Stress wave propagation and fracture of cement mortar bar

This paper concerns the longitudinal wave propagation in cement mortar bar and its fracture. In the study, the Hopkinson's bar technique was employed. Impact loading at one end of the cement mortar bar was given by using the air gun. The stress wave picked up by the wire strain gage was recorded on the synchroscope. At first the propagation and reflection of stress wave in the cement mortar bar without fracture was studied. Then, the speed of projectile from the air gun was increased in order to produce the fracture. Specimens of four cases of cross areas were used. The mechanism of stress wave propagation and fracture of cement mortar bar were made clear. These are the relations between the speed of the projectile and the stress level, fracture point of the bar.