Dynamic behaviour of normal-strength carbonate aggregate concrete at temperatures up to 800°C

Abstract

The impact resistance of normal-strength carbonate concrete at elevated temperatures up to 800°C was experimentally studied using a split Hopkinson pressure bar (SHPB). The SHPB impact tests focused on the effects of concrete design strengths, high temperature and strain rate on the dynamic behaviour of concrete at elevated temperatures. The stress–time and strain–time curves of the tested specimens were recorded to analyse the impact behaviour of concrete at elevated temperatures. The influences of static compressive strength, high temperature and strain rate on the dynamic peak strength of concrete are discussed. The test results show that the strain rate effect of concrete at elevated temperature is significantly different from that of concrete at room temperature. Within the scope of the SHPB impact tests in this work, the strain rate effects of concrete at 200°C and 300°C are obviously higher than at room temperature. Concrete heated to 400°C was found to recover to around the same level of the dynamic strength increase factor (DIF) values of concrete at 20°C. The strain rate effects of concrete at 600°C and 800°C deteriorated sharply compared with those of concrete at room temperature and lower than 600°C. This paper also shows that a previously recommended formula for the DIF is not suitable for predicting the dynamic behaviour of concrete at temperatures higher than 400°C.