Microstructural characterization of cement in the presence of alkanolamines

Abstract

In order to understand the potential issues regarding the cement performance over time in the presence of alkanolamines, such as triethanolamine (TEA) and triisopropanolamine (TIPA), this investigation provided a series of quantitative phase characterization to monitor the hydration and microstructure of cement pastes. The addition of 0.02 % alkanolamines to cement promoted the strength development and altered the hydration kinetics at early ages. The aluminate reaction was greatly promoted, which resulted in the formation of hydrosulfoaluminates with a high monosulfoaluminate-to-ettringite ratio due to the facilitated dissolution of the intermediate phase. The morphology and chemical composition of the hydrates, as well as the porosity of the pastes, were also influenced by the altered hydration kinetics. Particularly, TIPA markedly reduced Si/Ca ratio (from 0.61 to 0.51) and increased Fe/Ca ratio (from 0.016 to 0.036) in the C-S-H gel at the early stage of hydration. Based on the variations in microstructural features subjected to the alkanolamines, the durability and long-term performance of the cement, including the phase variation, resistance to sulfate or chloride ingression and volume stability, were discussed.