Cementitious materials in biogas systems: Biodeterioration mechanisms and kinetics in CEM I and CAC based materials

In anaerobic digestion plants, biological activities transform biowaste into a renewable energy: the biogas. This process produces aggressive and complex media in direct contact with the structure. Few studies have focused on the deterioration of concrete in such environments. In order to support the sustainable development of biogas production growing sector, this study intends to provide thorough information on the biowaste chemical composition and on materials biodeterioration mechanisms occurring in biogas plants. Cementitious materials with various surface compositions (pastes of CEM I, CAC and CEM I treated with oxalic acid) were immersed in the liquid phase of laboratory bioreactors reproducing anaerobic digestion conditions. Altered depths measurements in time highlighted the better resistance of the CAC material. The microbial biofilm coverage on the material's surface was delayed by the surface pretreatment with oxalic acid and was less dense for the CAC paste. Chemical and mineralogical analyses mainly showed leaching and carbonation phenomena