Impact of Waste Foundry Sand as a Partial Substitute for Sharp Sand on Compressive Strength and Water Absorption of Hollow Sandcrete Block

Abstract

The need for habitable and affordable shelter cannot be overemphasized but the high cost of components of shelter such as hollow sandcrete blocks, bricks etc. posed a challenge to our ability to access affordable and habitable shelter. Utilization of already discarded waste foundry sand (WFS) as eco-friendly construction material for production of hollow sandcrete blocks, will save cost and preserve our environment. In this study, impact of locally available waste foundry sand as partial substitute for sharp sand in production of hollow sandcrete blocks was investigated. Sharp sand was partially substituted with WFS at 0, 10, 20 and 30%. A mix ratio of 1:6 (ratio of cement to sharp sand) and a water-cement ratio of 0.5 were used. Hollow sandcrete blocks were subjected to compressive strength tests at 7th and 28th days as well as a water absorption test on the 28th-day. Outcomes of the research showed that an increase in the amount of WFS led to the loss of compressive strength across all curing ages, and that all sandcrete block samples including control samples did not satisfy the minimum 28th day strength requirement of 3.5 MPa stipulated for load-bearing hollow sandcrete blocks. However, block samples containing 0 and 10% of WFS can satisfactorily be used for the construction of non-load bearing walls since they meet the required minimum strength of 1.5 MPa at 28th day. It was also observed that increasing the quantities of WFS from 0 – 30% caused a corresponding increase in the water absorption for all the block samples although the recorded values did not exceed the recommended maximum of 12% except for samples containing 30% WFS. Conclusively, WFS has a negative impact on both compressive strength and water absorption properties of sandcrete blocks and as such cannot serve as a good partial substitute for sharp sand.