Biocementation as Rehabilitation Technique of Porous Materials

The main findings when using microbially induced calcite precipitation, MICP, in two case-studies, a sandy soil and a mortar surface, are presented. The first case is focused on studying biocementation in sands to improve their mechanical properties. Tests were carried out with the aim to check the biological activity and understand MICP effects on a porous medium. By visual inspection it was possible to see the presence of calcite in the top of the specimens confirming that this type of treatment is mainly superficial and must be improved to be more uniform in depth. In the second case, biodeposition was tested in order to understand how it would affect the main properties of porous cement mortar such as elastic stiffness, capillarity coefficient, water vapour permeability, roughness and open porosity. These properties are relevant mainly for walls. Treatment was applied in mortar specimens by submersion in the treatment solutions during the first 28 days of curing. The results were compared with those found in similar tests performed in samples which were not subjected to treatment, which were submerged in tap water or cured in wet environment. These different porous media are used as example of the improvement that can be achieved using this technique to treat volume or area. Considerations are done concerning the extrapolation of the results for other porous materials used for Civil engineering applications in the context of rehabilitation and how this technique could be implemented in the construction sites.