Viability of Bacillus subtilis immobilization using silica gel for self-healing of cement based materials

Cracks in concrete's structure may lead it to lose some properties, such as compressive strength. The use of self-healing concretes by the addition of bacteria is a way of sealing these cracks. In this work, 105 cells/ml of Bacillus subtilis showed favorable to this application. In the analysis of Dispersive Energy Spectroscopy coupled to Scanning Electron Microscopy, the Bacillus subtilis bacteria showed CaCO3 precipitants in mortars samples. By means of the analysis of optical microscopy, the closure of 0.4 mm induced crack was severe observed during 168 days. Furthermore, an increase in compressive strength was observed by the immobilization of Bacillus subtilis on silica gel, by the addition of only silica and only to the bacterium.