Premature rutting in flexible pavements remains a persistent challenge in urban infrastructure, particularly under increasing axle loads and elevated service temperatures. This study presents a performance-based investigation of a failed dual carriageway that developed rut depths exceeding 15 mm within three years of construction. The original asphalt mixture was designed using the Marshall method. A forensic reassessment was undertaken through renewed Marshall volumetric analysis and a theoretical Superpave-based performance evaluation. Laboratory reassessment identified an optimum binder content of approximately 5.6% under Marshall criteria, whereas field records indicated a constructed binder content closer to 6.0%. Although Marshall optimisation could have reduced deformation risk, the absence of climate-adjusted binder grading and mechanistic performance validation contributed to premature rutting. The findings suggest that empirical volumetric design remains adequate for moderate traffic conditions but is insufficient for high-temperature, high-traffic urban environments without supplementary performance-based evaluation.
Engr. Emeka Chukwuka (Tue,) studied this question.