Effect of Bactericide on the Deterioration of Concrete Against Sewage

Abstract

Antimicrobial concrete is an initial and effective measure to control microbially induced deterioration (MID) of concrete. In this study, five kinds of bactericides were added to concrete, and the changes in weight, strength, and surface pH, as well as the micro morphology, mineral composition, and pore structure of concrete in artificially intensified sewage were investigated. Furthermore, the sterilizing rate of bactericides in sewage, the retention rate of bactericides in concrete, and the distribution of dead and live microbes within the biofilms were also analyzed. The results show that copper phthalocyanine (CP) has the best effect on concrete’s resistance to MID. After 3 months of sewage corrosion, the mass loss and strength of concrete treated with CP is about 4 and 2% of that of plain concrete, respectively, and the surface pH is still as high as 1.6, whereas that of plain concrete is almost close to neutral. This is not only due to the high sterilizing effect and low dissolution rate for CPC in sewage; the increase of concrete strength after adding CP also makes some contribution to its high resistance to MID. MID behaviors of concrete with sodium tungstate and zinc oxide are inferior to that of concrete treated with CP. However, the cost of sodium tungstate is five to six times as high as that of the other bactericides, and its bactericidal effect on microbes in sewage is worse. The mass losses of concrete with sodium bromide and dodecyl dimethyl benzyl ammonium chloride reach as high as 8.3 and 9.73% after sewage immersion, and their strength shows no obvious improvement in comparison to plain concrete. Moreover, in the long run, sodium bromide is not suitable for concrete to fight against sewage-induced deterioration due to its high dissolution rate, and dodecyl dimethyl benzyl ammonium chloride is just one kind of liquid bactericide and is not suitable for use in preparing concrete. The results obtained are expected to provide some theoretical basis for the application of bactericides in concrete against MID.