Compressive impact tests of lightweight concrete with 155-mm-diameter spilt hopkinson pressure bar

Abstract

High-strength, lightweight concrete materials have been widely used in many building structures, while the dynamic behaviors under high-strain-rate loading are not well understood. Two groups of high-strength, lightweight concrete specimens were cast for static and dynamic tests. The compressive strengths and densities of the specimens were 39.6 N/mm2 and 1.3 t/m3, respectively. Specimens with length-to-diameter ratios of 0.5 and 150-mm-diameter were tested using a 155-mm-diameter split Hopkinson pressure bar (SHPB). A copper disc was applied as the pulse shaper, and the resulting impact velocity was proven to be stable in each test scenario. The damage mode of the concrete specimens was brittle failure, and fragments with different sizes were generated after each impact. The higher the impact velocity was, the smaller the sizes of the fragments became. A representative stress–strain curve was developed based on the geometric shape of the observed curve for each specimen. The dynamic strength generally increased with the impact velocity for strain rates ranging from 40 to 140 s−1. A new profile consisting of one parabola and two straight lines was developed to represent the experimental dynamic increase factor. The energy absorption density and fragility curves were computed to understand the energy absorption and fragility properties of the specimens.