Autocicatrização de materiais cimentícios por adição de bactérias imobilizadas em alginato

Abstract

Cementitious materials are widely used daily all over the world, due to their mechanical properties, durability and stability offered. For being exposed to weathering, there are several factors that contribute to the appearance of cracks, such as fluids, chemical agents, temperature gradients, and the action of overloads. The cracks impair the structure's stability and affect the material's compressive strength and water absorption properties. The cost for the maintenance of these cracks is often high, and such cracks may aggravate into larger cracks, besides not being sustainable with the environment. In this study the addition of Bacillus subtilis bacteria immobilized in sodium alginate incorporated in the mortar mixture (with a mix of 1:3:0.60, being one part of cement for three parts of sand) with the addition of calcium lactate for self-healing of cracks was studied. There were no significant differences in the results of water absorption, but in the compressive strength tests there was a reduction of approximately 21.24% at 7 days of cure and 22.83% at 28 days of cure in relation to the reference sample, while the addition of only calcium lactate resulted in an improvement of 4.34% at 28 days. The compositions containing calcium lactate and Bacillus subtilis bacteria immobilized in alginate showed better results in closing cracks up to 0.4 mm during the analysis time.