Sulfuric acid corrosion can cause severe damage to concrete and cement composites. Under certain conditions hydrogen sulphide, which occurs particularly in sewage systems, is converted into sulphuric acid by the action of sulphur bacteria. The bacterial and chemical activity in the sewers create a sulphur cycle, which leads to the reduction of surface pH and cause the deterioration of cement paste matrix until it dissolves. There are a variety of approaches to enhancing the sustainability of concrete and mortar one of which is to enhance the durability of concrete using different cement replacement. Granulated blast furnace slag is used in mortar and concrete, as a partial replacement of Portland cement, and this use has resulted in significant savings in the cost of production of concrete. Moreover the use of conventional concrete is notoriously subject to durability and corrosion issues. Laboratory experiments were conducted to investigate the compressive strength of cement composites samples with cement partially replaced by blast furnace slag. The samples with different share of slag (65%, 75%, 85%, and 95%) were exposed to a bacterial sulphate environment for 90 days. The paper presents the changes in compressive strengths, surface structures and chemical compositions of cement mortars after the microbial exposure of Acidithiobacillus thiooxidans.

DOI: https://doi.org/10.3846/enviro.2017.017