Journal Articles
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Item A review of the potential application of lignin in the production of bio-binder: challenges and opportunities(Springer, 2024) Yatish, R.G.; Kumar, D.H.; Chinnabhandar, R.K.; Raviraj, H.M.; Ravi Shankar, A.U.R.The aim is to treat nature in such a way that usage of natural resources has little to zero hazards to our environment. There is a need to protect the earth and its ecology from approaching disasters brought on by anthropogenic activity, particularly the combustion of fossil fuels for energy. The net-zero emission shall be achieved worldwide by embracing sustainable bio-energy resources. Under this domain, the invention of bio-ethanol also known as 2G-ethanol from crop residue (lignocellulosic biomass) took place and is contributing toward rural development and energy independence. Similarly, researchers have modified the conventional petroleum-based bitumen by incorporating various types of lignin, including wood lignin, kraft lignin, soda lignin, lignosulfonates, and lignin-derived from biofuel production. This review encompasses the growth in biofuel production and advantages stemming from bitumen modified using lignin obtained as a byproduct from bio-fuel industries. The study also explores potential approaches for producing a direct alternative bio-binder using lignin. However, there remains a necessity for dedicated research and development to optimize the production methods of bio-binders. Using bio-bitumen or bio-binder in constructing bituminous layers shall contribute to reducing the dependency on fossil fuels, lowering the carbon footprint, improving the performance, and valorizing the biowaste. This review comprehensively outlines the challenges in the production of bio-binder from lignin. Also, this shall serve as a starting point for further research projects by highlighting the potential of lignin as a source for developing a direct alternative bio-binder in pavement engineering. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2024.Item Strength behaviour of geogrid reinforced shedi soil subgrade and aggregate system(2006) Ravi Shankar, A.U.R.; Suresha, S.N.Shedi soil (Lithomargic clay), a yellowish-white silty soil underlying lateritic soil, is densely deposited along Konkan belt of India. The strength behaviour of Shedi soil under varying moisture content is major problem for road construction projects in this region. In the present investigation, the subgrade is stabilized with geogrid, keeping the geogrid at different positions from top of subgrade, to locate its optimum position. The plate load tests were also conducted at soaked and unsoaked conditions for unreinforeced, reinforced (with Geogrid) subgrade with aggregate base course. An equation has been established based on load-deflection values recorded for subgrade of un-reinforced and reinforced with geogrid at different levels. The deflection values obtained from equation and from the laboratory investigation were compared. In the case of reinforced subgrade with aggregate base course, the theoretical deflection values were computed based on Burmister's theory and compared with laboratory deflection values.Item A comparative study on properties of porous friction course mixes with neat bitumen and modified binders(2009) Suresha, S.N.; George, V.; Ravi Shankar, A.U.R.This paper summarises details of the laboratory investigation on the effect of various binders on the performance and durability of porous friction course (PFC) mixes. Three different modified binders and neat bitumen were investigated for three different aggregate gradations at two predetermined binder contents. The performance was evaluated in terms of stone-on-stone contact condition, air voids, and hydraulic-conductivity of compacted PFC mixes. The structural durability was investigated based on aged abrasion loss and moisture susceptibility. The findings provide a better understanding of the effect of each binder type on the performance and durability of PFC mixes. Crown Copyright © 2008.Item Characterization of porous friction course mixes for different Marshall compaction efforts(2009) Suresha, S.N.; George, V.; Ravi Shankar, A.U.R.Porous friction courses (PFCs) are mainly recommended as surface drainage layers on high-speed road-corridors and runway pavements. Permeability and sound attenuation characteristics are considered to be the indices for performance assessment of PFCs. One of the reasons for the loss of permeability in PFCs is densification under heavy traffic. But, resistance to ravelling too, is of main concern in the case of under-compacted PFCs. This paper summarises the details of laboratory investigation on the characterization of PFC mixes corresponding to four different gradations and two binder contents, for three levels of the Marshall compaction. The findings of the investigation suggest that the selection of the compaction level for PFC mix design should be based on the design traffic level, and the gradation selected. © 2009 Elsevier Ltd. All rights reserved.Item Effect of aggregate gradation and bitumen type on mechanical properties of semi-flexible asphalt mixtures(Elsevier Ltd, 2023) Kumar, D.H.; Chinnabhandar, R.K.; Chiranjeevi, K.; Ravi Shankar, A.U.R.Semi-Flexible Asphalt (SFA) mixture is a wearing course in which Open-Graded Asphalt (OGA) mixes having air voids of 20–35% are grouted with cement mortar. The grout consists of cement, sand, superplasticizer, and water. In the present work, an effort was made to assess the effect of the Sand-Cement (S/C) ratio in determining the optimal grout proportions. Taguchi technique combined with Grey Relational Analysis was used to obtain the optimal grout proportion. The optimum grout was found to be the mixture prepared with an S/C ratio of 0.6, a water-to-cement (W/C) ratio of 0.40, and a polycarboxylic ether-based superplasticizer (SP) content of 0.75% by weight of cement. The SP content was the most influencing factor, while the S/C ratio was the second most influencing factor. To investigate the effect of aggregate gradation and bitumen type on the mechanical properties of SFA mixtures, a new aggregate gradation with neat and modified bitumen was used to prepare OGA mixtures and later grouted with optimal grout proportion. The Marshall Stability, compressive strength, Indirect Tensile Strength, Cantabro loss, fatigue resistance, moisture and Oil spillage resistance tests were conducted. The results showed that the SFA mixtures prepared with polymer-modified bitumen and the new aggregate gradation have better mechanical properties, implying the significance of bitumen type and aggregate gradation. © 2023Item Utilization of recycled concrete aggregates for pavement base courses – A detailed laboratory study(Elsevier Ltd, 2024) Chiranjeevi, K.; R G, Y.; Kumar, D.H.; Mulangi, R.H.; Ravi Shankar, A.U.R.Pavement construction and maintenance have become prevalent globally due to increasing traffic volumes and higher vehicular axle weights, driven by population growth and technological advancements. However, the extensive reliance on natural resources raises concerns about their long-term availability and sustainability. An emerging trend in construction involves the application of alternative materials, such as demolished waste and industrial by-products, as substitutes for natural materials like aggregates. This study examined strength properties, including unconfined compressive strength (UCS), flexural strength, elastic modulus, indirect tensile strength (ITS) and the performance aspects of durability, shrinkage, and fatigue. Cement stabilized recycled concrete aggregate (CSRCA) mixes were prepared by varying the percentage of natural coarse aggregate (NCA) and recycled concrete aggregate (RCA) from 0% to 100% and cement content from 3% to 7%. The experimental findings demonstrated that the cement content had a more significant impact on the strength and performance characteristics of CSRCA mixes than RCA content. The mixes with RCA replacement up to 50% and a cement content of 5% satisfy the strength and durability criteria recommended by IRC 37. A higher proportion of RCA was found to have a detrimental effect on mechanical properties and fatigue characteristics. It was found that the CSRCA mixes with 50% RCA replacement to NCA can be used as a base layer instead of a conventional cement-treated base (CTB) for flexible pavement. © 2023 Elsevier LtdItem 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.