The object of research is quarry dust as a sustainable alternative to natural sand in M40-grade concrete, addressing the environmental and resource challenges caused by sand depletion in Russia. The study examines the effects of replacing fine aggregate with quarry dust (10% to 40%) on concrete's compressive strength, split tensile strength, and durability Method. The concrete mixes were designed following IS 10262-2019 guidelines, with materials hand-mixed and each component precisely weighed. The mix was placed in cubic molds, compacted, and cured in water for 28 days. A total of 45 specimens were prepared and tested for compressive strength and split tensile strength at 7, 14, and 28 days using a universal testing machine C040PN, adhering to IS 516-1959 standards. Results. Replacing up to 20% of fine aggregate with quarry dust enhances compressive strength, achieving a peak strength of 46.35 MPa at 28 days, slightly below the control mix's 47.23 MPa. And up to 20 % enhances tensile strength of concrete achieving a peak strength of 3.95 MPa at 28 days. However, beyond this threshold, performance declines, with strengths dropping to 35.21 MPa at 30% replacement and 34.04 MPa at 40%. making 20% the recommended limit for quarry dust substitution in M40-grade concrete. This approach enables sustainable use of quarry dust without sacrificing the structural qualities essential for construction.