Microbial Self-Healing of Concrete Using Expanded Perlite as a carrier

Abstract

Self-healing is most commonly defined as the ability of concrete to fix cracks on its own. Concrete cracks are a regular occurrence due to the material's poor tensile strength. Immobilization has been shown to be an effective method for maintaining the high-efficiency calcite-forming capacity of integrated bacteria in bacterium- based self-healing concrete throughout time using suitable carrier. This particular research is carried out to investigate the extent of self-healing in normal strength concrete by using Sporosarcina Aquimarina - NCCP-2716 immobilized in Expanded Perlite (EP) as the carrier. The efficacy of crack-healing was also tested using two alternative self-healing techniques i.e., expanded perlite (EP) concrete and direct introduction of bacteria in concrete. Bacterial solution was embedded in EP and Calcium Lactate Pentahydrate was added as the nutrient. Experiments revealed that specimens containing EP-immobilized bacteria had the most effective crack- healing after each healing interval. After 28 days of healing, the values of completely healed crack widths were up to 0.78 mm, which is higher than the 0.5 mm value for specimens with direct addition of bacteria. The specimen showed significant self- healing phenomenon caused by substantial calcite precipitation by bacteria. Cracks were examined using crack detection microscope. The induced cracks were observed to be repaired autonomously by the calcite produced by the bacteria and the strength of concrete remained normal. The results of this research could provide a scientific foundation for the use of expanded perlite as a novel microbe carrier and Sporosarcina Aquimarina as a potential microbe in bacteria-based self-healing concrete.