Interfacial fracture performance of engineered cementitious composites and fire-damaged concrete

This study investigated the interfacial fracture properties of engineered cementitious composites (ECC) and fire-damaged concrete using bi-material wedge splitting specimens. The full load versus crack mouth opening displacement (CMOD) curves of the bi-material specimens were obtained using wedge splitting tests, and the fracture toughness and fracture energy were calculated. The effects of the maximum temperature experienced by the concrete (20-700 degrees C) and the interfacial roughness (0-5 mm) on the interfacial damage mode, fracture toughness, and fracture energy were studied. The results indicated that when the maximum temperature expe-rienced by the concrete was lower than 400 celcius or the interface was smooth, the damage mode of the specimens was primarily adhesive failure. However, when the maximum temperature expe-rienced by the concrete was equal to or greater than 400 degrees C and the interface was rough, cohesive failure often occurred in the specimens. Owing to the change in the damage mode, the bi-material specimens had the highest values of the fracture toughness and fracture energy at 400 degrees C. When the maximum temperature experienced by the concrete exceeded 400 degrees C, both the fracture toughness and fracture energy decreased with the increasing temperature. In this study, the fracture toughness and fracture energy of the bi-material specimens first increased and subse-quently decreased with the increaseing roughness, and the maximum fracture toughness and fracture energy values were obtained when the interface roughness was 3 mm. The study results would provide a reference for the surface treatment when ECC was used in the strenthening of fire damaged concrete.

Automated summary

This study investigated the interfacial fracture properties of engineered cementitious composites (ECC) and fire-damaged concrete using bi-material wedge splitting specimens. The effects of maximum temperature and interfacial roughness on damage mode, fracture toughness, and fracture energy were studied. The results showed that the damage mode changed from adhesive failure to cohesive failure at a maximum temperature of 400 degrees C and with rough interface. The fracture toughness and fracture energy were the highest at 400 degrees C but decreased with increasing temperature. They initially increased and subsequently decreased with increasing roughness, with maximum values obtained at 3 mm interface roughness.