Hydration Of Tricalcium Aluminate Research Articles

Study of C 3A - gypsum - Tl 2CO 3 - H 2O system

Effect of thallous carbonate on the hydration of tricalcium aluminate containing 20% gypsum has been studied using isothermal microcalorimeter. The calorimetric results indicate that the hydration reaction is retarded in the presence of Tl 2CO 3. X-ray diffraction and differential thermal analyses indicate the formation of calcium carboaluminate and CaCO 3. The non-evaporable water content of the samples containing Tl 2CO 3 are found to be lower than those without Tl 2CO 3 for the same intervals of time.

Retardation of Tricalcium Aluminate Hydration by Sulfates

Journal of the American Ceramic SocietyVolume 60, Issue 3-4 p. 174-175 Retardation of Tricalcium Aluminate Hydration by Sulfates JAN SKALNY, JAN SKALNY Martin Marietta Laboratories, Baltimore, Maryland 21227. Member, the American Ceramic Society.Search for more papers by this authorM. E. TADROS, M. E. TADROS Martin Marietta Laboratories, Baltimore, Maryland 21227.Search for more papers by this author JAN SKALNY, JAN SKALNY Martin Marietta Laboratories, Baltimore, Maryland 21227. Member, the American Ceramic Society.Search for more papers by this authorM. E. TADROS, M. E. TADROS Martin Marietta Laboratories, Baltimore, Maryland 21227.Search for more papers by this author First published: March 1977 https://doi.org/10.1111/j.1151-2916.1977.tb15503.xCitations: 66 Supported by the Master Builders Division of Martin Marietta Corporation. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume60, Issue3-4March 1977Pages 174-175 RelatedInformation

The effect of glucose and some glucose oxidation products on the hydration of tricalcium aluminate

The effect of glucose and some glucose oxidation products on tricalcium aluminate hydration has been studied. The results are in agreement with the theory that stabilization of hexagonal C 4AH 13 determines the retardation. It is assumed that the glucose oxidation products are more effective retarders than glucose because they are more stable in alkaline conditions.

Hydration of cement — role of triethanolamine

Following addition of 0.1, 0.25, 0.35, 0.5 and 1.0 per cent triethanolamine, studies have been made of the hydration and hardening characteristics of (a) tricalcium aluminate, (b) tricalcium aluminate + gypsum, (c) tricalcium silicate, (d) dicalcium silicate, and (e) portland cement. Triethanolamine (TEA) accelerated the hydration of 3CaO.Al 2O 3 and 3CaO.Al 2O 3-CaSO 4.2H 2O systems and extended the induction period of the hydration of 3CaO.SiO 2. In portland cement paste TEA decreased the strength at all ages and setting characteristics were drastically altered, especially at higher TEA contents. Evidence was obtained also of the formation of a complex of TEA with the hydrating silicate phase.

The effect of lignosulphonate fractions on the hydration of tricalcium aluminate

Two commercial calcium lignosulphonates have been separated into various fractions by ion exchange and dialysis. The effect of these fractions on the hydration of C 3A has been studied and the nature of the active fraction elucidated. It is concluded that aldonic acids are responsible for the greater part of the retardation of C 3A.

Etude de la formation de l'hydrocarboaluminate de calcium

Calcium hydrocarboaluminate (H.C.A.) is produced during hydration of tricalcium aluminate in presence of calcium carbonate. H.C.A. has been prepared in two different ways : 1. - from tricalcium aluminate and calcium carbonate 2. - from C 3AH 6 and calcium carbonate. Hydrocarboaluminates have been studied by X Ray diffractometry, IR absorption spectrophotometry and scanning microscope observations. The relative reactivity of the different faces of a calcite single crystal has been studied.

Etude par thermoluminescence de l'hydration de l'aliminate tricalcique

Thermoluminescence shows that the hydration of tricalcium aluminate is deeply influenced by structural defects of the solid. Hydration reaction excites centers of the solid detected by thermoluminescence; this energy storage is related to trapped electrons. Hydration of tricalcium aluminate in the presence of gypsum is not influenced by traps but thermoluminescence allows to corroborate the well-known mechanism of this reaction.

Action of triethanolamine on the hydration of tricalcium aluminate

Hydration characteristics of tricalcium aluminate and tricalcium aluminate + gypsum were studied following addition of 0.5, 1.0, 5.0 or 10.0% triethanolamine (TEA) at a solution/C 3A ratio of 1.0 after hydration periods of 1 to 60 min. TEA accelerated the hydration of C 3A to the hexagonal aluminate hydrate and its conversion to the cubic aluminate hydrate. The rate of hydration increased with increased amounts of TEA, which also accelerated the formation of ettringite in the C 3A-gypsum-H 2O system.

Morphology and microstructure of hydrating portland cement and its constituents I. Changes in hydration of tricalcium aluminate alone and in the presence of triethanolamine or calcium lignosulphonate

Morphological changes which occur during the hydration of C 3A ∗ paste were observed by electron microscopy from the age of 5 minutes to 3 months. X-ray analyses were used to identify phases. The effects of the admixtures, triethanolamine and calcium lignosulphonate, were investigated with and without gypsum. The dosage of admixture was 0.5%; the water to C 3A ratio was 1.0. The results showed clearly the morphological changes that took place as hydration proceeded, and showed the specific influences of each of the two admixtures.

Effect of Organic Compounds on the Interconversions of Calcium Aluminate Hydrates: Hydration of Tricalcium Aluminate

The paste hydration of tricalcium aluminate (C3A) in the presence of organic compounds was investigated at several temperatures up to 75°C. The results confirm earlier hypotheses that the hexagonal calcium aluminate hydrates (principally C4AH13) which are first formed create a protective barrier around the remaining C3A and severely restrict further hydration. Above 30°C, conversion to C3AH6 breaks down this barrier and causes rapid hydration of C3A. Organic compounds retard the hydration of C3A by inhibiting the conversion reaction. Experiments with synthetic C4AH13 showed that organic molecules can form interlayer compounds, and it is considered that random sorption into the C3AH13 structure restricts the transformation to C3AH6. Other aspects of C3A hydration and of the reactivity of C4AH13 are also discussed.

Influence of amorphous silica on the hydration of tricalcium aluminate

AbstractAmorphous silica influences tricalcium aluminate (C3A) hydration both in pastes and in suspensions.Two heat peaks are found by isothermal calorimetry during the paste hydration of C3A. The addition of amorphous silica causes the second heat peak to shift towards shorter reaction times and become more pronounced.In suspensions, the change in ion concentration in the water phase is not influenced by the presence of amorphous silica except that the change in concentration occurs more quickly. Quantitative X‐ray analysis shows that more 3CaO.Al2O3.6H2O is present in suspensions containing amorphous silica than in silica‐free suspensions at equal hydration times.

Influence of amorphous Al(OH)3 on the hydration of tricalcium aluminate

AbstractThe influence of amorphous Al(OH)3 on the hydration of tricalcium aluminate was investigated in pastes and in suspensions. In suspensions it was found that amorphous Al(OH)3 started to dissolve almost immediately, and a stage was passed in which most of the anions present in the aqueous phase were polymeric aluminate units. Paste hydration results could be understood by assuming that highly soluble amorphous Al(OH)3 dissolved and, by so doing, adjusted the concentrations in the aqueous phase so as to cause precipitation of some less soluble form of Al(OH)3, thereby retarding hydration.

Discussion: Hydration of tricalcium aluminate with lignosulphonate additives

Discussion: Hydration of tricalcium aluminate with lignosulphonate additives

Hydration of tricalcium aluminate with lignosulphonate additives

Summary Lignosulphonates modify the hydration of tricalcium aluminate: acicular crystals form instead of the usual hexagonal plates, and by X-ray diffraction, DTA* and optical data it has been shown that these can represent more than one hydration product. The differences in reaction products are attributed to small changes in hydration conditions. In pastes of tricalcium aluminate, C2AH8† and C4AH13 crystallize with a new crystal habit, rather than forming a new hydrate. Current theories explaining the effect of lignosulphonates on the mechanical strengths of concrete are discussed.