Faculty Publications

Now showing 1 - 3 of 3

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.
Long-lasting Bacillus safensis CG1 and Bacillus cereus DKBovi-5 based coconut shell biochar spore composites as self-healing additives for bio-mortar production
(Elsevier B.V., 2024) Anoop, P.P.; Palanisamy, T.; Gupta, A.; Gopal, M.
The major challenge in the production of bio-mortar lies in the effective storage of immobilised bacterial carriers. This study explores the effective storage and use of coconut shell biochar as a carrier for bacterial spores. Bacillus safensis CG1 and Bacillus cereus DKBovi-5 were immobilised in biochar and stored at 4 °C and 25 °C for 120 days. The storage at 4 °C showed enhanced viability, and Field Emission Gun Scanning Electron Microscopy studies revealed the firm adherence of bacterial spores within the biochar pores, attributed to the secretion of extracellular polymeric substances. Biochar-based spore composites stored at 4 °C were subsequently added as self-healing additives in mortar. Mechanical, self-healing, and microstructural evaluations demonstrated that the biochar with Bacillus cereus DKBovi-5 exhibited superior results. Cracks up to 0.888 mm were healed within 56 days, indicating enhanced healing efficiency, as supported by higher ultrasonic pulse velocity and a lower resistivity ratio. Brunauer-Emmett-Teller 20-point adsorption-desorption analysis showed that biochar with Bacillus cereus DKBovi-5 mix possessed the smallest pore width of 3.086 nm. Additionally, Field Emission Gun Scanning Electron Microscopy- Energy Dispersive X-ray Spectroscopy, X-ray Diffraction, and Fourier Transform Infrared Spectroscopy analyses confirmed the formation of biogenic calcium carbonate in the healed regions. Overall, the biochar composite with Bacillus cereus DKBovi-5 showed significantly improved performance compared to Bacillus safensis CG1 and is recommended as a long-lasting self-healing additive for large-scale construction applications. © 2024 Elsevier B.V.
Solar-Driven additive Manufacturing: Design and development of a novel sustainable fabrication process
(Elsevier Ltd, 2025) Hazoary, A.; Panwar, M.; Singh Rajput, A.S.; Kapil, S.
Additive Manufacturing (AM) is revolutionizing industries by enabling layer-by-layer fabrication of complex components. Among AM techniques, Laser Powder Bed Fusion (LPBF) is widely used but is energy-intensive, limiting its sustainability. This study explores the potential of concentrated solar energy as an alternative heat source for sintering Thermoplastic Polyurethane (TPU) in a solar-powered 3D printing process. A custom-designed solar 3D printer, equipped with stepper motors and an Arduino UNO for precise control, was utilized to evaluate critical process parameters such as feed rate, hatch spacing, and layer thickness. The results indicate that feed rate and hatch spacing are pivotal to energy density, directly influencing sintering quality. Optimal sintering occurred at feed rates between 100–200 mm/min, which provided sufficient energy for uniform layer fusion, balancing surface finish and mechanical strength. Larger feed rates resulted in incomplete sintering and weaker parts, while a hatch spacing of 1.67 mm offered efficient pass binding with reduced build time. The study successfully demonstrated the fabrication of multilayer TPU structures using solar energy, achieving mechanical properties comparable to conventional LPBF techniques. This solar-powered approach underscores the potential for integrating renewable energy into additive manufacturing, offering a sustainable alternative to laser-based systems. Future refinements, such as dynamic solar tracking and real-time parameter adjustments, could further enhance its industrial viability. By leveraging renewable energy, this research represents a significant step toward eco-friendly manufacturing solutions, reducing energy consumption and carbon footprint while maintaining high-quality outputs. © 2025 International Solar Energy Society

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