Polymorph transformation kinetics of Ca₃SiO₅ with MgO

Abstract

Tricalcium silicate (Ca₃SiO₅ (C₃S)) is the primary cement phase in Portland cement. An understanding of its transformation kinetics is important to make use of its polymorphism. In this study, X-ray diffractometry and Rietveld refinement were used to qualitatively and quantitatively analyze the phase compositions of C₃S with 2.0% MgO. The results show that C₃S with 2.0% MgO is a monoclinic polymorph, M3. Heat treatment changes this monoclinic polymorph to a triclinic polymorph via the precipitation of MgO. The transformation kinetics follows the first-order exponential decay function $f=a\cdot \exp (-t/b)+c$.

Keywords:

• tricalcium silicate
• polymorph
• kinetics
• heat treatment

Acknowledgements

The authors are grateful for support from the facilities of the Modern Analysis and Testing Centre at NJTECH, where the detailed microstructural analyses were performed.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [51202109]; the Program for Changjiang Scholars and Innovative Research Team in University [IRT1146]; and the National Building Materials Industry Technology Innovation Programme [2013-M1-1].