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Over dependence on the sole use of river sand as fine aggregate in producing concrete over the years, has raised serious environmental concerns. Incessant mining of river sand accelerates the deterioration of the river bed, causes floods, and affects the diversity of aquatic life negatively. In this study, the possibility of using quarry dust to partially replace river sand in producing concrete was investigated. Central Composite Design (CCD) in Minitab was used to generate 31 mixes with different combinations of water to cement (W/C), Quarry dust to Sand (Q/S), Sand to Total Aggregate (S/TA) and Total Aggregate to Cement (TA/C) ratios. The fresh concrete was tested for workability using slump test. Three (3) concrete cubes were cast per sample point and tested for compressive strength at 28 days of curing. A regression model was developed and analyzed using response surface methodology (RSM) at 95% confidence level. Results obtained showed that compressive strength up to 27.44N/mm2 can be achieved with combination of W/C of 0.36, Q/S of 0.3, S/TA of 0.4 and TA/C of 3. Model developed has overall P value of 0, R2 value of 75.69% and Adjusted R2 value of 66.85% and validated to be well fitted. It was concluded among others, that quarry dust can be used as a constituent material in structural concrete, optimum percentage replacement of sand with quarry dust is 30% and that the developed model is valid, adequate and well fitted.
Abubakar et al. (Sun,) studied this question.