Improvement of the Hydration of a Fly Ash–Cement System by the Synergic Action of Triethanolamine and C–S–H Seeding
Jionghuang He, Guangcheng Long, Kunlin Ma, Youjun Xie, Zhiqing Cheng
Abstract
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), X-ray 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.