The effect of waste foundry sand (WFS) as partial replacement of sand on the mechanical, leaching and micro-structural characteristics of ready-mixed concrete

This study presents the potential re-use of waste foundry sand (WFS) in ready-mixed concrete (RMC) production. Regular sand was replaced with five percentages (0%, 10%, 20%, 30%, 40%) of WFS by weight and solidification/stabilization (S/S) process was applied to all concrete mixtures. Three aspects were investigated for the qualification of WFS-based-RMC, i.e., the mechanical, leaching and micro-structural properties. Various tests for the mechanical and physical performance of the solidified products were carried out, and the results indicated that the addition of WFS as partial replacement of sand reduced the strength performance and density and also increased the water absorption ratio of the concrete mixtures. Nevertheless, the concrete having 20% WFS exhibited almost similar results with the control one. Leachability characteristics of the entire concrete specimens at different pH conditions representing variant natural cases were also observed. Furthermore, micro-structural investigations of both control mix and concrete mix having 20% WFS were also performed by using XRD, XRF, SEM and EDS techniques. The findings of this research suggest that WFS can be effectively utilized in making good quality RMC as a partial replacement of fine aggregates with no adverse mechanical, environmental and micro-structural impacts; however, the partial replacement should not exceed 20%.

► Potential re-use of waste foundry sand (WFS) in ready-mixed concrete (RMC).
► Utilization of WFS as partial replacement of fine aggregate (regular sand).
► Regular sand has been replaced by WFS (0%, 10%, 20%, 20%, 40%).
► Effects of WFS on the mechanical, leaching and micro-structural properties of RMC.
► WFS can be effectively used in making good quality RMC with no adverse impacts.