The calcium aluminate monosulfate hydrates Ca 4 Al 2 O 6 (SO 4)·nH 2 O (where n=8–14) are ternary layered double hydroxides [1] with structures related to brucite, hydrotalcite and hydrocalumite. These materials are of particular interest because of their rich intercalation chemistry and structural diversity [2], [3].The best characterized is the 12-hydrate which occurs …
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Thermodynamic modeling was used to predict the stable hydrate phase assemblages in a ternary CSA-OPC-anhydrite system. On the basis of this modeling, five systems with diverging expected hydrate phases were chosen for experimental examination via QXRD and TGA.The aim of this study was to examine whether and to which extent the predicted …
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Various forms of calcium sulphate hydrate have been reviewed by Hand [1].Depending on the temperature, calcium sulphate exists as anhydrite (CaSO 4), subhydrate ([2]; CaSO 4.xH 2 O, 0
The binder comes as either an alpha hemi-hydrate (a stronger and harder crystalline form) or anhydrous Calcium Sulfate. When water is added the binders will form calcium Sulfate dihydrate – more commonly known as Gypsum. ... BAL DPM can be used on anhydrite screeds up to 87% RH. As a general rule thumb the drying time for a Calcium Sulfate ...
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FOLLOWING my November column in CFJ on subfloor moisture, I received a call from a reader asking for advice on dealing with moisture in calcium sulphate (ie. anhydrite or alpha-hemihydrate) screeds. When it comes to calcium sulphate screeds, the most common question I am asked is about drying times and what to do if a
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Anhydrite and Gypsum are chemically similar, except Gypsum has the addition of water. In fact, the name of Anhydrite is derived from " An " and " Hydra " - meaning "without water" - in …
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Direct precipitation of anhydrite from a solution results in the formation of the calcium sulphate polymorph β-anhydrite (β-CaSO4; insoluble), which is thermodynamically stable (Tang et al ...
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12. How long can a go without water? Cats can survive for 2-3 days without water, but dehydration will begin within 24 hours and become a serious problem. 13. Can I give my water with chicken broth? Adding a small amount of chicken broth or tuna juice to water can help encourage a dehydrated to drink. 14. Does wet food help hydrate ...
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Hydration of anhydrite Hydration is the incorporation of water mole-cule(s) into a mineral, which results in a structural as well as chemical change. This can drastically weaken the stability of a mineral, and make it very susceptible to other forms of chemical weathering. For example, hydration of anhydrite results in the formation of gypsum ...
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Anhydrate and hydrate compounds can display distinct physical properties due to the presence or absence of water molecules. Anhydrate compounds are often more stable and have a higher melting point compared to their hydrate forms. This increased stability is attributed to the absence of water molecules, which can introduce additional molecular ...
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The evidence for and against various possible calcium sulphate hydrates is reviewed. The hydrates that exist are calcium sulphate dihydrate CaSO 4 .2H 2 O, calcium sulphate hemihydrate CaSO 4 .1/2H 2 O, and three anhydrous phases : soluble calcium sulphate anhydrite, insoluble calcium sulphate anhydrite, and a high temperature calcium sulphate anhydrite phase. The α- …
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Our inorganic acids portfolio includes Hydrofluoric acid, Sulfuric acid ultra pure, Hydrazine Hydrate, Fluorosulfonic acid, Monohydrate, Anhydrite, Thionyl chloride, Oleum and Sodium bisulphite. They find application in semi-conductors, lithium batteries, crop protection, agrochemicals, and corrosion inhibitors.
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Rarely, anhydrite can be associated with smoky quartz and calcite on Alpine type veins (Alpine clefts/fissures). Naming and Discovery. Anhydrite was first discovered in 1794 in the Hall salt mine near Innsbruck, Austria, and named then or shortly after by Abraham Gottlob Werner. The depth of the occurrence was critical to the discovery, because ...
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anhydrite, an important rock-forming mineral, anhydrous calcium sulfate (CaSO 4). It differs chemically from gypsum (to which it alters in humid conditions) by having no water of crystallization. Anhydrite occurs most often with salt …
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ChEBI: Calcium sulfate hemihydrate is a calcium salt and a hydrate. General Description. Gypsum is a naturally hydrated calcium sulfate. It can also be easily synthesized in a partially hydrated or anhydrous form. The partially hydrated form is called hemihydrate calcium sulfate, while the anhydrous form is called anhydrite (Jorgensen 1994).
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Whilst there is a range of effective priming and sealing products that can form an effective barrier between anhydrite floor screeds and over-laid cement-based products, they still require the full drying period referred to above to reach the requirement of a 75% RH moisture reading in the anhydrite screed base.
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Influence of rock wettability on THF hydrate saturation and distribution in sandstones. GR Abbasi, A Al-Yaseri, A Isah, A Keshavarz, S Iglauer ... Multiscale Wettability Characterization of Anhydrite-Rich Carbonate Rocks: Insights into Zeta Potential, Flotation, and Contact Angle Measurements. ... The system can't perform the operation now. Try ...
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The load-bearing type gas hydrate and pore-filling type gas hydrate (figure 1) are two common occurrence states considered in rock physics investigations; the former implies that a gas hydrate is a part of the rock skeleton, while the latter implies that a gas hydrate fills in the pore space (Waite et al. 2004; Dong et al. 2018; Ma et al. 2019 ...
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Download scientific diagram | Calculated phase diagram of the thermodynamic stable hydrate assemblages of the system ye'elimite-calcium carbonate-water using a water/solid ratio of 1 at 20°C. C ...
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Hydrate compound: Hydrate compounds are chemical compounds with water of crystallization attached to it. For example, Gypsum (CaSO 4. 2 H 2 O), epsom salt (MgSO 4. 7 H 2 O). Anhydrate compound. Anhydrate compound is a chemical compound with no water of crystallization attached to it. For example, Silica gel.
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The binder comes as either an alpha hemi-hydrate (a stronger and harder crystalline form) or anhydrous calcium sulfate. When water is added the binders will form calcium sulfate dihydrate – more commonly known as gypsum. ... It is important to note that all anhydrite screeds require mechanical preparation prior to the use of any surface ...
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Anhydrite is an evaporite mineral that occurs in extensive layered deposits in sedimentary basins where large volumes of sea water have been evaporated. …
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Anhydrite may occur as a caprock above salt domes. See related terms: caprock, evaporite, gypsum, mineral, salt dome. Photomicrographs of anhydrite. 2. n. [Drilling Fluids] The …
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Three crystalline phases are known in the CaSO 4 –H 2 O system, distinguishable by their degree of hydration: gypsum (CaSO 4 ·2H 2 O), bassanite (CaSO 4 ·0.5H 2 O), and anhydrite (CaSO 4).On Earth, calcium sulfate is mainly encountered as gypsum or anhydrite related with evaporitic environments (e.g. Buick and Dunlop, 1990, Warren, 2006), although …
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Calcium sulfate can be precipitated as dihydrate (DH) or gypsum (CaSO 4 ·2H 2 O) at low temperatures and as hemihydrate (HH) (CaSO 4 ·0.5H 2 O) or anhydrite (AH) (CaSO 4) at elevated temperatures (Li and Demopoulos, 2005).All calcium sulfate hydrates are relatively insoluble and they are formed wherever calcium and sulfate occur together after the …
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Anhydrite exists in different polymorphs (anhydrite I-III) of which anhy- ... hydrate (with exactly 0.5 mole water), the amount of bassanite in the dehydrated samples could be recalculated by using equation (1). 0.5 ( ) ( ) 2 4 2 2 M H O M CaSO mBassanite m m H O H O = + ...
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Different hydrate phase assemblages can be expected to form in dependence of the dry mix composition [6]. ... Thermodynamic modeling presents a powerful tool for the qualitative prediction of the formed hydrate phases in ternary CSA-OPC-anhydrite systems. The modeled stable phase assemblages were already reached after 28d of hydration.
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Vice versa anhydrite can exist metastable below the transition temperature due to low rates of gypsum nucleation under conditions of not too high supersaturation ... of tedious dilatometric and tensiometric measurements of …
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We focused on the efflorescence induced microstructural evolution of ettringite-rich systems prepared with calcium aluminate cement (CAC) and anhydrite. The effects of anhydrite on the visible efflorescence, and the corresponding capillary absorption of CAC-anhydrite mortars were revealed. The composition and microstructure of efflorescence-causing substances were …
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Gypsum and gypsum plaster products can be made from an anhydrite or mixed anhydrite and gypsum starting material, of natural origin or derived chemically as a byproduct, by mixing the powdered anhydrite with part or all (but not more) of the water necessary for complete hydration to gypsum, compressing the mixture into compacted blocks or other bodies, and allowing the …
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