Influence of triethanolamine on the hydration product of portlandite in cement paste and the mechanism

The influences of triethanolamine (TEA) on the portlandite in hardened cement pastes (HCPs) were systematically investigated. Results show that the addition of TEA in cement pastes leads to a visible reduction of Ca(OH)2 (CH) content and considerably alters the morphology of CH crystals from large a...

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Bibliographic Details
Published in:Cement and concrete research 2016-09, Vol.87, p.64-76
Main Authors: Yan-Rong, Zhang, Xiang-Ming, Kong, Zi-Chen, Lu, Zhen-Bao, Lu, Qing, Zhang, Bi-Qin, Dong, Feng, Xing
Format: Article
Language:English
Subjects:
BEVERAGES
CALCIUM HYDROXIDES
Cement pastes
CEMENTS
Complexation
Crystal
CRYSTALLIZATION
HCP LATTICES
HYDRATION
INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
MATERIALS SCIENCE
NUCLEAR MAGNETIC RESONANCE
Portlandite
REDUCTION
Triethanolamine
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Summary:The influences of triethanolamine (TEA) on the portlandite in hardened cement pastes (HCPs) were systematically investigated. Results show that the addition of TEA in cement pastes leads to a visible reduction of Ca(OH)2 (CH) content and considerably alters the morphology of CH crystals from large and parallel-stacked lamellar shape to smaller and distorted actinomorphic one. For the first time, the CH micro-crystals and even non-crystalline CH in HCPs were observed in the presence of TEA. Due to integration of CH micro-crystals in C–S–H phase, remarkable higher Ca/Si ratio of C–S–H phase was found. The formation of TEA-Ca2+complex via the interaction between Ca2+ and the oxygen atoms in TEA molecule was evidenced by the results of NMR and UV. It is believed that TEA can be introduced into the crystallization process of portlandite and thus significantly alters the morphology of CH crystals and even the content of the crystalline CH phase.
ISSN:0008-8846
1873-3948
DOI:10.1016/j.cemconres.2016.05.009