Effects of slag on the degradation mechanism of ordinary Portland cement-calcium aluminate cement-gypsum ternary binder under the multiple erosive ions

Abstract

It is of great significance for the repair of concrete in marine engineering to reveal the effects of slag on the degradation mechanism of ordinary Portland cement-calcium aluminate cement-gypsum (OPC-CAC-C S-) ternary binder under the combined action of multiple erosive ions and dry-wet cycles. In this study, mechanical property, mass change, Cl− content, hydration products and morphology were investigated. The results show that the compressive strength, the Cl− erosion resistance and the stability of hydration products of the ternary binder were significantly improved by the partial substitution of slag, especially in the erosion environment containing SO42− and Mg2+. As the aluminum phase was sufficient when slag added, the combination rate of Cl− improved by the presence of SO42−, while slightly decreased by Mg2+ at early ages. Compared with corrosive solution including only Cl−, the presence of SO42− and Mg2+ reduced the generation of Friedel's salt. Moreover, the stability of ettringite was obviously enhanced by SO42−, while slightly reduced by the additional Mg2+ in corrosive solution.