Mechanical properties and microstructure of binding material using slag-fly ash synergistically activated by wet-basis soda residue-carbide slag

Abstract

To promote the coordinated resource utilization of multiple industrial solid wastes and reduce the associated environmental pollution problems, a quaternary binding material using ground granulated blast furnace slag (GGBS)-fly ash (FA) activated by wet-basis soda residue (SR)-carbide slag (CS) was developed. Through strength and workability tests, as well as SEM, XRD, and EDS examinations, the mechanical properties and hydration-hardening mechanism of the binding material were analyzed. The results show that the optimal mix ratio is as follows: SR: CS: GGBS: FA = 1: 0.5: 3: 0.5. The 28-day compressive strength of the mortar specimen is 51.82 MPa, and the flexural strength is 6.42 MPa, which basically meet the standard of P.O42.5 ordinary Portland cement. The synergistic activation effect formed by CS and SR plays a key role in the early strength development, and the FA can significantly improve the workability. The SEM, XRD, and EDS test analyses revealed that the hydration products of the quaternary binding material are mainly amorphous C-S-H gel and NaCl, 3CaO·Al2O3·CaCl2·10H2O, 3CaO·Al2O3·3CaSO4·30H2O crystal hydration products, which jointly constitute the main strength source of the quaternary binding material. The results obtained can provide a theoretical basis and technical support for the coordinated utilization of multiple industrial solid wastes.