Recent studies of cements and concretes by synchrotron radiation crystallographic and cognate methods

Abstract

The portfolio of available synchrotron radiation techniques is increasing notably for cements and pastes. Furthermore, sometimes the terminology is confusing and an overall picture highlighting similarities and differences of related techniques was lacking. Therefore, the main objective of this work is to review recent advances in synchrotron techniques providing a comprehensive overview. This work is not intended to gather all publications in cement chemistry but to give a unified picture through selected examples. Crystallographic techniques are used for structure determination, quantitative phase analyses and microstructure characterization. These studies are not only carried out in standard conditions but synchrotron techniques are especially suited to non-ambient conditions: high temperatures and pressures, hydration, etc., and combinations. Related crystallographic techniques, like Pair Distribution Function, are being used for the analysis of ill-crystalline phase(s). Furthermore, crystallographic tools are also employed in imaging techniques including scanning diffraction microscopy and tomography and coherent diffraction imaging. Other synchrotron techniques are also reviewed including X-rays absorption spectroscopy for local structure and speciation characterizations; small angle X-ray scattering for microstructure analysis and several imaging techniques for microstructure quantification: full-field soft and hard X-ray nano-tomographies; scanning infrared spectro-microscopy; scanning transmission and fluorescence X-ray tomographies. Finally, a personal outlook is provided.

Influence of experimental procedure on d-spacing measurement by XRD of montmorillonite clay pastes containing PCE-based superplasticizer

“…To extend the assessment of the influence of the experimental methodology on the final clay d-spacing and to confirm the reproducibility of the results obtained when testing fresh samples directly, in situ XRD measurements were performed with two different X-ray diffractometers at two different facilities: standard laboratory XRD (Cu X-ray tube) and X-ray synchrotron radiation analyses. It should be noted that synchrotron radiation techniques are especially suited for carrying out in situ studies on unaltered cement pastes [12]…”

Chemistry and Mass Density of Aluminum Hydroxide Gel in Eco-Cements by Ptychographic X-ray Computed Tomography

“…A review about the use of synchrotron radiation to investigate cements has been recently reported including an overview of the available imaging approaches. 33 The state-of-the-art evolution of these imaging techniques brings to ptychographic X-ray computed tomography (PXCT), which is a scanning technique that makes use of the coherent properties of synchrotron radiation. 34 In coherent diffraction imaging, the post-sample X-ray optics is replaced by phase retrieval algorithms which, combined with the ptychographic approach, make PXCT robust and reliable.…”

Synchrotron Radiation Pair Distribution Function Analysis of Gels in Cements

“…Total scattering data analyzed by PDF methodology may distinguish phases that are amorphous, nanocrystalline, or crystalline, and this methodology provides quantitative information concerning phase contents and local bonding environments [21]. In order to shed light and open questions in the chemistry and local atomic structure of C-S-H gels, neutron and synchrotron total scattering data analyzed by PDF methodology have been used, and these studies have been reviewed [25,26]. Here, we distinguish the PDF studies on synthetic C-S-H gels [13,[27][28][29] from those carried out for C-S-H gels formed from the hydration of alite [29][30][31], as the local atomic arrangements could be quite different.…”