The Effective Re-use of Foundry Sand Waste in the Production of Concrete

Foundry greensand waste is a by-product generated in large quantities from casting operations. In this study, Foundry Sand Wastes (FSW) were collected from three ferrous foundries. The samples were named Sample A, B and C. The samples were examined using an X-ray Diffractometer (XRD) to study the mineralogical phase of the FSW and X-ray Fluorescence (XRF) to determine the chemical composition of the FSW while a particle size distribution analyzer was used to determine the grain size distribution of the FSW. Scanning Electron Microscope was also used to determine the morphology of the samples. The silica sand in the mix was replaced by 50% FSW to produce concrete paver in the ratio of 1:1:2, 1:2:4 and 1:3:6. These ratios represent cement: silica sand + FSW: coarse aggregate. The ratio that produced the maximum compressive strength per concrete paver sample is the ratio 1:1:2 and this is similar to the split tensile strength test. The concrete paver samples were subjected to a compressive strength test and split tensile test. Quartz is the predominant mineral found in the FSW samples as revealed by XRF and XRD while the major constituents found in the three FSW samples are Silicon (Si), Iron (Fe), and Aluminium (Al). The trend of the compressive strength and split tensile strength results is consistent. Sample A compressive strength result at 28 days is 23 MPa which is below the acceptable value. Hence, Sample A was not recommended. However, samples B and C showed acceptable compressive strength results of 26MPa and 50MPa respectively at 28 days. Sample C showed the highest strength results for all the curing ages when compared with other samples. Beneficiation of the FSW that makes paving bricks within acceptable toughness and durability values is recommended.