Potential of applying bacteria of heal cracks in concrete

Concrete is a construction material that is used world-wide because of its first-rate properties. However, the drawback of this material is that it easily cracks due to its low tensile strength. As large costs are involved in crack repair, the potential of self-healing of these cracks by means of calcium carbonate (CaCO3) precipitating bacteria was investigated in this study. First, the survival of the bacteria was tested. Next, the optimal concentrations of bacterial cells, urea and Ca2+ were determined in order to obtain a maximum amount of CaCO3 precipitation. Finally, self-healing of cracks in mortar specimens, by means of bacteria, was investigated. Glass tubes, containing the healing agent were provided inside the mortar matrix. Upon crack occurrence, the tubes break and the healing agent, consisting of a filler material and bacteria, is released into the crack and can cause crack repair. Strength regain up to 60 % was thus observed due to self-healing.