Crack remediation in mortar via biomineralization: effects of chemical admixtures on biogenic calcium carbonate

Abstract

Limited research on biomineralization in cement-based systems suggested that self-healing of surface cracks could be obtained by triggering biogenic calcium carbonate (CaCO3) precipitation within the cracks. While this is encouraging, there is not enough information regarding the influence of admixtures on crack remediation and durability of the biogenic CaCO3 against weathering conditions. In this study, the microorganisms were introduced to mortar with their growth medium, which included corn steep liquor (CSL) and urea. With this approach, the cracks on mortar surface were sealed with the CaCO3 and the water absorption capacity of the so-called self-healed mortar decreased compared to its counterpart cracked mortar samples. The biogenic CaCO3 precipitate was found to be durable against freeze-thaw; however the precipitate was unstable under rain water and light. While the addition of air entraining agents (AEA) did not influence the self-healing ability of cells, use of superplasticizers improved the self-healing ability in terms of crack sealing, water absorption, and durability of the precipitate.