chloride penetration

sulfate attack

drying shrinkage

thaw cycles

rock salt

Construction and Building Materials

• Effect of dry-wet ratio on the mechanical strength of concrete under sulfate attack was investigated. • Effect of dry-wet ratio on mineralogical alteration and pore structure evolution was studied. • The concrete deteriorates most severely when the dry-wet ratio is 3:1. • The reduction of harmful pores (50 nm ≤ d < 200 nm) is the main reason for the refinement of concrete pore size. 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”.

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