Improvement on Strength, Durability, and Crack Closure Behavior of Bacteria Concrete under Marine Soil Exposures

Abstract

Abstract In the concrete industry, bacteria-precipitated calcium carbonate (CaCO3) can be used to repair cracks. If cracks in concrete are not repaired in a timely manner, other durability problems arise, necessitating expensive crack repair methods. Bacteria can be isolated from an appropriate physical environment so that they continue to function effectively in concrete. In this study, suitable self-healing bacteria are isolated from a concrete dump yard and incorporated into concrete specimens. After 3 days of normal curing, the specimens were pre-cracked and kept in marine exposure conditions for a period of 56 days. Strength and durability properties such as compressive strength regain, ultrasonic pulse velocity (UPV), and dynamic Young’s modulus were studied, and a water absorption test was carried out for cubes exposed in marine soil conditions. Marine soil treated with a bacteria and nutrient solution (1:9) exhibited improved crack-healing behavior as well as increased strength and durability. Compressive strength regain of 45.98 %, an increased modulus of 54.04 %, and crack healing of 83.05 % were reached with a 60 % reduction in water absorption and 32.49 % increment in UPV values. A microstructure study demonstrates the presence of CaCO3 compounds in healed crack surfaces and treated marine soil, which is primarily due to bacterial action under marine exposures conditions.