Microstructure evolution and impact resistance of crumb rubber concrete after elevated temperatures

Abstract

With the rapid development of the automobile industry, the disposal of scrap tires in an eco-friendly manner has become a global concern. Due to excellent toughness and durability performance of crumb rubber concrete (CRC), it is a promising approach for recycling massive scrap tires. In this study, the impact resistance of CRC after exposure to elevated temperatures (200 °C and 400 °C) was experimentally investigated using a split Hopkinson bar (SHPB). The pore structure, hydrates and morphology of CRC microstructure evolution after elevated temperatures were also studied using an ultra-depth of field test, TG-DSC, CT, and NMR. Results show that although rubber concrete is subjected to 200 °C high temperature, its strength and impact resistance do not decrease because rubber can release the capillary pressure caused by elevated temperature. However, a significant loss in the ultimate strength is observed at 400 °C. This is because when CRC with a rubber content of 100 kg/m3 is subjected to an elevated temperature of 400 °C, its void (pore size > 1 μm) ratio is 3.4 times higher than that of plain concrete. The addition of rubber particles improves the impact toughness of concrete even after the elevated temperature of 400 °C, and the ultimate compressive strength under dynamic load is linearly related to the porosity and logarithm of strain rate.