Feasibility of using Cr-containing vitrification product as cement admixture: Structural evolution and chromium immobilization

With China already committing to bring carbon dioxide emissions to a peak before 2030, reducing the amount of used cement is an economical and effective measure. In this study, chromium-containing vitrification products were used as a cement admixture to achieve chromium reduction and immobilization. This study presents the effect of MgO/B2O3/Cr2O3 on the relationship between the network structure and chemical resistance of a Cr-containing glass matrix. The acid/alkali resistance of the glass specimens improved with an increase in Cr2O3 content under the same matrix composition. With the replacement of CaO by MgO, the chemical resistance of boron-free glass specimens improved, while that of Mg/B-containing glass specimens significantly decreased. The behaviors of the glass matrix in chemical environments affected the hydration and chromium immobilization of cement clinkers. In paste specimens, the pozzolanic reaction of the glass powder enhanced the densification of specimens. The mechanical strength was attributed to the filling effect of pozzolanic gels and undissolved glass powder in the mortar samples. B-containing glass powder negatively affected the mechanical strength and chromium immobilization of cement samples, while an appropriate amount of MgO and Cr2O3 was beneficial to the physical and chemical properties of the material. Therefore, chromium-containing waste glass can be effectively used to produce eco-friendly building materials.