Comparative Analysis of the Compressive Strength of Concrete Utilizing Aggregates from Different Sources
Abstract
Concrete quality in Nepal is strongly influenced by the properties of locally sourced aggregates, yet localized data linking aggregate source to concrete performance remain scarce. This study comparatively evaluated the compressive strength of M20 grade concrete produced using coarse aggregates from three sources in the Bagmati Province of Nepal Dukuchhap (Lalitpur), Belkhu Quarry (Dhading), and Roshi Khola (Kavre), while keeping the fine aggregate (Belkhu sand) and binder (Shivam OPC 43 grade cement) constant. The aggregates were characterized through sieve analysis, aggregate crushing value (ACV), aggregate impact value (AIV), Los Angeles abrasion (LAA), specific gravity, and water absorption tests in accordance with IS 383:2016. Concrete cubes (150 mm) of nominal M20 mix (1:1.5:3) were cast in two independent batches per source and tested at 7 and 28 days of water curing. All three aggregates satisfied the mechanical property limits of IS 383:2016, although none fully complied with the graduation requirements for 20 mm graded aggregate. All mixes comfortably exceeded the M20 target, with mean 28-day strengths of 36.44 MPa for Dhading (+82.2%), 33.20 MPa for Roshi Khola (+66.0%), and 32.46 MPa for Dukuchhap (+62.3%). One-way ANOVA confirmed that aggregate source has a statistically significant effect on 28-day strength (F = 104.62, p = 1.55 × 10⁻⁹). Bonferroni-adjusted pairwise Welch’s t-tests showed that Dhading aggregate significantly outperformed both other sources (p < 0.001), while the difference between Roshi Khola and Dukuchhap was not significant at the adjusted level (p = 0.0444 > α′ = 0.0167). The superior performance of Dhading aggregate corresponded with its lowest ACV (21.53%) and lowest water absorption (0.62%), which enhance the aggregate–cement paste interfacial bond. The study concludes that aggregate source selection is a decisive, statistically verifiable factor in concrete strength, and recommends Dhading (Belkhu) aggregate for structural applications, with Roshi Khola and Dukuchhap aggregates suitable for M20-grade work under appropriate quality control.