Properties of concrete containing strengthened crushed brick aggregate by pozzolan slurry

Using crushed brick as a coarse aggregate to produce a new environmentally friendly recycled concrete is of particular interest to maintain natural aggregate (NA) and realize waste resources recycling. However, the low density and high porosity of crushed brick, as well as its relatively low compressive strength in comparison with NA make it difficult to meet conventional concrete specifications. The present study is an effort to investigate the properties of strengthened crushed brick aggregate (CBA) by various pozzolan slurries and experimentally evaluate the strength and durability properties of the concrete prepared using 100% treated CBA. The experimental results revealed that the porous structure of CBA together with the attached weak adhered mortar result in the decline of the physical and mechanical properties of CBA. The proposed treatment technique not only enhanced the CBA quality but also achieved concretes with better mechanical strength and higher resistance against chloride ion migration. Compared with natural aggregate concrete, the loss of compressive strength was 12-25%, flexural strength was 9-22%, and modulus of elasticity was 16-30% of the concrete containing treated CBA at 28 days curing age. Based on SEM observations, the surface of CBA and the interfacial transition zone (ITZ) between the cement paste and CBA were improved for the concrete treated by pozzolan slurries. (C) 2020 Elsevier Ltd. All rights reserved.