Mechanical properties and microscopic mechanism of gypsum and polyurethane modified waste slurry

This study employs a composite method involving gypsum and polyurethane to modify waste slurry to create a recycled roadbed material, aiming to promote the resource utilization of waste slurry. Through unconfined compressive strength (UCS) tests and various microscopic analyses, the mechanical properties and microscopic mechanisms of gypsum-polyurethane modified waste slurry with different moisture content at 1-day curing age were examined. The findings reveal that both single-doped gypsum and polyurethane enhance the UCS of the specimens, with the gypsum-polyurethane compound exhibiting significantly superior performance compared to single-doped variants. Scanning electron microscope (SEM) analysis indicates that polyurethane-modified waste slurry exhibits extensive crystal formation and agglomeration, forming a robust skeleton that enhances strength. On the other hand, gypsum-modified waste slurry demonstrates a cross-linked structure of crystalline hydrates and network stacking, contributing to improved specimen strength. Furthermore, under the condition of remixing, specimen pores are filled, leading to enhanced compactness and subsequently increased strength. These findings underscore the potential of gypsum-polyurethane modified waste slurry as a promising material for sustainable road construction applications.