In this study, the static and impact splitting tensile tests were carried out by loading the cylindrical mortar/granite specimens horizontally, and the crack propagation velocities were obtained by the image analysis using the ultra high-speed video camera, which is the fastest in the world, developed by Etoh et al.(2003). The correlations between the impulse and the crack propagation velocity indicate that there appears to be a critical state in which the crack propagation velocity does not exceed a certain value even though the increased impulse is applied. The critical value obtained was 2.6km/s for both mortar and granite specimens. Furthermore, crack propagation velocity determined by the image analysis was verified by the dynamic strain analysis.
