Abstract: Impact compression tests on concrete specimens are conducted using a split Hopkinson pressure bar (SHPB) device, with impact velocities of 5, 6 and 7 m/s and concrete aggregate volume ratios of 0, 32%, 37% and 42%, to explore comprehensively the influence of these two factors on the dynamic characteristics and energy transfer laws of concrete. We study the variations in dynamic deformation, dynamic strength growth, and energy transformation of concrete with the two factors, and examine their influence on the dynamic strength using two-factor variance analysis. The results indicate that under impact compression, concrete specimens are subjected to failure dominated by the tensile splitting mode. Aggregate content imposes a great influence on dynamic elastic modulus, while impact velocity affects little. Concrete dynamic strength increases as aggregate content or impact velocity increases, and impact velocity has a greater effect on dynamic strength than aggregate content. With an increasing aggregate content, the dynamic increasing factor (DIF) increases in the impact velocity range of 5 to 5.8 m/s, while it decreases in the range of 5.8 to 7 m/s. The transmitted energy increases with impact velocity or aggregate content; the reflected energy, absorbed energy, and the ratio of absorbed energy to incident energy all increase with impact velocity but decrease with aggregate content.

Key words: concrete, impact velocity, aggregate content, dynamic strength, energy