Comparative study of NFC with different coarse aggregate sizes by Taguchi grey method

No-fines concrete (NFC) is increasingly recognised for its effectiveness in urban drainage and environmental sustainability by reducing runoff and avoiding the use of river sand. This study investigates the influence of using different sizes of coarse aggregate of 4.75, 6.3, 8, and 9.5 mm on the mechanical and permeation properties of NFC. Results indicate that NFC made with a smaller-sized 4.75 mm aggregate size exhibited the highest performance across all curing periods. The optimised outcome, identified through Taguchi grey relational analysis, was achieved with 4.75 mm aggregate and 327 days of curing, which delivered the most favourable balance of strength and permeability. At 365 days, NFC-4.75 attained a maximum compressive strength of 10.77 MPa, representing a 15.18% improvement over NFC-9.5, while split tensile and flexural strengths increased by 17.33% and 16.56%, respectively. Although smaller aggregates slightly reduced permeability and porosity, all values remained within American Concrete Institute limits, confirming their suitability for drainage applications. These findings demonstrate that smaller aggregate sizes enhance both strength and durability without compromising essential water flow properties, supporting their adoption in sustainable pavement infrastructure for low- to medium-traffic applications.