Damage caused by projectile impact to high strength concrete elements

According to common penetration equations the resistance of concrete elements to projectile impact increases with increasing concrete strength. Therefore it is expected that using high strength concrete (HSC) will enhance the performance of elements that are designed to resist projectile impact. Normal strength concrete (NSC) and HSC plates were impacted, in an experimental study, by 160 g. (including the sabot) cylindrical projectiles, with a conical nose, at velocities that ranged between 100 - 250 m/sec. The experiments were done at NBRI laboratory with a gas gun that accelerated hard steel projectiles, whose impact velocities were measured by an electro-optical system. This paper describes a part of the study, in which craters at the rear and front faces of plate specimens were examined. The differences between the response of the NSC and of the HSC specimens under similar dynamic loading conditions (i.e., same projectile and similar impact velocities) were indicated by the fracture path in the rear face craters (around or through the aggregates). Other parameters that were examined were the crater volume and dimensions.