Strength assessment of sand stabilized with synthetic polymer and natural fibers

Soil stabilization using polymers and fibers has been widely investigated in recent years. This study introduces an innovative approach by integrating synthetic polymer (AH polymer) with natural fibers (sisal fiber) for sand stabilization. A comprehensive experimental framework was established to assess the impact of varying polymer content (1%, 2%, 3%, and 4%) and fiber content (0.2%, 0.4%, 0.6%, and 0.8%, by the mass of dry sand), and densities, on the mechanical properties of stabilized sand, including compressive strength (UCS), tensile strength (TS), and flexural strength (FS). The synergistic stabilization effects of the polymer and fibers were elucidated through SEM. The findings indicate that the synergistic application of AH polymer and sisal fibers significantly enhances the structural integrity of sand. Notably, the UCS, TS, and FS exhibited a well-linear relationship with both the polymer and fiber content. The strengthening effect of fiber was particularly pronounced in samples with higher polymer content. According to the strength increase rate, the optimal polymer content is 2%, and optimal fiber content is 0.6% for the UCS, 0.4% for the TS and 0.8% for the FS. An increase in density was observed to linearly augment the UCS and FS. For sand with 2% polymer and 0.8% fiber, the TS increased linearly with the increment in density, however, for sand with 4% polymer and 0.4% fiber, TS kept a non-monotonic relationship with density. The study also revealed that augmenting the content of polymer and fibers diminishes the brittleness of the stabilized sand, whereas an increase in density has the opposite effect. Furthermore, the incorporation of polymer and fibers resulted in an elevated deformation modulus. The polymer functions as an adhesive, binding fibers to sand particles, while the fibers create a network-like structure that amplifies the effective contact area among sand particles, thereby substantially improving the mechanical properties of the sand.