Evaluating the Properties of Self-healing Concrete: A Review

The development of cracks is a regular phenomenon that causes water and various chemicals to seep into the structure reducing the strength and longevity of the building. The intrusion of external materials might affect the reinforcements when exposed to moisture and CO2 exposure, degrading the structure. Regular maintenance and treatments are needed to fix the cracks and maintain the structure. Research is in progress identifying solutions to these issues with active and self-processes in concrete which aids in repairing the cracks by generating calcium carbonate (CaCO3) particles which could seal the porosity of concrete and micro-cracks. Various bacteria like Bacillus pasteurii, Bacillus subtilis, Bacillus cohnii and Bacillus sphaericus are chosen for the crack sealing treatment as those bacteria could survive in an alkaline medium. Distinct species of bacteria have various growth conditions. Bacterial self-healing treatments were situated in an environment containing various minerals and chemicals at a constant temperature and for a specific amount of time to develop healing properties. This paper investigates the different experimental works studied on self-healing processes in large concrete samples with different sizes and materials. Studies revealed that bacteria enhanced the systemic toughness, flow ability, durability, and flexural modulus of normal concrete. This paper also investigates the different mathematical formulations established to examine the stress-strain behaviour of bacterium, which has been utilized to increase the strength of concrete.