Influence of the binder on the behaviour of mortars exposed to H2S in sewer networks: a long-term durability study

The present study deals with the exposure of four different mortar formulations in the headspace of two distinct sewer networks prone to biodeterioration phenomenon due to the presence of hydrogen sulphide. Cylindrical specimens composed of two cements, ordinary Portland cement (OPC) and calcium aluminate cement (CAC), with or without a substitution of 75% of cement by blast furnace slag (BFS) were prepared and exposed. During the exposure, the evolution of cement materials was monitored. After 4 years exposure, OPC materials without BFS are deeply deteriorated at high speed. Best performances have been observed with CAC mortars correlated to their higher content in aluminium ion (Al3+). The rank of durability observed on site is OPC\OPC+BF\CAC+BFS\CAC. Molecular biology analysis revealed that microbial diversity is varying according to binder type as well as during the exposure duration.L'étude porte sur une exposition de 4 ans de mortiers dans deux réseaux d'assainissement présentant des concentrations éleÎes en H2S. les formulations des mortiers sont à base de ciment portland, de ciment aux laitiers de hauts fourneaux, de ciment d'aluminate de calcium avec ou sans laitier de hauts fourneaux. Après 4 ans, les mortiers à base de ciment portland sont très détériorés contrairement à ceux formulés avec les ciments d'aluminate de calcium et cela peut être corrélé avec la teneur éleÎe en ions aluminium dans ces derniers