Incorporating carbon sequestration materials in civil infrastructure: A micro and nano-structural analysis

Abstract The Calera method for carbon sequestration promotes carbon mineralization through aqueous precipitation. This work reports a comprehensive analysis on a carbonate obtained by the Calera process to evaluate its suitability as a cement replacement for concrete applications. This work focuses on the analysis of two hydrated cement pastes made with a blend of Portland cement and Calera carbonates by various advanced analytical techniques. Scanning Electron Microscopy (SEM) equipped with Energy Dispersive Spectroscopy (EDS) was used to observe microstructures and determine elemental compositions. The synchrotron X-ray diffraction technique combined with Rietveld analysis were applied to identify constituent phases and refine crystal structures, crystallite sizes as well as relative phase abundances. Calcite and vaterite are observed in all samples while CSH II and portlandite are dominant in the cement pastes. Near-Edge X-ray Absorption Fine Structure (NEXAFS) spectrometry and Scanning Transmission X-ray Microscopy (STXM) experiments were conducted to investigate chemical speciation and morphological information of carbonate minerals with different absorption energies. STXM results confirmed heterogeneity of the samples, and also provided a nano-scale phase map across multiple particles. Differential Thermogravimetric (DTG) was used to observe heat transfer through structures and changes in mass upon heating. A compressive strength tests were performed on materials and shown comparable strength to Portland cement.

[1]  B. Lothenbach,et al.  The Role of Calcium Carbonate in Cement Hydration , 2007 .

[2]  S. Simons,et al.  A review of accelerated carbonation technology in the treatment of cement-based materials and sequestration of CO2. , 2004, Journal of hazardous materials.

[3]  H. Taylor,et al.  Crystal structure of ettringite , 1970 .

[4]  R. Detwiler,et al.  THE USE OF LIMESTONE IN PORTLAND CEMENT: A STATE-OF-THE-ART REVIEW , 1996 .

[5]  H. Rietveld.  A profile refinement method for nuclear and magnetic structures , 1969 .

[6]  Hans-Rudolf Wenk,et al.  Combined texture and structure analysis of deformed limestone from time-of-flight neutron diffraction spectra , 1997 .

[7]  G. Renaudin,et al.  A Cementitious Compound with Composition 3CaO×Al2O3×CaCO3 ×11H2O. , 1998 .

[8]  L. R. Van Loon,et al.  Preferred orientations and anisotropy in shales: Callovo-Oxfordian shale (France) and Opalinus Clay (Switzerland) , 2008 .

[9]  V. Streltsov,et al.  X-ray study of the electron density in calcite, CaCO3 , 1993 .

[10]  T. Yamanaka,et al.  Compression mechanism and amorphization of portlandite, Ca(OH)2: structural refinement under pressure , 2000 .

[11]  H. Taylor,et al.  The crystal structure of jennite, Ca9Si6O18(OH)6·8H2O , 2004 .

[12]  S. Merlino,et al.  The real structure of tobermorite 11A: normal and anomalous forms, OD character and polytypic modifications , 2001 .

[13]  T. Tyliszczak,et al.  Scanning transmission X‐ray microscopy study of microbial calcification , 2004 .

[14]  G. Renaudin,et al.  A cementitious compound with composition 3CaO.Al2O3.CaCO3.11H2O , 1998 .

[15]  E. Bertaut,et al.  Structure du ferrite bicalcique et de la brownmillerite , 1959 .

[16]  S. Kamhi.  On the structure of vaterite CaCO3 , 1963 .

[17]  V. Kaučič,et al.  Evaluation of the hydration of portland cement containing various carbonates by means of thermal analysis , 2006 .