Integration of water-retaining polymers into cemented soil to revegetate steep rock-cut slopes in hydropower projects

Revegetation of excavated engineering slopes plays an important role in strengthening biological carbon assimilation. Cemented soil is widely deployed in ecologically restoring steep rock-cut slopes, serving as a substrate that combines both structural strength and revegetation capability. However, traditionally cemented soil often struggles to balance high strength and water stability with low alkalinity for plant germination and growth. This research investigated integrating synthetic water-retaining polymers of high molecular weight to resolve this issue and contribute to carbon fixation. Three types of polymers, namely polyacrylamide (PAM), polyacrylate emulsion (PAE) and polyvinyl alcohol (PVA), were investigated. Influence of the polymer type and dosage on change of the rheological properties, water stability and vegetation compatibility were experimentally examined and analysed. The results demonstrated that the polymers yielded remarkably enhanced resistance to water erosion by 35-98% and contributed to increasing water stability under repeated wetting-drying. The polymers did not impact the crystal structures or alter the content of dominant minerals in cemented soil whilst they exhibited more remarkably improved vegetation adaptability to cold-season plants. Difference of the mechanisms of polymer integration were analysed with the on-site application being carried out to verify the objective. These findings provide insights for advancing polymer-based strategies to improve slope restoration and rehabilitation. • Three different synthetic polymers were deployed in cemented soil for improving water-retaining. • The polymers increased water stability and resistance to water erosion and repeated wetting-drying. • Different polymers led to distinct pore structures and compactness in cemented soil. • Four herbaceous species confirmed the improved ecological compatibility of water-retaining polymers