Alite (Ca₃SiO₅: C₃S^*) and calcium aluminate (Ca₃Al₂O₆: C₃A) are the major phases in Portland cement, which have an essential role in the development of early age properties. The effects of gypsum content, fineness, and Na₂SO₄ addition on the early‐stage hydration kinetics are investigated for polyphase (co‐sintered) Ca₃SiO₅‐Ca₃Al₂O₆ model systems using calorimetry, X‐ ray diffraction, thermal analysis, and solid‐state ²⁷Al and ²⁹Si nuclear magnetic resonance (NMR) spectroscopy. The results demonstrate that the hydration of C₃A significantly affects the hydration of C₃S. The C₃S and C₃A hydration is hindered considerably in severely over‐sulfated systems (where C₃A hydration is suppressed due to a very high gypsum content) and systems with additional Na₂SO₄. Although there is a considerable amount of Al incorporation in the C‐S‐H phase, no clear trends with respect to gypsum content, hydration age or Na₂SO₄ addition are observed for the Al_IV/Si ratios of the C‐S‐H phase determined from ²⁹Si NMR. With the addition of Na₂SO₄, recrystallization of ettringite from the AFm phases is postponed from 1 day to 7 days.

中文翻译：

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石膏和Na2SO4存在下多相Ca3SiO5-Ca3Al2O6的水合

硅酸盐水泥中的主要相是阿利特（Ca ₃ SiO ₅：C ₃ S ^*）和铝酸钙（Ca ₃ Al ₂ O ₆：C ₃ A），它们在早期性能的发展中具有重要作用。使用量热法，X射线衍射法研究了多相（共烧结）Ca ₃ SiO ₅ -Ca ₃ Al ₂ O ₆模型系统中石膏含量，细度和Na ₂ SO ₄添加对早期水合动力学的影响。，热分析和固态²⁷ Al²⁹ Si核磁共振（NMR）光谱。结果表明，C的水合₃甲显著影响C的水合₃ S.的C ₃ S和C ₃甲水合在严重过硫酸化系统大大受阻（其中C ₃甲水合由于抑制非常高的石膏含量）和额外的Na ₂ SO _4系统。尽管C‐H‐H相中有大量的Al掺入，但C‐S‐ Al的Al _IV / Si比在石膏含量，水合年龄或Na ₂ SO _4的添加方面没有明显的趋势。H相由²⁹ Si NMR。通过添加Na ₂ SO ₄，钙矾石从AFm相的重结晶被推迟了1天到7天。