Experimental Study on the Mechanical Properties and Durability of Sand Using a Semicrystalline Hydrophobic Fluoropolymer

There has been an inclination towards using sustainable and environmentally friendly soil stabilizers to reduce the carbon footprint resulting from the production process of ordinary Portland cement. Polymers soil stabilizers have proven to be effective towards improving the strength of marginal soil. Despite this significant improvement, certain polymers are susceptible to the action of wetting, which results in a loss in strength. Thus, this study aims to investigate the mechanical properties and the durability of polymer-modified dune sand. Poly(vinylidene fluoride) (PVDF) polymer was used as the soil stabilizer in varying concentrations of 3, 6, 9, and 12%. The efficacy of the polymer was evaluated by conducting unconfined compressive strength (UCS) and direct shear tests. The durability test was divided into two categories: constant soaking and cyclic wetting-drying. Changes in the morphology of the sand as a result of polymer inclusion were investigated by scanning electron microscopy (SEM). The result showed that the UCS, shear strength and cohesion increased with polymer concentrations, while the frictional angle did not change significantly. The polymer-modified sand specimens lost about 60-75% of their strength after being submerged in water for 7-21 days. However, there was no reduction in strength for specimens subjected to 3 and 7 wetting-drying cycles. The action of drying following each wetting cycle reactivated the bond properties of the PVDF polymer. SEM confirmed the presence of the polymer links between the sand grains after constantly soaking. The loss of strength, in this case, can be linked to the presence of water molecules within the structure of the polymer-sand matrix. In conclusion, the PVDF polymer exhibits potential as an effective stabilizer against water susceptibility and elevated temperature.