Experimental Study on Dynamic Performance of Plain Concrete and Lightweight Aggregate Concrete under Uniaxial Loading

To examine the uniaxial behaviors of plain concrete and lightweight aggregate concrete under dynamic loadings, the plain concrete specimens and lightweight aggregate concrete specimens prepared by shale ceramsite were designed and tested under the loading strain rate range of 10(-5)/s-10(-2)/s. The hydraulic servo machine and shear device were applied to conduct the uniaxial compression, splitting tensile, and shear tests of both types of concretes, and the failure modes and stress-strain curves of two concrete at varying loading conditions were obtained from the test results. By comparing and analyzing the test results, the following conclusions are obtained: the failure of cementing layer occurs in plain concrete at low strain rates, while some coarse aggregates are damaged at high strain rates, but the failure of lightweight aggregate concrete is caused by the fracture of shale ceramsite at all strain rates. As the loading strain rate increases, the uniaxial compressive strength, splitting tensile strength, and shear strength of plain concrete and lightweight aggregate concrete are significantly increased, with the improved percentages of 35.63%, 43.75%, and 41.29% for plain concrete and 44.87%, 55.97%, and 49.44% for light aggregate concrete, respectively. For both types of concrete, the increase of strain rate has a more significant effect on the increase of splitting strength than compressive strength. In addition, the strain rate effect on the strength of lightweight aggregate concrete is significantly higher than that of plain concrete. The dynamic increase factor of peak stress of both concretes under uniaxial loadings is linearly related to the dimensionless logarithmic values of the strain rate. Based on the test results and analysis, two different relationship expressions between compressive strength, splitting tensile strength, and shear strength of two types of concretes are proposed, and the dynamic effects of concrete are explored from the perspective of the damage mechanism. This study is meaningful to the engineering applications and development of plain concrete and lightweight aggregate concrete. (C) 2021 American Society of Civil Engineers.