Hydration Heat and Hydration Kinetics of Cement Paste Compound with Molybdenum Tailings Powder: A Research Article

Abstract

Molybdenum tailings powder (MTs) has potential pozzolanic activity and can be used as a mineral admixture. In order to comprehend the influence of MTs powder on the cement hydration process, the hydration heat and kinetics of composite cementitious materials (CCMs) were investigated using an isothermal calorimeter and the Krstulovic–Dabic model. Furthermore, the influences of fly ash (FA), slag (SL), and MTs powder on hydration heat were compared and analyzed, considering the same content. The results show that the proper amount of MTs can promote the hydration of CCMs. When the content of MTs is 5% and 15%, the second exothermic peak of the CCMs appears 2.30% and 4.27% earlier, and the exothermic peak increases by 2.72% and 1.34%, respectively. The cumulative heat release of CCMs gradually decreases with an increasing content of MTs powder. When the replacement of MTs, FA, and SL is 15%, respectively, the second exothermic peak of CCMs increases by 1.34%, −16.13%, and −12.04% for MTs, FA, and SL, respectively. The final heat release of MTs is higher than that of FA, but lower than that of SL. The hydration process of CCMs undergoes three stages: nucleation and crystal growth (NG), interactions at phase boundaries (I), and diffusion (D).