Development of self-healing property in self compacting concrete

Abstract

Self compacting concrete is incorporated with a high amount of fines and chemical admixtures with a low w/c ratio, which leads to shrinkage and microcracks. Shrinkage in the concrete, along with the congested reinforcement, leads to a heavy number of cracks. To stop the damage due to these cracks, the self-healing property was developed in self-compacting concrete by incorporating self-healing materials like bacteria and calcium lactate into it. To optimise the self-healing materials, including the reference mix, 10 mixes are cast and tested for strength and healing properties. In those mixes, both bacteria and lactate are used by 0.2%, 0.4%, 0.5%, 0.6%, 0.8%, 1%, and 1.2% by weight of cement. The compressive strength, UPV, and rebound hammer tests are done on cubes with 100 mm sides. Split tensile strength and self-healing tests are done on cylinders with a 100 mm diameter and a 200 mm height. When a small amount of calcium lactate was used, the compressive strength of the concrete was higher compared to the reference mix. However, increasing the amount of calcium lactate resulted in a decrease in the strength of the concrete. Maximum healing and relatively good strength were found with 0.5% bacteria and 0.5% calcium lactate. FESEM-EDS and XRD results make it clear that the precipitation formed is in the form of rhombohedral calcite.

Keywords

• Bio-Concrete
• Rebound
• Ultrasonic pulse
• Self-compacting
• Self-healing