Deterioration of interfacial bonding performance between metal mortar and concrete under the coupling effect of freeze-thaw cycle and abrasion

In cold regions, hydraulic concrete structures are often severely damaged by the combined effects of freeze-thaw cycle and hydraulic abrasion, and it is critical for safe operation of the structure to repair the damage. The actions of freeze-thaw cycles (0, 25, 50, 75, 100, 125, and 150 cycles), abrasion (24, 48, 72, 96, 120, and 144 h), and the coupled action of freeze-thaw cycles and abrasion on the metal mortar-concrete interface were investigated. The apparent damage, mass loss, abrasion resistance, and interfacial splitting tensile and shear strengths of metal mortarconcrete are discussed. The changes in the bond properties of metal mortar-concrete interface were also investigated from a microscopic point of view. The results showed that the alternating action of freeze-thaw cycles and abrasion resulted in more apparent damage and mass loss, and the coupling damage became more pronounced as the number of alternations increased. The interfacial bond strength was reduced by 33.7 %-50.06 % under a single freeze-thaw or abrasion action. And interfacial bond strength decreases by 54.94 %-66.33 % under coupled freeze-thaw and abrasion. The interfacial splitting tensile and shear strengths have a good linear relationship under various actions (the correlation coefficients are higher than 0.97). The microscopic tests showed that the maximum width of the interface under the coupled action of freeze-thaw cycles and abrasion reaches 80-110 mu m, which is significantly higher than the single action (30-45 mu m).