Shear strength of the interface between full lightweight ceramsite concrete and normal concrete: Effect of interfacial roughness and pouring time interval

In this study, the effects of interfacial roughness and pouring time interval on the shear strength of the FLWCCNC interface were investigated by direct shear tests, grey relation analysis, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) tests. The results showed that the interfacial roughness affected the shear failure mode of the interface. The effect of the pouring time interval on the interfacial shear failure mode was not obvious. Reliable bonding between the FLWCC and NC was achieved when the interfacial roughness of the NC surface exceeded 2 mm or the roughness of the NC surface exceeded 1 mm, and the age did not exceed 1 day. The effect law of interfacial roughness on interfacial shear strength could be affected by the pouring time interval. Similarly, the effect law of pouring time interval on interfacial shear strength would be affected by interfacial roughness. The degree of influence of interfacial roughness on interfacial shear strength was higher than the degree of influence of pouring time interval on interfacial shear strength. Based on the experimental data, an equation describing the FLWCC-NC shear strength considering interfacial roughness and pouring time interval was established. At the micro level, the interfacial roughness and pouring time interval significantly affected the pore conditions and the ratio of the Ca to Si contents in the FLWCC part near the interface.