BITS Faculty Publications
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Item A Feasibility Study on the Potential Usage of Engineered Cementitious Composites in Indian Pavements(Springer, 2022-09) Lahoti, MukundThe global concrete consumption has been rising at over 2.8% per annum, reaching as high as 4.08 billion metric tons in FY-2021 alone. A significant chunk of this is being used in pavement construction to eventually reduce the usage of traditionally utilized asphalt and RCC in pavements and to improve environmental impact, pavement performance, and life. This study addresses the potential of using engineered cementitious composites (ECC) in comparison with traditional materials like RCC. The scope of this paper includes an in-depth analysis of material properties, economic benefit, and the lifecycle assessment of ECC, in comparison with RCC and an another alternative fiber-reinforced concrete (FRC). The framework thus established to analyze the feasibility of ECC in the Indian context is based upon the use case of FRC as discussed subsequently in the form of a case study. A similar basis has been utilized to discuss a case study on an M45 ECC mix. A similar skeleton approach can be followed to comprehend and analyze the cases of ECC usage in any alternative geography or climatic condition by choosing a mix suitable to the respective location, material availability, and logistics. It is found that ECC offers a 30% reduction in total lifecycle costs as compared to conventional concrete if a 50-year analysis period is considered.Item A Universal Metric for Robust Evaluation of Synthetic Tabular Data(IEEE, 2024-01) Lahoti, Mukund; Narang, PratikSynthetic tabular data generation becomes crucial when real data are limited, expensive to collect, or simply cannot be used due to privacy concerns. However, producing good quality synthetic data is challenging. Several probabilistic, statistical, generative adversarial networks and variational autoencoder-based approaches have been presented for synthetic tabular data generation. Once generated, evaluating the quality of the synthetic data is quite challenging. Some of the traditional metrics have been used in the literature, but there is lack of a common, robust, and single metric. This makes it difficult to properly compare the effectiveness of different synthetic tabular data generation methods. In this article, we propose a new universal metric, TabSynDex, for the robust evaluation of synthetic data. The proposed metric assesses the similarity of synthetic data with real data through different component scores, which evaluate the characteristics that are desirable for “high-quality” synthetic data. Being a single score metric and having an implicit bound, TabSynDex can also be used to observe and evaluate the training of neural network-based approaches. This would help in obtaining insights that was not possible earlier. We present several baseline models for comparative analysis of the proposed evaluation metric with existing generative models. We also give a comparative analysis between TabSynDex and existing synthetic tabular data evaluation metrics. This shows the effectiveness and universality of our metric over the existing metrics.Item Concrete Compressive Strength Prediction Using Boosting Algorithms(Springer, 2023-02) Lahoti, Mukund; Muthukumar, G.This study proposes intelligent machine learning (ML)-based methods for concrete compressive strength prediction by utilizing a publicly available dataset. The methods employed are the XGBoost, CatBoost and TabNet algorithms. A total of 1030 data points are collected wherein the independent input variables are the amounts of the different components of the concrete mix design and the output variable is the compressive strength at different curing ages. The proposed boosting algorithm approaches are contrasted with a few other popular ML techniques used in this field, such as logistic regression, classification and regression tree, and artificial neural networks. It is found that XGBoost and CatBoost show significantly lower mean errors between predicted values and actual observations of the compressive strength than the contemporary architectures, while TabNet is not so efficient. TabNet’s lower efficiency of prediction can be attributed to the relatively small dataset that was used for this study.Item Tailoring Properties of Electric Arc Furnace Slag Based Geopolymer Through Fly Ash Incorporation(Springer, 2023-02) Lahoti, MukundGeopolymers are novel binders and are sustainable alternatives for conventional Portland cement. Geopolymers have emerged as a phenomenon of exceptional interest for the construction industry due to their excellent mechanical properties and sustainability in the past few years. A significant factor in producing geopolymers is the selection of the precursors. In this study, electric arc furnace slag (EAFS) obtained as waste from the steel industry is used as the precursor, and the influence of fly ash (FA) on the properties of the developed geopolymer is investigated. Scanning electron microscopy (SEM), X-Ray diffraction (XRD), and X-ray fluorescence (XRF) are used for material characterization and for analysing the microstructural development.Item Effect of sodium hydroxide concentration on EAFS based alkali activated binder(Elsevier, 2023-04) Lahoti, MukundThe emission of greenhouse gases primarily CO2 during the production of cement is a substantial global threat. Along with this the disposal of industrial waste is also a key concern due to leachate. In order to lower the emissions and make better use of industrial waste, a novel technology termed alkali-activated binder (AAB) can be a potential alternative to ordinary portland cement. In the past few years, AAB’s have been a phenomenon of remarkable interest to the construction sector because of their exceptional mechanical qualities and sustainability. The selection of the source material is a critical factor to develop AAB’s. This research attempts to utilize the electric arc furnace slag (EAFS) generated from the production of steel through EAF route as the primary precursor. Four different variations of sodium hydroxide (SH) molarity (8, 10, 12, and 14) were used to investigate its effect on the fresh and mechanical properties of EAFS-based AAB. The alkali to binder ratio of 0.40, curing temperature 80 °C, and 85% humidity were used for preparing the AAB. Scanning electron microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDX), X-ray fluorescence (XRF), and X-Ray diffraction (XRD), are used for material characterization and for analyzing microstructural development.Item High volume fly ash and basalt-polypropylene fibres as performance enhancers of novel fire-resistant fibre reinforced cementitious composites(Elsevier, 2023-11) Lahoti, MukundThis study attempts to address the fire resistance of fibre reinforced cementitious composite (FRCC) while considering sustainability. Sustainable FRCC mixes were developed by varying the contents of silica fume and high-volume fly ash (up to 60% by wt.), along with a hybrid combination of basalt and polypropylene fibres. The FRCC was exposed to temperatures up to 800 °C, and its appearance, mass loss, and compressive properties were analysed. Exceptional performance in terms of resistance to cracking and strength retention was observed. The relative residual compressive strength of one of flyash based mixes was found to be 93.46%, 117.48%, 102.03% and 38.48% between 200 and 800 °C. Also, fly ash enhanced the mass retention properties especially with higher replacement levels and at higher temperatures. The influence of temperature on hydration products in the system has been explained using scanning electron microscope, X-ray diffraction, and thermogravimetric analysis. Furthermore, the improvement in thermal performance is demonstrated as a novel incentive for addition of fly ash in high volumes.Item A comprehensive review on applications of engineered cementitious composites in pavements(Elsevier, 2023-12) Lahoti, Mukund; Muthukumar, G.A significant proportion of the pavement network around the world uses asphalt as the construction material. However, asphalt reserves are expected to last no more than 50 years. The apparent alternative, Portland Cement Concrete, has its limitations, such as environmental emissions and poor riding quality. Since its inception, Engineered Cementitious Composite (ECC) has been suggested as an alternative pavement material in scattered studies over the years. This study aims to compile and present the state-of-art in ECC-related pavement applications and clearly define the research gaps so that future researchers in this area can carry out their work efficiently. It is observed that ECC has primarily been used as an overlay over both asphalt and concrete substrates rather than as a full-depth pavement material. Other application areas include bridge deck pavements, repair works, multi-layer pavements, and special function applications. Research related to the comparative life cycle and life cycle cost assessment of ECC pavements is also reviewed in this study. One significant benefit of using ECC in pavements that is noted is that slab joints can be eliminated due to the high ductility of ECC. ECC also has the potential to greatly reduce pavement reflective cracking and life-cycle environmental impacts. While the absence of coarse aggregates produces a smooth surface for excellent riding quality, it also poses the risk of low pavement skid resistance. Another important and well-known drawback of ECC, especially for such a large-scale application, is the high construction cost. Some of these problems have been solved to a certain degree using waste alternative materials and rough fine aggregates such as corundum. More research is needed to understand the prospects of ECC as a full-depth pavement material rather than just an overlay. Future work revolving around more large-scale field demonstration, durability enhancement, further cost reduction, and life-cycle impact reduction is desirable for enhanced applicability of ECC in road infrastructure.Item Preparation of Calcite-Precipitating Bacteria-Embedded Magnesium Phosphate Cement for Self-Healing Application(DergiPark, 2024) Lahoti, MukundThe present study was undertaken to check the feasibility of magnesium phosphate cement (MPC) for the immobilization of calcite-precipitating bacteria. An aqueous route of MPC synthesis was followed using magnesium phosphate Mg3(PO4)2 powder and ammonium phosphate solution. The Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analysis confirmed the synthesis of MPC. The thermal decomposition analysis (TGA) showed decomposition of struvite between 50–60 °C - Paenibacillus sp. NCIM 5410 was used due to its urea hydrolysis ability. pH 9 was found to be optimum for urea hydrolysis. The urea hydrolysis steadily decreased with an increase in temperature from 30 °C to 60 °C. The hydrolysis was seen to increase with an incubation time of up to 72 h and subsequently reduced. The bacteria showed 90% urea hydrolysis at pH 9, 30 °C temperature, and after 72 h. The bacterial spores were incorporated during MPC synthesis, which helped their immobilization. The bacterial spore-containing MPC decomposed around 70 (±0.48)% of urea. Further, calcite precipitation was studied. The precipitate formed due to bacterial action in the MPC crack showed the presence of calcium. The calcite precipitation helped to reduce the water absorption by MPC specimens. The spore containing MPC specimens showed around 2.62 (±0.55) % water absorption. These results suggest that it is possible to synthesize bioactive MPC by immobilizing bacterial spores in MPC.Item Influence of activator ratios and concentration on the physio-mechanical and microstructural characteristics of the geopolymers derived from sandstone processing waste(Springer, 2024-03) Bhunia, Dipendu; Lahoti, Mukund; Chakraborty, SayantanNatural stones have been utilized to meet various needs of human civilization since ancient times. The exploitation of any resource is associated with the production of redundant materials called wastes. Sandstone waste (SW) is one such waste obtained during the industrial processing of sandstones. Due to its siliceous composition, extensive yield, and disorganized dumping, noxious conditions related to land and human health are promoted. However, the lack of comprehensive engineering studies, mineralogical analysis, and design methodologies associated with the utilization of sandstone processing wastes restricted their applicability only to fillers or partial substitutes with pozzolans and traditional cement in meager volumes. In the past, limited efforts have been made to utilize SW as a construction entity, particularly for binding purposes. Thus, to enhance the scope of its utilization, a comprehensive investigation has been performed in this research to transform sandstone waste into a novel construction material by geopolymerization. Mix design tailoring and laboratory tests were implemented to understand the effects of sodium hydroxide concentration and sodium silicate to sodium hydroxide ratio on the dissolution and physio-mechanical characteristics of SW-based geopolymers. The activator-to-binder ratio was restricted to 0.4 to obtain pastes with sufficient workability without hindering the properties of the matrix. Besides, a high temperature-curing regime was selected based on SW's crystallographic and reactivity analysis. Subsequently, a total of 48 samples were prepared and tested at the curing age of 28 days. Detailed characterization of SW and SW-based geopolymer samples was performed using optical, X-ray, and infrared spectroscopies aided by electron imaging and thermogravimetric techniques. SW-based geopolymer samples showed compressive strengths in the range of 6-12 MPa, ~2 to 3 times higher than those obtained in previous experimentations. Phase analysis and microstructural examinations confirmed SW's participation in geopolymerization. Overall, it could be advocated that geopolymerization is an innovative approach for solving issues related to the disposal and re-utilization of SW, extending its possible application to the fields of cement mixes, wall tiles, mortars, and masonry as per the commendations of ASTM and ACI committee.Item Fired clay bricks synergistically valorizing hazardous nickel chrome-plating sludge and fly ash: Performance assessment(Elsevier, 2024-04) Singhal, Anupam; Routroy, Srikanta; Bhunia, Dipendu; Lahoti, MukundNickel Chrome Plating Sludge (NCPS) is a hazardous waste containing 25%-30% nickel and chromium. Previous attempts to immobilize NCPS into fired clay bricks resulted in weakened strength due to porosity and microstructure deterioration. This study introduces co-valorization of NCPS and fly ash in fired clay bricks to address these issues. Factory-scale firing of green bricks, alongside conventional clay bricks, assessed the commercialization potential. The optimal proportion of NCPS, fly ash, and clay was found to be as 12.5:37.5:50.0, respectively. Fly ash addition significantly improved brick properties, causing compressive strength to increase from 3.2 MPa to 11.6 MPa for a NCPS content of 12.5%. Microstructural analysis highlighted fluxing oxides in NCPS, amorphous silica-alumina in fly ash, synergistic ceramic bond formation, enhanced sintering and pore filling during vitrification. The study also demonstrated substantial fuel savings of 40%-50% due to NCPS's high heat of combustion causing internal firing of green bricks. The developed bricks exhibited almost double linear attenuation coefficients, indicating enhanced gamma radiation shielding. Leaching tests confirmed successful heavy metal immobilization. This co-valorization approach not only overcomes previous drawbacks but also offers significant environmental and economic benefits in utilizing NCPS in brick production.