Improving the consolidation properties of hydrophilic polyurethane for feldspathic sandstone water erosion prevention

Feldspathic sandstone is a type of sandstone that is severely eroded by wind, rainfall, and gravity forces. The land surface in feldspathic area is degraded and covered with extremely low vegetation coverage. In this study, we propose a type of hydrophilic polyurethane (W-OH) to control its erosion and conduct the experiment to evaluate the consolidation performances. The results showed that the cementing materials (such as montmorillonite) are the main reason for the vulnerability of feldspathic sandstone to erosion, which expands by absorbing water. Additionally, the organic content is extremely low and is not suitable for vegetation growth. However, when the different concentrations of W-OH solution were sprayed on the feldspathic sandstone surface, the solution could penetrate in several minutes and form a flexible and porous consolidation layer. The anti-scourability index (K) of the layer could increase from approximately 0.2 to 1.0 which significantly increased the water resistance. The water retention benefit increased by 50%. In the simulated rainfall test, the sediment yield reduction in the treated slopes sprayed with the W-OH solution could reach 99% compared with that on the control slopes. The SEM images indicated that the W-OH solution enveloped the feldspathic sandstone particles and connected them tightly together. Therefore, the consolidation layer could decrease water erosion rate and reduce evaporation.