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The low reactivity of fly ash (FA) restricts its application in concrete. To promote the utilization of FA, the research on the activation of FA has been one of important hotspots in related fields. The synergic action of triethanolamine (TEA) and C−S−H seeding on improving the hydration of a fly ash−cement (FAC) system was investigated by combination of methods containing isothermal calorimetry, boundary nucleation and growth (BNG) model, thermogravimetric analysis (TGA), Xray diffraction (XRD), and scanning electron microscopy (SEM). Results indicate that TEA can promote the hydration of FAC but hinders nucleation at an early age, resulting in retardation of the early hydration of FAC. In contrast, C−S−H seeding can remarkably promote the early hydration of FAC containing TEA by accelerating nucleation. With incorporating both TEA and C−S−H seeding, the contents of chemical bound water and the amorphous phase in FAC were increased; meanwhile, the hydrates coated on an FA particle surface were also increased but the portlandite content of hydrating FAC paste was decreased. Furthermore, the mechanism behind the synergic action of TEA and C− S−H seeding on the hydration of FAC was discussed.

As a high-output industrial byproduct, fly ash can partially replace Portland cement in concrete, which is one of the important treatment methods to improve its utilization. However, the low activity of fly ash limits its substitution level. Previous studies demonstrated that adding triethanolamine (TEA) and elevated curing temperature are useful methods to promote the pozzolanic activity of fly ash, while the effect of TEA on the hydration kinetics of the cement–fly ash system (CFA) under elevated curing temperature is unclear. In this study, the hydration kinetics of the CFA system with different dosages of TEA under elevated curing temperature were investigated. The activation energy and pore solution of samples were analyzed to further clarify the corresponding mechanism. The results show that the effect of TEA on the hydration kinetics of the CFA pastes at 60 °C is different from that at 20 °C. The mean activation energies for each hydration process (NG, I, and D) of CFA pastes all decrease with the increased TEA dosage. The effect of TEA on the hydration kinetics of the CFA pastes at elevated temperature is closely related to the dissolution of the CFA system. These findings will further promote the high-value-added utilization of fly ash.