The Hydration of Plaster of Paris

Birss, F. W.; Thorvaldson, T.

doi:10.1139/v55-105

Cited by 27 publications

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“…Our data clearly show that bassanite nanorods transform to gypsum via a dissolution/reprecipitation pathway within a controlled liquid environment, where this was confirmed by complementary in situ Raman and cryo‐TEM studies. This is consistent with the literature describing the hydration of plaster of Paris (bassanite) for applications within the construction industry 30–33 . No evidence was obtained for the oriented assembly of bassanite nanorods prior to direct transformation into gypsum.…”

Section: Discussionsupporting

confidence: 90%

Evaluation of correlated studies using liquid cell and cryo‐transmission electron microscopy: Hydration of calcium sulphate and the phase transformation pathways of bassanite to gypsum

Ilett

Freeman

Aslam

et al. 2022

Journal of Microscopy

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Insight into the nucleation, growth and phase transformations of calcium sulphate could improve the performance of construction materials, reduce scaling in industrial processes and aid understanding of its formation in the natural environment. Recent studies have suggested that the calcium sulphate pseudo polymorph, gypsum (CaSO 4 ⋅2H 2 O) can form in aqueous solution via a bassanite (CaSO 4 ⋅0.5H 2 O) intermediate. Some in situ experimental work has also suggested that the transformation of bassanite to gypsum can occur through an oriented assembly mechanism. In this work, we have exploited liquid cell transmission electron microscopy (LCTEM) to study the transformation of bassanite to gypsum in an undersaturated aqueous solution of calcium sulphate. This was benchmarked against cryogenic TEM (cryo-TEM) studies to validate internally the data obtained from the two microscopy techniques.When coupled with Raman spectroscopy, the real-time data generated by LCTEM, and structural data obtained from cryo-TEM show that bassanite can transform to gypsum via more than one pathway, the predominant one beingThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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Section: Discussionsupporting

confidence: 90%

Evaluation of correlated studies using liquid cell and cryo‐transmission electron microscopy: Hydration of calcium sulphate and the phase transformation pathways of bassanite to gypsum

Ilett

Freeman

Aslam

et al. 2022

Journal of Microscopy

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“…(8), CaS04.+Hz0 (12), and dead-burnt CaO (13). In only one case has a different inechanism been observed: the hydration of soft-burnt (i.e.…”

Section: Of Reference 7 )mentioning

confidence: 99%

Solid–liquid Reactions: Part Ii. Solid–liquid Reactions Amongst the Calcium Aluminates and Sulphoaluminates

Kelly¹

1960

Can. J. Chem.

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When 3CaO.Al2O3.6H2O (i.e. C3AH6) was placed in contact with a solution of Ca(OH)2 labeled with Ca45 and maintained at 25 °C, there was very little change in either the activity or composition of the liquid. These observations, when taken together, indicate that the compound is probably stable in the system used. On the other hand, when either C3AH6 or 3CaO.Al2O3.CaSO4.12H2O (i.e. C3AΣH12) was added to a mixed Ca(OH)2–CaSO4 solution, the composition of the liquid varied in a manner consistent with the formation of 3CaO.Al2O3. 3CaSO4.31H2O (i.e. C3AΣ3H31). The activity also changed markedly, and a detailed consideration of the relations between activity and composition enabled the reaction mechanisms to be determined. In further experiments, the reactions of C3AH6 and C3AΣH12 to form C3AΣ3H31 were shown to proceed also at 70° and 90 °C. The consistently greater ultimate stability of C3AΣ3H31 over C3AΣH12 between 25° and 90 °C is to be contrasted with the fact, observed in the course of preparing the C3AΣH12, that when solutions of A12(SO4)3, CaSO4, and Ca(OH)2 are mixed the immediate precipitate is C3AΣ3H31 at room temperature, but C3AΣH12 at boiling temperature.

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“…A theoretical expression for the liberation of raclioactivity by a labelled sample of the hemihydrate of calcium sulphate when hydrated in a solution of inactive calcium sulphate has been cleveloped in the preceding paper ( 1 ) .…”

Section: "Throz~gh-solution" Iiydration Of Limementioning

confidence: 99%

“…The activity values obtained for the hydration liquids were correctecl for changes in concentration (1). From the figures obtained the proportion of the calcium oxide apparently hydrated by a through-solution mechanism was calculated by means of the theoretical equation.…”

Section: Comparison Of the Hydration Of Samples A B And Cmentioning

confidence: 99%

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The Mechanism of the Hydration of Calcium Oxide

Birss¹,

Thorvaldson²

1955

Can. J. Chem.

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Three sarnples of c a l c i~~~n oxide, designated as .A, B, ancl C, \\.ere preparecl from c a l c i~~m carbonate labelled with calci~~m-45. : \ \vas heated to constant weight a t 700°C.; B was hcated an additiollal three hours a t 1400 to l55OoC.; and C was heated six hours a t the same temperature. 'The samples \\.ere hydratetl in a supersaturated lime solution a t 21°C., the develop~llent of activity and the changes in collcentratiol~ of thc solution being deterlnined. l'he activity cnterillg the solution accourlted, according to theory, for the f~l l o \ \~i~l g percentages of the sanlples passing through the solutioll during the hydration: r \ , 27'5;; R , 57%; C, 94%. These results indicate that samplc C ("clead-burnt" lime) hydratcd by a "through-solutior~" mechanism, but that .\ and B cither hydrated partly according to some other mechanisrn, such as a vapor phase process ill the pore> of the particles of lirnc, or the c a l c i~~m ions failed to reach the bull; of thc hyclrating liq~lid bcfore precipitation as calci~lrn hyclroxicle. INTRODUCTIOK

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The Hydration of Plaster of Paris

Cited by 27 publications

References 0 publications

Evaluation of correlated studies using liquid cell and cryo‐transmission electron microscopy: Hydration of calcium sulphate and the phase transformation pathways of bassanite to gypsum

Evaluation of correlated studies using liquid cell and cryo‐transmission electron microscopy: Hydration of calcium sulphate and the phase transformation pathways of bassanite to gypsum

Solid–liquid Reactions: Part Ii. Solid–liquid Reactions Amongst the Calcium Aluminates and Sulphoaluminates

The Mechanism of the Hydration of Calcium Oxide

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