Influence of dry-wet ratio on properties and microstructure of concrete under sulfate attack

This experimental study aims to determine the effect of dry-wet ratio on properties and microstructure of concrete under sulfate attack. Under the condition of oven drying, four different dry-wet time ratios were designed: 1:1, 3:1, 5:1, and 7:1. In this paper, the deterioration law of concrete under sulfate attack was investigated through compressive strength, splitting tensile strength and relative dynamic elastic modulus (RDEM). Moreover, microstructure and phase composition were investigated by SEM and XRD respectively, and evolution of the pore characteristics of the concrete were examined by MIP. The results show that when the dry-wet ratio is 3:1, sulfate deteriorate concrete the most. Wetting time affects chemical attack strength of sulfate and the capability of concrete to accommodate the expansion phase, the drying process only deteriorate the concrete in the middle and late stages of erosion. The generation and filling of micro-voids are the main reasons for the evolution of concrete performance, in this process, concrete has experienced fatigue damage of steady state-unsteady state-new steady state. (C) 2020 Elsevier Ltd. All rights reserved.