Cyclic and post-cyclic behavior of stabilized marl soil for pavement engineering applications

Marl is a clayey soil that exhibits a significant reduction in strength when exposed to moisture. As a result, it is considered problematic in civil engineering and often stabilized to improve performance. High-strength stabilization is not always required for road construction applications. In such cases, Metakaolin and rice husk ash provide suitable and eco-friendly alternatives to cement. Although the monotonic behavior of stabilized marl has been studied, less is known about its response under and after cyclic loading. The current study evaluated the cyclic and post-cyclic behavior of marl soil stabilized with metakaolin and rice husk ash after curing for 1, 7, and 28 days. The unconfined compressive strength (UCS) and secant modulus at 50 % maximum strength (E50) of the stabilized soil were determined under monotonic and cyclic axial tests following the monotonic compression tests. The damping ratio, secant modulus, and axial strain accumulated during cyclic loading also were evaluated, with SEM used for microstructural analysis. The results showed that, unlike samples with 30 % metakaolin after cyclic loading, the specimen containing RHA experienced an increase in strength compared to the monotonic loading condition. The greatest UCS and E50 values were observed in samples with 15% rice husk ash and 15 % metakaolin under monotonic loading following cyclic preloading. After 30 cycles, the stabilized specimens recorded lower damping ratios than for non-stabilized soil, although the effect of curing time on the damping ratio was negligible.