Multi-parameter performance evaluation of concrete incorporating Deccan basalt manufactured sand

Purpose The study aims to evaluate the feasibility of Deccan basalt manufactured sand (DBM) as a sustainable fine aggregate substitute for natural river sand in concrete. It focuses on an integrated performance assessment covering mechanical strength, durability under sulphate exposure, microstructural features and economic viability. Design/methodology/approach Concrete of M50 grade was designed using a constant water–cement ratio (0.33), with river sand replaced by DBM in increments of 0%–100%. Experimental investigations included compressive and flexural strength testing, slump measurement and durability assessment through immersion in 5% Na2SO4 solution for 120 days. Microstructural analyses were conducted using scanning electron microscopy (SEM) to examine the interfacial transition zone (ITZ) and calcium silicate hydrate (CSH) formation. Economic performance was analysed using cost per unit compressive strength (₹/MPa/m³). Findings Results revealed that DBM incorporation enhanced compressive and flexural strengths by 12.7% and 16.49%, respectively, at full replacement. Sulphate resistance improved markedly, with weight and strength losses reducing from 7.51% and 13.51% (control) to 2.84% and 5.17% (100% DBM). SEM images confirmed denser ITZ, compact CSH formation and reduced ettringite deposits. Economic evaluation indicated up to 19.1% improvement in cost efficiency compared to river sand concrete. Originality/value This study provides one of the first comprehensive evaluations of basalt-derived manufactured sand (M-sand) from the Indian Deccan region as a fine aggregate in concrete, integrating mechanical, durability, microstructural and cost analyses. The findings establish DBM as a technically robust, durable and economically viable alternative to natural river sand for high-performance concrete, particularly under chemically aggressive environments.