Influences of triethanolamine on the performance of cement pastes used in slab track

• Published in: Construction & building materials Vol. 238; p. 117670
• Main Authors: Zhang, Yanrong, Gao, Liang, Cai, Xiaopei, Li, Qiangqiang, Kong, Xiangming
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 30.03.2020
• Subjects: Ca(OH)2 morphology; Cement hydration; Mechanical properties; Pore structure; Triethanolamine; Mechanical properties; Triethanolamine; Ca(OH)2 morphology; Cement hydration; Pore structure
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2019.117670

•Effects of TEA on hydration, pore structure, morphologies of hydrates and strength were investigated.•Ca(OH)2 crystals with varied morphologies were synthesized in TEA solutions for the first time.•Relationships between hydration, pore structure and morphologies were established.•The mechanism of TEA on tuning strength at different dosages and ages was elucidated.•Actinomorphic Ca(OH)2 results in a loose structure and reduces late strength. In this study, the impacts of triethanolamine (TEA) on the performance of hardened cement pastes (HCPs) used in slab track were systematically investigated. For the first time, Ca(OH)2 powder was synthesized in TEA solutions with different concentrations, aiming at revealing the mechanism of TEA tuning strength from a microstructural point of view. Results show that low dosages of TEA increase hydration degree owing to its effects on the hydration of C3S and on the second hydration of C3A. The filling of hydrates in capillary pores facilitates a refined pore structure, and thereby increasing the early strength of HCPs. On the contrary, a high dosage of TEA decreases the hydration degree and the early strength. Microstructural experiments prove that the inclusion of TEA causes a transformation of Ca(OH)2 morphology from large and regular crystal shape to small and distorted actinomorphic one. Thus, the existence of numerous actinomorphic Ca(OH)2 results in a loose structure and decreases the late strength of HCPs, especially at a high dosage of TEA.