Stress overshoot and its evolution of ceramsite concrete with freeze–thaw cycles under impact loading

Abstract

In the present study, the impact characteristics of ceramsite concrete after freeze–thaw cycles are studied. The split Hopkinson pressure bar (SHPB) device is applied to conduct impact compression tests on ceramsite concrete samples with different volume fractions and freeze–thaw cycles under different strain rates. The performed analyses show that there is an obvious stress overshoot evolution after the peak stress of the stress–strain curve. The obtained results show that the stress and damage evolution of the stress overshoot platform has an obvious strain rate effect. It is found that with an increase in freeze–thaw cycles, freeze–thaw damage increases, while the magnitude of platform stress and overshoot stress decreases. The volume fraction of ceramsite affects the evolution of the stress overshoot platform. It is pointed out that the physical nature of the plateau trend originates from the competition between the effects of damage softening and secondary strain strengthening. The dynamic constitutive relationship of ceramsite concrete considering the influence of freeze–thaw cycles and damage evolution is established. The performed analyses demonstrate that the theoretical model can be applied to accurately analyze the stress–strain characteristic curve of ceramsite concrete. The results demonstrate that the impact failure images obtained from the finite element method are good consistent with the experimental results.