Mechanical properties of high strength concrete made with pyrophyllite aggregates exposed to high temperature

This paper presents the results of an experimental research on the assessment of the residual mechanical properties of high strength concretes (HSCs) made with pyrophyllite aggregate (PA) after high temperature. In the study, HSC mixtures with varying PA ratios (0, 25, 50, 75, and 100%) were subjected to elevated temperature (150, 300, 450, 600, and 750°C) and then cooled in two different cooling regimes (air and water-cooling). The properties examined included compressive strength, weight loss, effects of cooling regime, and microstructure of HSC. The results of the study show that the increase in the PA ratios leads to a decrease in the compressive strength values. The results showed that weight loss of the specimens decreased with increasing PA ratios. It was found that the compressive strength values of HSC with PA cooled in air-cooling are higher than that cooled in water. When the compressive strength loss and the weight loss values are taken into consideration according to the control samples, the group with the highest resistance to high temperature (750°C) effect was 100% PA group. Also, the internal structures of the samples exposed to high temperature were examined using scanning electron microscope and visual observations. © 2020 fib. International Federation for Structural Concrete