Fracture performance of concrete-epoxy mortar interface subjected to bending and shear: Experimental and numerical study

To investigate the fracture performance of concrete-epoxy mortar interfaces, experimental and numerical simulation methods were employed to obtain the failure patterns and applied load P versus opening displacement curves of specimens. A special emphasis is placed on the discussions of crack initiation load (P-ini), maximum load (P-max), corresponding deformation (CTOD(ini )and CTODmax, CTSDini and CTSDmax), KR and GR curves of I-Type and stress intensity factors of I-IIType cracks (K-I(ini) and K-II(ini)) and facture energy (GF). Test results show that increasing both concrete compressive strength and interface roughness enhances the load carrying capacity and crack initiation toughness, as well as crack extension resistance. Higher concrete compressive strength improves the moment capacity of the interface and increases the proportion of K-I(ini). An increase in the interface roughness enhances the mechanical interlocking interaction at the concrete-epoxy mortar interface, thereby decreasing the CTSD/CTOD ratio and increasing the proportion of K-II(ini) for the I-II Type crack. As the mode ratio (K-II(ini)/K-I(ini)) increases, the proportion of shear and bending moment acting on the interface changes continuously, with the shear effect becoming more dominant. Basically, the increase in both the crack-height ratio (a(0)/D) and initiated crack offset ratio (C-1/C-0) decreases the fracture performances of specimen. The observations provide a deeper understanding to the design and practice of concrete-epoxy mortar interface.