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<p>Triethanolamine (TEA), widely used as a grinding aid in cement production, can significantly influence cement hydration through complex and not yet fully understood mechanisms. In particular, its effect on tricalcium silicate (C₃S) hydration remains insufficiently clarified, especially when decoupled from aluminate–sulfate interactions and evaluated using oscillatory rheometry. This study investigates the influence of TEA on the hydration kinetics, viscoelastic evolution, and microstructural development of C₃S–limestone model pastes. TEA was incorporated at dosages ranging from 0.05 to 0.5&#xa0;wt.% in systems composed of 70% C₃S and 30% limestone. The pastes were characterized by small-amplitude oscillatory shear (SAOS) test for 2h, isothermal calorimetry (48h), X-ray diffraction with Rietveld quantitative phase analysis (RQPA), and thermogravimetric analysis (TGA), with particular focus on early-age hydration. The results show that TEA significantly delays early C₃S hydration, increasing the induction period from 61 to 380&#xa0;min and shifting the main hydration peak from 6.15 to 10.97h at 0.5&#xa0;wt.% TEA. At later ages, however, TEA enhances hydration, increasing the C₃S degree of hydration from 35.3 to 55.3% at 1&#xa0;day and from 63.1 to 83.7% at 7&#xa0;days. These changes are accompanied by increased precipitation of C–S–H and portlandite, as confirmed by TGA and XRD. Additionally, TEA alters portlandite morphology, reducing the R-index from 1.97 to 1.56 at 0.5&#xa0;wt.%, and appears to promote C–S–H formation at the expense of portlandite, modifying their relative balance.</p>

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Insights into the effect of triethanolamine on the early hydration and viscoelastic evolution of C3S model pastes

  • 期刊论文

  • 发表日期：

    2026年6月16日

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  • Ivo C. Carvalho,
  • Paulo Matos,
  • Ana P. Kirchheim,
  • José S. Andrade Neto

摘要

Triethanolamine (TEA), widely used as a grinding aid in cement production, can significantly influence cement hydration through complex and not yet fully understood mechanisms. In particular, its effect on tricalcium silicate (C₃S) hydration remains insufficiently clarified, especially when decoupled from aluminate–sulfate interactions and evaluated using oscillatory rheometry. This study investigates the influence of TEA on the hydration kinetics, viscoelastic evolution, and microstructural development of C₃S–limestone model pastes. TEA was incorporated at dosages ranging from 0.05 to 0.5 wt.% in systems composed of 70% C₃S and 30% limestone. The pastes were characterized by small-amplitude oscillatory shear (SAOS) test for 2h, isothermal calorimetry (48h), X-ray diffraction with Rietveld quantitative phase analysis (RQPA), and thermogravimetric analysis (TGA), with particular focus on early-age hydration. The results show that TEA significantly delays early C₃S hydration, increasing the induction period from 61 to 380 min and shifting the main hydration peak from 6.15 to 10.97h at 0.5 wt.% TEA. At later ages, however, TEA enhances hydration, increasing the C₃S degree of hydration from 35.3 to 55.3% at 1 day and from 63.1 to 83.7% at 7 days. These changes are accompanied by increased precipitation of C–S–H and portlandite, as confirmed by TGA and XRD. Additionally, TEA alters portlandite morphology, reducing the R-index from 1.97 to 1.56 at 0.5 wt.%, and appears to promote C–S–H formation at the expense of portlandite, modifying their relative balance.