Gypsum is one of the most important minerals on earth, and its dehydration product, plaster of paris, is mainly used as a building material. Furthermore, there are abundant deposits of gypsum mineral in nature; moreover, recent studies have indicated that Mars also has an abundance of gypsum mineral as well as other mineral calcium …
Two experiments were performed: open and closed. The one step process under open conditions is replaced by a two step dehydration under closed conditions, with a mass loss ratio of 3:1. (right) Measured NMR signal of dry gypsum during slow dehydration. The signal is shown as a function of the relative mass of the sample.
This article focuses on the role of water on the properties of gypsum produced from a β-hemihydrate due to its combined effect on both hydration and dehydration. The …
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 …
The stable isotopes of the structurally-bound water (d 17 O, d 18 O and dD, or d 2 H) -also called gypsum hydration water (GHW)have been used to reconstruct the isotopic composition of paleolake ...
During the hydration process, SO 4 2− can be replaced by HPO 4 2− into gypsum crystals to form a solid solution, which further affects the gypsum performance . In addition, the crystal morphology of CaSO 4 ·2H 2 O is modified by the impurities in phospho-gypsum, and needle-like gypsum crystals have a higher compressive …
Gypsum (CaSO 4 ·2H 2 O) has been an important building material since ancient times and was traditionally used for a wide variety of interior/exterior and structural applications (Fig. 1), including columns, load-bearing walls, arches, vaults, cantilevered staircases, façades, and floors [1], [2], [3].By comparison, todaýs industrially produced …
formation from gypsum to bassanite to anhydrite represents steps of a progressive dehydration process (Chang et al. 1996; Putnis et al. 1990; Ballirano and Melis 2009). Other studies (Prasad et al. 2001, 2005) questioned the direct formation of bassanite from dehydration of gypsum and indicated that it may form by rehydration from c-anhydrite
This paper gives an outline of the process of hydration, dehydration and setting of gypsum of the various admixtures on gypsum. This paper is also concerned with the …
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 in two formations of α- and β-type. Among them β-hemihydrate is mainly used to produce gypsum plasterboard since the hydration product of the α …
The industrial byproduct gypsum is a general term for byproducts discharged from industrial production with calcium sulfate as the main ingredient. Due to the high number of impurities and production volume, the industrial byproduct gypsum is underutilized, leading to serious environmental problems. At present, only …
Building gypsum is tagged by the order of name, bending strength and standard number. For example, the building gypsum of 2.5 MPa bending strength can be tagged as: Building Gypsum 2.5 GB 9776.. The hydration of building gypsum technically requires that water requirements accounts for 18.6% of the weight of semi-hydrate gypsum.
This article addresses the microstructure and related mechanical properties of gypsum produced from β-hemihydrate using information of its hydration process, from …
As explained the heating up of gypsum products results in heating up of water crystals present in the gypsum material. This dehydration of gypsum by heat is called as calcination. The calcination results in a covering over the materials that stop it to undergo combustion and allow the material near them to maintain a lower safer temperature.
We analyzed the stable isotopes (δ 17 O, δ 18 O and δD) of gypsum hydration water (GHW) in a variety of speleothems, as well as condensation and infiltration waters in five caves of the semiarid gypsum karst of Sorbas basin (Almeria, SE Spain). Microclimate parameters (air temperature, relative humidity and effective …
The molecular structure and the identified vibrational characteristic Raman bands can be used to monitor compounds' compositional and phase transformation [16].A series of Raman spectra of the gypsum powder (dihydrate CaSO 4 ·2H 2 O) and gypsum paste prepared are captured to monitor the hydration and dehydration process for two …
Setting of Gypsum Plaster: The hydration process occurring in the paste causes the setting of the plaster and thereby develops its strength. ... H.J.H.Brouwers, Microstructure and mechanical properties of β …
DOI: 10.1016/j.conbuildmat.2023.130361 Corpus ID: 255909899; Influence of calcination temperature on hydration behavior, strength, and weathering resistance of traditional gypsum plaster
The effect of compound retardant powder P on the hydration process, ion concentration in liquid and supersaturation degree, and crystal morphology of dehydrate of FGD building gypsum is investigated.
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 …
1. Introduction1.1. General context. Gypsum plaster is an inorganic binder that is prepared in a two-step process. The first step is dehydration: heated to 100–200 °C, gypsum (CaSO 4 ·2H 2 O) releases water as vapor [1, 2] and, depending on temperature and water vapor partial pressure (p H2O) [3, 4] forms either hemihydrate …
The origin of gypsum, its genesis, varieties and properties are discussed, and the focus is then on the most common binding material produced from it, plaster of Paris (β …
The mineralogical composition, microstructure, and reactivity of traditional gypsum, a multiphase product, is closely connected to its calcination temperature, but …
Flue gas desulfurization (FGD) gypsum is a byproduct of the combustion of coal, used for electricity generation. This material is generated during the process of scrubbing flue gases from power plants to remove sulfur dioxide emissions, which contribute to acid rain and other environmental problems.
Capillary water absorption is an important parameter to evaluate the durability of cement mortars. For testing the capillary water absorption of cement mortars, drying is a necessary and crucial procedure. However, different standards have different requests on drying temperatures for doing the tests. Since the calcium aluminate cement …
The associated effect of sodium chloride and dihydrate gypsum on the mechanical performance of a slag-based geopolymer activated by quicklime was investigated by compressive strength, shrinkage, and square circle anti-cracking tests of mortar with a 0.5 water–binder ratio and a 1:3 binder–sand ratio, as well as paste …
An interesting approach named as "In-situ Loading-Hydration Process" is proposed and demonstrated to develop a new type of compact gypsum product with load-bearing ability, benefited from excellent hardness and bending strength.In detail, bassanite (CaSO 4 ·0.5H 2 O) is press-formed in a mold and in-situ hydrated into gypsum (CaSO …
The initial and final setting time of building gypsum prepared by this process is 4.183 and 6.75 min, and 2 h and 3 d flexural/compressive strengths reach 2.8/6.2 and 3.5/10.6 MPa, respectively ...
The stockpiling of phosphogypsum is a waste of land resources and also causes serious pollution to natural resources such as water and atmosphere. This paper explores the mechanism of efficiently modified phosphogypsum and constructs a model and evaluation system for heavy metal leaching and migration transformation. The modified …
The utilization of gypsum reinforced composites as building materials has garnered considerable attention owing to their exceptional amalgamation of mechanical strength, fire resistance, and versatile applications. This review initiates by introducing gypsum as a pivotal mineral in construction, subsequently exploring the concept of …
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نشانی: شماره 1688، جاده شرقی گاوک، منطقه جدید پودونگ، شانگهای، چین.
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