Mechanical properties and microscopic mechanism of steel slag, sodium sulfate and cement stabilized road demolition waste

When recycled aggregate (RA) from road demolition waste is used as a road base, its engineering performance tends to be poor and requires stabilization. Cement is the most commonly used stabilizer, but it is a high energy consuming product. Therefore, in this article, steel slag powder (SP) and sodium sulfate (SS) are used to replace part of cement to stabilize crushed stone (RCS). The effects of SP content, SS content and curing age on the mechanical properties and microstructure of cement stabilized aggregates were studied using unconfined compression, triaxial shear, Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and X-ray diffraction (XRD) tests. The results show that appropriate SP and SS adding improve the compressive strength of RCS, and the RCS strength reaches its maximum when the SP content was 10 %. Moreover, the SS addition can further enhance the strength of cement+SP stabilized RA, a maximum strength was obtained when the SS content is 1.5 %. The shear strength of specimen was enhanced by SP and SS its increasing its cohesion. SP promote the hydration reaction and fills the pores in the RCS specimen, while SS can stimulate SP to accelerate the SP hydration reaction in the SP stabilized RCS specimen, thus further improving the strength of the stabilized RA, and generating gels such as C-S-H gel, C-A-H gel, C-A-S-H gel in the cement stabilized RA with SP+SS powder.