Durability of cement mortars and concretes exposed to biological attack as one of the sustainability parameter – a correlation analysis

Among the pillars of the sustainability, the aspect of prolongation of life of constructions has to be involved. Focus on sustainability of construction leads to study of durability of building materials. Phenomenon called biocorrosion, existing mainly in concrete sewer systems, agricultural structures and septic tanks, can results in structure deterioration due to of various microbial processes. Special attention is paid to oxidation of hydrogen sulphide to sulfuric acid by bacteria community established on a concrete surface. The type of the binder and composition of aggregate is very important factor for investigation of the biocorrosion processes of concrete. In this paper, a comparison of deleterious processes proceeded in cement mortars and in concrete composite exposed to bacterial influence was investigated. The process of biocorrosion was evaluated by statistical analysis on leached-out quantities of selected ions (Ca and Si) and sulphur content in leachates over a period of 270-day exposure to Acidithiobacillus thiooxidans. Concentrations of dissolved ions as well as amount of elementary sulphur in leachate (as an indicator of sulphate bio-corrosion) were measured every 7 days during the experiment. The attributes of the large-size mortars and small-size concrete specimens were compared each other. The correlation analysis was confirmed to be a useful tool to help the interpretation of the experimental findings.