Deterioration of Concrete Caused by Complex Attack in Sewage Treatment Plant Environment

One of the most severe exposure conditions for concrete structures is a sewage environment where various kinds of chemical and biological aggressive ions exist. These substances react with concrete through different mechanisms and lead to the deterioration of concrete and corrosion of the reinforcement. Most of the publications have focused on a biogenic sulfuric acid attack on concrete exposed to sewage, and not many authors have considered other aggressive phenomena, such as chloride diffusion and carbonation in a sewage environment. In this paper, the level of damage in concrete structures of a sewage treatment plant was assessed by a comprehensive set of experiments. The test results showed that a complex attack occurred in poorly constructed structures, which deteriorated concrete and caused cement paste decomposition, efflorescence formation, spalling of concrete, the occurrence of cracks, and considerable chloride penetration in concrete resulting in the corrosion of the reinforcement.