A comprehensive study on the impact of direct electric curing on the performance of molybdenum tailings in cementitious materials

Abstract

Developing a suitable activation method to extend the application of molybdenum tailings (MT) in construction materials is crucial for maximizing MT utilization and reducing carbon emissions in the construction industry. In this study, MT was substituted for different levels of cement to prepare cement-MT composite paste, and direct electric curing (DEC) was used attempting to improve the reactivity of MT. The results indicated that MT doping decreased the compressive strength of the specimens, increased the pore content, and reduced the generation of hydration products. On the other hand, DEC effectively improved the early strength of the cement-MT composite and the hydration activity of MT. At 28 d, the cementitious coefficient of MT using DEC increased by 6.25 %-675 % compared with standard curing (SC) prepared specimens. Meanwhile, XRD and TG test results showed that DEC effectively promoted the hydration process through the ohmic heating effect. However, it did not change the types of hydration products or the morphology of the specimens. DEC reduced the pore content and refined the pore size distribution in the early stage of the specimens. Moreover, the carbon emission and cost per unit of strength in the early stage of DEC specimens were significantly reduced compared with those of SC. This paper proved that DEC was a feasible way to activate MT activity, and DEC could effectively promote the application of MT in construction materials.

Keywords

• Molybdenum tailings
• Mechanical properties
• Cementitious activity
• Direct electric curing
• Environmental and economic benefits