Experimental Study on the Influence of Size Effects on Compressive Dynamic Behavior of Lightweight Concrete

Abstract

To study the impact of the strain rate effect and size effect on the compressive dynamic behavior of lightweight concrete (LC), 3 cube sizes and 10 strain rates were set up, and uniaxial compression tests were conducted utilizing a servohydraulic compression-testing machine. The failure modes and compressive strength of LC under varying load cases were obtained via testing. Following an examination of the change law of strain rate effect and size effect on failure modes and compressive strength and a discussion of the relevant literature on normal-weight concrete for comparison and assessment, the primary conclusions obtained are as follows: under a strain rate effect, failure modes of LC develop from vertical cracks with an even distribution at a low strain rate to oblique cracks dominant at a high strain rate, which resembles that of normal-weight concrete. It is found that as the strain rate rises, the compressive strength of LC gradually increases while the percentage increase in the compressive strength gradually decreases withthe rise of cube sizes affected by the strain rate. The compressive strength of LC at three varying cube sizes (70, 100, and 150 mm) is increased by 53.70%, 44.71%, and 33.76%, respectively. The compressive strength of LC gradually decreases as the cube size increases. The higher the strain rate, the greater the percentage decrease of the compressive strength of LC due to size effects. The percentage decrease in the compressive strength of LC at different strain rates is between 18.24% and 28.85% under the size effect. The influence of the strain rate effect and size effect on the compressive strength of LC is more obvious than on the compressive strength of normal-weight concrete. In this study, the coupling effects of strain rate and size on the compressive strength of LC were examined from a quantitative perspective. The findings of the study have important implications for project applications and model tests of LC.