Improving the Bio-Resistance of Cement Concretes by Means of Fungicidal Poly-Functional Modifiers

Abstract

The research findings of physical and chemical properties of heavy and light concretes, contaminated with water suspension of mold fungi spores, are presented. It is noted that the concretes’ funginertness (resistance to fungi) is significantly influenced by their age, porosity and the alkalinity of medium. In the course of time the strength of concrete decreases, which is conditioned by the activation of mold fungi growth processes, as a result of de-alkalization of concrete, due to carbonization of cement stone and release of organic acids into the material. To improve the concrete’s resistance in biologically aggressive media, it is suggested to modify concrete with a new poly-functional fungicidal modifier, obtained on the basis of resorcine production waste. It has been demonstrated that the addition of resorcinol-formaldehyde oligomers to concrete mix completely inhibits mold fungi growth and allows obtaining concretes with the increased density and strength, which can be used in conditions of biologically aggressive media. The strength characteristics of the cement stone with the researched modifiers are not reduced at mold fungi spores’ contamination, but, on the contrary, slightly increase, due to the increase of cement paste fluidity, decrease of W/C ratio, reduction of micro-cracks in concrete and compaction of its structure, due to the peptizing action of the modifier.