Tolerance Level of Bricks in Recycled Concrete Aggregates

The complete segregation of bricks from construction and demolition waste is quite challenging, leading to a reduction in the quality and suitability of recycled concrete aggregates (RCA) for rigid pavement applications. This investigation fundamentally studied the effect of brick waste (BW) on the performance of pavement quality concrete (PQC) made with RCA with the aim of identifying the tolerance limit of different BW fractions (coarse and fine) in RCA. This was achieved by mapping the fresh and hardened state behavior of PQC as well as mortar post-inclusion of BW fractions (0%–30%). Contrary to the general perception, the intermixing of BW in RCA was found to be beneficial, as it overcomes the negative effects of hydrated cement mortar paste present in RCA. The presence of BW in RCA resulted in 9%–36%, 15%–25%, and 5%–17% increases in the workability, compressive strength, and modulus of rupture of PQC, respectively. These increases have been attributed to the better morphology of BW compared with RCA and natural aggregates. In addition, BW possesses some pozzolanic reactivity, which facilitates chemical bonding between the aggregate surface and surrounding mortar paste. In fact, BW grains were found to retain moisture, leading to a reduction in the drying shrinkage of PQC by 54%–115%. Based on this study, the presence of 10%–15% BW in RCA could be considered as a threshold limit.