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Case studyStudy on physical and chemical characteristics of β
2022年12月1日· Natural gypsum is taken from gypsum mines presenting as blockshaped Therefore, crushing, prehomogenization, and grinding were required before calcination for preparing hemihydrate Because of the impurities in phosphogypsum, pretreatmentconsumption of hemihydrate and formation of dihydrate 1 Ultrasonic results indicate gypsum hydration reaction consists of two stages: the dissolution of hemihydrate in theGypsum hydration: a theoretical and experimental study
Hemihydrate an overview | ScienceDirect Topics
Because of the highmoisture content of synthetic gypsum, autoclaving technologies are most common for obtaining αhemihydrate (highstrength gypsum) The water remains2016年1月1日· Gypsum remains one of the most common mineral binders Gypsumbased products are known as being environmentally friendly materials The main component ofSustainability of gypsum products as a construction material
Estimation of gypsum hemihydrate content in recycled gypsums
Therefore, the gypsum board waste has to be crushed, fractured and separated before the gypsum powder (gypsum dihydrate) is heated to be transformed into gypsum2011年11月1日· Gypsum looses water when burnt at different temperatures as follows: βhemihydrate (CaSO 4 ·05H 2 O) is formed when gypsum is heated at temperaturesGypsum hemihydrate–cement blends to improve
Influence of dehydration method on the morphology
2018年1月1日· Gypsum raw material dehydration in dry air environment using microwaves does not significantly influence the morphology of hemihydrate gypsum, hemihydrate phosphogypsum or processed2020年12月10日· βhemihydrate gypsum Dihydrate gypsum Compressive strength Phase conversion 1 Introduction In contrast to Portland cement (PC), calciumInsight into the influences of βhemihydrate and
Calcium sulphate hemihydrate hydration leading to
2007年3月1日· Calcium sulphate hemihydrate hydration leading to gypsum crystallization ScienceDirect Progress in Crystal Growth and Characterization of Materials Volume2022年12月8日· Gypsum crystal partly dehydrated, cleaved along cleavage plane, with observable dihydrate, αhemihydrate and βhemihydrate Yellow circle = still dihydrate, blue circle = alphaFormation of αHemihydrate Inside of a Gypsum
Calcium sulphate hemihydrate hydration leading to gypsum
2007年3月1日· The hydration of calcium sulphate hemihydrate (CaSO 4 ·05H 2 O) leading to the crystallization of gypsum (calcium sulphate dihydrate – CaSO 4 ·2H 2 O) has been the subject of several investigations over a long period and a vast amount of data is widely distributed throughout in the literature In this review article an overall picture of2016年1月1日· The dehydration process consists of two stages: first, one with a hemihydrate formation (254) CaSO 4 · 2 H 2 O → CaSO 4 · 05 H 2 O + 15 H 2 O and, second, one with an anhydrite formation (255) CaSO 4 · 05 H 2 O → CaSO 4 + 05 H 2 O All the reactions are endothermic (energyabsorbing) Depending on the equipmentSustainability of gypsum products as a construction material
Gypsum in construction: origin and properties | SpringerLink
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 (βhemihydrate), known in France as ‘plâtre de Paris’, in the USA as ‘calcined gypsum’, and in Germany as ‘Stuckgips’ Details are given of the properties of gypsum2023年1月31日· Preparation of αhemihydrate gypsum crystal is an approach for utilization of phosphogypsum (PG), but the soluble phosphorus impurities in PG have a crucial influence on the performance of αhemihydrate gypsum In this article, different forms of soluble phosphorus (H3PO4, H2PO4− and HPO42−) on the setting time andEffect of Soluble Phosphorus on the Mechanical Properties of α
Phosphorus and Phosphates | SpringerLink
2017年8月2日· Liberation of the phosphate is accomplished by crushing to 9 mm followed by grinding to 07 mm Following grinding, Hemihydrate recrystallized gypsum that is relatively pure, 02–04% total P 2 O 5 This makes it2022年12月8日· Gypsum (calcium sulfate dihydrate) is one of the most used inorganic binding materials in the world During calcination, calcium sulfate subhydrates are formed and, for technical reasons, are mixed with water to form dihydrate again Therefore, the dehydration process of gypsum and the rehydration of hemihydrate were investigatedFormation of αHemihydrate Inside of a Gypsum Crystal during
Influence of dehydration method on the morphology of hemihydrate gypsum
2018年1月1日· The morphology and the crystal size of PG crystals depend on the presence of watersoluble and waterinsoluble impurities in phosphates (Becker 1989) In addition, dihydrate and hemihydrate2022年8月1日· This paper investigated a lowenergyconsumption preparation from PG of an environmentally friendly building material PG was converted to α hemihydrate gypsum (αHH) using the nonautoclaved methodMechanical strength, water resistance and drying shrinkage of
Physical and Mechanical Properties of GypsumLike Rock
2020年2月10日· In the process of tunnel construction, gypsum rock is often encountered, and the volume of gypsum rock expands when encountering water, which is easy to cause the occurrence of rock fall, collapse, and other disasters, bringing serious challenges to the safe construction of the tunnel Therefore, in this paper, four groups of samples under2020年9月30日· The production of gypsum can be ment ioned in stages (excavation, crushing (~ 25 mm diamete r), grinding, calcination CaSO 41 /2 H 2 O= Plaster of Paris or (hemihydrate gypsum) At higherThe Effect of Particle Size Distribution on some Properties of Gypsum
Estimation of gypsum hemihydrate content in recycled gypsums
2014年10月24日· In order to utilize reclaimed gypsums (gypsum board waste) derived from waste plasterboards as geomaterials, thermal behaviors of the reclaimed gypsums and reagent gypsum are investigated in this paper Furthermore, simple density measuring method of judging quality of the reclaimed gypsums is examined to determine theGypsum 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 sulfate phases (βCaSODehydration Pathways of Gypsum and the Rehydration
Evidence of a new phase in gypsum–anhydrite transformations
Gypsum CaSO 4 52H 2O Gypsum 231–233 51 o80 1C Monoclinic I2/a C2/c53 0625subhydrate CaSO 4 510625H 2O 263 65–180 1C Trigonal C2 4,5 Bassanite CaSO 4 05H 2O aHemihydrate 2757 51 95–235 1C Monoclinic I24–8 bHemihydrate 263732 I26–8 P3 1 9 gAnhydrite ‘gCaSO 4’ Anhydrite III46 (soluble anhydrite) 25851 160–380 1C2023年3月16日· This paper aims to study the effects of gypsum type and dosage on the rheological and strength properties of steelslag cemented paste backfill (SSBCPB) using fluorogypsum (FG), phosphogypsum (PG), and desulfurization gypsum (DG) Experimental results indicate that the yield stress and the viscosity of fresh SSBCPB are the smallestMinerals | Free FullText | Rheological and Strength Properties of
Reinforced dental plaster with low setting expansion and
2020年5月27日· Three types of gypsum products were commonly used in dentistry to fabricate dental casts and dies which includes dental plaster, dental stone, and improved stone Improved stone could be used as final casts and dies for building of final indirect dental restorations Even though the cost of dental plaster is very low, their inherent2007年3月1日· The hydration of calcium sulphate hemihydrate (CaSO 4 ·05H 2 O) leading to the crystallization of gypsum (calcium sulphate dihydrate – CaSO 4 ·2H 2 O) has been the subject of several investigations over a long period and a vast amount of data is widely distributed throughout in the literature In this review article an overall picture of theCalcium sulphate hemihydrate hydration leading to gypsum
Materials | Free FullText | Experimental Study and Mechanism
2022年5月9日· Fluegas desulphurization (FGD) gypsum is a highly prevalent industrial byproduct worldwide, which can be an excellent alternative to natural gypsum due to its high content of CaSO4·2H2O The preparation of αcalcium sulfate hemihydrate is a highvalue pathway for the efficient use of FGD gypsum Here, a dynamic method, or an improvedIt has been reported that gypsum plasterboard wastes can be recycled in a sequential process by crushing, separating, and burning to transform the dihydrate into the hemihydrate phase According to their report, it is useful as geomaterial or ground improvement material due to its effectiveness in many engineering and economicThe Mechanism of the First HydrationDehydration Cycle of Pure
Preparation of specific gypsum with advanced hardness and
2015年1月1日· An interesting approach named as “Insitu LoadingHydration Process” is proposed and demonstrated to develop a new type of compact gypsum product with loadbearing ability, benefited from excellent hardness and bending strengthIn detail, bassanite (CaSO 4 ·05H 2 O) is pressformed in a mold and insitu hydrated into gypsum (CaSOPROBLEM TO BE SOLVED: To provide a quantification method of α type hemihydrate gypsum and β type hemihydrate gypsum in cement for accurately and quickly quantifying the amounts of the α type hemihydrate gypsum and the amounts of the β type hemihydrate gypsum regardless of the scale of the content of the α type hemihydrateQUANTIFICATION METHOD FOR α TYPE HEMIHYDRATE GYPSUM