Investigation of usability of waste foundry sand in readymixed concrete

Concrete is the most widely used man-made material in the world. Aggregate owing to 75% proportion in the ready-mixed concrete (RMC) is an important component; but its natural resources are in the limit of extinction. Thus, the usage of industrial wastes together with aggregates in RMC production will be helpful in overcoming problems related to possible aggregate demand in the upcoming years. In this study, the usability of waste foundry sand (WFS) in the production of RMC was carried out. Concrete specimens were prepared using 0% (control), 10%, 20%, 30%, 40%, 50%, 75% and 100% WFS by weight as replacement of silica sand and the mechanical, leaching and micro-structural properties of WFS-based RMC products. In order to determine the performance of fresh and hardened concrete specimens prepared by solidification/stabilization (S/S) process as two control and seven concrete specimens and performed at four different curing periods; physical and mechanical properties such as slump, unit weight, temperature, setting time, compressive and tensile splitting strength, modulus of elasticity, water absorption ratio and density were examined and the most suitable replacement ratio was determined as 20%. Leachability characteristics of the solidified concrete specimens at three different pH conditions were also observed. Furthermore, micro-structural properties of both control concrete and concrete having 20% WFS were investigated by using XRD, XRF, SEM and EDS techniques. As a result, it's suggested that WFS can be effectively utilized in the production of RMC by a maximum of 20% replacement instead of fine aggregates with no adverse physical, mechanical, environmental and micro-structural impacts.