Bacterial carbonate precipitation improves the durability of cementitious materials

Shortcomings of conventional surface treatments have drawn the attention to alternative techniques for the improvement of the durability of concrete. This paper reports the effects of bacterial carbonate precipitation (biodeposition) on the durability of mortar specimens with different porosity. Durability was assessed from the permeation properties and resistance towards degradation processes. The surface deposition of calcium carbonate crystals decreased the water absorption with 65 to 90% depending on the porosity of the specimens. As a consequence, the carbonation rate and chloride migration decreased by about 25–30% and 10–40% respectively. An increased resistance towards freezing and thawing was also noticed. The results obtained with the biodeposition treatment were similar as those obtained with conventional surface treatments.