Study on the bond performance and reliability of the interface between full-lightweight ceramsite concrete and frost damage concrete under freeze-thaw cycles

To study the interface durability of frost damaged concrete (FDC) reinforced by full-lightweight ceramsite concrete (FLWCC) in cold regions. The macro-micro structure and interface bond strength of FLWCC-FDC composite specimens under different freeze-thaw cycles (FTCs) were evaluated by FTCs test, splitting tensile test, slant shear test and scanning electron microscope (SEM) test. The reliability prediction model of FLWCC-FDC interface bond strength was established based on Wiener random process. The results show that the bond strength of FLWCC-FDC interface decreased with the increase of FTCs. The slight frost damage was beneficial to the interface bond strength in the early stage of freeze-thaw, especially the interface slant shear strength, but the severe frost damage was harmful. The increase of bond strength by interface treatment can effectively offset the decrease of bond strength caused by frost damage, so as to improve the overall bond strength. The porosity of the interfacial transition zone (ITZ) increased with the increase of FTCs, and there was a significant negative linear correlation between porosity and bond strength. The Wiener random process model can effectively predict the interface life of FLWCC-FDC under FTCs, and the sensitivity of using slant shear strength as damage index is the highest.