Microbial life on the surface of the soft coral for solve the self-healing concrete

Abstract

The cracking in concrete can be caused by the nature of concrete which is not strong against tensile and shrinkage stresses. In addition, environmental factors such as rainwater also affect concrete structures. The method commonly used to overcome crack problems in concrete is the impregnation method. However, this method is relatively expensive, difficult and has an impact on the environment and health. Therefore, it is necessary to look for other alternatives to increase the durability of concrete. The efforts that have been made by several researchers are by adding bacteria which have activity to precipitate calcium carbonate on the cracked concrete surface. This method is commonly called Microbial Induced Calcite Precipitation (MICP). The source of bacteria in this study is bacteria that symbiont with soft corals. The results showed that the concrete made with the addition of MICP-70 isolates as much as 1.6x108 cells/mL had a greater compressive strength than the concrete without the addition of isolates. The value of compressive strength and absorbency of concrete water with the addition of MICP-70 isolates has a compressive strength of 6.0 Mpa and absorption capacity of 4.2%. So when compared to concrete without the addition of isolates and concrete with the addition of MICP-70 isolates, the value of concrete compressive strength occurred at 9%, while the absorption of water decreased by 3%. The results of microstructure analysis showed concrete with the addition of MICP-70 isolates little pores because the pore is covered by calcium carbonate deposits.