Abstract：In this work, an experimental study on the thickness-dependent size effect of concrete fracture parameters, as one of the experiments stipulated by RILEM TC265-TDK Technical Committee (testing methods of determining the double-K criterion for crack propagation in concrete), is carried out. The double-K fracture toughness and the fracture energy of 29 beam specimens in 5 groups with the thicknesses varying from 100mm to 300mm is measured based on the three-point bending test. The relationship between the fracture parameters and the thickness of specimens is evaluated quantitatively. In addition, the thickness-dependent size effect of concrete fracture parameters is discussed based on the linear elastic formula of fracture toughness, the theory of Weibull size effect and the multi-axial strength theory of concrete. Experimental results and theoretical analysis indicate that there exists no remarkable thickness-dependent size effect for the fracture parameters of concrete.
