Investigation of the influence of blast-furnace slag on the resistance of concrete against organic acid or sulphate attack by means of accelerated degradation tests

Replacement of ordinary Portland cement (OPC) by blast-furnace slag (BFS) alters the durability behaviour of concrete. In this research, the influence of BFS on the concreteʹs acid or sulphate resistance is investigated by accelerated degradation tests and the results are related to microstructural and physico-chemical parameters. A significant reduction of acid deterioration was recorded for BFS concrete, which is mainly attributed to the different chemical composition of the binder. General durability indicators like open porosity cannot solely explain the different performances of OPC and BFS concrete. In contrast, the resistance of concrete cyclically and partially submerged in sulphate solutions decreases when high amounts of cement are replaced by BFS. Crystallisation pressure causes more severe deterioration in these cases.