Study on interface shear strength between polyurethane treated and original Pisha sandstone under dry-wet cycles

Currently, utilization of hydrophilic polyurethane (W-OH) materials for slope protection in arid areas has proved to be a cost-effective protocol. The treatment effect highly depends on the interfacial performance between the W-OH treated and the original sandstone. This study aims to investigate the corresponding shear strength and its long-term performance under dry-wet cycles under the arid environment. The results from the direct shear test indicate the interface shear strength increases with W-OH solution concentration and decreases with the increase of water content of the Pisha sandstone. Further investigations under dry-wet cycles indicate the interface cohesion is obviously weakened by the dry-wet cycles, while the influence on the internal friction angle is not obvious. The correlation between the degradation level and the dry-wet cycles can be well fitted with the inverted S-curve using two combined exponential functions. Furthermore, the ethylene-vinyl acetate (EVA) content is utilized to enhance the durability performance under dry-wet cycles. It is found the EVA can obviously improve the bonding property and the resistance to dry-wet cycles. This study's results can serve as a solid base for the application of W-OH materials to resolve the soil erosion in the arid region.