RSM-based evaluation of mechanical and durability properties of recycled aggregate concrete containing GGBFS and silica fume

Concrete is the most consumed material in the construction industry, and using recycled concrete aggregates (RCA), silica fume (SF) and ground-granulated blast-furnace slag (GGBFS) in concrete could reduce its negative environmental impacts by preserving natural resources and reducing construction and demolition (C&D) waste generation and CO2 emissions. Optimizing the mix design based on both mechanical and durability properties of RAC has not been performed. In this study, the mechanical properties and durability of Recycled Aggregate Concrete (RAC) containing GGBFS and Silica Fume (SF) were evaluated via Response Surface Methodology (RSM). The GGBFS was used to reduce the environmental pollution caused by cement production and balancing the negative effect of RA on the mechanical properties of concrete. The results indicated that RA had a negative effect on durability properties of concrete at 7 and 28 ages, while it had no effect on the properties at 90 days. Finally, optimized mix designs were obtained based on two specific scenarios. In the first scenario, the mix design with the highest of both mechanical and durability properties was obtained. In the second one, a mix design with the highest amounts of GGBFS, SF and RA, was achieved, due to the environmental issues related to concrete production. (C) 2020 Elsevier Ltd. All rights reserved.