Browsing by Author "Chaudhary, P."

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A two identical unit standby system with inspection, two types of repair and delayed replacement of standby
(DAV College rkishan05@rediffmail.com 606-10 D.A.V (P.G) College Flats, Muzzaffarnagar 251-001, 2019) Gupta, S.; Chaudhary, P.; Vaishali
The paper deals with reliability and profit function analysis of a two identical unit standby system model with two modes- Normal and Total failure of each unit. Initially one unit is operative and the other is kept into cold standby. Upon failure of the operative unit the standby unit takes a random time to replace the operative unit. The time is called the delay time for replacement of the operative unit. Inspection is required to detect the type of failure after which the type of repair (either Type-1 or Type-2) is made. Whenever, the operative unit fails, a repairman is called to come at the system for the replacement of failed operative unit with standby and he takes some significant time to reach at the system. Failure time distribution is taken as exponential. The repair and inspection time distributions are also taken as exponential. Whereas the arrival and replacement time distribution are taken as general. By using supplementary variable technique, the various important measures of system effectiveness have been obtained. © 2019 DAV College. All rights reserved.
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 28Â 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 37.4Â MPa, 45.7Â MPa, and 58Â 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). Â© The Author(s), under exclusive license to Springer Nature Switzerland AG 2024.
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 25â€“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. Â© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2025.
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
A two identical unit standby system with inspection, two types of repair and delayed replacement of standby
(2019) Gupta, S.; Chaudhary, P.; Vaishali
The paper deals with reliability and profit function analysis of a two identical unit standby system model with two modes- Normal and Total failure of each unit. Initially one unit is operative and the other is kept into cold standby. Upon failure of the operative unit the standby unit takes a random time to replace the operative unit. The time is called the delay time for replacement of the operative unit. Inspection is required to detect the type of failure after which the type of repair (either Type-1 or Type-2) is made. Whenever, the operative unit fails, a repairman is called to come at the system for the replacement of failed operative unit with standby and he takes some significant time to reach at the system. Failure time distribution is taken as exponential. The repair and inspection time distributions are also taken as exponential. Whereas the arrival and replacement time distribution are taken as general. By using supplementary variable technique, the various important measures of system effectiveness have been obtained. 2019 DAV College. All rights reserved.