Topsoil reinforcement of sandy slope for preventing erosion using water-based polyurethane soil stabilizer

The topsoil of sandy slope suffers from serious erosion due to its weak internal cohesion. Most of the efforts have been made to improve the stability of topsoil by recovering the inter-particle cohesion without due concern to environmental and ecological aspects. Thus, water-based polyurethane (PU) soil stabilizer is introduced to reinforce the topsoil of sandy slope for erosion control purpose. This study aims at understanding its reinforcement effect and proving the feasibility of polyurethane treatment in practice. A series of laboratory tests were performed on treated specimens with different PU concentrations and also compared to a fallow one by which the effect of this stabilizer on soil mechanical and hydrological properties, vegetation growth and erosion resistance were investigated. The results indicated that PU treatment can significantly increase the shear strength, unconfined compressive and tensile strength of natural sand. An increasing amount of PU resulted in marked improvements in cohesion, but slight changes in internal friction angle. On the other hand, the presence of PU conferred low permeability and good water stability to the natural sand. Even with a relatively small amount of PU treatment, a positive potential is observed in promoting the anti-erodibility of topsoil by enhancing its inter-particle cohesion due to the unique network membrane structure. Moreover, PU treatment also improved soil water retention characteristics and can provide a suitable environment for vegetation growth. Under the synergistic action of vegetation and polymer treatment, stronger erosion resistance of topsoil was observed. Thus, PU treatment can be used as an ecological and effective alternative method with regard to topsoil stabilization on sandy slope.