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Quantitative X‐ray diffraction of free, not chemically bound water with the PONKCS method
Author(s) -
Scherb Sebastian,
Beuntner Nancy,
Thienel Karl-Christian,
Neubauer Jürgen
Publication year - 2018
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s1600576718012888
Subject(s) - scattering , amorphous solid , calcination , diffraction , bound water , materials science , small angle x ray scattering , x ray crystallography , chemistry , yield (engineering) , free water , mineralogy , analytical chemistry (journal) , crystallography , chromatography , optics , physics , molecule , metallurgy , geology , organic chemistry , geotechnical engineering , catalysis
The free water in calcined phyllosilicate–water mixtures exhibits a distinctly different behaviour in its X‐ray amorphous scattering contribution as opposed to fly ash– or limestone powder–water mixtures. While fly ash and limestone powder yield a continuous increase in the scattering contribution when water is added, the scattering contribution stagnates for calcined phyllosilicates over a wide range of water addition. There is a direct correlation between the consistency of the sample and the X‐ray amorphous scattering contribution caused by the water. The same correlation can also be found in in situ X‐ray diffraction measurements of hydrating systems. As long as the sample has a pasty consistency, the scattering contribution of the water decreases with progressive reaction. After the transition from fresh paste to final set, there is no further reduction of the X‐ray amorphous scattering contribution caused by the free water, which means that the free water cannot be quantified correctly from this point in time.