Influence of triethanolamine on the hydration and the strength development of cementitious systems

Abstract

The influence of triethanolamine (TEA) at varying dosages on the strength development of pure cement (PC) and fly ash cement (FAC) pastes was systematically investigated. Techniques including mercury intrusion porosimetry, X-ray diffraction, thermogravimetric analysis and scanning electron microscopy were employed to characterise the microstructure of hardened cement pastes and to monitor the cement hydration process with the aim of correlating strength variations with microstructural changes caused by TEA addition. The results showed that 0·03–0·10% addition of TEA visibly enhances the early strength but decreases the compressive strength after 3 d for PC pastes. A high dosage of TEA (1%) leads to a sharp decrease in 28-d strength for both PC and FAC pastes. Mechanistic explanations regarding why TEA affects the strength development differently at different dosages and ages are discussed by considering the impacts of TEA on the hydration degree, pore structure, composition and morphology of hydration products.