ABSTRACT
This study comprises the application of a multi proxy approach, where a strongly deteriorated Austrian sewer system was intensively investigated. Understanding the underlying reaction mechanisms leading to the deterioration by microbial induced sulfuric acid attack on concrete structures is highly complex and often not fully understood. The aim of this study is to contribute to a deeper understanding by introducing a novel approach that comprises a range of mineralogical methods, as well as hydro-geochemical analyses, analyses of gases, hydro-geochemical modelling, and microbiological analyses Results revealed an extremely fast propagating Microbial Induced Concrete Corrosion (MICC), with corrosion rates of up to 1 cm/y. Expressed pore fluids contained sulfate concentrations of up to 104 g/1 at low pH of between 0.7 and 3.1. Sulfuric acid produced triggered the dissolution of the cementitious matrix and the carbonatic additives, as well as massive formations of gypsum, anhydrite and bassanite. Microprobe analyses revealed sequences of element distributions within the corrosion fronts, controlled by the suggested pH gradient of 13 to <1 within the pore fluids (Figure 1).
