Study of hydration of sulphoaluminate cement by in situ synchrotron diffraction
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2017
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RAU ANNUAL USERS MEETING LNLS/CNPEM
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The hydration of calcium sulphoaluminate cement mixtures was studied in situ by
synchrotron X-ray diffraction at the XRD1 beamline at the Laboratório Nacional de Luz
Síncrotron (LNLS – Campinas). The specimens were analyzed in borosilicate glass
capillary tubes of 0.7 mm and imbued with deionized water. As the hydration reaction is
very fast, the data collection was started after two minutes of mixing with water. The Xray
wavelength chosen to get an adequate flux for these short time acquisitions was
1.033258 Å (12 keV), determined with a corundum standard. Diffraction patterns were
collected every 35 seconds at temperatures ranging from 40 °C to 55 °C with accuracy
better than 0.1 °C attained with a hot air blower. The diffracted signal was collected with
an array of 24 Mythen detectors [1]. The diffraction patterns accumulated had appropriate
statistics to determine the kinetics of the reaction either by quantitative Rietveld analysis
or by fitting isolated diffraction peaks to Gaussian curves as a function of time. The most
important phases involved in the hydration are Klein´s salt, also known as Ye’elimite,
Ca4(AlO2)6SO4, and gypsum, CaSO4.2H2O to yield Ettringite,
Ca6Al2(SO4)3(OH)12·26H2O, phase responsible for the mechanical properties. These
studies show the potential of XRD1 beamline to investigate at controlled temperatures in
situ fast reactions involving crystalline phases with time resolutions inferior to one
minute, which is ideal for the hydration of cementitious mixtures.
The series of diffraction patterns collected for one and half hour are shown in Figure 1(a)
and (b). In Figure 1(c) the evolution of the relative proportions of crystalline phases can
be seen. Non-crystalline phases such as CSH gel or Al(OH)3 (gibbsite) are not taken in
consideration [2].
The figures clearly show that the ettringite formation happens in two stages, the second
one starting after approximately forty minutes. It is also interesting to notice that this
stages seem to coincide with the depletion of Ca2SiO4 (C2S) for the first stage and the
depletion of Ca3SiO5 (C3S) for the second one.
Como referenciar
ROSSETTO, C.M.; MARTINEZ, L.G.; ICHIKAWA, R.U.; CAREZZATO, G.L.; CARVALHO, A.M.G.; TURRILLAS, X. Study of hydration of sulphoaluminate cement by in situ synchrotron diffraction. In: RAU ANNUAL USERS MEETING LNLS/CNPEM, November 22-24, 2017, Campinas, SP. Abstract... p. 135-135. Disponível em: http://repositorio.ipen.br/handle/123456789/28669. Acesso em: 20 Mar 2026.
Esta referência é gerada automaticamente de acordo com as normas do estilo IPEN/SP (ABNT NBR 6023) e recomenda-se uma verificação final e ajustes caso necessário.