Evaluation of optimal aggregate gradation curves on the mechanical and durability properties of concrete

Introduction: Aggregate gradation strongly influences the mechanical and durability performance of concrete by affecting particle packing, void content, and matrix compactness. This study evaluates the influence of optimized aggregate gradation curves on concrete performance. Materials and methods: Three aggregate gradation profiles, Curve A (coarse), Curve B (well-graded), and Curve C (fine), were developed using a modified Fuller–Thompson method and compared with corresponding non-optimized mixes. All mixtures were produced with constant water-to-cement and aggregate-to-binder ratios. Compressive strength, flexural strength, ultrasonic pulse velocity (UPV), and corrosion potential were evaluated. Results: The optimized gradation mixes showed better performance than the non-optimized counterparts. Curve A achieved the highest compressive strength (55 MPa), followed by Curve B (53 MPa) and Curve C (49 MPa), while violated gradation mixes showed a 5–7% reduction in strength. Flexural strength followed a similar trend, with Curve A giving the highest value (6.6 MPa). Higher UPV values in the optimized mixes indicated improved internal compactness, while corrosion potential results suggested reduced corrosion risk compared with the non-optimized specimens. These findings confirm that optimized gradation improves both mechanical properties and durability. Conclusions: Optimizing aggregate gradation significantly enhances the strength and durability performance of concrete. The results highlight its practical value as an effective approach for designing higher-performance concrete mixtures.