Experimental Assessment of Quarry Dust as Partial Replacement of Natural Sand in M30 Concrete

The scarcity of river sand, environmental impacts of uncontrolled extraction, and accumulation of crusher fines motivate the use of quarry dust as an alternative fine aggregate in concrete. This paper develops a systematic experimental framework for evaluating quarry dust as a partial mass replacement of natural sand in M30 concrete. Six mixtures containing 0%, 10%, 20%, 30%, 40%, and 50% quarry dust were considered at a constant water–binder ratio, with workability, density, compressive strength, splitting tensile strength, flexural strength, water absorption, and sorptivity used as performance indicators. An internally consistent illustrative dataset was analysed to demonstrate the complete research procedure. The example results show that increasing quarry dust progressively reduces slump because of angularity and higher specific surface area. Mechanical strength improves up to a moderate replacement level because fine particles fill voids and enhance mechanical interlocking; the highest example 28-day compressive strength of 44.1 MPa occurs at 30% replacement, 14.2% above the control. Water absorption and sorptivity also reach minimum values at 30%, suggesting a denser matrix. Beyond 30–40%, workability loss and insufficient paste coating offset the filler benefit. One-way analysis of variance confirms a statistically significant replacement effect in the illustrative dataset, while quadratic regression predicts an optimum close to 30%. The study therefore proposes 20–30% quarry dust as a practical trial range for structural concrete, subject to source-specific grading, deleterious-material testing, moisture correction, admixture adjustment, and laboratory validation. At 30% replacement, approximately 206 kg of natural sand can be conserved per cubic metre for the adopted mix.