Bacterial sustainable concrete for repair and rehabilitation of structural cracks

Abstract

Self-healing concrete is an advanced, sustainable technique that has the potential to reduce maintenance costs by automatically repairing cracks. Some Bacillus species produce a urease enzyme to precipitate calcite during biomineralization, which can act as a binding filling material. This study investigated the effects of bacteria type, content and concentration, and nutrient content on the properties of self-healing concrete, especially at the age of 90 days. Bacillus Sphaericus and Bacillus Megaterium were introduced into the concrete at two concentrations, 2 × 108 and 2 × 109 (CFU/ml), and different percentages of bacteria were selected using calcium lactate as a nutrient material. Tests were performed for compressive strength, SEM, EDS, water permeability, rapid chloride permeability, and TGA/DTG. The results show significant development in compressive strength and microstructure characterization of concrete, especially with Bacillus Megaterium using a 2.5% bacterial proportion with a concentration of 2 × 109 CFU/ml and 1% of calcium lactate.