Formation of carbonate phases and their effect on the performance of reactive MgO cement formulations

N.T. Dung, A. Lesimple, R. Hay, Kemal Celik, C. Unluer

Research output: Contribution to journalArticlepeer-review

Abstract

This study investigated the formation of different phases and their influence on the microstructural and mechanical development of carbonated reactive MgO cement formulations. Hydrated magnesium carbonates (HMCs) were identified and quantified via XRD, TG-DTG and SEM. Visual observations of the 3D internal structure at different depths were performed by X-ray computed tomography and confocal Raman microscopy. Elastic modulus of different components was obtained by nano-indentation. The expansive formation of HMCs led to dense microstructures composed of well-connected carbonate networks. The transition of artinite to hydromagnesite/nesquehonite was observed over time. The initial formation of a dense carbonate layer on sample surface inhibited continuous diffusion of CO2, resulting in a slower strength development at later ages. Despite this limitation, the continuation of hydration and evolution of carbonate morphology led to 28-day strengths of 60 MPa in concrete samples, supported by the higher elastic modulus of HMCs than brucite (19.4 vs. 2.5 GPa).
Original languageEnglish
Article number105894
Pages (from-to)1-12
Number of pages12
JournalCement and Concrete Research
Volume125
Early online date6 Sept 2019
DOIs
Publication statusPublished - Nov 2019

Keywords

  • Microstructure (B)
  • Carbonation (C)
  • MgO (D)
  • Diffusion (C)
  • Expansion (C)

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