Testing concrete durability in sewer environment

Laboratory and field investigations were conducted in order to develop additives to mitigate the microbial-induced corrosion of concrete-based infrastructure in sanitary sewer systems. A laboratory system was developed to simulate the conditions facilitating microbial-induced corrosion of concrete in a sanitary sewer environment. Various concrete formulations were examined based on their resistance to microbial-induced corrosion in simulated laboratory and also in field exposure conditions. Of the various strategies considered, the mix formulation incorporating both polymer emulsion and fine pozzolan proved to be a viable means of enhancing concrete resistance to acid attack and moisture sorption, and to microbial-induced corrosion in simulated laboratory condition and also in an actual sewer environment. The polymer emulsion lines the capillary pore surfaces, and partially blocks the capillary pore system. Pozzolans further refine the size distribution and the connectivity of capillary pores, and also favourably affect the chemistry of concrete. Control of moisture sorption, enhancement of acid resistance, and alteration of the capillary pore surfaces and connectivity are the primary means through which the combination of polymer emulsion and fine pozzolans enhance the resistance of concrete to microbial-induced corrosion.