Investigation of mechanical and durability properties of concrete made with a mixture of waste foundry sand and domestic treated wastewater

Two crucial and challenging issues that threaten the environment are the significant amount of drinking water for concrete production and the vast quantity of waste foundry sand (WFS) generated each year. Using WFS and treated wastewater (TW) in concrete instead of sand and drinking water is a new method for solid waste recycling and water reuse. In this research study, two types of concrete mixtures were made by partial replacement of natural sand with WFS, and simultaneously using both the WFS and the TW as a part of sand and drinking water. Then, the mechanical properties and durability of mixtures were determined. The results indicated that increasing WFS and TW ratios decreased the workability of concrete. The sample contained 20% WFS plus 50% TW (W20-TW50) showed the best results, which increased compressive strength by 33.9, 19.2, and 6.2% at the age of 7, 28, and 90 days respectively, and decreased 30- minute and 24- hour water adsorption by 10.6 and 14.3% compared to the control samples. Furthermore, using WFS and TW simultaneously in concrete did not significantly impact on ultrasonic pulse velocity and rapid chloride migration. Scanning electron microscopy images indicated that the W20-TWSO sample had the best structural density and lowest pores.

Automated summary

This study explores the use of waste foundry sand and treated wastewater in concrete production as a means of recycling solid waste and reusing water resources. The results show that the combination of 20% waste foundry sand and 50% treated wastewater improves the mechanical properties and durability of concrete, while reducing water adsorption.