Alkali activated lightweight aggregate as bacterial carrier in manufacturing self-healing mortar

Abstract

A bacteria-based self-healing concrete has been proposed for the autonomous repair of micro-cracks. However, the bacteria need protection to survive in concrete until cracks would appear. Here, vegetative cells of Bacillus sphaericus have been encapsulated into novel alkali activated lightweight aggregate (LWA) generated from fly ash and Sidoarjo volcanic Mud (Lusi). For the production of self-healing mortar, 30% by volume of the fine aggregates were replaced by bacteria impregnated LWA. The mechanical properties of the resulting mortar, the healing performance, sealing efficiency and healing product morphology were investigated. The results show that with vegetative cells as healing agent, a significant decrease in healing performance was observed when cracks were fabricated at later age. Furthermore, fly ash based LWA provided comparable healing and sealing performance as a commercial expanded clay carrier used for comparison. In addition, the fly ash-based LWA carrier provided excellent autogenous healing in young mortar.