Viabilidade do uso de sílica gel na imobilização da bactéria Bacillus subtilis para materiais cimentícios autocicatrizantes

Abstract

Concrete is the second material most consumed worldwide, but the contact´s structure with fluids can lead to damage. Fissures can allow the entry of these fluids causing the concrete 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. This work examined the use of Bacillus subtilis at a concentration of 105 cells / ml and they were favorable to this type of application. For Energy Dispersive Spectroscopy analysis coupled to scanning electron microscopy, bacteria Bacillus subtilis proved CaCO3 precipitating in mortar samples. Through Optical Microscopy analysis, the closing of a 0.4 mm crack was observed over 168 days and assigned to the precipitation of CaCO3. It was noticed that the immobilization of Bacillus subtilis on silica gel, influencing the increase in compressive strength test (13.90% in the 7 day and 25.29% in the 28 day). This increase was also due to the addition of only silica (3.25% in the 7 day and 14.22% in the 28 day) and only to the bacterium (11.18% in the 7 day and 17.40% in the 28 days). There were no significant changes in the results of water absorption testing.