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 Optimisation of recycled concrete aggregates for cement-treated bases by response surface method(Taylor and Francis Ltd., 2023) Chiranjeevi, K.; Kumar, D.H.; Srinivasa, A.S.; Ravi Shankar, A.U.Sustainability is a primary concern that needs to be addressed since infrastructure development requires significant natural resources. Using Recycled Concrete Aggregates (RCA) for road construction has numerous benefits in saving natural resources and the environment. In the present investigation, the demolition waste is being used for road construction, partially/fully replacing natural aggregates. The Cement Treated Recycled Concrete Aggregate (CTRCA) specimens were prepared at 3%, 5%, and 7% cement with various blends of RCA and Natural Coarse Aggregates (NCA) ranging from 0 to 100%. The strength characteristics in terms of Unconfined Compressive Strength (UCS), Flexural Strength (FS), Elastic Modulus, Indirect Tensile Strength (ITS) and durability tests were conducted on cured samples. Microstructural analysis using Scanning Electronic Microscope (SEM) revealed that the pores and cracks in the old mortar have a detrimental influence on the mechanical properties of CTRCA mixes. However, Energy Dispersive Spectroscopy (EDS) and durability tests have shown positive results. The Response Surface Method (RSM) was utilised to optimise the RCA and cement content in CTRCA mixes. The research resulted in the maximum possible RCA of up to 70% with a cement content of 5.8%, which met the Indian Road Congress (IRC) specifications for Cement Treated Bases (CTB). © 2023 Informa UK Limited, trading as Taylor & Francis Group.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 Optimization and Characterization of Ferrochrome and Recycled Concrete Aggregate Mixes for Pavement Base Layers(American Society of Civil Engineers (ASCE), 2025) Chiranjeevi, K.; Kumar, D.H.; Yatish, R.G.; Mulangi, R.H.; Ravi Shankar, A.U.Utilizing alternate aggregates is crucial for conserving resources, promoting sustainability, and managing waste effectively. The focus of the current study was the utilization of ferrochrome aggregate (FCA) and recycled concrete aggregate (RCA) in cement-treated base layers with the objective of entirely replacing natural coarse aggregate (NCA). The study meticulously prepared cement treated recycled and ferrochrome aggregate (CTRFA) specimens with 3%, 5%, and 7% cement content. These specimens incorporated varying blends of RCA and FCA, ranging from 0% to 100%. Response surface method (RSM) was used to optimize the mixes by considering strength and durability criteria for cement treated bases (CTB). Microstructural characterization was aimed to explore aggregate surface roughness, mortar hardness, mineral phases, cracks, and elements within the matrix. The outcomes of optimization revealed that the optimal mixture, meeting the specifications of the Indian Road Congress, could be achieved by substituting 61% RCA and 39% FCA with 4.8% cement content. © 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.Item Performance Evaluation of Jute Geocell-Reinforced Sand Subgrade with an Integrated Wooden Anchor Grid(Springer Science and Business Media Deutschland GmbH, 2025) Kumar, P.; Kumar, D.H.; Bandyopadhyay, T.S.; Raveendran, D.; Kolathayar, S.; Mulangi, R.H.The efficient confinement capabilities of geocells make them a popular reinforcement technique for improving soil stability and load-bearing capacity. However, the high costs of synthetic geocells and environmental concerns have driven interest in more sustainable and natural alternatives. This study presents a novel approach to subgrade reinforcement using a jute geocell (JG) made from jute fabric, further improved with a wooden anchor grid (WAG). The newly developed jute geocell with wooden anchor grid (JGWAG) consists of a natural wooden grid integrated with anchor pins placed at the center of each JG pocket, aiming to enhance load-bearing capacity. The effectiveness of this innovative reinforcement system was evaluated through static plate load tests on sand subgrade reinforced with JG mattresses of varying widths (1.33D, 2D, and 3.33D, where D is the loading plate diameter) and a WAG placed beneath the 2D-width geocell. The results demonstrated significant performance enhancements: load-bearing capacity increased by 41%, 83.8%, and 116% for 1.33D, 2D, and 3.33D, respectively, compared to unreinforced subgrade. Notably, adding WAG under the 2D-width geocell achieved a remarkable 186% improvement over the unreinforced case. Settlement reduction was also significant, with the JGWAG system decreasing settlement by 84.6% as compared to the unreinforced case, showcasing its superior effectiveness. This system improves load-bearing performance and provides a cost-effective solution by reducing the width of JG. Furthermore, the surface roughness of the JG was analyzed using a 3D surface profilometer, ensuring optimal contact and friction between the soil and reinforcement for improved load transfer. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2025.