Faculty Publications
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Item Performance of alkali activated slag concrete mixes incorporating copper slag as fine aggregate(Elsevier Ltd, 2016) Mithun, B.M.; Narasimhan, M.C.In this present study, copper slag (CS) is proposed as an alternative to river sand as fine aggregate in alkali-activated slag concrete (AASC) mixes. The relative performance of alkali activated slag concrete mixes with CS as fine aggregate is compared to conventional Ordinary Portland Cement concrete (OPCC) mix in terms of their workability, strength and durability parameters. The results indicate that, AASC mixes with CS, as a replacement to sand upto 100% (by volume), show no marked loss in strength characteristics. AASC mixes with either sand or CS possess similar modulus of elasticity, lower total porosity, lesser water absorption and reduced chloride ion penetration as compared to OPCC. Strength-retention characteristics of AASC mixes with sand/CS on exposure to sulphate and acid-rich environment are also studied. Use of AASC mixes for structural application reduces carbon footprint, decreases water consumption and cost. Use of CS as fine aggregate reduces river sand consumption as an added benefit. © 2015 Elsevier Ltd. All rights reserved.Item Optimizing Solid Waste Management: A Holistic Approach by Informed Carbon Emission Reduction(Institute of Electrical and Electronics Engineers Inc., 2024) Hegde, S.; Sumith, N.; Pinto, T.; Shukla, S.; Patidar, V.Reducing carbon monoxide (CO) emissions is imperative for safeguarding human health and environment. CO adversely affects respiratory health, contributing to respiratory problems and, in severe cases, fatalities. Its reduction aligns with the broader efforts to combat climate change, as CO is often emitted alongside other greenhouse gases. Environmental consequences include air pollution and its detrimental impact on ecosystems. Compliance with emission standards is essential, and reducing Carbon emissions can lead to social and economic benefits, such as increased productivity and reduced healthcare costs. Moreover, the focus on emission reduction drives technological innovation, fostering the development of cleaner and sustainable technologies. In essence, addressing CO emissions is vital for creating a healthier, more sustainable future. However, in most of the cases, there has been no much importance given in scientific management of solid wastes. This has therefore resulted in large magnitude of carbon emission causing serious implications. This paper presents a novel approach to solid waste management, combining carbon emission assessment with advanced object detection technology. We develop an integrated waste management model that employs machine learning techniques for the identification and categorization of metals, non-metals, and plastics within the solid waste stream. To optimize waste sorting and recycling processes, we implement an efficient object detection system that leverages computer vision algorithms. This system enhances the precision of material identification within solid waste, thereby improving sorting accuracy. Additionally, we establish a database to quantify carbon emissions associated with distinct waste management methods, encompassing incineration, composting, recycling, bioremediation, and landfills is used for this work. The novelty of the work lies in the integration of CO2 emissions data and object detection resulting into a decision-making model, providing a holistic evaluation of the environmental impact of varied waste management scenarios. The formulation of recommendations for sustainable waste management practices based on the integrated assessment of carbon footprints and material identification is easy to implement in real world.The technical framework proposed here, aims to inform decision-makers on adopting environmentally conscious strategies for waste management. © 2024 The Authors. This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.Item Identification and characterization of chitinase producing marine microorganism: Unleashing the potential of chitooligosaccharides for bioethanol synthesis(Elsevier B.V., 2024) Atheena, P.V.; Rajesh, K.M.; Raval, K.; Subbalaxmi, S.; Raval, R.The dwindling supply of the petroleum product and its carbon footprint has initiated search for a sustainable fuel and alternate feed-stocks. One such underexplored feedstock is chitin, a waste derived from sea food processing. The limitation of insolubility and crystallinity inherent in chitin is addressed with the chitin hydrolysates. In the present study, a chitinases producing marine isolate was isolated from the sediments of Arabian Sea from a depth of 20 m. In order to increase the expression of the chitinases, sequential optimisation using one factor at a time and Taguchi experimental designs were employed which resulted in a yield of 13.46 U/mL which was 2.62 fold higher than the initial bioprocess condition values. In a two-step refinery protocol, Candida albicans was evolved towards chitooligosaccharides using chemically synthesized hydrolysates. In a fed –batch fermentation design the Candida yielded a 12.8 % conversion of these commercial chitin oligosaccharides into bioethanol in a run time of 48 h. This is the first report demonstrating the potential of Candida to utilise chitin oligosaccharides for the production of bioethanol. © 2024 The Author(s)Item Biochar-concrete: A comprehensive review of properties, production and sustainability(Elsevier Ltd, 2024) Barbhuiya, S.; Das, B.B.; Kanavaris, F.The utilisation of biochar in concrete has attracted considerable attention due to its potential in enhancing the properties and sustainability of this construction material. This in-depth review delves into various aspects of biochar-concrete composites. It commences by defining biochar and exploring its production methods, physical and chemical properties. Additionally, the review provides an overview of concrete, emphasising its composition, properties and the challenges associated with traditional production methods. The incorporation of biochar in concrete brings forth several benefits, such as improved strength and durability, enhanced thermal properties and the potential for carbon sequestration. The paper examines the production process of biochar-concrete composites, covering aspects like incorporation methods, biochar selection, mixing techniques and quality control measures. Furthermore, the sustainability aspects of biochar-concrete are evaluated, considering its environmental impact, life cycle assessment, carbon footprint reduction and economic feasibility. The review also addresses the challenges and future perspectives of biochar-concrete composites, along with opportunities for research and development. This comprehensive review presents valuable insights into the properties, production and sustainability of biochar-concrete composites. It serves as a guide for further advancements in the realm of sustainable construction. © 2024 The AuthorsItem Optimizing nailing parameters for hybrid retaining systems using supervised learning regression models(Springer Science and Business Media B.V., 2024) Menon, V.; Kolathayar, S.The work focuses on creating a hybrid retaining wall using geocell, geogrid, and soil-nailing techniques for a road embankment in Mangalore, India. Soil nailing reinforces the soil, geogrids give extra support, and geocell serves as a protective facia against external weathering impacts, decreasing the requirement for conventional shotcreting and lowering the carbon footprint of concrete. This promotes the United Nations’ Sustainable Development Goals (SDGs). The usage of concrete and steel in soil nailing can be minimized using supervised learning regression models (SLRMs), a branch of machine learning (ML). The soil properties in the site were collected by standard penetration tests (SPT). From the limit equilibrium method (LEM) study, 600 iterations are carried out to estimate the factor of safety (FoS), which serves as input training and testing data for the ML model. The surrogate model produces findings for the entire site to identify ideal nail parameters. The random forest (RF) model was found to be useful with a mean square error (MSE) value of 0.009. The finite element method analysis (FEM) yields a modest overestimation of roughly 4.5% while validating the results of the RF model in a typical slope. This study demonstrates the practical application of sustainable methodologies and machine learning to meet crucial development goals, explicitly improving slope stability and road development in the study area through environmentally conscious engineering practices. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024.Item Flexural and fracture performance of fiber reinforced self compacting alkali activated concrete– A DOE approach(Elsevier B.V., 2024) Prakash, G.B.; Prashanth, M.H.; Narasimhan, M.C.; Mahendra, K.; Das, A.K.Owing to their much-reduced carbon footprint and lower embodied energy, compared to conventional Portland Cement (OPC-based) Concrete mixes, Alkali Activated Concrete (AAC) mixes represent a pivotal advancement towards achieving sustainability goals. The fracture properties were investigated using Three-Point Bending Tests (3-PBT) under the mode I failure mechanism. This study utilises Taguchi analysis to analyse and optimise Self-Compacting Alkali-Activated Concrete (SAAC), focusing mainly on its flexural strength and fracture characteristics. An L-16 orthogonal array of experiments with three input parameters − replacement of Blast Furnace Slag (BFS) with Fly ash (FA) (0 %, 30 %, 40 %, and 50 %), Steel Fibers (SF) volume content (0 %, 0.25 %, 0.5 % and 0.75 %) and Notch to Depth (a0/d) ratio (0.2,0.3,0.4 and 0.5), at four levels each, was adopted. The Work of Fracture Method (WFM) and Double K Fracture Criterion (DKFC) were utilised to determine the Fracture Energy (GF) and fracture toughness, respectively. The results obtained from all the sixteen mixes showed that the F0-S0.75-N0.5 mix demonstrated better values in several parameters, such as flexural strength of 7.82 MPa,KICini of 0.928 MPa√m, KICuns of 6.99 MPa√m and KICini/ KICuns of 0.133. A maximum GF of 2350 N/m was obtained with F50-S0.75-N0.2 mix. However, all the inferior values of these parameters were observed with F50-S0-N0.5 mix, which recorded a flexural strength of 4.90 MPa, KICini of 0.612 MPa√m,KICuns of 1.16 MPa√m, KICini/ KICuns of 0.528 and GF of 125 N/m. Through Taguchi analysis, the optimal combination for flexural strength was identified as FA 0 %, SF 0.75 %, and a0/d 0.5 and for both Initial Fracture Toughness (KICini) and Unstable Fracture Toughness (KICuns) at FA 0 %, SF 0.75 % and a0/d 0.4. For both the ratio of initial to unstable fracture toughness (KICini/ KICuns) and fracture energy (GF), the optimum combination was FA 0 %, SF 0.75 % and a0/d 0.2. Furthermore, the results indicate that FA significantly influences KICini, while SF predominantly affects all other parameters. The predictive performance of the regression equations demonstrates good agreement with experimental outcomes. © 2024 Elsevier LtdItem Development and performance evaluation of self-compacting lightweight alkali-activated concrete incorporating hydroton clay balls(Elsevier Ltd, 2025) Kuttagola, I.; Prashanth, M.H.Alkali-activated concrete has emerged as a promising alternative in construction due to its enhanced performance characteristics and reduced carbon footprint. This study introduces a novel category of self-compacting lightweight alkali-activated concrete using hydroton clay balls (lightweight expanded clay aggregate, LECA) as coarse aggregate and manufactured sand as fine aggregate. The research investigates the influence of fly ash content in the binder and maximum aggregate size (MAS) on the mechanical properties of the concrete mixes. Three series of mixes were developed with MAS varying at 10 mm, 12.5 mm, and 16 mm, and fly ash proportions at 0 %, 30 %, and 50 %. A novel pre-treatment method involving geopolymer slurry was employed to enhance the stability of LECA by mitigating water absorption, crucial for achieving self-compacting properties. The lightweight concrete mixes demonstrated excellent filling and passing abilities, adhering to EFNARC guidelines, with the mix L10FA50 (smallest MAS and highest fly ash) achieving the highest workability. Compared to the normal-weight mix N16G100, the mix L10FA50 recorded 17 % higher slump flow, 45 % better sieve segregation resistance, and 34 % faster V-Funnel flow times. Dry densities of lightweight mixes ranged from 1851 to 1943 kg/m³, about 19–20 % lower than normal-weight concretes. The pre-treated LECA enhanced the mechanical performance of lightweight mixes, achieving maximum compressive strengths of up to 49.17 MPa, splitting tensile strengths of 3.40 MPa, flexural strengths of 8.60 MPa, and fracture energy of 161.51 N/m, approximately 65 % of the normal-weight mixes. Higher strength gains were particularly notable with higher GGBFS content and larger MAS. The microstructural analysis confirmed dense morphologies with C-S-H and C-A-S-H gel formations, contributing to improved strength. This research establishes the feasibility and performance benefits of utilizing LECA in alkali-activated concrete formulations for sustainable construction practices with enhanced mechanical and microstructural properties. © 2025 Institution of Structural EngineersItem Red Mud Neutralisation by CO2 Promotes Alkali Recovery and Higher Scandium Extraction(Springer Science and Business Media B.V., 2025) Abhilash; Shrivastava, S.K.; Rahman, M.R.; Meshram, P.To ensure the complete utilization of red mud and parallel reduction in carbon footprints from alumina production, it is very important to tackle the alkalinity in red mud which poses problems in the processing of bauxite residue. Despite various methods, this article stresses the use of CO2 neutralization which has been employed to address alkalinity (2176 ppm) and simultaneously recovers the alkali under atmospheric pressure, which assisted in improved scandium extraction. Under conditions of particle size < 50 ?m, 20% pulp density, 3-4 atm pressure, room temperature, in 30 min brought down the pH from 9.99 to 6.26, with 36–37% alkali recovery and capturing 28.8 g CO2/kg red mud. The neutralized red mud serves as an excellent feed for acid leaching to extract Ti and REEs. With 2 M sulfuric acid at 10% pulp density and 90 oC, 96% La, 95% Ce, and ~ 90% Sc were recovered in 2 h. The residue after the second stage operation was rich in Fe, Al and Si and thus can be processed by a hybrid pyro-hydro-metallurgical process, for achieving complete valorization of red mud while recovering critical metals. © The Author(s), under exclusive licence to Springer Nature B.V. 2024.Item 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 SocietyItem Microstructural insights of geopolymer mortar using binary blended sustainable fine aggregates(Elsevier Ltd, 2025) Clement, D.; C, R.; Agarwal, S.; Pratap, M.The socio-economic growth of a nation depends heavily on the availability of adequate infrastructure, which relies on essential materials like river sand (RS) and cement. However, the rising demand for RS, combined with its excessive extraction causing ecological damage, and its increasing cost, has raised significant concerns. At the same time, the production of cement contributes significantly to environmental damage, especially through CO2 emissions. In this scenario geopolymer technology has emerged as a sustainable alternative to cement, offering environmental benefits and reducing the carbon footprint of construction materials. This study investigates the impact of replacing RS with copper slag (CS) and laterite soil (LS) in geopolymer mortar (GM) on key properties such as setting time, flowability, compressive strength, and microstructure. The results showed that as LS content increased, setting time and flowability decreased considerably, while increasing CS content caused a reduction in these values. Unlike the other observed parameters, the compressive strength values showed no distinct upward or downward trend. Moreover, the microstructural analysis, including SEM, EDS, XRD, FTIR, TGA and BET, provided valuable insights to support the observed results across various mix designs. Overall, the findings highlight that optimised binary blends of CS, LS and RS not only improved the compressive strength but also enhanced the microstructural characteristics of geopolymer mortar, reinforcing their potential as sustainable and high-performance alternatives to conventional fine aggregates. © 2025 The Authors