Feasibility study on the use of microalgae as an external crack healing agent for cement mortar rehabilitation

As conventional concrete repairs have shortcomings and impact the environment, multiple attempts exist to find alternative sustainable measures to address this issue. Microbial-induced carbonate precipitation (MICP) using microalgae is one of the proven methods that can heal microcracks. In this study, the method used in repairing micro-cracks is by spraying microalgae species, namely, Arthrospira platensis and Synechococcus elongatus, cultured in a high calcium-based medium onto the surface of the cement mortar. The crack healing was evaluated for 14 days after the cracks were induced by applying 65-70% of the maximum threshold load. The results show that the microalgal-treated specimens exhibited a higher strength recovery, crack closure, and less water absorption than the control specimen. It is also observed that over 75-80% (0.26 mm, approx.) of the cracks can be healed within the span of 14 days sustainably using microalgae.