From Molten Calcium Aluminates through Phase Transitions to Cement Phases

Hao Liu, Wenlin Chen, Ruikun Pan, Zhitao Shan, Ang Qiao, James W. E. Drewitt, Louis Hennet, Sandro Jahn, David P. Langstaff, Gregory A. Chass, Haizheng Tao, Yuanzheng Yue, G. Neville Greaves

Research output: Contribution to journalArticle (Academic Journal)peer-review

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Abstract

Crystalline calcium aluminates are a critical setting agent in cement. To-date, few have explored the microscopic and dynamic mechanism of the transitions from molten aluminate liquids, through the supercooled state to glassy and crystalline phases, during cement clinker production. Herein we report the first in situ measurements of viscosity and density across all the principal molten phases, relevant to their eventual crystalline structures. Bulk atomistic computer simulations confirm that thermo-physical properties scale with the evolution of network substructures interpenetrating melts on the nanoscale. We have demonstrated that the glass transition temperature (Tg) follows the eutectic profile of the liquidus temperature (Tm), coinciding with the melting zone in cement production. We have uniquely charted the viscosity over 14 decades for each calcium aluminate phase, projecting and justifying the different temperature zones used in cement manufacture. We have revealed the fragile-strong phase transitions across all supercooled phases coinciding with heterogeneous nucleation close to 1.2Tg, where sintering and quenching occur in industrial-scale cement processing.
Original languageEnglish
Article number1902209
Number of pages10
JournalAdvanced Science
Volume7
Early online date26 Nov 2019
DOIs
Publication statusPublished - 22 Jan 2020

Keywords

  • aerodynamic levitation
  • calcium aluminates
  • cement
  • fragile–strong phase transitions
  • molecular dynamic simulation

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