On the Effect of Aggregate Size on Concrete Spalling Strength
骨料尺寸对混凝土层裂强度的影响

As a major ingredient of concrete, aggregate has an important effect on concrete mechanical behaviors, but up to now, less work was addressed to the influence of aggregate size on concrete spalling strength. Slender concrete rod spalling experiment was carried out by using a large diameter Hopkinson pressure bar equipment, in which stress pulse produced in buffer bar mounted behind the concrete rod was measured to determine spalling strength. Experiment is focused on the influence of two kinds of concrete with different aggregate sizes and subjected to different impact velocities on the concrete spalling. Results indicate that concrete containing larger size aggregates has lower spalling strength under the same loading condition. This can be attributed to the weakened strength in the larger aggregate interfacial transition zone. Results also reveal that spalling strength of concrete has a rate effect, namely, the higher loading rate is, the higher spalling strength is. However, when loading wave exceeds a threshold, the spalling strength decreases due to the evolution and accumulation of compressive damage in concrete.