Concrete Protection from Sulfate Aggression by Coating Based on Zeolite-Like Binders

Abstract

The article is dedicated to concrete protection, exploited in sulfate mediums. Protective surface coating based on based on zeolite-like binder was proposed as a mean to restrict SO42- ions transport in concrete. It was demonstrated that the coating with a 3 mm thickness provides total protection of concrete. The ions transport in concrete depending on cation of sulfate medium lowers in the row (NH4)2 SO4>Na2 SO4>Mg SO4. The simulation of coating work was realized by adding the specified salts in zeolite-like binder. pH value decreasing of water extracts during binder hydration while applicated 2.5 % Mg SO4 is evidence of higher crystallinity of zeolite-like hydroalumino silicates, containing sulfate, with including of Mg2+ ions equal to Ca2+ ions. While the content of (NH4)2 SO4 was rised up to 5.0 %, minor pH was fixed due to declined synthes of other zeolite-like minerals. The absence of effect on structure formation was caused by the stability of pH values in the presence of Na2SO4 (0.5…2.5 %). Thus, the limitation of SO42- ions transport in the coating is due to their binding in zeolite-like minerals with advanced crystallinity in the appearance of Na+, NH4+, and Mg2+ sulfate cations.