Rheology of an alkali-activated Fe-rich slag suspension: Identifying the impact of the activator chemistry and slag particle interactions

Abstract Iron-silicate slags, originating from metallurgical industry, are upon alkali-activation precursors for synthesis of inorganic polymer binders, which can be used in construction. The slag's rheology is important for certain construction applications, which is for alkali-activated Fe-rich slag suspensions (AAS) still largely unmapped. To identify the contribution of the activator and of an early formed binder to the rheology, the activator SiO2/Na2O molar ratio and H2O content was modified. The flow behaviour of AAS was compared with an activator alone, and a quartz suspension to reveal the effect of the slag particles on the rheology and its degree of activation. Raising SiO2/Na2O molar ratio resulted in a higher yield stress and elasticity, explained by the increase of silicate complexes, while decreasing SiO2/Na2O molar ratio resulted in more monomers. AAS exhibited a yield stress fluid-like behaviour conform to the Herschel-Bulkley model and driven by the strong physical interaction between the slag particles.