Thermal and residual mechanical profile of recycled aggregate concrete prepared with carbonated concrete aggregates after exposure to elevated temperatures

Thermal and residual mechanical performance of recycled aggregate concrete (RAC) prepared with recycled concrete aggregates (RCAs) after exposure to high temperatures has so far received less attention than that of conventional concrete prepared with natural aggregates (NAs). This study experimentally investigated thermal and residual mechanical performance of RAC prepared with different replacement percentages of non-carbonated and carbonated RCAs after exposure to high temperatures. The residual mechanical properties, including compressive strength, modulus of elasticity, and peak strain at the maximum strength, were measured for evaluating the fire resistance of RAC. The experimental results showed that although the fire-resistant ability of natural granite aggregates was high, thermal deterioration of the conventional concrete after exposure to 600 degrees C, presented by thermal induced mesocracks, was more serious than that of RAC due to thermal incompatibility between NAs and mortar. Using the carbonated RCAs can reduce the width of thermal mesocrack in RAC. The residual mechanical properties of RAC after exposure to 600 degrees C can be obviously improved by incorporating 20% to 40% of the carbonated RCAs. For the RAC made with the 100% carbonated RCAs, the ratio of residual to initial compressive strength after exposure to above 500 degrees C was even higher than that of the conventional concrete.