A novel all-solid-waste binder prepared by salt-alkali synergistic activation system constructed from phosphogypsum, soda residue and calcium carbide slag

Abstract

Conventional alkali-activated slag materials apply strong industrial alkalis with high cost and potential corrosion risk. Alternatively, this study utilized industrial solid waste phosphogypsum, soda residue, and calcium carbide slag to construct a salt-alkali synergistic activated system. A new salt-alkali synergistic activation effect was formed by the SO42- introduced by PG together with the Cl- and OH- provided by SR and CS, which promoted the hydration reaction. AFt, Friedel's salt, C-(A)-S-H, and other hydration products were generated and congregated, and a new all-solid-waste binder was created with 3d/28d strengths of 17.9/43.9 MPa, meeting the P·O 42.5 cement strength standard requirements. By conducting compressive strength and drying shrinkage tests on mortar and paste specimens with varying ratios, and employing XRD, TG-DTG, FTIR, and SEM-EDS analyses, the mechanical attributes of the binder were systematically assessed, and its hydration process was elucidated.