Abstract: In order to study the effect of rubber powder on the fracture performance of C60 high performance concrete after high temperature, high temperature tests were carried out on C60 HPC with rubber powder content of 5% and 8% to determine the compressive strength and splitting tensile strength, and based on the double- K fracture theory, a three- point bending fracture test was performed on the specimen, the fracture parameters were calculated, and the initiation toughness and instability toughness were plotted against temperature. The results show that as the temperature increases, the compressive strength and splitting tensile strength of C60 HPC show a downward trend, and the addition of rubber powder will reduce the mechanical properties of C60 HPC. The initiation toughness and instability toughness of C60 HPC mixed with rubber powder at 400 ℃ decreased by 8.7% and 12.2%. At 400~600 ℃, the initiation toughness and instability toughness decreased by more than 50%. Analysis and fit curve shows that the thresholds for the initiation toughness and instability toughness loss of C60 HPC blended with rubber powder are 400 °C and 500 °C separately.

Key words: high performance concrete, high temperature, rubber powder, mechanical properties, fracture parameters