Experimental Research on Unconfined Compressive Properties of Marine Clay Stabilized Reinforced by Polypropylene Fibers and Cement

In order to study the effect of cement and polypropylene fibers combined stabilization on the mechanical properties of marine silt soft soil, factors such as cement content (5%, 10%, 15%, 20%), fiber length (6, 9, 12, 15 mm), and fiber content (0.2%, 0.4%, 0.6%) were considered. Unconfined compressive tests were conducted on marine silt soft soil stabilized with fibers and cement. The optimal fiber length and fiber content were selected, and the soil at the crack site was collected for SEM and XRD analysis. The experimental results showed that the failure modes of the only cement-stabilized soil and the cement and fiber combined stalilization soil were brittle failure and plastic failure, respectively, and the latter also had a relatively large residual strength; with the increase of fiber content, the strength of the stablized soil first increased and then decreased, and there exists an optimal content; when the cement content did not exceed 15%, the optimal fiber content was 0.4%. When the cement content was 20%, the optimal fiber content was 0.2%; compared with other lengths of fibers (6, 9, 15 mm), fibers with a length of 12 mm had the best stabilization effect on cement soil; with the increase of cement content, the strength of the stabilized soil increased almost linearly. When the cement content increased from 5% to 20%, the strength of the non-fiber soil increased by 15% to 20%, while the strength of the soil added with polypropylene fibers increases by 15% to 20%. From microscopic analysis, it could be concluded that the strength of cement stabilized soil mainly comes from the bonding effect of hydrates produced by the hydration of cement and water in the sludge.