Capillarity of concrete incorporating waste foundry sand

Currently, most of the waste foundry sand (WFS) generated in the UK and many parts of the world are sent to landfill. The rising cost of land-filling and the associated environmental problems have prompted the metal casting industry into reusing the WFS. Concrete is a potential material where WFS can be utilised to partially replace the natural fine aggregate. This paper presents the results of an experimental investigation into concrete produced by replacing the fine aggregates (natural sand) with various amounts of WFS. The natural fine aggregate was replaced with 0%, 30%, 60% and 100% WFS. The water content, coarse aggregate, cement and the water to cement ratio remained constant. Concretes were cured at 1, 7, 28 and 90 days. The properties investigated at the various curing times were; water absorption by capillary action, compressive strength and ultrasonic pulse velocity (UPV). The results indicate that there is systematic increase in water absorption by capillary action, a decrease in compressive strength and UPV with increasing amounts of WFS in concrete. There seems to be a linear relationship between strength and capillary water absorption. Also an exponential relationship exists between strength and UPV.