Investigation on the combined interactin of sulfate and acidic attack on concretes exposed to aggressive environments

Abstract

The study presented the results about the sulfuric acid corrosion, at very low pH, of a concrete containing blast furnace slag and fly-ash as SCM. Since no standard method are present regarding the acid corrosion, the comparison of the results between different laboratories is strongly related to the experimental conditions. In this research two methods were compared based on the complete concrete immersion in a sulfuric acid solution with different approaches to keep the pH 2 constant. The evolution of damage was followed by the loss of mass (kg/m2); moreover, the microstructure was observed by electron-scanning microscopy and the elastic modulus was performed as non-destructive test (NDT). The rate of degradation after 35 days of exposure, according the loss of mass due to the calcium dissolution of cement paste, is comparable between the two methods. The influence on the experimental parameters and the relation with the combined sulphate and acidic attack is discussed.