STRENGTH CHARACTERISTICS OF CONCRETE MADE WITH CRUSHED GRANITE OF VARYING PARTICLE SIZES FOR STRUCTURAL APPLICATIONS

Summary

The selection of appropriate coarse aggregate characteristics is essential for producing concrete with adequate strength for structural applications. This study investigated the strength characteristics of concrete produced with crushed granite of varying particle sizes. Five aggregate treatments comprising 12, 14, 16 and 20 mm granite fractions and an equal-proportion combined aggregate were evaluated using a 1:2:4 mix proportion and a water–cement ratio of 0.50. Portland limestone cement, River Benue sand and crushed granite were used for concrete production. Aggregate properties, workability, density, compressive strength and splitting tensile strength were determined using standard laboratory procedures. Concrete specimens were cured for 7, 14 and 28 days. The results showed that the 20 mm aggregate produced the highest 28-day compressive strength (29.40 N/mm²) and splitting tensile strength (2.33 N/mm²), while the 12 mm aggregate recorded the lowest values of 25.33 and 2.06 N/mm², respectively. Both compressive and splitting tensile strengths generally increased with curing age. Two-way analysis of variance (ANOVA) showed that aggregate treatment, curing age and their interaction significantly affected compressive strength (p < .001), with the model explaining 99.3% of the observed variation (R² = .993). For splitting tensile strength, aggregate treatment and curing age had significant effects (p < .001), whereas their interaction was not significant (p = .135). The study concludes that coarse aggregate particle size significantly influences concrete strength, with 20 mm producing the highest strength under the conditions investigated. The use of 20 mm coarse aggregate is recommended where higher strength is required and member dimensions permit its use.

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