Microbially-induced deterioration of concrete from hydroelectric power plants – an initial study

Abstract

Microorganisms can grow on the surface of concrete and inside its pores and microcracks, producing different metabolites. Microbial metabolites, particularly acids, degrade concrete components and enhance its deterioration by abiotic factors. Deterioration of concrete is a serious problem worldwide since it affects construction functionality and requires high maintenance costs. This paper presents microbiological and chemical analyses of 12 concrete samples originating from 6 hydroelectric power plants in Serbia, investigated in order to evaluate the key chemical factors affecting microbial growth on concrete. In most of the concrete samples, microorganisms from all examined groups were present in high numbers (bacteria 8.64 × 103–3.4 × 108, fungi 9 × 102–2.08 × 106, sulphur-oxidising bacteria 16.8–2.5×104 CFU/g). The high number and the presence of various physiological groups of microorganisms indicate the high intensity of deterioration caused by biological sources. Values of pH of the concrete samples were in the range 8.46–11.23, Ca content 5.43–19.93%, Fe 151–61100 ppm, sulphate 37.4–623.7 ppm and chloride 96.3–914.1 ppm. Correlation analysis between microbiological and chemical factors indicated a statistically significant strong negative correlation between sulphur-oxidising bacteria and pH (–0.759, p < 0.01).