2018 Volume 72 Issue 1 Pages 328-335
Cracks generated in concrete structures accelerate the penetration of harmful substances, resulting in decrease of durability. Several methods are used for repairing crack in concrete. Recently, a new method using microorganisms has been proposed. In this method, carbon dioxide, which is a metabolite of microorganisms, reacts with calcium ions in a crack and clogs it by precipitation of calcium carbonate. In order to obtain a better effect, it is necessary to use microorganisms that can survive for a long time in alkaline concrete. In this study, the authors conducted repair experiment for artificially cracked specimens and alkali silica reaction（ASR）specimens using two repair agents including yeast fungus and Bacillus pasteurii. Permeability test and water absorption test were performed to evaluate the healing effect. The result showed that water permeability and absorption of all the specimens reduced remarkably after the repair. Microscope observation indicated that the cracks in mortar specimens were almost closed because of calcium carbonate precipitate.
