Mechanical properties, durability and environmental evaluation of rubberized concrete incorporating steel fiber and metakaolin at elevated temperatures

Abstract

In this study, the effects of metakaolin (MK), as a replacement for the Portland cement, in the ratios of 0%, 10% and 20% by cement weight and steel fiber (SF) dosages of 0%, 0.25%, 0.5%, and 1% by concrete volume were investigated on the microstructure, mechanical properties, durability and global warming potential (GWP) of concrete containing 25% volume percentage of crumb rubber replaced with natural fine aggregates at elevated temperatures. Several specimens were exposed to the high temperatures of 150, 300, 450 and 600 °C for an hour, and were then compared in terms of mass loss, compressive strength, ultrasonic pulse velocity (UPV), splitting tensile strength (STS), and impact resistance at the ambient temperature. The role of MK and SF on the concrete microstructure at high temperatures was investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. The results show that not only does the combination of MK and SF improve the mechanical properties and durability of rubberized concrete at high temperatures, but it can also introduce more environmentally friendly mixes by reducing CO2 emissions, compared to a plain concrete mix.