Ferro-vanadium Slag in Improving Inner Chloride Solidification Rate of Cement Materials

We investigated the effects of ferro-vanadium slag(FVS)as a supplemental cementing material which can dissolve a large amount of active aluminum phases without excessive pretreatment or excitation to enhance the inner chloride solidified rate(CSR)of cement-based materials.Cement-FVS pastes with 0-30%content of FVS was designed,and the CSR was examined.Hydrates at different curing ages were studied by X-ray diffraction(XRD)and thermo-gravimetric analysis(TGA);hydration heat and^(29)Si nuclear magnetic resonance(^(29)Si-NMR)were tested to analyze the hydration degree of the system;mechanical properties in cement-FVS system were evaluated by compressive strength test,pore structure and the fractal regression.Results revealed that the incorporation of FVS could greatly promote the CSR of cement-FVS system.Compared with the control groups,30%dosage of FVS could increase the CSR by 69%at 3 d,47%at 7d,36%at 28 d and 34%at 60 d.It was demonstrated that the incorporation of FVS could enhance the chemical solidifying ability of chloride,and the main reason was the promoted generation of Kuzel’s salt and the Friedel’s salt in hydrate products,and the enhanced chloride migration resistance capacity by increasing the volume of gel pores in the cement-FVS system.Considering the influence of FVS on strength performance,this paper suggested that the suitable dosage of FVS as a supplemental cementing material was around 10%.The study in this paper might provide one efficient path to promote the chloride solidifying capacity of cement-based material and meanwhile the comprehensive utilization of FVS.