Compressive strength and pore structure of high-performance concrete after exposure to high temperature up to 800°C

An experimental program was carried out to study the mechanical properties and pore structure of high-performance concrete (HPC) and normal-strength concrete after exposure to high temperature. After the concrete specimens were subjected to a temperature of 800 degrees C, their residual compressive strength was measured. The porosity and pore size distribution of the concrete were investigated by using mercury intrusion porosimetry. Test results show that HPC had higher residual strength, although the strength of HPC degenerated more sharply than the normal-strength concrete after exposure to high temperature. The changes in pore structure could be used to indicate the degradation of mechanical property of HPC subjected to high temperature. A model was developed by optimizing the parameters in the Ryshkewitch model to predict the relationship between porosity and the strength of HPC. (C) 2000 Elsevier Science Ltd. All rights reserved.