Empirical Study of the Effect of Aggregate Quality on Long-Term Pavement Performance in North West Nigeria

The long-term performance of flexible road pavements in North West Nigeria is significantly influenced by the quality of aggregate used in surface and base course layers, yet systematic empirical evidence linking aggregate property variability to pavement performance degradation in this zone is limited. This study empirically examines the effect of aggregate quality on long-term pavement performance for 15 road sections in Sokoto, Kebbi, and Zamfara States. Pavement condition surveys using the PCI method were conducted on each road section. Core samples were extracted and tested for aggregate characteristics including aggregate crushing value, polished stone value, Los Angeles abrasion, specific gravity, and water absorption. Original construction records provided mix design and specification data for comparison. Multiple regression and survival analysis assessed the relationship between aggregate quality indicators and pavement performance life. Results indicate that Polished Stone Value shows the strongest correlation with surface texture deterioration rate (r = -0.68, p < 0.001). Aggregate Crushing Value is the strongest predictor of base course structural deterioration (regression beta = 0.54). Pavements constructed with aggregate exceeding the 30 percent ACV specification threshold show service life reductions of 35 to 45 percent compared to compliant materials. The study fills an empirical gap in the region-specific pavement-aggregate relationship literature and recommends revising Sokoto, Kebbi, and Zamfara state road specifications to include mandatory polished stone value requirements for surface course aggregates. Keywords: aggregate quality, pavement performance, North West Nigeria, surface deterioration, empirical study