Effects of ages on the ITZ microstructure of crumb rubber concrete

In this study, the microstructure of crumb rubber concrete (CRC) was investigated using scanning electron microscopy (SEM) and pore structure analyzer (PSA). The specimens were cured for 3, 7, 14, 28, and 56 days respectively before testing. Besides microscopic tests, compressive strengths of the specimens with different curing periods were also measured. The results showed that the hydration products in CRC were similar to those of normal concrete (NC). The porosity and average pore size in CRC were greater than those in NC, while the pore spacing coefficient of CRC were smaller than those of NC in the whole. When the curing period was within 56 days, with the increase in curing period, the compressive strength of CRC was increasing similarly to that of NC. However, the pore spacing coefficient of CRC was decreasing gradually with the increase of curing period. At the early two weeks, with the increment in curing period, the other microstructure parameters were fluctuating. Two weeks later, the porosity and the length density of microcracks were increasing, and the average pore radius was decreasing gradually with the increment in curing period. It can be concluded that there is a negative correlation between the compressive strength and the pore spacing coefficient of CRC. (C) 2020 Elsevier Ltd. All rights reserved.