Influence of Replacement Level of Recycled Coarse Aggregate on Fracture Properties of Recycled Aggregate Concrete

摘要

recycled aggregate concrete made with recycled aggregate was one of the effective ways to reuse the construction and demolition waste. Due to the weak complex interface transition zone of recycled aggregate concrete, the defect had great effect on the bearing capacity and durability of recycled aggregate concrete. The fracture performance of recycled aggregate concrete was studied, which was of great practical significance and engineering value. The wedge splitting test of 200mm x 200mm x 230mm specimens was carried out using the fatigue testing machine (MTS). The elastic modulus of the specimens were measured and calculated by strain gauge and dynamic resistance strain gauge, and the elastic modulus was about 4GPa lower than that of standard test. Based on double-K fracture model of recycled aggregate concrete, the crack initiation fracture toughness and the unstable fracture toughness was obtained. The test results show that the replacement level of recycled aggregate is not obvious to the crack initiation fracture toughness, and the unstable fracture toughness is lower than that of natural concrete. Using the exponential function to fit the tail of the Ph-COMD curve of the wedge splitting test, it is found that the fracture energy of the recycled aggregate concrete is not reduced with the increase of the replacement level of the recycled aggregate.