Studies of detailed Biofilm characterization on fly ash concrete in comparison with normal and superplasticizer concrete in seawater environments

Abstract

In cooling water systems, many concrete structures in the form of tanks, pillars and reservoirs that come in contact with aggressive seawater are being deteriorated by chemical and biological factors. The nuclear industry has decided to partially replace the Portland cement with appropriate pozzolans such as fly ash, which could densify the matrix and make the concrete impermeable. Three types of concrete mixes, viz., normal concrete (NC), concrete with fly ash and superplasticizer (FA) and concrete with only superplasticizer (SP) were fabricated for short- and long-term exposure studies and for screening out the better concrete in seawater environments. Biofilm characterization studies and microscopic studies showed excellent performance of FA concrete compared to the other two. Laboratory exposure studies in pure cultures of Thiobacillus thiooxidans and Fusarium oxysporum were demonstrated for the inhibition of microbial growth on fly ash. Epifluorescence and scanning electron microscopic studies supported the better performance of the FA specimen. Thus, the present study clearly showed that FA concrete is less prone to biofilm formation and biodeterioration.