EFFECT OF THE PARTIAL REPLACEMENT OF FINE AGGREGATE WITH QUARRY DUST ON THE COMPRESSIVE STRENGTH OF CONCRETE

The increasing demand for natural river sand in concrete production has led to environmental degradation, resource depletion, and rising material costs, prompting the need for sustainable alternatives. This study investigates the effect of partially replacing fine aggregate (river sand) with quarry dust on the compressive strength of concrete. Quarry dust, a by-product of stone crushing operations, has been identified as a potential substitute due to its abundance, economic viability, and favorable particle characteristics. The experimental program involved producing concrete mixes with 0%, 10%, 20%, 30%, 40%, and 50% replacement of sand with quarry dust by weight. A total of 36 concrete cubes were cast using a standard mix ratio of 1:2:4 and a water-cement ratio of 0.6. The specimens were cured and tested for compressive strength at intervals of 7, 14, 21, and 28 days to assess strength development over time. The results revealed that the compressive strength of concrete increased with the inclusion of quarry dust up to an optimal replacement level of 25%, where a peak strength of 17.85 N/mm² was recorded, compared to 16.5 N/mm² for the control mix. This enhancement is attributed to better particle packing, pozzolanic activity, and improved interfacial bonding between the cement paste and aggregates. However, beyond the 25% replacement level, compressive strength declined, reaching 12.6 N/mm² at 100% replacement. The reduction in strength at higher replacement levels was primarily due to increased water demand, reduced workability, and the formation of internal voids, leading to a weakened aggregate-cement matrix. This study concludes that quarry dust can be effectively used as a partial replacement for fine aggregate in concrete up to 25% without compromising structural integrity. The incorporation of quarry dust not only enhances the mechanical properties of concrete at optimal levels but also contributes to environmental sustainability by minimizing the use of natural sand and reducing quarry waste. These findings support the potential of quarry dust as a viable material in sustainable concrete production, particularly in regions facing scarcity of river sand.