Evaluation of self-healing of internal cracks in biomimetic mortar using coda wave interferometry

Calcium carbonate biomineralization is a bio-chemical process in which calcium carbonate precipitation is obtained by leveraging the metabolic activity of microorganisms. Studies have shown that biomineralization can be used to repair surface cracks in cement-based materials. One of the challenges in determining whether biomineralization is a feasible option for internal crack repair pertains to how to monitor and quantify self-healing of internal microcracks. In this study, mortar samples with and without microcracks and microorganisms were cured in different environments until 50 days. Coda wave interferometry measurements, a nondestructive method that is very sensitive to small changes in material, were conducted on these samples to evaluate the extent of self-healing during the entire curing period. Compressive strength tests were performed after 7 and 28 days of curing. The results indicated that the cracked mortar samples with microorganisms showed significantly higher strength development and higher relative velocity change than samples without microorganisms.