Interactions between alkali-activated and cement-based mortars and biofilm and their influence on microbial induced mortar deterioration

Abstract

Alkali-activated fly ash (AAF) and alkali-activated slag (AAS) mortars were exposed to the sewage environment with acidophilic sulfur oxidizing bacteria and high concentration H2S to study their interaction. It was found that when they suffered the biogenic sulfuric acid attack, both the AAF and calcium aluminate cement (CAC) mortars had a strong inhibition effect on the growth and activity of microorganisms. There are more aluminum ions dissolved from AAF mortar into sewage, and its structure was characterized by the increase in 100-1000 nm pores. Still, a hard high silicon skeleton was formed to keep the apparent intact. However, CAC mortar had a higher killing rate for the bacteria in the attached biofilm. For AAS mortar, the formation of excessive gypsum increased the macropores content and was more conducive to the growth of biofilm, thereby accelerating the penetration of corrosive medium and the deterioration of mortar.