Conference Papers
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Item 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.Item Impact of Hemp Fiber on Mechanical and Durability Characteristics of Bacterial-Based Cement Mortar(Springer Science and Business Media Deutschland GmbH, 2025) Pandey, D.; Chaudhary, P.; Palanisamy, T.Natural fibers are currently highly valued due to the need for environmentally friendly alternatives. Integrating self-healing bacteria with natural fiber-reinforced mortar creates a unique and sustainable building material that enhances strength and facilitates crack repair. This study evaluates the performance of natural fiber and bacteria in improving the mechanical properties and durability of impaired mortars. The methodologies adopted include a bio-based approach incorporating directly added bacteria and a bio-based strategy utilizing bacteria and fiber reinforcement. Bacteria were identified from a suitable environment and directly added to the cement mortar, along with varying percentages of hemp fibers (0, 0.25, 0.5, and 1). Intentionally induced cracks, subjected to 80% peak compressive stress, undergo water curing with regular monitoring. The effects of hemp fiber content and pH value of acid attack on the mass loss of tested concrete were investigated. The results indicate that the Bacillus strain, Bacillus licheniformis, achieves higher values in compressive strength and lower values of sorptivity tests by 26% and approximately 7%, respectively, with the incorporation of 0.5% hemp fibers leading to a 25–30% increase in 28-day compressive strength. Microstructural investigation reveals that microbial-induced precipitation of various calcium carbonate polymorphs densifies the porous microstructure of the cement matrix. The process was analyzed using SEM imaging to observe bacterially induced carbonate crystals, while FTIR spectroscopy was employed to reveal the variety of CaCO3 crystals formed and to predict the bonding mechanisms responsible for calcium carbonate formation. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2025.