Investigation of the viscoelastic evolution of reactive magnesia cement pastes with accelerated hydration mechanisms

Yiming Peng, Cise Unluer

Research output: Contribution to journalArticlepeer-review

Abstract

Viscoelasticity of reactive magnesia cement (RMC) pastes containing 3 different hydration agents (HCl, Mg(CH3COO)2 and MgCl2) were investigated. Amplitude sweep, frequency sweep and time sweep of RMC pastes were examined within 3 h of hydration. Time-dependent evolution of storage modulus, loss modulus, phase angle, and shear stress were recorded. Measurements of pH, isothermal calorimetry, XRD, TG-DTG and FTIR were used to analyze hydration reaction and products. Addition of hydration agents (HAs) accelerated the growth rate of storage modulus/loss modulus over time. MgCl2 demonstrated the greatest acceleration influence, also reflected in non-destructive structural build-up and buildability related to 3D printing applications. Addition of MgCl2 and HCl advanced the initial setting time of RMC pastes to 100-110 min, during which yield stress reached maximum, and decreased afterwards. Within 3 h of hydration, pastes containing MgCl2 revealed lowest pH, highest heat release and brucite concentration. HAs inclusion precipitated brucite away from MgO particles in the bulk solution, creating a bridge between MgO particles and enabling denser microscopic network structure.
Original languageEnglish
Article number105191
JournalCement and Concrete Composites
Volume142
Early online date21 Jun 2023
DOIs
Publication statusPublished - 1 Sept 2023

Keywords

  • Reactive magnesia cement
  • hydration agents
  • rheology
  • viscoelasticity
  • microstructure evolution
  • Viscoelasticity
  • Hydration agents
  • Rheology
  • Microstructure evolution

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