Damage evolution of cement mortar with high volume slag exposed to sulfate attack

•The 3D crack distribution of mortar by sulfate attack was quantitatively performed.•The deterioration law of mortar by sulfate attack was investigated.•The deterioration process of mortar with high volume slag is revealed. Sulfate attack is one of the important reasons for the premature failure of cement-based materials. In this paper, the deterioration law of mortar by sulfate attack was investigated through expansion, mass change, relative dynamic elastic modulus (Erd) and the distribution of sulfate ion content. Moreover, the pore size distribution, corrosion products and three-dimensional crack distribution were performed by Mercury intrusion porosimetry (MIP), X-ray diffraction (XRD) and X-ray computed tomography (X-ray CT), respectively. In addition, the degradation process of mortar with slag immersed in sulfate solution was investigated. The results showed that combined the mass change and Erd can more accurately evaluate the damage of mortar by sulfate attack. The increase of water-to-cement ratio significantly aggravates the mortar deterioration. Adding slag can significantly improve the pore size distribution and improve the sulfate resistance of mortar. The deterioration process of mortar with slag by sulfate attack is different from that of mortar without slag. The degradation process of the mortar with slag is that the surface layer peels off first, and then the sulfate ion continues to invade the interior of the sample to form a new expansion area.