's performance at high temperatures, reducing its stiffness and resistance to rutting. Therefore, an optimal percentage of crumb rubber needs to be established to balance workability and performance. Fig. No. 4 Bitumen Viscosity Test result 3.4 Ductility Test The Ductility Test was conducted as per IS:1208–1978( IS 1201 to 1220 (1978): Methods for Testing Tar and Bituminous Materials , 1978) to assess the elongation capacity of bitumen modified with crumb rubber at 0%, 2%, 4%, 6%, and 8% by weight. The results in Fig. 5 show a gradual decrease in ductility from 55 cm (0% CR) to 53 cm (8% CR), indicating a reduction of approximately 3.6%. This reduction in ductility suggests that the addition of crumb rubber increases the stiffness of the bitumen, which may enhance its resistance to deformation but could reduce its flexibility. Reduced flexibility could make the modified binder more susceptible to cracking under low temperatures or heavy traffic loads. Fig. No. 5 Bitumen Ductility Test Results 3.5 Marshall Test The Marshall Stability Test was conducted to evaluate the performance of asphalt mixtures modified with crumb rubber and basalt fiber, as per IRC:111–2009(Sinha, 2009 ) shows in table no. 5. The results are analysed through graphs plotting for Mix ID (M1 to M9) against Marshall Stability, Flow Value, Air Voids (Vv), and Voids Filled with Bitumen (VFB), presented and discussed in the study. Table No. 5 Marshall Test Results for Bituminous Mixes with Varying Proportions of Crumb Rubber and Basalt Fiber. Mix ID Crumb Rubber (%) Basalt Fiber (%) Bitumen Content (%) Marshall Stability (kg) Flow Value (mm) Gm (g/cm³) Gt Vv (%) VMA (%) VFB (%) M1 0% 0% 4 650 2.8 2.02 2.473 18.5 26.19 29.3 M2 2% 0% 4.5 680 3 2.03 2.478 17.5 26.45 33.8 M3 4% 0% 5 720 3.2 2.04 2.482 16.5 26.67 38.1 M4 6% 0% 5.5 710 3.4 2.045 2.487 15.8 26.82 41.1 M5 8% 0% 6 690 3.6 2.05 2.492 15 26.92 44.3 M6 2% 0.20% 4 750 2.9 2.03 2.483 17.5 27 29 M7 4% 0.40% 4 800 3 2.04 2.488 16.8 27.43 28.5 M8 6% 0.60% 4 780 3.2 2.035 2.492 16 27.8 28 M9 8% 0.80% 4 760 3.4 2.025 2.497 15.5 28.15 27.5 Fig. No. 6 Marshall Test Specimen 3.5.1 Marshall Test Results and Discussion for Crumb Rubber In figure no. 6: The graph shows Marshall Stability for M1–M5 from Table 5. Stability rises from 650 kg (M1) to 720 kg (M3), a 10.8% increase, then falls to 690 kg (M5). This peak at 4% CR and 4% bitumen shows CR improves strength, similar to (Rangaraj & Mukesh, 2020 ) with 820 kg at 15% rubber. It’s close to IRC:111–2009’s 820 kg for heavy traffic but needs slight improvement. Fig. No. 7 Marshall Stability Test on bitumen with CR In Figure no. 7: the graphs show Flow Value for M1–M5 from Table 5. Flow Value increases linearly from 2.8 mm (M1) to 3.6 mm (M5), a 28.6% rise, due to CR softening the mix. This trend matches Rangaraj and Mukesh (2019), who reported 4.3 mm at 15% rubber. All values (2.8–3.6 mm) are within the IRC:111–2009 range of 2–4 mm, indicating good workability for high-traffic pavements. Fig. No. 8 Flow value on bitumen with CR In Figure no. 8: The graphs show Unit Weight (Gm) for M1–M5 from Table 5. Gm increases from 2.02 g/cm³ (M1) to 2.05 g/cm³ (M5), a 1.5% rise, as bitumen content increases from 4% to 6%. This trend reflects improved density with CR modification, enhancing load distribution for pavements. Fig. No. 9 Unit Weight (Gm) On Bitumen with CR In Figure no. 9: The graph shows Air Voids (Vv) for M1–M5 from Table 5. Vv decreases from 18.5% (M1) to 15.0% (M5), a 18.9% reduction, as bitumen content rises from 4% to 6%. This improvement in packing is noted, but values exceed IRC:111–2009’s 3%–5% range, suggesting potential moisture risks. Fig. No. 10 Air Voids in Bitumen with CR In Figure no. 10: The graph shows Voids Filled with Bitumen (VFB) for M1–M5 from Table 5. VFB increases from 29.3% (M1) to 44.3% (M5), a 51.2% rise, as bitumen content grows from 4% to 6%. However, values are below IRC:111–2009’s 65%–75% range, indicating insufficient bitumen for long-term durability, suggesting a need for mix optimization. Fig. No. 11 Voids Filled with Bitumen and CR 3.5.2 Marshall Test Results and Discussion for Basalt Fiber with Crumb Rubber In Figure no. 11: The graph shows Marshall Stability for M1, M6–M9 from Table 5. Stability rises from 650 kg (M1) to 800 kg (M7), a 23.1% increase, then falls to 760 kg (M9). The peak at 4% CR and 0.4% BF (M7) shows improved strength, aligning with Rangaraj and Mukesh (2019) at 820 kg with 15% rubber. It’s close to IRC:111–2009’s 820 kg for heavy traffic but needs slight adjustment. Fig. No. 12 Marshall Stability on Bitumen with BF and CR In Figure no. 12: The graph shows Flow Value for M1, M6–M9 from Table 5. Flow Value dips to 2.9 mm (M6), rises to 3.4 mm (M9), a 17.2% increase from M1’s 2.8 mm, due to CR softening. Values stay within IRC:111–2009’s 2–4 mm range, ensuring workability, consistent with Rangaraj and Mukesh (2019) at 4.3 mm with 15% rubber. Fig. No. 13 Flow value on bitumen with CR and BS In Figure no. 13: The graph shows Unit Weight (Gm) for M1, M6–M9 from Table 5. Gm rises from 2.02 g/cm³ (M1) to 2.04 g/cm³ (M7), a 1.0% increase, then drops to 2.025 g/cm³ (M9). The peak at 4% CR and 0.4% BF (M7) indicates better density, improving load distribution for pavements. Fig. No. 14 Unit Weight (Gm) On Bitumen with CR and BF In Figure no. 13: The graph shows Air Voids (Vv) for M1, M6–M9 from Table 5. Vv decreases from 18.5% (M1) to 15.5% (M9), an 16.2% reduction, as CR and BF improve packing. However, values exceed IRC:111–2009’s 3%–5% range, indicating potential moisture susceptibility. Fig. No. 15 Air Vois in Bitumen with BS and CR In Figure no. 15: The graph shows Voids Filled with Bitumen (VFB) for M1, M6–M9 from Table 5. VFB decreases from 29.3% (M1) to 27.5% (M9), a 6.1% drop, as CR and BF increase. Values remain below IRC:111–2009’s 65%–75% range, suggesting insufficient bitumen and a need for mix adjustment. Fig. No. 16 Voids Filled with Bitumen, CR, and BF 4. Conclusion The research formulated asphalt mixes using crumb rubber (CR) at 0%, 2%, 4%, 6%, and 8% of the weight of bitumen and basalt fiber (BF) at 0%, 0.2%, 0.4%, 0.6%, and 0.8% of the weight of the total mix. The modified bitumen was obtained by applying the wet process at 180°C–200°C, and the Marshall samples were tested according to IRC:111–2009. Laboratory tests defined the nature of the modified bitumen and modified asphalt to categorize them as being applicable for flexible pavements. 1. 7.9% reduction in penetration was recorded from 70.7 mm to 65.1 mm while using 8% CR, which was stiffer. Softening point rose from 47°C to 51.9°C with enhanced high-temperature stability according to IRC: SP:53-2010.Viscosity reduced by 4.3% (90°C to 86.1°C), making it more workable, whereas ductility reduced by 3.6% (55 cm to 53 cm), suggesting possible low-temperature cracking risk. 2. CR improved stability by 10.8% (720 kg at M3) from 650 kg (M1), and CR + BF gained strength by 23.1% (800 kg at M7) before decreasing to 760 kg (M9) because of excessive BF. Flow increased from 2.8 mm (M1) to 3.6 mm (M5) with CR, a 28.6% improvement, and to 3.4 mm (M9) with CR + BF, within IRC:111–2009's 2–4 mm working range. Unit weight was enhanced by 1.5% (2.02 g/cm³ to 2.05 g/cm³, M5) with CR, and to 2.04 g/cm³ (M7) with CR + BF, increasing load distribution. Our 800 kg (M7) compares favourably with Rangaraj and Mukesh's 820 kg at 15% CR but requires minor adjustment. 3. Air voids reduced by 18.9% (15.0% at M5) with CR and to 15.5% (M9) with CR + BF, but were over IRC:111–2009's 3%–5%, which implies potential moisture susceptibility. VFB increased to 44.3% (M5) with CR and decreased to 27.5% (M9) with CR + BF, below IRC's 65%–75%, and indicating insufficient bitumen and the need for optimization of mix to offer durability. Declarations Author Contribution declaration- All authors contributed equally to the conception, execution, and analysis of the study. The manuscript was drafted and reviewed collaboratively. 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Materials Today: Proceedings , 21 , 460–464. https://doi.org/10.1016/j.matpr.2019.05.465 Sharma U, Singh SK (2018) Engineering and Technology (A High Impact Factor. Int J Innovative Res Sci 7(5). https://doi.org/10.15680/IJIRSET.2018.0704009 Shi C, Wang J, Sun S, Lv D, Xu L, Zhang S (2023) Research on properties of basalt fiber-reinforced asphalt mastic. Frontiers in Materials , 10 . https://doi.org/10.3389/fmats.2023.1277634 Sinha VK (2009) IRC: 111-2009-SPECIFICATIONS FOR DENSE GRADED BITUMINOUS MIXES. INDIAN ROADS CONGRESS Zhang X, Gu X, Lv J, Zou X (2017) 3D numerical model to investigate the rheological properties of basalt fiber reinforced asphalt-like materials. Constr Build Mater 138:185–194. https://doi.org/10.1016/j.conbuildmat.2017.01.110 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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Engineering","correspondingAuthor":false,"prefix":"","firstName":"Sumit","middleName":"","lastName":"Shetty","suffix":""},{"id":527367954,"identity":"306da4b6-1156-4bc3-a69f-16635920939f","order_by":2,"name":"Ashutosh Verma","email":"","orcid":"","institution":"MIT Academy of Engineering","correspondingAuthor":false,"prefix":"","firstName":"Ashutosh","middleName":"","lastName":"Verma","suffix":""},{"id":527367955,"identity":"ceab0cc3-7aaf-43c2-b310-ef24873aa6b6","order_by":3,"name":"Om Tekale","email":"","orcid":"","institution":"MIT Academy of Engineering","correspondingAuthor":false,"prefix":"","firstName":"Om","middleName":"","lastName":"Tekale","suffix":""},{"id":527367956,"identity":"23554bfc-e7e2-4cd6-9346-9931ccd7c32d","order_by":4,"name":"Sahil Ilapate","email":"","orcid":"","institution":"MIT Academy of 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1","display":"","copyAsset":false,"role":"figure","size":225577,"visible":true,"origin":"","legend":"\u003cp\u003eBasalt Fiber\u003c/p\u003e","description":"","filename":"Picture1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7695110/v1/9cda534bbd6ac49f184b872c.jpg"},{"id":93716084,"identity":"9fd27fbc-3a97-4121-9a8a-42a1694f5651","added_by":"auto","created_at":"2025-10-16 19:40:54","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":72409,"visible":true,"origin":"","legend":"\u003cp\u003ePenetration test on Bitumen with the % addition of\u003c/p\u003e","description":"","filename":"Picture2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7695110/v1/58572f22930bcc9c66375a55.jpg"},{"id":93716243,"identity":"0e05feae-f1e5-4a31-8900-1eb021916eda","added_by":"auto","created_at":"2025-10-16 19:48:54","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":77095,"visible":true,"origin":"","legend":"\u003cp\u003eBitumen softening test result\u003c/p\u003e","description":"","filename":"Picture3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7695110/v1/f7cfb10aac1fed315886ba52.jpg"},{"id":93715601,"identity":"fd7313b4-15b8-43f3-a067-988d1cd965b8","added_by":"auto","created_at":"2025-10-16 19:32:54","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":92939,"visible":true,"origin":"","legend":"\u003cp\u003eBitumen Viscosity Test result\u003c/p\u003e","description":"","filename":"Picture4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7695110/v1/cd22c41fd43618a2a69eec1f.jpg"},{"id":93715602,"identity":"1e5b2aa8-a7fd-44b8-bc43-4adfe1be5595","added_by":"auto","created_at":"2025-10-16 19:32:54","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":75892,"visible":true,"origin":"","legend":"\u003cp\u003eBitumen Ductility Test Results\u003c/p\u003e","description":"","filename":"Picture5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7695110/v1/0fa5f35cf67438133d2359b6.jpg"},{"id":93716244,"identity":"03dcf137-618b-4862-a6ae-7ecac9876e78","added_by":"auto","created_at":"2025-10-16 19:48:54","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":116139,"visible":true,"origin":"","legend":"\u003cp\u003eMarshall Test Specimen\u003c/p\u003e","description":"","filename":"Picture6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7695110/v1/00465d43c964a6ced647767f.jpg"},{"id":93716089,"identity":"721dd9c2-8d70-46ab-aa75-f181f1dc33d1","added_by":"auto","created_at":"2025-10-16 19:40:55","extension":"jpg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":87895,"visible":true,"origin":"","legend":"\u003cp\u003eMarshall Stability Test on bitumen with CR\u003c/p\u003e","description":"","filename":"Picture7.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7695110/v1/c8047d23c9182ba3c9d3048b.jpg"},{"id":93715605,"identity":"42ca2545-c0f3-4396-97ab-7fa9c4405f84","added_by":"auto","created_at":"2025-10-16 19:32:54","extension":"jpg","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":69475,"visible":true,"origin":"","legend":"\u003cp\u003eFlow value on bitumen with CR\u003c/p\u003e","description":"","filename":"Picture8.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7695110/v1/19282bfd5bdbe32c7471550d.jpg"},{"id":93715610,"identity":"1128c325-04ec-4e98-949a-2bef39b56d4c","added_by":"auto","created_at":"2025-10-16 19:32:54","extension":"jpg","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":84399,"visible":true,"origin":"","legend":"\u003cp\u003eUnit Weight (Gm) On Bitumen with CR\u003c/p\u003e","description":"","filename":"Picture9.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7695110/v1/28f602c6cdbb792416af86b3.jpg"},{"id":93715613,"identity":"f7a2d68b-79e1-45a8-be12-323d105f46a3","added_by":"auto","created_at":"2025-10-16 19:32:55","extension":"jpg","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":69608,"visible":true,"origin":"","legend":"\u003cp\u003eAir Voids in Bitumen with CR\u003c/p\u003e","description":"","filename":"Picture10.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7695110/v1/1065835ab6b3a19d9e4ba8aa.jpg"},{"id":93716088,"identity":"6c04acde-58e5-43a0-93de-8f5bfc7229d2","added_by":"auto","created_at":"2025-10-16 19:40:55","extension":"jpg","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":73759,"visible":true,"origin":"","legend":"\u003cp\u003eVoids Filled with Bitumen and CR\u003c/p\u003e","description":"","filename":"Picture11.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7695110/v1/c93d12a8a1524ea6b49268ff.jpg"},{"id":93716086,"identity":"3ab48d75-bb44-4037-8efd-4a342af33510","added_by":"auto","created_at":"2025-10-16 19:40:54","extension":"jpg","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":113337,"visible":true,"origin":"","legend":"\u003cp\u003eMarshall Stability on Bitumen with BF and CR\u003c/p\u003e","description":"","filename":"Picture12.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7695110/v1/ef4017a6cba0b56567caaea0.jpg"},{"id":93715612,"identity":"85c468ac-6101-467b-b980-7f6d3867c870","added_by":"auto","created_at":"2025-10-16 19:32:55","extension":"jpg","order_by":13,"title":"Figure 13","display":"","copyAsset":false,"role":"figure","size":77088,"visible":true,"origin":"","legend":"\u003cp\u003eFlow value on bitumen with CR and BS\u003c/p\u003e","description":"","filename":"Picture13.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7695110/v1/c34fc2c9881158462dbab85c.jpg"},{"id":93715611,"identity":"5f4ba555-12a3-414b-80dd-7dd79b11a5ad","added_by":"auto","created_at":"2025-10-16 19:32:55","extension":"jpg","order_by":14,"title":"Figure 14","display":"","copyAsset":false,"role":"figure","size":71369,"visible":true,"origin":"","legend":"\u003cp\u003eUnit Weight (Gm) On Bitumen with CR and BF\u003c/p\u003e","description":"","filename":"Picture14.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7695110/v1/12c4a5f1878f06f41a2dc3c7.jpg"},{"id":93715621,"identity":"7835bba6-c11f-4ea3-ac79-47f30318f2d6","added_by":"auto","created_at":"2025-10-16 19:32:55","extension":"jpg","order_by":15,"title":"Figure 15","display":"","copyAsset":false,"role":"figure","size":66509,"visible":true,"origin":"","legend":"\u003cp\u003eAir Vois in Bitumen with BS and CR\u003c/p\u003e","description":"","filename":"Picture15.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7695110/v1/221a8d845241c6d1bf3be3bf.jpg"},{"id":93715622,"identity":"872472b8-07ae-416f-b064-64b3338c37a1","added_by":"auto","created_at":"2025-10-16 19:32:55","extension":"jpg","order_by":16,"title":"Figure 16","display":"","copyAsset":false,"role":"figure","size":77237,"visible":true,"origin":"","legend":"\u003cp\u003eVoids Filled with Bitumen, CR, and BF\u003c/p\u003e","description":"","filename":"Picture16.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7695110/v1/ca73e8ea31b9607fe1835b3a.jpg"},{"id":99789747,"identity":"033d3325-4edf-478f-aced-7ae91da3a473","added_by":"auto","created_at":"2026-01-08 12:50:30","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2395198,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7695110/v1/666764a5-4be0-4197-a1e6-33c4abe46c02.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Performance Evaluation of Crumb Rubber and Basalt Fiber Modified Asphalt Mixes for Sustainable Flexible Pavements","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eIn India, the construction sector faces challenges due to highly variable climatic conditions, diverse terrains, and mixed traffic patterns, which elevate the demand on road infrastructure. These factors increase stress on traditional bitumen and bituminous concrete layers, making them prone to rutting, fatigue cracking, deformations, pothole formation, and wear-and-tear issues. To address these challenges and improve the resilience of flexible pavements, it is essential to enhance bitumen and its mixtures through the incorporation of specialized additives, known as bitumen enhancers (Sinha, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2009\u003c/span\u003e). Various enhancement methods and materials are utilized, including polyethylene (PE), ethylene vinyl acetate (EVA), ethylene butyl acrylate (EBA), ethylene-methyl-acrylate (EMA), styrene-isoprene-styrene (SIS), styrene-butadiene-styrene (SBS), styrene-butadiene rubber (SBR), natural rubber (NR), and crumb rubber modifiers. (Koti Marg \u0026amp; Puram, n.d.) (IS 15462 (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2004\u003c/span\u003e\u003cem\u003e) - Polymer and Rubber Modified Bitumen\u003c/em\u003e, 2004)\u003c/p\u003e\u003cdiv id=\"Sec2\" class=\"Section2\"\u003e\u003ch2\u003e1.1 Basalt Fiber:\u003c/h2\u003e\u003cp\u003eThe durability of pavement is influenced by multiple factors that affect the quality of service provided by road networks. Consequently, research into advanced asphalt materials has become a critical focus in road engineering. The integration of fibers into asphalt has emerged as an effective strategy to boost the performance of asphalt blends. Studies have demonstrated that Basalt Fiber-reinforced Asphalt Mixture (BFAM) exhibits excellent rheological properties under high temperatures (Zhang et al., \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2017\u003c/span\u003e), enhances resistance to permanent deformation(Celauro \u0026amp; Pratic\u0026ograve;, \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2018\u003c/span\u003e), enhances resistance to permanent deformation(Kong et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) and strengthens fatigue endurance. Studies have highlighted that basalt fiber exhibits limited asphalt absorption, which can lead to poor adhesion of unbound asphalt within the mixture. This phenomenon contributes to pavement bleeding, a deterioration process where unbound asphalt migrates to the surface due to pressure gradients or thermal softening (Krishnan \u0026amp; Rao, n.d.). Consequently, insufficient asphalt absorption by the fibers may trigger bleeding on road surfaces, reducing skid resistance and compromising traffic safety. Previous research has identified factors such as aggregate properties, asphalt binder characteristics, traffic loads, climate, and environmental conditions as contributors to bleeding in asphalt mixtures (Krishnan \u0026amp; Rao, n.d.). This work targets bleeding in basalt fiber-reinforced asphalt mixtures through the use of SEM to examine microstructure and validate phenomena. ECF indicates 9.09% improvement in pavement performance, with the addition of mixed lignin and basalt fibers lowering bleeding by 16.7%. Bleeding is a result of the smooth surface of basalt fibers, low energy, and high expansive voids that bring about bonding problems. The addition of mixed fibers provides reinforcement and presents a suitable solution (Chen et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Orthogonal analysis was utilized in this research to examine the reinforcement of asphalt mastic using basalt fiber, focusing on fiber concentration, filler-to-asphalt proportions, and asphalt viscosity impacts. Fuzzy Comprehensive Evaluation (FCE) identified optimal ratios for both gap-graded and dense-graded asphalt blends at viscosity levels of 2%, 1.0, 0.7 Pa\u0026middot;s, and 3%, 1.8, 1.1 Pa\u0026middot;s, respectively. Flocculated basalt fiber (FBF) outperformed other fibers, enhancing tensile strength and rheological properties, with the rutting resistance factor improving by over fourfold. The tensile fracture energy of FBF asphalt mastic was three times higher than that of standard mastic, though bundled basalt fiber (BBF) requires pre-breaking due to limited reinforcement efficacy (Shi et al., \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Studies indicate basalt fiber reinforced asphalt mixtures (BFRAM) exhibit a critical stress intensity factor decreasing and then increasing with an increase in M at medium and low temperatures. Basalt fiber reduces this factor at temperatures of 20\u0026deg;C but increases fracture energy at these temperatures. It optimizes reinforcement for mixed mode fractures, with the generalized maximum tangential stress (GMTS) criterion predicting fracture initiating angles, and a linear empirical fracture criterion efficiently examining mixed modes (Guo et al., \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Incorporating basalt fiber (BF) improves asphalt mixture and pavement quality. Studies responded to the paucity of data on BF's high-temperature performance through the use of AC-13, SMA-13, and SUP-13 mixtures with dynamic creep, modulus, penetration, and wheel tracking tests. Results indicate BF enhances dynamic stability, penetration strength, modulus index, and flow number, lowering rutting deformation. Dynamic stability follows a polynomial correlation with these parameters, which facilitates high-temperature performance estimation(Jiu et al., \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). From the literature realted to basalt fibers, it is an eco-friendly and cost-effective inorganic fiber, offers high tensile strength, chemical stability, and resistance to thermal variations, corrosion, alkalis, and acids. Literature confirms that basalt fiber asphalt concrete outperforms both conventional asphalt concrete and other fiber-reinforced asphalt concretes in terms of high- and low-temperature performance, water stability, and fatigue resistance, significantly enhancing the pavement properties of asphalt mixtures. As a result, basalt fiber has been widely adopted to improve the mechanical stability of asphalt concrete. Research has determined that the optimal asphalt content for SBS-modified asphalt mixtures with basalt fiber contents of 0.00%, 0.15%, 0.25%, and 0.35% is 4.90%, 5.05%, 5.15%, and 5.20%, respectively. The fiber\u0026rsquo;s irregular distribution forms a three-dimensional network structure within the mixture. Experimental studies further established that the ideal basalt fiber weight content for optimal performance is 0.3%.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003e1.2 Crumb Rubber:\u003c/h2\u003e\u003cp\u003eThe disposal of rubber waste is a growing concern, with 60% of waste tyres discarded in urban and rural sites, causing air and aesthetic pollution, health issues, and environmental harm. Crumb rubber, made by grinding distressed tyres into small pieces, is increasingly used in road construction in developing countries, following technical, economic, and ecological guidelines. In India, millions of tons of rubber waste are generated annually, prompting authorities to study its use in highway construction to address pollution and disposal challenges. Using waste tyres in road building reduces the need for natural rocks, mitigates global warming, and improves financial outcomes. The aggregate form of waste tyres mixes well with bitumen, making it a sustainable material for nationwide road construction (Sharma \u0026amp; Singh, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). The normal procedure included adding modifiers to bitumen for enhancing its strength and extending mix durability while simultaneously reducing global waste tire amounts. Crumb rubber represents auto scrap tire recycling products that consolidate rubber materials from natural sources with both synthetic and carbon black elements. Steel elements and tire lacing remove during recycling until tire rubber remains with either granular or milled-cracked structure. A scrap tire is reduced to small pieces of 1mm to 0.075mm using a crack mill equipped with mechanical blades. The bitumen paving mix receives scrap tire rubber through two fundamental methods known as wet process and dry process. Crumb rubber undergoes the wet process where it receives addition to pure bitumen at temperatures of 180\u0026deg;C to 200\u0026deg;C (Rana Magar, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2014\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eIn brief, the mechanical properties of asphalt pavement can be enhanced with the addition of basalt fiber to an asphalt mixture to improve the high-temperature resistance, cracking resistance, and fatigue resistance. Otherwise, its low asphalt absorption can lead to bleeding issues, which can affect the pavement skid resistance. Crumb Rubber: From waste tires, it is an eco-friendly choice to enhance elasticity, durability, and long-term sustainability in asphalt with a positive impact on waste product disposal issues. In this study, asphalt modification using crumb rubber and basalt fiber will be applied for enhancements of performance, durability, and sustainability of pavements. In this study, these materials will be integrated to attain the best mechanical characteristics of flexible pavements while assisting the environment.\u003c/p\u003e\u003cp\u003eA set of laboratory tests such as Penetration Test, Softening Point Test, Viscosity Test, Ductility Test, Marshall Test were employed to analyse the appropriate properties of basalt fiber asphalt for various structural types. The basalt fiber-reinforced asphalt mix shows good performance particularly when it still experiences bleeding that would compromise road safety but not passenger comfort.\u003c/p\u003e\u003c/div\u003e"},{"header":"2 Methodology","content":"\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\u003ch2\u003e2.1 Material\u003c/h2\u003e\u003cdiv id=\"Sec6\" class=\"Section3\"\u003e\u003ch2\u003e2.1.1 Bitumen\u003c/h2\u003e\u003cp\u003eMany people make the mistake of calling bitumen from petroleum the same thing as tar. Both bitumen and coal tar appear to be black and sticky substances yet maintain different origins and chemical structures as well as fundamental characteristics. Coal tar emerges as a waste product from the heating process of coal at high temperatures during gas and coke manufacturing. Petroleum bitumen fulfilled the role of binding agent in road asphalt in the first part of the twentieth century until producers substituted 70 percent asphalt with 30 percent bituminous mix components. For Highway Department a combination of VG10 grade bitumen and passageway level 60\u0026ndash;70 is utilized while tests must be performed at 160 C heating level with room temperature maintenance before measuring the bitumen's consistency, degree, thickness and temperature.\u003c/p\u003e\u003cp\u003eThe 60/70 penetration-grade bitumen utilized in this research shows its main physical along with chemical characteristics in the following list. These characteristics ensure its compatibility with crumb rubber and basalt fiber modifications, enhancing the performance of the flexible pavement mix. The physical properties for VG10 grade bitumen shows in table no. 1.\u003c/p\u003e\u003cp\u003e\u003cb\u003eTable No. 1\u003c/b\u003e Properties of 60/70 Penetration-Grade Bitumen (VG10)\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Taba\" border=\"1\"\u003e\u003ccolgroup cols=\"5\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSr. No.\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eName of Property\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eRange as per IS Standard\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eIS Code Reference\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eResult\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePenetration (0.1mm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e60\u0026ndash;70\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eIS 1203(\u003cem\u003eIS 1201 to 1220 (1978): Methods for Testing Tar and Bituminous Materials\u003c/em\u003e, 1978)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e65\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSoftening Point (\u0026deg;C)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e40\u0026ndash;55\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eIS 1205(\u003cem\u003eIS 1201 to 1220 (1978): Methods for Testing Tar and Bituminous Materials\u003c/em\u003e, 1978)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e48\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDuctility (cm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026ge;\u0026thinsp;75\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eIS 1208(\u003cem\u003eIS 1201 to 1220 (1978): Methods for Testing Tar and Bituminous Materials\u003c/em\u003e, 1978)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e80\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAbsolute Viscosity (Poise)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e800\u0026ndash;1200\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eIS 1206 (Part 2)(\u003cem\u003eIS 1201 to 1220 (1978): Methods for Testing Tar and Bituminous Materials\u003c/em\u003e, 1978)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1000\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSpecific Gravity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026ge;\u0026thinsp;0.99\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eIS 1202(\u003cem\u003eIS 1201 to 1220 (1978): Methods for Testing Tar and Bituminous Materials\u003c/em\u003e, 1978)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.02\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec7\" class=\"Section3\"\u003e\u003ch2\u003e2.1.2 Aggregate\u003c/h2\u003e\u003cp\u003eAg Aggregates are the primary strength foundation for road structures, forming the base material in construction. Sourced from natural glacial deposits or mines, mineral aggregates for bituminous mixes are processed or used unprocessed to create concrete. Processing enhances their performance quality. Replacing natural aggregates with industrial byproducts like steel slag, blast furnace slag, and fly ash can improve mixed product performance. Aggregates, constituting over 90% of mixture weight, provide the main force-bearing and strength properties. Controlled quality and physical property management are essential for quality pavements. Mixtures were prepared using limestone quarry dust, 10 mm crushed aggregate, and 20 mm graded aggregate in specific proportions with bitumen.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec8\" class=\"Section3\"\u003e\u003ch2\u003e2.1.3 Crumbed Rubber\u003c/h2\u003e\u003cp\u003eCrumb rubber, derived from recycled waste tires, is incorporated into bitumen as a sustainable modifier to enhance the mechanical properties and durability of flexible pavements while addressing environmental concerns related to tire disposal. Waste tires, composed primarily of natural rubber, synthetic rubber (e.g., styrene-butadiene rubber), and reinforcing agents like carbon black, exhibit excellent physical properties such as high elasticity, tensile strength, and resistance to abrasion and fatigue. These characteristics make crumb rubber a promising additive for improving bitumen\u0026rsquo;s performance, particularly in reducing temperature susceptibility and enhancing overall pavement resilience. In India, where millions of tons of rubber waste are generated annually, utilizing this material in road construction offers both economic and ecological benefits by minimizing landfill use and pollution.\u003c/p\u003e\u003cp\u003eThe current study, crumb rubber was sourced from a local tire recycling facility, where discarded automotive tires were processed to remove steel and fabric components, leaving a granular rubber product. The crumb rubber was produced via the crack mill process, yielding particle sizes ranging from 0.075 mm to 1 mm, as this range ensures effective dispersion and interaction with bitumen (Das, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). The crumb rubber with a particle size of 0.1 mm was used, and the physical and chemical properties of crumb rubber are presented in Table no. 2 \u0026amp; Table no. 3.\u003c/p\u003e\u003cp\u003e\u003cb\u003eTable No. 2\u003c/b\u003e Physical Properties of Crumb Rubber\u003cem\u003e(\u003c/em\u003eRangaraj \u0026amp; Mukesh, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2020\u003c/span\u003e\u003cem\u003e)\u003c/em\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Tabb\" border=\"1\"\u003e\u003ccolgroup cols=\"2\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eProperties\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRange\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSpecific Gravity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.52\u0026ndash;1.2\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBulk Density\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e524\u0026ndash;1273 kg/m\u003csup\u003e3\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eTable No. 3\u003c/b\u003e Chemical Properties of Crumb Rubber\u003cem\u003e(\u003c/em\u003eRangaraj \u0026amp; Mukesh, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2020\u003c/span\u003e\u003cem\u003e)\u003c/em\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Tabc\" border=\"1\"\u003e\u003ccolgroup cols=\"2\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eChemical Properties\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePercentage [%]\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSBR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e48\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCarbon black\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e47\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eExtender oil\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1.9\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eStearic acid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.5\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAccelerator\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.7\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec9\" class=\"Section3\"\u003e\u003ch2\u003e2.1.4 Basalt Fiber\u003c/h2\u003e\u003cp\u003eAs shown in Fig.\u0026nbsp;1, this study used 6 mm long short-chopped basalt fibres. The graph shows the technical criteria of Basalt Fibre Chopped Strand (Hayael Aerospace India Private Limited, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). Every parameter follows set criteria. With a density of 2.65 g/cm\u0026sup3;, a length of 6 mm, and a diameter of 13 \u0026micro;m, the fibres show a golden-brown colouration. Non-flammable, they show significant oil absorption (78%), outstanding tensile strength (2365 MPa), and noteworthy heat resistance (91% strength retention). Every test outcome qualifies; therefore, the material is fit for use on bituminous pavements.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eFig. No. 1\u003c/b\u003e Basalt Fiber\u003c/p\u003e\u003cp\u003e\u003cb\u003eTable No. 4\u003c/b\u003e Technical Data Sheet Basalt Fiber Chopped Strand (Hayael Aerospace India Private Limited, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2024\u003c/span\u003e)\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Tabd\" border=\"1\"\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSr. No.\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eContent and Requirements of Tested Items\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eResults\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eIndividual Judgment\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAppearance\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eGolden Brown\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eQualified\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAppearance qualified rate\u0026thinsp;\u0026ge;\u0026thinsp;90%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eYes\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eQualified\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDensity (g/cm\u0026sup3;): 2.6\u0026ndash;2.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2.65\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eQualified\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNominal length (mm): 3\u0026ndash;15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eQualified\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNominal diameter (\u0026micro;m): 7\u0026ndash;25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e13\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eQualified\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eOil absorption rate: \u0026ge;50%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e78\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eQualified\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFlammability\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eCannot be ignited by open fire\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eQualified\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eContent of combustible materials: 0.1\u0026ndash;1.0%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.52\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eQualified\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eContent of water\u0026thinsp;\u0026le;\u0026thinsp;0.2%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.003\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eQualified\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eTensile strength (MPa): \u0026ge;1200\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2365\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eQualified\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eElasticity modulus (GPa): \u0026ge;75\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e93.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eQualified\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eElongation at break\u0026thinsp;\u0026le;\u0026thinsp;3.1%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eQualified\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e13\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eProperty of heat resistance, Retention rate of strength at break\u0026thinsp;\u0026ge;\u0026thinsp;85%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e91\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eQualified\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e\u003ch2\u003e2.2 Sample Preparation\u003c/h2\u003e\u003cp\u003eIn this study, crumb rubber is used as a partial replacement for bitumen at varying proportions of 0%, 2%, 4%, 6%, and 8% by weight. For the Marshall Stability Test, a combination of crumb rubber (0%, 2%, 4%, 6%, and 8%) and basalt fiber (0%, 0.2%, 0.4%, 0.6%, and 0.8%) is used to evaluate the performance characteristics of the modified asphalt mixtures. The aim is to determine the optimal mix ratio that provides enhanced stability, durability, and resistance to deformation.\u003c/p\u003e\u003c/div\u003e"},{"header":"3. Result and Discussion","content":"\u003cp\u003eThe present study worked to assess the performance characteristics of asphalt mix material as it used CR to replace bitumen in quantities between 0% and 8% by weight while adding BF from 0% to 0.8% by weight of the entire mix for the Marshall Stability Test. The study determined the crumb rubber modified bitumen properties through four assessments: Penetration Tests and Softening Point, Ductility, and Viscosity Tests. This part presents and examines solutions to identify the mix ratio that maximizes stability alongside durability and deformation resistance based on the stated objectives. A discussion about the modified bitumen properties begins the section while presenting the Marshall Stability Test results of the asphalt mixtures.\u003c/p\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003e3.1 Penetration Test\u003c/h2\u003e\u003cp\u003eThe Penetration Test was conducted to assess the consistency of bitumen modified with crumb rubber at 0%, 2%, 4%, 6%, and 8% by weight, following IS:1203\u0026ndash;1978(\u003cem\u003eIS 1201 to 1220 (1978): Methods for Testing Tar and Bituminous Materials\u003c/em\u003e, 1978). The results are presented in Fig.\u0026nbsp;2, which plots penetration values (in mm) against crumb rubber content.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eFig. No. 2\u003c/b\u003e Penetration test on Bitumen with the % addition of\u003c/p\u003e\u003cp\u003ePenetration decreased from 70.7 mm (0% CR) to 65.1 mm (8% CR), a 7.9% reduction, indicating that crumb rubber stiffens the bitumen. This trend contrasts with (Rangaraj \u0026amp; Mukesh, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2020\u003c/span\u003e)who reported an increase from 70 mm (0%) to 94 mm (10%), peaking at 99 mm (15%). The stiffening effect suggests improved resistance to deformation at high temperatures, reducing rutting risk in hot climates. For VG30 bitumen, IRC: SP:53-2010 specifies a penetration range of 50\u0026ndash;70 mm. The value at 8% CR (65.1 mm) falls within this range, making it suitable for high-traffic roads in warm regions. However, the reduced flexibility may increase brittleness at low temperatures, which warrants further investigation for cold climate applications.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\u003ch2\u003e3.2 Softening Point\u003c/h2\u003e\u003cp\u003eThe Softening Point Test was conducted as per IS:1205\u0026ndash;1978(\u003cem\u003eIS 1201 to 1220 (1978): Methods for Testing Tar and Bituminous Materials\u003c/em\u003e, 1978). The results in Fig.\u0026nbsp;3 show that the softening point increased from 47\u0026deg;C (0% CR) to 51.9\u0026deg;C (8% CR), indicating improved thermal stability with crumb rubber addition. This trend enhances resistance to deformation at higher temperatures. All modified mixes meet the IRC: SP:53-2010 requirement of a minimum 47\u0026deg;C, making them suitable for high-temperature regions.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eFig. No. 3\u003c/b\u003e Bitumen softening test result\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\u003ch2\u003e3.3 Viscosity Test\u003c/h2\u003e\u003cp\u003eThe Viscosity Test was performed as per IS:1205\u0026ndash;1978(\u003cem\u003eIS 1201 to 1220 (1978): Methods for Testing Tar and Bituminous Materials\u003c/em\u003e, 1978) to evaluate the flow characteristics of bitumen modified with crumb rubber at 0%, 2%, 4%, 6%, and 8% by weight. The results, presented in Fig.\u0026nbsp;4, indicate a gradual decrease in viscosity from 90\u0026deg;C (0% CR) to 86.1\u0026deg;C (8% CR), corresponding to a reduction of approximately 4.3%. This decrease suggests that the addition of crumb rubber reduces the flow resistance of the bitumen, enhancing its workability during mixing and compaction processes. However, lower viscosity could potentially affect the binder's performance at high temperatures, reducing its stiffness and resistance to rutting. Therefore, an optimal percentage of crumb rubber needs to be established to balance workability and performance.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eFig. No. 4\u003c/b\u003e Bitumen Viscosity Test result\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e\u003ch2\u003e3.4 Ductility Test\u003c/h2\u003e\u003cp\u003eThe Ductility Test was conducted as per IS:1208\u0026ndash;1978(\u003cem\u003eIS 1201 to 1220 (1978): Methods for Testing Tar and Bituminous Materials\u003c/em\u003e, 1978) to assess the elongation capacity of bitumen modified with crumb rubber at 0%, 2%, 4%, 6%, and 8% by weight. The results in Fig.\u0026nbsp;5 show a gradual decrease in ductility from 55 cm (0% CR) to 53 cm (8% CR), indicating a reduction of approximately 3.6%. This reduction in ductility suggests that the addition of crumb rubber increases the stiffness of the bitumen, which may enhance its resistance to deformation but could reduce its flexibility. Reduced flexibility could make the modified binder more susceptible to cracking under low temperatures or heavy traffic loads.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eFig. No. 5\u003c/b\u003e Bitumen Ductility Test Results\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec16\" class=\"Section2\"\u003e\u003ch2\u003e3.5 Marshall Test\u003c/h2\u003e\u003cp\u003eThe Marshall Stability Test was conducted to evaluate the performance of asphalt mixtures modified with crumb rubber and basalt fiber, as per IRC:111\u0026ndash;2009(Sinha, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2009\u003c/span\u003e) shows in table no. 5. The results are analysed through graphs plotting for Mix ID (M1 to M9) against Marshall Stability, Flow Value, Air Voids (Vv), and Voids Filled with Bitumen (VFB), presented and discussed in the study.\u003c/p\u003e\u003cp\u003e\u003cb\u003eTable No. 5\u003c/b\u003e Marshall Test Results for Bituminous Mixes with Varying Proportions of Crumb Rubber and Basalt Fiber.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Tabe\" border=\"1\"\u003e\u003ccolgroup cols=\"11\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMix ID\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCrumb Rubber (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eBasalt Fiber (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eBitumen Content (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eMarshall Stability (kg)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eFlow Value (mm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eGm (g/cm\u0026sup3;)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003eGt\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003eVv (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c10\"\u003e\u003cp\u003eVMA (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c11\"\u003e\u003cp\u003eVFB (%)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eM1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e650\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e2.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e2.02\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e2.473\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e18.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e26.19\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e29.3\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eM2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e4.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e680\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e2.03\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e2.478\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e17.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e26.45\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e33.8\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eM3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e720\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e3.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e2.04\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e2.482\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e16.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e26.67\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e38.1\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eM4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e6%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e5.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e710\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e3.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e2.045\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e2.487\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e15.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e26.82\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e41.1\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eM5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e8%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e690\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e3.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e2.05\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e2.492\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e26.92\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e44.3\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eM6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.20%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e750\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e2.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e2.03\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e2.483\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e17.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e27\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e29\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eM7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.40%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e800\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e2.04\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e2.488\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e16.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e27.43\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e28.5\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eM8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e6%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.60%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e780\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e3.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e2.035\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e2.492\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e27.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e28\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eM9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e8%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.80%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e760\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e3.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e2.025\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e2.497\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e15.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e28.15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e27.5\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eFig. No. 6\u003c/b\u003e Marshall Test Specimen\u003c/p\u003e\u003cdiv id=\"Sec17\" class=\"Section3\"\u003e\u003ch2\u003e3.5.1 Marshall Test Results and Discussion for Crumb Rubber\u003c/h2\u003e\u003cp\u003eIn figure no. 6: The graph shows Marshall Stability for M1\u0026ndash;M5 from Table\u0026nbsp;5. Stability rises from 650 kg (M1) to 720 kg (M3), a 10.8% increase, then falls to 690 kg (M5). This peak at 4% CR and 4% bitumen shows CR improves strength, similar to (Rangaraj \u0026amp; Mukesh, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2020\u003c/span\u003e) with 820 kg at 15% rubber. It\u0026rsquo;s close to IRC:111\u0026ndash;2009\u0026rsquo;s 820 kg for heavy traffic but needs slight improvement.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eFig. No. 7\u003c/b\u003e Marshall Stability Test on bitumen with CR\u003c/p\u003e\u003cp\u003eIn Figure no. 7: the graphs show Flow Value for M1\u0026ndash;M5 from Table\u0026nbsp;5. Flow Value increases linearly from 2.8 mm (M1) to 3.6 mm (M5), a 28.6% rise, due to CR softening the mix. This trend matches Rangaraj and Mukesh (2019), who reported 4.3 mm at 15% rubber. All values (2.8\u0026ndash;3.6 mm) are within the IRC:111\u0026ndash;2009 range of 2\u0026ndash;4 mm, indicating good workability for high-traffic pavements.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eFig. No. 8\u003c/b\u003e Flow value on bitumen with CR\u003c/p\u003e\u003cp\u003eIn Figure no. 8: The graphs show Unit Weight (Gm) for M1\u0026ndash;M5 from Table\u0026nbsp;5. Gm increases from 2.02 g/cm\u0026sup3; (M1) to 2.05 g/cm\u0026sup3; (M5), a 1.5% rise, as bitumen content increases from 4% to 6%. This trend reflects improved density with CR modification, enhancing load distribution for pavements.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eFig. No. 9\u003c/b\u003e Unit Weight (Gm) On Bitumen with CR\u003c/p\u003e\u003cp\u003eIn Figure no. 9: The graph shows Air Voids (Vv) for M1\u0026ndash;M5 from Table\u0026nbsp;5. Vv decreases from 18.5% (M1) to 15.0% (M5), a 18.9% reduction, as bitumen content rises from 4% to 6%. This improvement in packing is noted, but values exceed IRC:111\u0026ndash;2009\u0026rsquo;s 3%\u0026ndash;5% range, suggesting potential moisture risks.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eFig. No. 10\u003c/b\u003e Air Voids in Bitumen with CR\u003c/p\u003e\u003cp\u003eIn Figure no. 10: The graph shows Voids Filled with Bitumen (VFB) for M1\u0026ndash;M5 from Table\u0026nbsp;5. VFB increases from 29.3% (M1) to 44.3% (M5), a 51.2% rise, as bitumen content grows from 4% to 6%. However, values are below IRC:111\u0026ndash;2009\u0026rsquo;s 65%\u0026ndash;75% range, indicating insufficient bitumen for long-term durability, suggesting a need for mix optimization.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eFig. No. 11\u003c/b\u003e Voids Filled with Bitumen and CR\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec18\" class=\"Section3\"\u003e\u003ch2\u003e3.5.2 Marshall Test Results and Discussion for Basalt Fiber with Crumb Rubber\u003c/h2\u003e\u003cp\u003eIn Figure no. 11: The graph shows Marshall Stability for M1, M6\u0026ndash;M9 from Table\u0026nbsp;5. Stability rises from 650 kg (M1) to 800 kg (M7), a 23.1% increase, then falls to 760 kg (M9). The peak at 4% CR and 0.4% BF (M7) shows improved strength, aligning with Rangaraj and Mukesh (2019) at 820 kg with 15% rubber. It\u0026rsquo;s close to IRC:111\u0026ndash;2009\u0026rsquo;s 820 kg for heavy traffic but needs slight adjustment.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eFig. No. 12\u003c/b\u003e Marshall Stability on Bitumen with BF and CR\u003c/p\u003e\u003cp\u003eIn Figure no. 12: The graph shows Flow Value for M1, M6\u0026ndash;M9 from Table\u0026nbsp;5. Flow Value dips to 2.9 mm (M6), rises to 3.4 mm (M9), a 17.2% increase from M1\u0026rsquo;s 2.8 mm, due to CR softening. Values stay within IRC:111\u0026ndash;2009\u0026rsquo;s 2\u0026ndash;4 mm range, ensuring workability, consistent with Rangaraj and Mukesh (2019) at 4.3 mm with 15% rubber.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eFig. No. 13\u003c/b\u003e Flow value on bitumen with CR and BS\u003c/p\u003e\u003cp\u003eIn Figure no. 13: The graph shows Unit Weight (Gm) for M1, M6\u0026ndash;M9 from Table\u0026nbsp;5. Gm rises from 2.02 g/cm\u0026sup3; (M1) to 2.04 g/cm\u0026sup3; (M7), a 1.0% increase, then drops to 2.025 g/cm\u0026sup3; (M9). The peak at 4% CR and 0.4% BF (M7) indicates better density, improving load distribution for pavements.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eFig. No. 14\u003c/b\u003e Unit Weight (Gm) On Bitumen with CR and BF\u003c/p\u003e\u003cp\u003eIn Figure no. 13: The graph shows Air Voids (Vv) for M1, M6\u0026ndash;M9 from Table\u0026nbsp;5. Vv decreases from 18.5% (M1) to 15.5% (M9), an 16.2% reduction, as CR and BF improve packing. However, values exceed IRC:111\u0026ndash;2009\u0026rsquo;s 3%\u0026ndash;5% range, indicating potential moisture susceptibility.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eFig. No. 15\u003c/b\u003e Air Vois in Bitumen with BS and CR\u003c/p\u003e\u003cp\u003eIn Figure no. 15: The graph shows Voids Filled with Bitumen (VFB) for M1, M6\u0026ndash;M9 from Table\u0026nbsp;5. VFB decreases from 29.3% (M1) to 27.5% (M9), a 6.1% drop, as CR and BF increase. Values remain below IRC:111\u0026ndash;2009\u0026rsquo;s 65%\u0026ndash;75% range, suggesting insufficient bitumen and a need for mix adjustment.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eFig. No. 16\u003c/b\u003e Voids Filled with Bitumen, CR, and BF\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eThe research formulated asphalt mixes using crumb rubber (CR) at 0%, 2%, 4%, 6%, and 8% of the weight of bitumen and basalt fiber (BF) at 0%, 0.2%, 0.4%, 0.6%, and 0.8% of the weight of the total mix. The modified bitumen was obtained by applying the wet process at 180\u0026deg;C\u0026ndash;200\u0026deg;C, and the Marshall samples were tested according to IRC:111\u0026ndash;2009. Laboratory tests defined the nature of the modified bitumen and modified asphalt to categorize them as being applicable for flexible pavements.\u003c/p\u003e\u003cp\u003e1. 7.9% reduction in penetration was recorded from 70.7 mm to 65.1 mm while using 8% CR, which was stiffer. Softening point rose from 47\u0026deg;C to 51.9\u0026deg;C with enhanced high-temperature stability according to IRC: SP:53-2010.Viscosity reduced by 4.3% (90\u0026deg;C to 86.1\u0026deg;C), making it more workable, whereas ductility reduced by 3.6% (55 cm to 53 cm), suggesting possible low-temperature cracking risk.\u003c/p\u003e\u003cp\u003e2. CR improved stability by 10.8% (720 kg at M3) from 650 kg (M1), and CR\u0026thinsp;+\u0026thinsp;BF gained strength by 23.1% (800 kg at M7) before decreasing to 760 kg (M9) because of excessive BF. Flow increased from 2.8 mm (M1) to 3.6 mm (M5) with CR, a 28.6% improvement, and to 3.4 mm (M9) with CR\u0026thinsp;+\u0026thinsp;BF, within IRC:111\u0026ndash;2009's 2\u0026ndash;4 mm working range. Unit weight was enhanced by 1.5% (2.02 g/cm\u0026sup3; to 2.05 g/cm\u0026sup3;, M5) with CR, and to 2.04 g/cm\u0026sup3; (M7) with CR\u0026thinsp;+\u0026thinsp;BF, increasing load distribution. Our 800 kg (M7) compares favourably with Rangaraj and Mukesh's 820 kg at 15% CR but requires minor adjustment.\u003c/p\u003e\u003cp\u003e3. Air voids reduced by 18.9% (15.0% at M5) with CR and to 15.5% (M9) with CR\u0026thinsp;+\u0026thinsp;BF, but were over IRC:111\u0026ndash;2009's 3%\u0026ndash;5%, which implies potential moisture susceptibility. VFB increased to 44.3% (M5) with CR and decreased to 27.5% (M9) with CR\u0026thinsp;+\u0026thinsp;BF, below IRC's 65%\u0026ndash;75%, and indicating insufficient bitumen and the need for optimization of mix to offer durability.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution declaration-\u003c/h2\u003e\n\u003cp\u003eAll authors contributed equally to the conception, execution, and analysis of the study. The manuscript was drafted and reviewed collaboratively. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003ch2\u003eFunding \u0026ndash;\u003c/h2\u003e\n\u003cp\u003eThere is no agency involved in any type funding for the work.\u003c/p\u003e\n\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\n\u003cp\u003eAll authors contributed equally to the conception, execution, and analysis of the study. The manuscript was drafted and reviewed collaboratively. 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Constr Build Mater 138:185\u0026ndash;194. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.conbuildmat.2017.01.110\u003c/span\u003e\u003cspan address=\"10.1016/j.conbuildmat.2017.01.110\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Asphalt Pavements, Crumb Rubber, Basalt Fiber, Flexible Pavements, Sustainable Construction","lastPublishedDoi":"10.21203/rs.3.rs-7695110/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7695110/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis study explores the enhancement of asphalt mixtures for flexible pavements by incorporating crumb rubber (CR) at varying percentages and basalt fiber (BF) as a reinforcing agent. The research focuses on modifying bitumen using the wet process, with bitumen content adjusted from 4% to 6%, and evaluates the performance of the resulting asphalt mixtures. The investigation aims to improve the mechanical properties and durability of pavement materials under diverse environmental conditions. The methodology involves preparing Marshall specimens and conducting a series of standard tests to assess the modified bitumen and asphalt mixes. The findings reveal significant improvements in stability and load-bearing capacity with increasing CR and BF percentages, achieving up to 23.1% enhancement in strength. Additionally, the study observes a notable increase in workability and density, reaching up to 1.5% improvement, while addressing air void reduction by up to 18.9%. These enhancements suggest potential for sustainable pavement solutions, though further optimization is indicated to meet stringent durability standards. The research contributes to the development of eco-friendly asphalt materials, utilizing waste rubber and fiber reinforcement, offering insights for future pavement design and construction practices.\u003c/p\u003e","manuscriptTitle":"Performance Evaluation of Crumb Rubber and Basalt Fiber Modified Asphalt Mixes for Sustainable Flexible Pavements","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-16 19:32:50","doi":"10.21203/rs.3.rs-7695110/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"dd1d2fdf-68d8-4a4f-8386-b68e03fbac52","owner":[],"postedDate":"October 16th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-01-04T02:09:08+00:00","versionOfRecord":[],"versionCreatedAt":"2025-10-16 19:32:50","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7695110","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7695110","identity":"rs-7695110","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}