Self healing of alkali active mortars with expanded perlite aggregate

The use of alkali-activated mortars instead of cemented mortars provides an advantage in terms of various properties such as high strength, fast curing, and high durability by terminating cement production. However, concrete cracks reduce durability and strength, thus, it is crucial that they be healed. This study aimed to investigate the healing of early microcracks in geopolymer mortars by using Sporasarcina pasteurii, which makes carbonate precipitation, and expanded perlite aggregate as the bacteria carrier. This is the first study to investigate the bacterial healing of an alkali-activated geopolymer mortar using expanded perlite aggregate without applying a complex encapsulation process to the bacterial agents. For this purpose, optical, physical, and mechanical changes caused by self-healing were observed ahead of and after the cure period with tests like water absorption, compressive strength, UPV, SEM, FTIR, and optical microscope images. The results showed that bacterial cells could sporulate directly on the expanded perlite aggregate, visually improving the crack closure rate of the samples by a majority to 100 %, and the unit weights of all samples healed in DM and containing bacteria increased by up to 5 %.