Influence of the cement type and water/cement ratio in concretes exposed in sewage treatment plants

•Chemical, physical and mechanical properties of produced specimens were evaluated.•A year of exposure was enough to identify mechanisms of gases attack.•The cement CP V was more susceptible to the attack of sewage gases, tested in compression strength, SEM and XRD tests.•The SEM images showed the presence of deleterious products, like ettringite.•At the end of the study all the series presented visible signs of degradation. The objective of this paper is to evaluate the influence of the cement type (CP V, CP II and CP IV) and water/cement radio (0.40, 0.50 and 0.65) in concretes exposed in sewage treatment plant. The parameters monitored for one year were: compressive strength, pulse velocity, electrical resistivity, SEM e XRD. Some characteristics of aggressiveness, such a disintegration of part of the concrete, became visible in the visual inspections. The 0.65 water/cement ratio series, for all cements, was the only one to present compressive strength drop. The SEM and XRD proved the occurrence of the attack, with the identification of deleterious products.