The Mechanism of the Hydration of Calcium Oxide

Birss, F. W.; Thorvaldson, T.

doi:10.1139/v55-106

Cited by 23 publications

(17 citation statements)

References 2 publications

(5 reference statements)

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“…[11,45,73], and (b) so-called ''through-solution'' or ''wet hydration''. For this second mechanism, it is at present unclear whether (a) the CaO first dissolves in the solution phase (water) and subsequently precipitates as Ca(OH) 2 [12,84,101,128], or (b) direct conversion of CaO into Ca(OH) 2 occurs, as in vapour phase hydration, followed by (partial) dissolution (and re-precipitation) of the Ca(OH) 2 formed [12,113].…”

Section: Model For Foc Development and Application To Cao Hydrationmentioning

confidence: 99%

Reaction-driven casing expansion: potential for wellbore leakage mitigation

2017

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It is generally challenging to predict the postabandonment behaviour and integrity of wellbores. Leakage is, moreover, difficult to mitigate, particularly between the steel casing and outer cement sheath. Radially expanding the casing with some form of internal plug, thereby closing annular voids and fractures around it, offers a possible solution to both issues. However, such expansion requires development of substantial internal stresses. Chemical reactions that involve a solid volume increase and produce a force of crystallisation (FoC), such as CaO hydration, offer obvious potential. However, while thermodynamically capable of producing stresses in the GPa range, the maximum stress obtainable by CaO hydration has not been validated or determined experimentally. Here, we report uniaxial compaction/expansion experiments performed in an oedometer-type apparatus on precompacted CaO powder, at 65°C and at atmospheric pore fluid pressure. Using this set-up, the FoC generated during CaO hydration could be measured directly. Our results show FoC-induced stresses reaching up to 153 MPa, with reaction stopping or slowing down before completion. Failure to achieve the GPa stresses predicted by theory is attributed to competition between FoC development and its inhibiting effect on reaction progress. Microstructural observations indicate that reaction-induced stresses shut down pathways for water into the sample, hampering ongoing reaction and limiting the magnitude of stress build-up to the values observed. The results nonetheless point the way to understanding the behaviour of such systems and to finding engineering solutions that may allow large controlled stresses and strains to be achieved in wellbore sealing operations in future.

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Section: Model For Foc Development and Application To Cao Hydrationmentioning

confidence: 99%

Reaction-driven casing expansion: potential for wellbore leakage mitigation

2017

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“…As pointed out in reference 7, these effects tend to nlalte the activity the same for all mechanisms in the later stages of reaction. Thus for the C3AHs-C3AZ3H31 reaction, assuming nl --t 0, the activity \vould alnrays be close to (from equation [13] …”

Section: Stabilitiesmentioning

confidence: 78%

“…could also be obtained as a product of a solid-liquid reaction. Samples of C,AH, and C3AZH12 weighing about 0.05 g were added to 50-cc portions of a inixed Ca(OH)?-CaSOd solution such that each portion contained 13.334 X lo--' mole calcium and 6.45 X 10-Qlnole sulphate, and were shaliel~ inside a n oven for periods of up to 7 days. For temperatures of 70" and 90" C the reaction products were consistelltly acicular, and solution analyses confirmed that C3AZ3H31 had formed.…”

Section: Reactions At Elevated Temperaturesmentioning

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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“…solid-liquid reactio~is were described a s following mechanisms based on the clegree of mixing (1,3,1). There is reason to believe, however, that the procluct solids in a t least t\\~o of the reactions (the hydrations of CaSOl.+H20 (3) ant1 CaO (4)) exhibit rapicl, ~uultidirectional external excl~ange.~ T h e reactions in question are therefore perhaps better represe~lted in terms of "surface" or "internal" mechanislns; passage through solution may still have occurrecl, but was not rigorously demonstrated.…”

Section: Previously S T~~d I E Dmentioning

confidence: 99%

“…+I-120 (3), and CaO (4); the conversion of illsoluble sulphates to carbonates (5, p. 585); and the reactions described in reference 6. Innumerable variations in the details of solid-liquid reaction mechanisms are undoubtedly possible; however, the mechanisms will tend to fall into general classes or systems which represent to first approximation the liinits of experiinental distinguishability. One such system, much usecl in past work (1,3,4), considers the degree of mixing with the liquid of successively reacting portions of the reacting solid (Fig. 1A).…”

Section: Introductionmentioning

confidence: 99%

Solid–liquid Reactions: Part I. The Determination of Solid–liquid Reaction Mechanisms

Kelly¹

1960

Can. J. Chem.

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A tracer method has been described by Graham, Spinks, and Thorvaldson for investigating the mechanisms of solid-liquid reactions. The present work represents an attempt to develop the theory of this method in detail and thereby allow for a greater variety of experimental conditions. Thus, no restrictions are placed on the compositions of the reacting and product solids, nor on the initial location of the tracer. The effect of exchange between the liquid and both solids is talcen into account. Furthermore, two different systenls of mechanisms are considered. In the one, which is shown to be the more realistic when rapid, multidirectional "external" exchange is present, mechanisms are classified according to whether or not the reaction proceeds a t the surfaces of the solids; in the other, applicable in the absence of "external" exchange or when the exchange is slow, mechanisms are classified according t o the degree of mixing with the liquid of successively reacting portions of the reacting solid. INTRODUCTIONA solid-liquid reaction may be defined as one in which a solid of low solubility (the reacting solid) reacts with a liquid to forin a second solid of even lower solubility (the product solid), the term liquid being here intended to include both solveilt and solute indiscriminately. Reactions of this kind are of particular interest in cement chemistry, since they are responsible for both the setting and deterioratioil of cenlentitious substances (2). Specific examples include the hydrations of the calciuin silicates (I), CaS04.+I-120 (3), and CaO (4); the conversion of illsoluble sulphates to carbonates (5, p. 585); and the reactions described in reference 6. Innumerable variations in the details of solid-liquid reaction mechanisms are undoubtedly possible; however, the mechanisms will tend to fall into general classes or systems which represent to first approximation the liinits of experiinental distinguishability. One such system, much usecl in past work (1,3, 4), considers the degree of mixing with the liquid of successively reacting portions of the reacting solid (Fig. 1A). Thus, in a "through-solutio~~" inechanisin the reacting solid passes into solution before precipitating as product solid (7). In a "direct" mechanism, on the other hand, the reacting solid is converted to the product solid \vithout an intermediate inixing with the body of the liquid; the liquid is, however, assunled to receive or supply inaterial as required by the balanced reaction equation (3, 4). Depending on the relative ease of the "throughsolution" and "direct" routes, mixed nlechanisnls inight also occur.A possible alternative to the above s>.stein of mechanisms considers whether or not the reaction proceeds a t the surfaces of the solids (Fig. 1B). In a "surface" mechanism material is transferred from the surface of the reacting solid to that of the product solid, with or without mixing with the body of the liquid. In an "internal" mechanism reaction proceeds as a result of liquid diffusing, or otherwise penetrating, ...

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The Mechanism of the Hydration of Calcium Oxide

Cited by 23 publications

References 2 publications

Reaction-driven casing expansion: potential for wellbore leakage mitigation

Reaction-driven casing expansion: potential for wellbore leakage mitigation

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

Solid–liquid Reactions: Part I. The Determination of Solid–liquid Reaction Mechanisms

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