Effect of brick aggregate on failure process of mixed recycled aggregate concrete via X-CT

Producing mixed recycled aggregate (MRA) from construction and demolition waste (C&DW) to replace the use of sand and gravel can help relieve supply and demand imbalances. However, the basic properties of MRA are poor, and the effects of brick aggregates on the mechanical properties of mixed recycled aggregate concrete (MRAC) remain unclear. Consequently, the non-destructive X-ray computed tomography technology was used to continuously observe the changes in the pore structure of the MRAC with different brick contents under load in this study. The influence mechanism of the brick aggregates on the failure process of the MRAC under load was explored. The results showed that the presence of brick aggregates and impurities caused differences in the internal properties and surface areas of MRAC. The volume change trends of gravel aggregate and brick aggregate under load were different, which ultimately led to changes in the MRAC failure mode. Increasing the brick content also increased the deformability of the MRAC, resulting in more evident volume changes during compaction. The results of this study could be helpful in promoting the use of MRA and also have significant economic and environmental benefits.