Optimization of Flexible Pavement Layer Composition Considering Fatigue and Rutting Distresses

Abstract

This study investigates the impact of pavement layer and material composition on the structural durability of flexible road surfaces, focusing on fatigue cracking and rutting resistance. Based on Flemish Class B6 roads, eight pavement design scenarios were modeled using 3D-Move Analysis software under static triple-axle truck loading conditions. Variations included surface materials (SMA-C, ZOA-B), asphalt layer thickness, and base stabilization methods (cement, lime, or unbound). Results demonstrate that cement-stabilized crushed stone bases significantly outperform lime-treated and unbound stone bases, reducing rutting and fatigue strain values. Fatigue damage was most influenced by horizontal strains at the bottom of the asphalt layers, while rutting correlated with vertical strains in the base layer. Cement-bound bases showed up to 36 times longer fatigue life and 54% better rutting resistance compared to unbound stone. Although surface layer properties had a secondary effect, minor material changes could still shift performance by hundreds of thousands of load repetitions. The findings underline the dominant role of base layer treatment in enhancing pavement longevity and advocate for the inclusion of cement-stabilized bases in future sustainable road designs.