Effect of silicate modulus on tensile properties and microstructure of waterproof coating based on polymer and sodium silicate-activated GGBS

摘要

This paper investigated a novel and environmentally-friendly waterproof coating produced by the organic (i.e., styrene-acrylate copolymer) and inorganic (i.e., waterglass and ground granulated blast-furnace slag (GGBS)) compounds. The good cohesion of polymer and sodium silicate-activated GGBS can provide good mechanical properties, and this material also shows a better environmental benefit as no cement was used for coating. In this work, an appropriate proportion of polymer, waterglass and GGBS was given, and the effect of silicate modulus on the macro-performances and microstructures of the waterproof coating was studied. The optimal silicate modulus was 1.75, and the corresponding tensile strength and breaking elongation were 2.20 MPa and 90.48%, respectively. Furthermore, the waterproof coating also exhibited favorable tensile properties, flexibility or water impermeability after subjected to high temperature, alkali, water immersion, low temperature and high water pressure. This new waterproof coating exhibited the favorable tensile properties owing to (i) appropriate reaction rate, (ii) high degree of polymerization of C-S-H gel, (iii) high content of C-S-H gel and CaCO3 crystal, (iv) high reaction degree between emulsion and sodium silicate-activated GGBS, (v) nano-sized CaCO3 crystals and mechanical bond between the CaCO3 particles. (C) 2020 Elsevier Ltd. All rights reserved.