Abstract: It’s a well-known fact that concrete structures are susceptible to cracking which allows gases and water to enter and degrade the concrete, reducing the performance of the structure requiring expensive maintenance and repairs. Cracking in the surface layer of concrete mainly reduces its durability, since cracks are responsible for the transport of liquids and gasses which contain potentially deleterious substances. When micro cracks growth reaches the reinforcement, not only the concrete itself may be damaged, but also corrosion occurs in the reinforcement due to exposure to water and oxygen. Micro- cracks are therefore the main downside to structural health. In the project ‘Surface Protection Bio-Mortar’ we are incorporating a calcite precipitating bacteria namely Bacillus Subtilis with a source, Calcium Lactate which is mainly the supplemental substance used at bacterial food to promote the self-healing mechanism. The bacteria utilizes the supplemental material and gives out precipitates of limestone. To start with, we did literature review of several similar projects and research papers respectively, from which we worked certain values of the bacterial solution and calcium lactate which can lead us to the best possible results. We used a mortar mix of 1:4 which consisted of 1 part of 53 grade Ordinary Portland Cement (OPC) and 4 parts of crushed sand (m-sand). We also formally worked out the mix design where we, based on the reviews of various literatures, decided that we shall make 4 batches of trials with varying content of bacterial culture and the calcium source specifically, 0% of OPC, 7.5% of OPC, 15% of OPC, 22.5% of OPC. The reason behind doing 4 trials is to determine the most optimum dosage and the fastest time period wherein we can achieve the best crack healing. On the day of casting, we prepared 2 plasters, casted 6 cubes for compression testing and 1 cuboidal prism for capillary test. On the plaster samples, we made 2 groves approximately 2 mm thick each of different depths. We also conducted slump test which gave us satisfactory results confirming that the workability is not affected. The compression tests were conducted at 7 days and 28 respectively which also gave expected results which indicate that the bacterial impregnation has actually enhanced the strength of the sample. According to the research papers, we had to observe the plaster sample for at least 40 days under normal environmental conditions which is considered to be optimum to confirm that the self-healing mechanism is active and the cracked or the grooved portion of limestone precipitation which seals the crack making it practically impermeable giving a perfectly alkaline environment for the concrete and the reinforcement halting any further damage caused by corrosion activity, restoring the strength of the surface. Hence it can be averred that such a practice with conventional mortar can be very helpful for maintaining the structural health which in turn can help save a large amount of money.This document gives formatting instructions for authors preparing papers for publication in the Proceedings of an International Journal. The authors must follow the instructions given in the document for the papers to be published. You can use this document as both an instruction set and as a template into which you can type your own text.
Keywords: Subtilis; self-healing; Calcium Lactate.
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