Residual compressive strength and microstructure of high performance concrete after exposure to high temperature

Experimental programs were carried out tl, study compressive strength and m icrostructure of high performance concrete (HPC) subjected to high temperat ure compared with normal strength concrete (NSC). After the concrete specim ens were exposed to a peak temperature of 800 degrees C, the compressive st rength was tested. Changes of porosity and pore size distribution of the co ncrete were measured by using mercury intrusion porosimetry (MIP). Test res ults show that high performance concrete had higher residual strength altho ugh the strength of high performance concrete degenerated much more than th e normal strength concrete after high temperature exposed. Variations in po re structure of high performance concrete after high temperature indicated the degradation of the mechanical properties. A model by optimizing the par ameters ill Ryshkewitch model was developed to predict the relationship bet ween porosity and compressive strength of the high performance concrete.