Hydration heat: The hydration heat flow rate and total heat of hydration of the gypsum pastes were recorded by a standard isothermal calorimeter (Calmetrix I-Cal 8000). A total of 20 g of powder (pure gypsum, gypsum with silica flour, or gypsum with talc powder) and 12 g of deionized water were mixed manually for 30 s in the …
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The results show the retardant effect of CMC on the hydration process. The retardant effect of CMC is attributed to the presence of carboxylic groups, which …
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Flue gas desulfurization (fgd) is a waste incineration process that employs limestone slurry (CaCO 3) as a scrubber to remove SO 2 from exhaust gases, thereby reducing pollutant emissions. CaCO 3 reacted with SO 2 to form calcium sulphite (CaSO 3), which was then oxidized to form anhydrite (CaSO 4) and gypsum (CaSO 4 ⋅2H 2 O), …
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The dehydration process of gypsum under high pressure. Physics and Chemistry of Minerals, Vol. 39, Issue. 1, p. 65. ... Pressure-induced structural phase transition and dehydration for gypsum investigated by Raman spectroscopy and electrical conductivity. Chemical Physics Letters, Vol. 706, Issue., p. 151.
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Hydration process and kinetics of PG-slag pastes with and without NaAlO 2. ... The peak at 120∼160 °C (peak 2) mainly corresponds to the dehydration of gypsum and can reflect the gypsum consumption during hydration in PG-slag binder system [33, 53]. Download: Download high-res image (641KB)
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The effects of pressure on the dehydration of gypsum materials were investigated up to 633 K and 25 GPa by using Raman spectroscopy and synchrotron X-ray diffraction with an externally heated diamond anvil cell. At 2.5 GPa, gypsum starts to dehydrate around 428 K, by forming bassanite, CaSO4 hemihydrate, which completely …
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Calcium sulfate occurs in nature mainly in form of three different minerals distinguished by their degree of hydration: gypsum (CaSO 4 ), bassanite (CaSO 4 ⋅0.5H 2 O) and anhydrite (CaSO 4 ...
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Mass losses vary between 13.7 and 16.5% and heat of dehydration values between 377 and 420 J g −1 for the dehydration of ground and mixed inhomogeneous gypsum samples. As for the dehydration of CaSO 4 ·2H 2 O, the dehydration of synthetic gypsum proceeds via multi-step reactions. Using a heating rate of 5°C min −1, the very …
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The dehydration process of a synthetic gypsum indicates that it has an interstitial gypsum phase dehydrating in a similar way to the interstitial phase found in the Terra Alba gypsum. For all ...
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particle size of the dihydrate gypsum [12]. During the hydration process, SO4 2 can be replaced by HPO4 2 into gypsum crystals to form a solid solution, which further affects the gypsum performance [13]. In addition, the crystal morphology of CaSO4 2H2O is modified by the impurities in phospho-gypsum, and needle-like gypsum …
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Shreesh Khadilkar reviews the present situation of gypsum, and takes us through a variety of gypsum products, its merits and demerits. Gypsum (CaSO4.2H2O) is used widely in various industries either as gypsum, i.e., the gypsum di-hydrate crystalline variety or as the gypsum hemi hydrates, also known as plaster of Paris (POP) or …
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The production process of gypsum generates environmental efficiency, including lower calcination temperatures in the range of 125-180℃ and lower greenhouse gas emissions [22]. ... Effect of protein peptides with different molecular weights on the setting and hydration process of gypsum. Construction and Building Materials, …
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The third illustrates the hydration energy of hemihydrate as it reacts with water. Diagram 1 - Dehydration. The first process is the formation of hemihydrate or anhydrite from dihydrate. To obtain more information about this step, gypsum crystals were grown from sodium sulphate and calcium chloride via a diffusion process.
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According to the hydration products and micro-morphological analysis in Section 3.5 and Section 3.6, the hydration reaction process of gypsum-based …
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Waste gypsum has low hydration activity, especially fluorogypsum with anhydrite as the main composition. Its hydration reaction is slow at early age and requires a long hydration time. The activation of waste gypsum and the hydration reaction process in cement-based materials and the formation mechanism of the microstructure …
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How is Gypsum Formed? Gypsum forms through two primary geological processes: Evaporative Precipitation: This process occurs in environments with high evaporation rates, such as shallow marine environments, saline lakes, or near geothermal springs.When a body of water rich in dissolved calcium (Ca²⁺) and sulfate (SO₄²⁻) ions undergoes …
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The application of α-hemihydrate gypsum (α-HH) is limited by several factors, such as a rapid hydration rate, short setting time, poor water resistance, and high cost. Especially because of the high production cost, although α-HH has excellent mechanical strength, it is rarely used in the field of building materials. In this study, …
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The Simulation and Analysis of Dehydration Process of FGD Gypsum Grouted Wall: ZENG Ziyue 1,2, YANG Jiansen 1, WEI Yongqi 2: 1 School of Civil and Hydraulic Engineering, Ningxia University, Yinchuan 750021, Ningxia, China 2 School of Material Science and Engineering, Tongji University, Shanghai 201804, China
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In this work, the dehydration pathways of gypsum and the rehydration mechanism of soluble anhydrite were mainly investigated by thermodynamic modeling and MC simulations. The dehydration pathways of gypsum are largely determined by …
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Aiming to enhance the comprehensive utilization of steel slag (SS), a solid waste-based binder consisting of SS, granulated blast furnace slag (BFS), and desulfurization gypsum (DG) was designed and prepared. This study investigated the reaction kinetics, phase assemblages, and microstructures of the prepared solid waste …
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In the process of cement hydration, the dissolved SO 4 2− of PG reacts with hydrated calcium aluminates to generate polysulfide-like ettringites, which are adsorbed on the surface of PC clinker particles, which can slow the process of cement hydration and thus achieve retardation. Low-strength gypsum blocks were prepared …
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1. Introduction. Flue gas desulfurization (FGD) gypsum is an industrial by-products, which primarily consists of dihydrate gypsum (CaSO 4 ⋅2H 2 O),and the treatment of 1 t of SO 2 in coal flue gas by limestone-gypsum wet desulfurization technology will produce about 2.7 t of FGD gypsum, and China emitted nearly 100 …
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Gypsum rock is converted into gypsum plaster by driving off some of the chemically combined water. Heating gypsum at 154°C with results in a hemi-hydrate (CaSO4. 1⁄2H2O) – with three quarters of the water removed. Gypsum hemi-hydrate is …
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Established in 2010, GLOBAL GYPSUM BOARD CO LLC is the first to operate gypsum board and value added plaster plants in the Sultanate of Oman, with production capacities of 15 Million sqm for 12.5mm thicknesss plasterboards, 60,000 MT/year of value added plaster and 150,000 MT/year stucco production capacity.
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Role of Gypsum in Cement The main purpose of adding gypsum in the cement is to slow down the hydration process of cement once it is mixed with water. The process involved in hydration of cement is that, when …
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Therefore, the dehydration process of gypsum and the rehydration of hemihydrate were investigated. This dehydration process is technically performed in three different ways. Heating up, i.e., in a ...
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The hydration process of gypsum rock was accelerated due to the weak sedimentary surface and the swelling and cracking of filling minerals, but the macroscopic damage of the sample was also accelerated. In the process of water absorption, anhydrite crystal and water molecules were broken and recombined, filling the micro-pores formed …
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Mirwald performed a study of CaSO 4 ·H 2 O system by differential pressure analysis (DPA), following the dehydration process up to 623 K and 3.5 GPa and …
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The first describes the process of water leaving the structure of gypsum to form hemihydrate or anhydrite. The second depicts the temperature-dependent …
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Gypsum in PG is an important raw material in building materials, hence, the recycling of PG into building materials is a more prospective direction regarding resource saving and cutting down CO 2 emission. ... and the hydration process, quantity and quality of the hydration products, slag hydration degree, microstructure and morphology, etc ...
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