Abstract: Groundwater and soils in the western regions of China are rich in sulfate, which impairs concrete structures and reduces their service life. During concrete pouring, a cold joint forms between two concrete layers; on its surface, many micro-cracks and large pores serve as the main channels for salt ions to flow and cause a weakness prone to salt erosion damage. This study conducts experimental compression-shear tests on concrete specimens and examines the adhesion degradation of the cold joint surface and its variations under sulfate dry-wet-salt corrosion cycling, focusing on the joints with pouring intervals of 0.25 d, 0.5 d, 7 d and 28 d under the condition of 0, 30, 90 and 150 cycles. The results show that a longer pouring interval lead to lower adhesion on the joint surface while a shorter one to greater variations in the adhesion, which follow a logarithmic relationship. Within 30 dry-wet-salt corrosion cycles, the effect of pouring interval on the corrosion resistance of the joint surface is insignificant, while this effect increases gradually after 90 cycles. Accelerating adhesion failure on the cold joint surface is possible in the case of a long pouring interval and a large number of cycles.

Key words: Kconcrete, sulfate, cold joint, adhesion, corrosion resistance