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the difference between dihydrate gypsum and hemihydrate gypsum in Oman

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the difference between dihydrate gypsum and hemihydrate gypsum in Oman

Difference Between Gypsum and Anhydrite

Difference Between Gypsum and Anhydrite Gypsum vs Anhydrite Gypsum, also called hydrated calcium sulphate (CaSO4 · 2H2O) and anhydrite (CaSO4), also called hydrous calcium sulphate are the major minerals in the sedimentary rocks of rock gypsum and rock anhydrite respectively. Gypsum consists of calcium, sulfur and …

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α or β?-hemihydrates transformed from dihydrate calcium sulfate …

1. Introduction. Calcium sulfate is the subject of much research due to its wide scope and large-scale of industrial applications [1], [2], [3].It occurs in nature mainly in form of three different phases distinguished by the content of crystal water: dihydrate (DH, CaSO 4 ·2H 2 O), hemihydrate (HH, CaSO 4 ·0.5H 2 O), and anhydrite (AH, CaSO …

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Investigation of hydration mechanisms of alpha and beta hemihydrate …

Gypsum-based binders are generally based on the reaction between calcium sulfate hemihydrate (HH) and water to form calcium sulfate dihydrate (DH). Often gypsum can be used as a raw material to obtain hemihydrate. In this study, the obtained alpha hemihydrate consists of large crystals that have more or less lattice defects according …

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Structures of a) gypsum, b) hemihydrate, and c) …

The most prevalent sulfate mineral in the surrounding natural environment is calcium sulfate, which can be found as calcium sulfate dihydrate or gypsum (CaSO 4 ⋅2H 2 O), hemihydrate (CaSO 4 ⋅ ...

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Effects of different carboxyl additives on the growth habits of

2.2. Preparation of hemihydrate gypsum whiskers. In this experiment, hemihydrate gypsum whiskers were prepared with the autoclave method. A YZF-2A type autoclave (Wuxi Xidong Building Material Equipment Factory, the diameter of the kettle body: 160 mm, the volume of the kettle body: 8.5L) was utilised for the preparation, and …

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Gypsum vs. Anhydrite: What's the Difference?

Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, whereas anhydrite is its anhydrous form, lacking water in its structure. Key Differences Gypsum, a widely used mineral, is known for its softness and is composed of calcium sulfate dihydrate.

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Gypsum Board Vs. Drywall: Understanding the Differences

Understanding the differences between gypsum board and drywall is critical for making sound decisions in construction and restoration projects. Gypcore, the …

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The α- and β-Forms of Calcium Sulphate Hemihydrate

Kelley, Southard and Anderson1 have shown that the thermodynamic properties of calcium sulphate hemihydrate depend on whether the hemihydrate is produced from gypsum calcined in a steam-saturated ...

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Gypsum hydration: a theoretical and experimental study

Calcium sulphate dihydrate (CaSO4·2H2O or gypsum) is used widely as building material because of its excellent fire resistance, aesthetics, and low price. Hemihydrate occurs …

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Effect of sodium fluoride on the crystal regulation of high …

As one of the extensively used inorganic cementitious material, hemihydrate gypsum (HH, CaSO 4 ·0.5H 2 O) has two forms, namely β-HH and α-HH. β phase is a dehydration product of calcium sulfate dihydrate (DH, CaSO 4 ·2H 2 O) in dry air at 105–180 °C and has a longer history of application, whilst α-HH can be produced …

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Reuse of phosphogypsum as hemihydrate gypsum: The

The results indicates that H3PO4 accelerated hemihydrate gypsum dissolution and dihydrate gypsum precipitation, which included route I, involving Ca²⁺ and SO4²⁻, and route II, involving ...

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Influencing the Morphology of Gypsum | SpringerLink

Gypsum is a well-known mineral that is obtained from natural resources or from technological processes. Gypsum (calcium sulfate dihydrate) is burned to calcium …

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Insight into the influences of β-hemihydrate and dihydrate …

It is still uncertain whether β-hemihydrate and dihydrate gypsum influence the properties, especially the phase conversion, of white calcium aluminate cement …

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Anhydrite and gypsum

Anhydrite (CaSO 4) and gypsum (CaSO 4 ·2H 2 O) are the two most abundant minerals of ancient marine evaporite deposits and are also common in non-marine evaporite deposits. Sedimentary gypsum forms by direct precipitation out of evaporating seawater under arid climatic conditions in hydrologically restricted marine …

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Influence of modified calcium sulfate hemihydrate whisker …

Calcium sulfate whiskers (CSWs) are columnar crystalline synthetic microfibers with excellent heat resistance, high elastic modulus, and good processability [20], [21].CSWs not only offer the advantages of a fiber and inorganic filler, but also have the same chemical composition as that of the gypsum matrix, which results in good …

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Influence of calcination and GGBS addition in preparing β-hemihydrate …

This is because the main composition of PG is dihydrate gypsum (CaSO 4 ⋅2H 2 O), ... Hemihydrate gypsum is found in two forms: α-hemihydrate gypsum (α-CaSO 4 ⋅0.5H 2 O) and β-hemihydrate gypsum (β-CaSO 4 ⋅0.5H ... while the difference in mass loss between calcined PG at 220 °C and 180 °C was negligible, with a variation …

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Gypsum hydration: A theoretical and experimental study

According to the data obtained for β-hemihydrate binder with SP and lime has low deformations started with low shrinkage in the initial time up to 0.04 mm/m with subsequent expansion up to 0.17 ...

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12: Gypsum materials

Chapter 12 Gypsum materials DEFINITION. Gypsum (calcium sulphate dihydrate) is a naturally occurring mineral used in dentistry to fabricate models (Figure 12.1a), casts and dies (Figure …

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Crystallization Kinetics of -Hemihydrate Gypsum …

According to the difference in hydration, calcium sulfate can be divided into dihydrate gypsum (CaSO4 2H2O), hemihydrate gypsum (CaSO4 0.5H2O), and anhydrite (CaSO4) [1–3]. ... the solubility difference between DH and -HH, thus accelerating the transformation (crystallinity). However, the potential relationship between DH to -HH …

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12: Gypsum materials

Gypsum (calcium sulphate dihydrate) is a naturally occurring mineral used in dentistry to fabricate models (Figure 12.1a), casts and dies (Figure 12.1b). Calcination is the process of heating the gypsum to …

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Structural characteristic and formation mechanism of hemihydrate …

There are two significant differences between the gypsum structure and the prepared HH-CSW structure: one difference is that there are two H 2 O channels in the gypsum structure ... cost-effective transformation of FGD gypsum to calcium sulfate hemihydrate whiskers. Particuology, 54 (2021), pp. 173-180.

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Effects of glutaric acid, tricarballylic acid and citric acid on …

GA has two carboxyl groups, while TA and CA have three carboxyl groups. The difference between TA and CA is that CA has one more hydroxyl group at the middle carbon atom than TA. α-HH gypsum has a hexagonal prismatic crystal form (Fig. 1 c), and in the absence of crystal modifiers, the crystal grows fastest along the c-axis [32].

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Setting time of construction gypsum, dental plaster, and …

Introduction. Gypsum is one of the natural minerals that contain calcium, hydrogen, water, and sulfur, known as calcium sulfate dihydrate (CaSO 4.2H 2 O). 1 Gypsum products are available in the form of a fine white powder which has undergone calcination or heating at a temperature of 110‒130°C in the open air. This process …

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Microstructure and mechanical properties of β-hemihydrate …

1. Introduction. Gypsum (CaSO 4 ·2H 2 O, also known as dihydrate) plaster is one of the earliest building materials elaborated by mankind, and gypsum plasterboard is used widely as indoor building material because of its easy fabrication feature, environmental friendliness, fire resistance, aesthetics, low price, etc. The global …

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Why is the hemihydrate gypsum (CaSO4 0.5H2O) …

Why is the hemihydrate gypsum (CaSO4 0.5H2O) transformed from anhydrite (CaSO4) different from that transformed from dihydrate (CaSO4 2H2O)? At temperatures above 200 degree C, the dihydrate phase ...

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What Is the Difference between Gypsum and Plaster of Paris?

The primary difference between gypsum and plaster of Paris lies in their chemical composition and their uses. Gypsum is a naturally occurring mineral composed primarily of calcium sulfate dihydrate (CaSO₄·2H₂O). It is a stable, solid material that is commonly used in construction and agriculture.

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ALPHA GYPSUM POWDER VS BETA GYPSUM …

2. With the continuous progress of hydration, β-type hemihydrate gypsum produces more and more colloidal particles of dihydrate gypsum. These particles are smaller than the original, have a large specific surface …

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Gypsum | Properties, Formation, Uses and …

Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate (CaSO4·2H2O). It is commonly found in sedimentary rock formations and is often associated with other minerals such as …

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Recycling of waste gypsum from αlpha-hemihydrate …

Schematic diagrams of recycling between dihydrate and hemihydrate gypsum: (a) theoretical principles of recycling; (b) practical problems of recycling. ... (4 0 0) crystal planes also decreased with the decrease of the pH value of the reaction medium, but the difference between the pH values of 3.6 and 2.3 was not obvious. This …

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Materials | Free Full-Text | Experimental Study and …

Flue-gas desulphurization (FGD) gypsum is a highly prevalent industrial by-product worldwide, which can be an excellent alternative to natural gypsum due to its high content of CaSO4·2H2O. The preparation of α-calcium sulfate hemihydrate is a high-value pathway for the efficient use of FGD gypsum. Here, a dynamic method, or an improved …

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