Rear face damage of normal and high-strength concrete elements caused by hard projectile impact

Rear face damage assessment od scabbed, punched, or perforated concrete barriers due to hard projectile impact was evaluated according to the spalling volume and size by using existing, classical and more modern penetration formulas. The damage-level calculations are done for various velocity ranges, below and above the perforation limit. An experimental work included a comparison between the response of normal strength concrete (NSC) and high-strength concrete (HSC) barriers to hard projectile impact. The experiments were done with a gas gun that accelerated 165 fi (including the saber), hard steel projectiles, whose impact velocities ranged between 100 and 250 m/sec, and were measured by an electro-optical system. Craters at the rear-face of the plate specimens were examined and showed that the NSC and HSC volumes were similar at similar velocity levels (i.e., relative to the perforation velocity). The NSC experimental results showed an increased damage level at velocities that were near or less than the perforation limit velocity. This trend is similar that of a theoretical model prediction.