Production of calcium carbonate-precipitating biomass powder as self-healing additive in concrete and performance evaluation in mortar

Abstract

A sequential batch reactor (SBR) was used to enrich and produce a self-protected CaCO3-precipitating biomass powder (CPB) that hydrolzes urea and reduces nitrate. The self-protected CPB, consisting of 50% biomass and 50% inorganic matter, was incorporated into a mortar and its self-healing performance was assessed. Crack closure observations showed that specimens containing CPB showed higher crack healing ratio in complete water immersion, while Bacillus sphaericus spores containing samples only exhibited crack healing under cyclic wet-dry incubation. During corrosion monitoring, CPB addition revealed a corrosion inhibition effect equivalent to that achieved by the addition of the chemical corrosion inhibitor nitrite (0.7 w/w% cement weight). Overall, CPB is a suitable self-healing bio-additive for effective crack closure in cementitious composites used in immersed structural elements. It is compatible with the cementitious matrix and resulted in promising results concerning crack healing and corrosion inhibition.