Further phase-equilibrium studies involving the potash compounds of portland cement

Taylor, W. C.

doi:10.6028/jres.029.027

Cited by 10 publications

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“…In agreement with th e work previously reported by Taylor [4], K 20.23CaO.12Si02 was found to react with CaS0 4 in an equimolar ratio upon h eating mixt.ures of t hose compounds in t he r egion of clinkering temperatures. The observed reaction products after quen ching th e mixture fr om 900° wer e i3-2CaO.Si02, ' Y-2CaO.Si02 and K 2S04. Preheated mixtures of K 20 .23CaO.12Si0 2 and CaS0 4 having molecular ratios K 20 jSOa, of 1, 2, and 3 (4 , 36, and 47, respectively, table 2) showed an endothermic transformation in the region of the K 2S04 m elting point during thermal analysis.…”

Section: Reaction Of K20 23caol2si02 With Cas04supporting

confidence: 90%

“…These equations, in the convenient weight per centage form , appear in table 4. The appl~cation of the equations in table 4 (B ) (for those mIxtures having R 2 0 j80 3 molecular ratios greater than l.0) requires the preliminary calculation of the value of K s the mole fraction of K 280 4 in the sulfate, for th~ mixture as outlined in table 3.…”

Section: Discussionmentioning

confidence: 99%

“…23CaO .12Si02. He reported , however , [4] that t his compound is unstable when heated in the presence of S0 3, the r eaction being represented b.I' the equation , H e found molten. poLassi um sulfaLe to be immiscible with tbe clinker liquid , Lo show no Lendency Lo r eact wi th the componenLs of mixtures containing 3CaO.Si02, 2CaO.…”

Section: Introductionmentioning

confidence: 98%

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Effect of SO3 on the alkali compounds of portland cement clinker

Newkirk¹

1951

J. RES. NATL. BUR. STAN.

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This investiga tion ShOWR t!lat the compound Na20. 8CaO.3Ah03, whi ch is known io bp one of t h e form s in which N azO may occur in por t lan d cem ent clin ke r.!, is unstll,ble at clinkering tem p eratures in thc pres(')nce of 803. This compound rea cts wit h b 0 3 to form N a28 0 . and 3CaO .AI20 3. Any excess of Na20 wi ll remain as Na20.8CaO.3Ah03, become a constituent of the clinker glass, or enter into SOlid . solu tion with one of tbe other clinker components.I n cl inker compositionE containinf!; bot h soda and potash together wit h 80 " an a lka lisulfate phase is produced t hat contai ns hoth of the alkalies. For molecular ratios H zOi 8 0 a greater t h an uni ty, a preferential reap-tion of the 8 0 3 with K 2 0 is indicated. Empirical relationships between t h e alkali('s and t he 803 of the cement mixture indicate that t he al kalies fi rst combine wit h t h e 8 0 3 in t he approximate molec ular rlttio K20/N a~0 = 3 t o t Ile extent that t he compositio n limits of the mixture p ermit. The composition of t he a lkalisu lfate phase for mi-·tures of var.ving soda-potash contellis with H 20 /803 molocu lar ratios equal to 1, 2, and 3 h ave been determined . Equat ions are d evcloped for calculatin g the ~lppr ox im ate com position of the a lkal i sulfaLe awl t he potential phase co mposition of cl ink crtype m ixt u res having other R l O/R 0 3 ratios.

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Section: Reaction Of K20 23caol2si02 With Cas04supporting

confidence: 90%

Section: Discussionmentioning

confidence: 99%

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Effect of SO3 on the alkali compounds of portland cement clinker

Newkirk¹

1951

J. RES. NATL. BUR. STAN.

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“…The results of this study showed that, under equilibrium cooling, the prismatic form was not observed in any case. Under more rapid cooling the prismatic form appeared in those compositions in which C3A wa one of the compounds anticipated from the phase diagram [41]. If the charge were quenehed from a temperature above that at which C3A was formed, the prismatic phase was not found .…”

Section: Prismatic Tricalcium Aluminatementioning

confidence: 96%

Some recent advances in our understanding of the chemistry of portland cement

Bogue¹

1947

J. RES. NATL. BUR. STAN.

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A review is given of so me of the more important advances that have been made in our un derstandin g of portland cement during the war years, or m ore specifically from 1942 to 1946. The fi eld covered is limited strictly to chemical research, and no attempt is made to inclu de more than t he o utstanding contrib u tions. The presen tatio n is give n of thi r teen i nv estigational fields of study, cl assified in four major divisions. The more sig nifi cant results are brought together in a summary, NotationThe commonly used abbreviated symbols for the cement components ar e used interchangeably with the conven tional notation. Thus, C-CaO, S-Si02, A-AI20 3, F-Fe20 e, H-H20 , N-NazO, K-K20 , M-M gO, H ence, CzAHs-2CaO.Al20 3.8HzO, etc. II. IntroductionSince the close of the war, scientists from countries throughout the world have been concerned with catching up on the progress made in other co untries during the years when communication was barred. In our laboratories, as in others, our friends seek to learn of the advances that have come from chemical research on portland cement. The answer is not to be found in anyone place. To meet that n eed is one of the purposes of this paper.No attempt is made at a comprehensive picture. Only a few of t he more significant st,udies can be presented, and these are confin ed to the strictly chemical fields . A more extf'nsive treatment has recently been published elsf'where [I V Many importan t advaD ces likewise have been made in the fields of physics, engineering, manufacture, architectUl'e, etc, But what we see in our own fif'ld gives promise of a most interesting future. The treatment will be directed to a r eview of research on phase composition, crystal structure, reactions of hydration, and new technics. Combinations of PotashAlthough the alkali es in cement ara probably never present in amounts exceeding 2 percent, and usually thell' total is under 1 percent, yet t heir presen ce in even smaller quantit les is known t o produce effects which, under certain conditions, are the subject of concern. One observed effect [12] is that increasing amoun ts of alkali in the mix result in increased difficulty, dUTing manufacture, in keeping clown the free C;tO. Another [36] is t he undue expansion of high-alkali cements with certain types of siliceous aggregates. In order to understand the action of the all' alies in cement, it is essential to know the forms in which these elements exist in clinker, and the phase relations by which t hey may be controlled.In a study of t he system K20 -CaO-Ab03' Brownmiller r5] found that only one compound of potash was formed which could exist in the general composition-range of portland cement. Thls was the binary compound KA. 'r aylor [39] showed later that this compound was stable in the presence of the iron compound of cement, C4AF. The latter compound was known to form a solid solu tion with C2F [1 3], aJid t hi s solid solution was found to act as a psendobinary system with the 177 l

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“…Se pudo comprobar claramente el sulfato potásico en el clinker. De este modo se confirmaron los resultados de Taylor [1]: el K2SO4 es estable en presencia de las fases del clínker. El sulfato sódico, por el contrario, influye en la formación de las fases alita, belita y aluminato con la misma tendencia que el carbonato sódico, aun cuando de manera decididamente menor, pues a la temperatura de sinterización sólo se puede disponer de una fracción del óxido de sodio para la formación de las fases del clínker.…”

Section: Influencia De Los Sulfatos Alcalinos Sobre Las Fases Del CLIunclassified

Influencias ejercidas por los álcalis sobre las propiedades del clinker de cemento y del cemento portland

Knöfel¹

1972

Mater. construcc.

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Influencias ejercidas por los álcalis sobre las propiedades del clinker de cemento portland y del cemento portland Existe ya literatura acerca de la incorporación de álcalis en las fases de los clínkeres, así como acerca de la importancia de las fases de clinker que contienen álcalis [1] - [14]. Vamos a informar acerca de los ensayos propios con el fin de completar la literatura ya existente.Se prepararon en el laboratorio cuatro series de clínkeres que contenían álcalis. A un crudo de cemento sintético sin álcalis compuesto de sustancias químicamente puras se aña-dieron escalonadamente K2SO4 (serie KS), Na2S04 (serie NS), K2CO3 (serie KC) y NagCOg (serie NC). En los clínkeres se incorporó de O a 3 % K2O ó O a 4 % NagO (designación de las muestras: por ejemplo 0,8 KC significa 0,8 % Kfi en el clinker por adición de K2CO3 al crudo). Junto a estos clínkeres que continen álcalis se investigó una muestra sin álcalis (muestra 0). Todos los clínkeres presentaron un standard de cal de 91, un módulo de silicatos de 1,6 y un módulo de fundentes de 2,2.Los clínkeres fueron investigados químicamente, microscópicamente y radiográficamente. De todos ellos se prepararon cementos de la misma finura y del mismo contenido de SO3. En todos los cementos se mantuvo constante el contenido total de SO3 (clínker-SOg y yeso-S03). En estos cementos se determinó la resistencia a la compresión, la resistencia a la temperatura ambiente, el comportamiento en el fraguado y el grado de hidratación. Influencia de los carbonatos alcalinos en las fases de los clínkeresHay que considerar aquí las cuatro fases: alita, belita, aluminato calcico y ferritoaluminato calcico.En los campos investigados se incorporaron totalmente los álcalis en las fases del clinker. La proporción predominante se encuentra siempre en la fracción aluminato-ferrito. Esta fracción tiene una concentración de KgO 3 a 5 veces superior, o una concentración de NaaO 4 a 10 veces superior, que la de los silicatos. Especialmente está claro, en el caso de concentraciones reducidas de álcalis, el enriquecimiento relativamente fuerte en la fracción aluminato-ferrito. Esto muestra que, especialmente con una baja aportación de álcalis, éstos se incorporan preferentemente en el aluminato calcico. Entre los silicatos 41

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Further phase-equilibrium studies involving the potash compounds of portland cement

Cited by 10 publications

References 5 publications

Effect of SO3 on the alkali compounds of portland cement clinker

Effect of SO3 on the alkali compounds of portland cement clinker

Some recent advances in our understanding of the chemistry of portland cement

Influencias ejercidas por los álcalis sobre las propiedades del clinker de cemento y del cemento portland

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