The sulfate corrosion resistance behavior of slag cement mortar

•We studied the sulfate corrosion behavior of slag cement mortar in 10% Na2SO4 spray.•The results were compared with the sulfate resistance mortar and Portland mortar.•Slag mortar shows good sulfate resistance ability.•The mechanism explains the sulfate resistance of the slag cement mortar. The sulfate corrosion behavior of slag cement mortar, sulfate resistance mortar and Portland mortar were investigated by means of XRD, XRF, SEM and compression test method. The results indicate that the slag cement mortar shows the best corrosion behavior since the alive powder in it produces hydration reaction together with water, which prevents SO42− permeation and slows down the formation of CaSO4⋅2H2O and AFt.