Static and dynamic mechanical properties of concrete after high temperature exposure

The aim of this paper is to investigate the static and dynamic mechanical properties of concrete before and after high temperature exposure. Quasi-static and impact loading experiments were carried out on concrete before and after exposure to the temperature of 200–800 °C by using a servo-hydraulic testing machine and a 100-mm-diameter split Hopkinson bar (SHPB) apparatus, respectively. The results show that, mechanical properties of concrete after high temperature exposure change evidently, and the critical temperature for those changes acquiring dramatic character is 400 °C. With the rise of temperature up to 400 °C, compressive strength and critical strain change little compared with that of at room temperature. While with temperature increasing from 400 to 800 °C, the decrease in strength and the increase in critical strain become obvious. Consequentially, specific energy absorption (SEA), which is the synthetic exhibition of strength and ductility, decreases much less than those observed for strength over 400 °C. Dynamic compressive mechanical properties of concrete before and after high temperature exposure increase with the rise in strain rate rapidly, which exhibits strong strain rate dependency. Dynamic increase factor (DIF) increases approximately linearly with strain rate. In a word, concrete can be recognized as an excellent thermal-resistant and anti-impact construction material.

► The critical temperature is 400 °C.
► Concrete after high temperature exposure exhibits strong strain rate dependency.
► Concrete is an excellent thermal-resistant and anti-impact construction material.