Study of concrete changes characteristics after biocorrosion processes affected by wastewater

Numerous studies have addressed the problem of chloride ingress in concrete structures. However, in addition to sulphate penetration, biological processes can accelerate the deterioration process by modifying severely the structural durability and reliability. The strength parameters and weight changes were evaluated as an average value from 3 concrete samples. Compressive strength value of reference samples were measured at the concrete cubes (150 mm x 150 mm x 150 mm) after 28 days of hardening; other samples were tested after taken out the sewerage (same cubes 150 mm x 150 mm x 150 mm) and were evaluated according to the STN EN 206. X-ray fluorescence method was used for investigation of the chemical composition of the concrete samples before and after the experiment. Compressive strength increase of concrete samples was observed for all samples exposed to the wastewater from combined gravitational sewage system comparing to the initial compressive strength value of reference set. The percentage content (after 6 months) of Fe, Al and Mg has been a little increased compared to the reference sample and the similar trend was visible (after 18 months) only for Aluminium. In case of the other chemical components, the values remained almost the same or only very small changes were determined.