Faculty Publications

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Publications by NITK Faculty

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Author: search.filters.author.Palanisamy, T.Subject: search.filters.subject.Compressive strength

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    Prediction of Compressive Strength and Workability Characteristics of Self-compacting Concrete Containing Fly Ash Using Artificial Neural Network
    (Springer Science and Business Media Deutschland GmbH, 2023) Netam, N.; Palanisamy, T.
    This study aims to propose an artificial neural network (ANN) model for predicting the properties of self-compacting concrete (SCC). SCC has enhanced properties such as very high workability and it can go through very tight spaces between reinforcements without any application of vibration. To get the desired strength and workability, it is necessary to understand the parameters determining the nature and properties of SCC and the relationships involved among those parameters. In this study binder content, water to binder ratio, fly ash percentage, coarse aggregate, fine aggregate, and superplasticizer content are chosen as input parameters, and output results from the model are slump flow value, L-box ratio, V-funnel time, and compressive strength. An ANN model is constructed and its architecture is selected by evaluating the performance of a network with a different number of neurons for the optimum results. Then this model is trained, tested, and validated through a database of experimental test results gathered from various literature. The accuracy of this model is evaluated by evaluation matrices such as R and MSE. To check the efficiency, the current model comparison was made with an existing data envelopment analysis model (DEA). © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.
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    Examining the Effect of Diverse Calcium Sources on Cement Mortar Using Bacillus Subtilis Through MICP: A Preliminary Investigation
    (Springer Science and Business Media Deutschland GmbH, 2024) Hosamane, C.C.; Chaudhary, P.; Palanisamy, T.
    Calcite, a crystal form of calcium carbonate, plays a crucial role in Microbially Induced Calcium Carbonate Precipitation (MICP). In this process, bacteria aid in forming calcite crystals, strengthening materials like mortar. Bacteria interact with calcium ions, causing calcite to precipitate, thus enhancing the strength and durability of the cement matrix. This study presents a method to improve cement mortar properties through MICP. Gram-positive Bacillus subtilis bacteria were introduced into cubes containing four different calcium sources: calcium chloride, calcium hydroxide, calcium lactate, and calcium oxide. After curing for 7, 14, and 28 days, calcium carbonate quantification, EDTA testing, and compressive strength testing were conducted on the mortar cubes. Results showed that cubes with calcium chloride exhibited peak compressive strengths of approximately 37.4 MPa, 45.7 MPa, and 58 MPa after each respective curing duration. This highlights the superior performance of cubes with CaCl2 compared to other calcium sources. The increase in strength and decrease in water absorption is attributed to the proliferation of calcite crystals within the cement matrix voids, confirmed by microstructural analyses using scanning electron microscopy (SEM). © The Author(s), under exclusive license to Springer Nature Switzerland AG 2024.
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    Environmental sustainability of waste glass as a valuable construction material - A critical review
    (EM International rktem@pn3.vsnl.net.in, 2018) Sudharsan, N.; Palanisamy, T.; Yaragal, S.C.
    The increased demand for concrete as a construction material leads to increase in cement production. The formulation of cement, emits a significant amount of CO2 to the atmosphere, which causes severe environmental pollution. Many efforts are being made to reduce the use of Portland cement in concrete to avoid environmental issues. These efforts mainly involve the utilization of value added materials in concrete. In this context, the waste glass powder has excellent pozzolanic properties, to use glass powder as a supplementary cementitious material in concrete. The use of waste glass powder in concrete has many economic and environmental benefits. This paper summarizes the literature regarding the utilization of waste glass powder as a supplementary cementitious material in mortar and concrete. © 2018 EM International. All rights reserved.
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    Non-reactive biochar and Bacillus pumilus RSB17-based healing powder: A sustainable solution for enhanced bacterial viability in self-healing mortar
    (Elsevier B.V., 2025) Anoop, P.P.; Palanisamy, T.
    Existing mortar uses self-healing powders that are based on mineral admixtures, whose reactive nature negatively impacts bacterial viability and diminishes their effectiveness over time. This study aims to develop non-reactive, sustainable biochar-based healing powders with extended bacterial viability to serve as self-healing admixture in bio-mortar. Biochar from coconut husk, coconut shell, and coconut leaf petiole was evaluated for compatibility with Bacillus pumilus RSB17, emphasizing bacterial growth and calcium carbonate precipitation. Coconut shell biochar demonstrated superior performance and was used to formulate a microbial biochar healing powder. Another healing powder was prepared by lyophilizing the bacterial spore solution without protectants. The shelf life was evaluated for 180 days at 4 °C and 25 °C, demonstrating that microbial biochar healing powder at 4 °C maintained bacterial viability above the 4.5 log CFU/g threshold necessary for effective calcium carbonate precipitation, while lyophilized spore powder stored at 25 °C dropped below the threshold at 90 days. Microbial biochar healing powder stored at 4 °C for 180 days was integrated into the mortar, which healed crack width up to 0.80 mm at 56 days under submerged rainwater maintained at 27 °C ± 2 °C and 85 % ± 5 % relative humidity. Electrical resistivity decreased from 28.16 ?·m to 21.35 ?·m, the permeability coefficient dropped from 153.90 mm/s to 0 mm/s, and compressive strength regained 90.53 %, which collectively indicated enhanced self-healing. Microstructural analysis confirmed the stable cuboid calcite crystals with a crystallite size of 86.62 nm. Thus, Microbial biochar healing powder produced from coconut shell biochar and Bacillus pumilus RSB17 and stored at 4 °C is an effective self-healing admixture for bio-mortar applications with a minimum storage period of 180 days. © 2025 Elsevier B.V.
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    Macro and microstructure evaluation of self-healing cement mortar enhanced with microbe-immobilized hemp fiber
    (Elsevier Ltd, 2025) Chaudhary, P.; Palanisamy, T.; Gupta, A.; Gopal, M.
    Sustainable construction materials are gaining attention in structural engineering to improve performance and reduce environmental impact. This study presents an eco-friendly composite of hemp fiber-reinforced cement mortar with self-healing bacteria, aimed at improving mechanical properties and crack repair efficiency. Microbe immobilized fiber enhanced (MIFE) cement mortar was developed by incorporating dormant bacterial spores of Priestia megaterium and Bacillus licheniformis through the mixing water, with hemp fibers serving as carrier medium. The MIFE mortar was tested at various fiber content levels, specifically 0 %, 0.5 %, 1 %, and 1.5 % by weight of cement, to evaluate its structural efficacy through comprehensive compressive strength tests, strength regain assessments, water absorption analysis, and detailed microstructural evaluations. The results revealed a significant 22 % increase in compressive strength with 1 % hemp fiber content, attributed to enhanced particle cohesion and reduced microstructural voids. The fiber's ability as a carrier to uniformly facilitate calcite precipitation also led to a notable 4.31 % reduction in water absorption. Morphological studies of CaCO3 from healed cracks in biomortar specimens demonstrated that the bio-environment and microbial interactions significantly influenced calcite polymorph formation, with vaterite crystals showing improved mechanical integrity and reduced chemical reactivity. The present study underscores the potential of microbe-immobilized hemp fibers as a green reinforcement option in cementitious materials, offering improved mechanical performance, self-healing capabilities, and environmental sustainability. These findings also align with the increasing focus on bio-based composites in the evolution of structural engineering, complementing the industry's shift toward sustainable construction materials. © 2025 Institution of Structural Engineers