Development of novel antimicrobial air-entraining admixtures for biocorrosion control of concrete

Microbially induced concrete corrosion poses a significant threat to the durability of concrete structures in sewage systems. Conventional antimicrobial agents often fail to provide prolonged protection and to address structural degradation of concrete caused by biogenic sulphate acids. This study proposes a novel approach by developing antimicrobial air-entraining admixtures (AAEAs) that combine the bactericidal properties with the air-entraining capabilities for accommodating deleterious expansive reaction in sulphate attacks, to enhance concrete resistance to biocorrosion. Two types of AAEAs were synthesized using dodecyl trimethyl ammonium chloride (DTAC) as the active ingredient, with montmorillonite and activated carbon as carriers. The synthesized admixtures were characterized for their chemical structures, and their effects on concrete workability, mechanical properties, air void structure, and cement hydration were evaluated. Simulated biocorrosion tests demonstrated that the AAEAs reduced biocorrosion depth by up to 17.4 % and suppressed bacterial activity by up to 30.4 %. Immobilization on carriers drastically reduced DTAC leaching rates from 30-90 % to 1–20 % in cement paste, ensuring sustained efficacy. Notably, the controlled release of DTAC in acidic environments further optimized its bactericidal performance, minimizing ineffective leaching and prolonging protective effect. This study provides a promising solution to enhance the durability of concrete in corrosive environments, offering tailored options for regions with specific conditions, such as coastal or cold areas.