Effects of spray-dried co-cultured bacteria on cement mortar

•Spray-dried co-cultured bacterial spores are incorporated in cement mortar.•Visual crack closure, TGA, sorptivity, and CFU confirm bacteria activity in mortar.•Negative effects such as high-water porosity and strength reduction are reported. Co-cultured bacterial spores from alkaliphilic and alkali-tolerant strains exhibit superior performance compared with those from single strains because of their higher resistance to pH and harsh environments, which promotes biofilm formation and CaCO3 precipitation. In this study, spray-dried co-cultured bacteria spores have been incorporated into cement mortar to explore their effects on its self-healing, mechanical properties, and durability. They showed high survival, decreased mortar sorptivity, and well-crystalline CaCO3 formation; on the other hand, the 28-day compressive strength of the mortar was severely reduced, and the water porosity raised.