The biodegradation of cement-based matrices by agro-industrial effluents is a very complex phenomenon. In this work, a test was developed - the Build-Mat Bio-test (BMB test) - to examine the degradation mechanisms caused by microbial activity on any type of building material. The main objective of this device was to analyze and distinguish between the effects caused by the bacteria and those caused by their metabolites in the deterioration. In this study, the BMB test was used to evaluate the impact on cementitious matrices of the bacterium Escherichia coli, found in liquid manure. The mechanisms and kinetics of deterioration resulting from exposure to the bacterial culture or to the metabolites were compared with those obtained with synthetic organic acids alone. It was notably observed that the bacterial suspension caused more intense deterioration and higher alteration kinetics as compared to the medium without microorganisms and to the synthetic acid solution. (C) 2011 Elsevier Ltd. All rights reserved.