Soil stabilization using synthetic polymer for soil slope ecological protection

Polymer treatment can protect soil slopes by enhancing topsoil macro-properties and promoting vegetation growth. In the present study, laboratory and field application tests were performed on polyurethane (PU)-treated soil to investigate its effect on soil slope ecological protection, and the mechanism related to achieving the ecological protection of soil slopes was revealed. Laboratory tests show that PU addition could greatly enhance the unconfined compression strength of silty sand and its tensile and shear strengths, especially the first two, which increased from about zero to 952.61 and 211.47 kPa, respectively. The addition of PU also led to a reduction in permeability and an enhancement in water retention capacity. The permeability coefficient decreased by an order of magnitude, whereas the water retention capacity remained at a high and stable level for a long period with little water supplementation. In addition, the PU-treated soil showed satisfactory erosion resistance and protected vegetation growth to some extent, both depending on the amount of PU, whereas a competitive relationship was observed between the contribution of the PU amount to anti-erosion and the environment for plant growth caused by the PU content. Field observations showed that PU treatment could effectively and ecologically protect soil slopes by enhancing topsoil erosion resistance, mechanical strength, and water retention, thereby accelerating vegetation growth and cover. The PU stabilization effect benefits from the improvement in the microstructure of silty sand caused by PU adsorption, connection, and filling effects. This induced a denser and stiffer whole that covered on the slope surface, which, on the one hand, enhanced the stability of the slope surface and weakened the influences induced by rainfall and runoff and, on the other hand, promoted vegetation growth by reducing soil erosion and providing moisture.