Laboratory experiments on the effect of rebar in reinforced concrete on crack initiation by blasting

Abstract

The effect of rebar in reinforced concrete on blasting demolition was clarified through laboratory tests. In this study, blasting tests were conducted using concrete plate specimens containing iron bar, and the strain/stress state around the rebar and crack propagation were examined. The strain generated in the specimen after ignition of the explosive was calculated by the digital image correlation method. This method successfully visualized cracks that could not be seen visually and clarified stress wave propagation and crack propagation behavior around the rebar before and after crack initiation. The results showed that the presence of rebar in the propagation path of a stress wave causes more regular cracking than when no rebar is present due to reflection and diffraction of the stress wave.