A wedge loading compact tension(WLCT) system was used in this study to investigate the phenomenon of crack propagation in rock slabs. The rock slabs under investigation were selected from natural building stones. A high-resolution crack-strain-gage system was used to measure the fractal crack propagation velocity. The proposed experimental procedure is able to determine the crack velocity

fractal dimension and fracture toughness of the test specimen. This study finds: the steady-state crack velocity near the crack tip is measured in the range of 0.113 to 313.043 cm/s; the unstable crack velocity near the crack tip is measured in the range of 0.094 to 2 489.816 cm/s; the subcritical fractal dimension is found to be 0.994 3 to 1.036 6; the initial fracture toughness is found to be 1.891 5 to 3.500 1 MPa?m1/2; the fractal subcritical fracture toughness is found to be 2.063 6 to 3.712 8 MPa?m1/2.