Faculty Publications
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Item Evaluation of properties of nonfoaming Warm mix asphalt mixtures at lower working temperatures(American Society of Civil Engineers (ASCE) onlinejls@asce.org, 2017) Shiva Kumar, G.; Suresha, S.N.Warm mix asphalt (WMA) is a green technology which has the potential to replace hot mix asphalt (HMA) because it reduces greenhouse gas emissions and energy consumption by lowering the temperature at which asphalt mixtures are produced and placed. During the design process, evaluation of the mix design and mechanical properties of WMA mixtures is necessary. Therefore, the ability to quantify compactability would be very useful. This paper presents details on the evaluation of asphalt mix design, workability, and mechanical properties of asphalt mixtures modified with nonfoaming WMA additives at lower working (mixing and compaction) temperatures. Further, it seeks to provide a wider gap between mixing and compaction temperatures to ensure that WMA mixtures are suitable for longer haul distances. Asphalt mix design properties were evaluated by the Superpave method for various design gyrations (Ndes), and workability properties were evaluated in terms of Superpave gyratory compactor (SGC) densification indices using the Bahia and locking point methods. Mechanical properties such as resistance to moisture-induced damage were evaluated by the tensile strength ratio (TSR) approach, rutting resistance was evaluated by a laboratory wheel tracking test using a wheel rut tester (WRT), and flexural fatigue characteristics were evaluated by four point bending using a repeated load testing (RLT) machine. The effects of nominal maximumaggregate size (NMAS), working temperature, and type of mixture on the properties ofWMAmixtures were investigated. The experimental results were statistically analyzed to identify the major influencing factors and their significance. © 2017 American Society of Civil Engineers.Item Laboratory Evaluation of SMA Mixtures Made with Polymer-Modified Bitumen and Stabilizing Additives(American Society of Civil Engineers (ASCE) onlinejls@asce.org, 2019) Shiva Kumar, G.; Ravi Shankar, A.U.; Ravi Teja, B.V.S.Stone matrix asphalt (SMA) is a gap-graded mixture that consists of two parts, a high concentration coarse aggregate skeleton and a high binder content mortar. The coarse aggregate skeleton provides the mixture with stone-on-stone contact, giving it strength, while the high binder content mortar adds durability. The mortar is typically composed of fine aggregate, mineral filler, asphalt binder, and a stabilizing additive. A stabilizing additive such as natural fibers, mineral fibers, or polymers is added to SMA mixtures to prevent draindown. In addition, it has the potential of reinforcing and improving the tensile strength and cohesion of SMA mixtures. In this study, banana fiber (BF) and pelletized fiber (VP) are used as stabilizing additives to prepare SMA mixtures with conventional viscosity-graded (VG) 30 bitumen. Mixtures were prepared with different levels BF and VP content, and another mixture without any stabilizers was also prepared using polymer-modified bitumen (PMB). Superpave mix design, draindown, fatigue, rutting, workability, and moisture-induced damage properties were evaluated. Results indicated that addition of natural and pelletized fiber controls binder draindown and improves resistance to rutting, fatigue, and moisture-induced damage of SMA mixture. Further, polymer-modified SMA mixtures take less energy for densification compared to SMA mixtures with natural and pelletized fiber. Results also showed that even though polymer-modified SMA mixtures performed better, SMA mixtures with pelletized fiber provided comparable results. © 2019 American Society of Civil Engineers.Item Study of Rheological and Creep Recovery Properties of Asphalt Binder Modified with Waste Toner(American Society of Civil Engineers (ASCE), 2020) Showkat, B.; Suresha, S.; Ningappa, N.Large quantities of waste toner (WT) are generated annually either due to the incessant manufacturing process or from copying machines. Disposal of WT is primarily in landfills, which deteriorates the environment. This study attempts to overcome this predicament by utilizing WT for asphalt pavement construction by means of incorporating it in asphalt binder. The effect of WT on rheological properties of asphalt binder was explored in this research. An unmodified asphalt binder AC30 was adopted and modified with three contents of WT (7%, 14%, and 21% by weight). Tests including high-temperature performance grade (PG), temperature sweep, frequency sweep, and multiple stress creep and recovery (MSCR) were performed in this study. Mixing and compaction temperature was observed to marginally increase on introduction of WT. The addition of WT was perceived to cause a bump in high-temperature PG of AC30 binder. Improvement in rutting resistivity of AC30 binder was recorded. However, a degradation of fatigue resistance was observed. Master curves indicated an enhancement in complex shear modulus (|G*|) and reduction in phase angle (?) at low frequencies due to incorporation of WT. However, at higher frequencies, convergence of the curves was observed. MSCR analysis indicated that WT addition enhanced percent recovery (R) and decreased nonrecoverable creep compliance (Jnr). Overall, the addition of WT was observed to cause changes in the rheological behavior of AC30 binder and an improved resistance to rutting at high temperature. © 2020 American Society of Civil Engineers.Item Properties of Rejuvenated Reclaimed Asphalt Pavement Mixtures with Waste Glass Powder and Sisal Fibers for Pavements(American Society of Civil Engineers (ASCE), 2025) Marathe, S.; Akarsh, A.P.; Bhat, A.K.By exploring the usage of reclaimed asphalt pavement (RAP) mixtures in pavement construction, this study fills a substantial gap in the literature. The research includes a number of experimental investigations ranging from enhancing binder qualities to efficiently using waste engine oil (WEO) as a rejuvenator, as well as detailed performance evaluations using waste glass in powdered form. RAP materials were meticulously graded to provide stone matrix asphalt compositions. Throughout the study, a reinforcing supplement of 0.30% sisal fiber was utilized. The determination of optimal (fresh) binder content (OBC) of 3.50% and the selection of a lowered OBC of 2.50% with the adding of 20% WEO rejuvenator are among the preliminary key results. The study also effectively modified RAP mixes by including waste glass powder (WGP) as a mineral additive, yielding an optimal dose of 5.0% for a selected RAP mix. Performance testing on the improved RAP mixtures produced remarkable results. The Marshall stability value was increased by 20% with 5.0% WGP content. The Marshall quotient constantly fell between 2 and 5 kN=mm, which is the desired range. Tensile strength ratios often crossed 80%, and the drain-down potential was decreased by the use of WGP drastically. The combination with a 5.0% WGP content excelled the control mixture in rutting and fatigue testing and had a maximum retained Marshall stability of 93.1%. Additionally, pavement design utilizing Indian Roads Congress criteria demonstrated the viability of building pavements for low-volume roads using RAP mixtures in an efficient and sustainable manner. This study highlights the utilization of RAP to achieve sustainability in pavement building, offering a viable approach to bituminous pavement rehabilitation. © 2024 American Society of Civil Engineers.Item Preliminary evaluation of treated bio-residue as a modifier for bitumen(Elsevier B.V., 2025) Yatish, R.G.; Chiranjeevi, K.; Kumar, D.H.; Raviraj, H.M.; Ravi Shankar, A.U.R.With the global shift toward sustainable construction practices, the reuse of organic industrial by-products in pavement applications is gaining momentum. Bio-residues, when appropriately treated, can serve as eco-friendly alternatives to conventional binders. This study presents a preliminary investigation into the use of thermally treated Caffeine Spent Residue (CSR) as a partial replacement for bitumen in binder formulations. The CSR, derived from organic industrial waste, underwent thermal pretreatment to improve compatibility with the bituminous phase. The treated CSR was then mixed with bitumen (VG-40) by replacing it at varying levels—0 %, 3 %, 6 %, 9 %, 12 %, and 15 % by weight using a laboratory-scale high-shear mixer to produce Bio-residue Modified Bitumen (BRMB). The resulting BRMB samples were evaluated through penetration and softening point tests, along with rheological characterization using the Superpave rutting parameter (G?/sin ?) to assess the influence of treated CSR on fundamental binder properties. Both unaged and RTFO-aged samples were analyzed to capture the impact of short-term ageing on consistency and rutting resistance. Additionally, a cradle-to-gate assessment of embodied energy (EE) and embodied carbon (EC) revealed that replacing 10 % of bitumen with treated CSR significantly reduced the energy consumption and carbon emissions per kilogram of binder. The findings establish that treated CSR, particularly at a 9–10 % replacement level, offers a promising pathway for enhancing the sustainability of bituminous binders. © 2025 Elsevier B.V.