Faculty Publications
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Item Review of Various Microbial Immobilization Methods Towards Self-healing Application(Springer Science and Business Media Deutschland GmbH, 2023) Baby, B.; Palanisamy, T.; Sundaramoorthi, S.Crack development and propagation in concrete structures, associated with internal and external stresses possess a severe threat to the performance and durability. Repair works of such concrete structures impart an immense financial toll. Self-healing mortar and concrete are developed with a view to provide a solution to address the aforementioned problem. The viability and performance of calcite precipitating microbes inside the concrete, in the long term, is always a concern when it comes to self-healing application. Among different methods to introduce such bacteria inside, immobilisation is considered to yield better results having the advantage of lesser impact from the adverse environment. This paper reviews the available immobilisation and encapsulation methods for microbial transport into the mortar or concrete, which makes use of porous media, hydrogels, polymeric coatings, etc., and its effectiveness in making a resilient building material. The current practices and the challenges associated with encapsulation methods to make a viable bio-mortar is critically reviewed and presented. The interaction of microbial colonies with the transporting medium and crack healing efficiency is compared based on different encapsulation methods. An experimental study was conducted to determine the impact of nutrients on the compressive strength of cement mortar was also conducted to identify the impact on strength parameters. The nutrients like calcium lactate, calcium nitrate, urea, calcium formate, and yeast extract in different dosages were analysed to achieve the optimum dosage value. It was observed nutrients other than urea and yeast extract, improved the compressive strength of bio-mortar at respective optimum dosages. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.Item Self-healing bacterial concrete: A bibliometric overview and state-of-the-art review on fundamentals, techniques and future perspectives(Elsevier Ltd, 2025) Ranjith, A.; Das, B.B.The augmentation of micro-cracks in concrete is unavoidable, and under varying external ambience, such cracks have the potential to cause concrete deterioration due to the ingress of deleterious substances. The utilization of bacteria enabled self-healing methods displayed promising outcomes in the sealing of such minute cracks, offering considerable benefits and reducing the need for human intervention. From this point of view, this article aims to provide comprehensive review of the existing literature on bacteria based self-healing concrete using Bibliometric analysis. The critical evaluation of the significant features that have a notable impact on the self-healing efficacy of cementitious composites incorporating bacteria is presented. These factors encompass primary aspects involving bacteria selection, healing conditions, influence of crack width, effect of pre cracking, influence of carrier compounds etc., emphasizing their significance on the healing performance. Also, the improvement in mechanical and durability properties through the utilization of bacteria-enabled cementitious composites for self-healing purposes is scrutinized. Furthermore, the performance of bacteria based self-healing concrete in aggressive environments like corrosion and carbonation exposure are critically reviewed. Additionally, this article delves into research on the application of Artificial Intelligence (AI) and Machine Learning (ML) in relation to bacteria enabled self-healing concrete. Finally, suggestions for future research directions and practical implementations in this domain are put forward. © 2025 Elsevier LtdItem An experimental investigation on mitigating cracks and augmenting the endurance of concrete structures in marine environment by bio-mortar immobilised with halophilic bacteria(Elsevier Ltd, 2024) Baby, B.; Palanisamy, T.In coastal areas, built structures encounter hostile conditions and forces that can cause them to deteriorate over time owing to saltwater exposure, tidal forces, reinforcement corrosion, and freeze–thaw cycles. Early age cracks in such structures accelerate the rate of deterioration, and the current research focuses on alleviating such threats. This paper evaluates the performance of a self-healing mortar made by encapsulating expanded perlite with the bacterium Halobacillus Halophilus MCC2188. Mortar cube specimens of size 70.6 mm × 70.6 mm× 70.6 mm were prepared with cement: fine aggregate in 1:3 ratios. A 10% volume of the fine aggregate fraction was substituted with the expanded perlite immobilised with bacterial spores and nutrients. The expanded perlite aggregates were coated with sodium silicate and cement solution to protect the spores from the nonconducive environment. The specimens were subjected to fully and partially submerged marine water curing. The mechanical properties and self-healing potential were evaluated, and the precipitated polymorphs in completely healed cracks were identified and examined by characterisation techniques such as XRD, FEGSEM, FTIR, and TGA-DTG. The marine bacterium under investigation can tolerate the high salt concentrations commonly found in seawater and saline marshy soil and produce calcite through the metabolism of organic compounds, making it a suitable microorganism for self-healing applications. Crack widths of up to 0.84 mm and 92.79% average strength recovery were achieved in 56 days post-cracking, and the pace of healing was quicker in partially submerged curing conditions. The results showed improved self-healing, strength regain and mechanical strength and proved to be an efficient tool for enhancing the endurance of biomortar in severe marine exposure conditions. © 2024 Elsevier LtdItem Long-lasting Bacillus safensis CG1 and Bacillus cereus DKBovi-5 based coconut shell biochar spore composites as self-healing additives for bio-mortar production(Elsevier B.V., 2024) Anoop, P.P.; Palanisamy, T.; Gupta, A.; Gopal, M.The major challenge in the production of bio-mortar lies in the effective storage of immobilised bacterial carriers. This study explores the effective storage and use of coconut shell biochar as a carrier for bacterial spores. Bacillus safensis CG1 and Bacillus cereus DKBovi-5 were immobilised in biochar and stored at 4 °C and 25 °C for 120 days. The storage at 4 °C showed enhanced viability, and Field Emission Gun Scanning Electron Microscopy studies revealed the firm adherence of bacterial spores within the biochar pores, attributed to the secretion of extracellular polymeric substances. Biochar-based spore composites stored at 4 °C were subsequently added as self-healing additives in mortar. Mechanical, self-healing, and microstructural evaluations demonstrated that the biochar with Bacillus cereus DKBovi-5 exhibited superior results. Cracks up to 0.888 mm were healed within 56 days, indicating enhanced healing efficiency, as supported by higher ultrasonic pulse velocity and a lower resistivity ratio. Brunauer-Emmett-Teller 20-point adsorption-desorption analysis showed that biochar with Bacillus cereus DKBovi-5 mix possessed the smallest pore width of 3.086 nm. Additionally, Field Emission Gun Scanning Electron Microscopy- Energy Dispersive X-ray Spectroscopy, X-ray Diffraction, and Fourier Transform Infrared Spectroscopy analyses confirmed the formation of biogenic calcium carbonate in the healed regions. Overall, the biochar composite with Bacillus cereus DKBovi-5 showed significantly improved performance compared to Bacillus safensis CG1 and is recommended as a long-lasting self-healing additive for large-scale construction applications. © 2024 Elsevier B.V.Item 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.Item 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