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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 …
Phospho-gypsum is an industrial solid waste discharged from the phosphate production process. The waste includes complex impurities such as phosphoric acid and its salts, fluoride, and organics. Usually, …
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) Download: Download full-size image; Fig. 7. TG-DTG curves of PG-slag pastes after 3 d- and 28 d-hydration.
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
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 …
Sodium tripolyphosphate can inhibit the gypsum dissolving rate, delay the early hydration reaction, and infusibility calcium phosphate salt will adsorb and cover on the surface of C3A and gypsum ...
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 …
This article addresses the microstructure and related mechanical properties of gypsum produced from β-hemihydrate using information of its hydration process, from …
1. Introduction. Precisely controlling the rheological properties of fresh Portland cement (PC) concrete is of utmost importance to produce high quality and durable infrastructure [1], [2], [3].The rheological properties of PC concrete are time-dependent due to the continuous hydration which leads to setting behavior [3], [4], [5].In engineering …
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 …
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
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.
Consequently, the hydration process of building gypsum becomes greatly extended and is slowed down significantly. View. Show abstract. Effects of the addition of glass fibres, mica and vermiculite ...
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.
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 …
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 number of inquiries to the Gypsum Association about water-damaged gypsum panels always increases during the winter, early spring, after hurricane season or after any other significant water exposure event. Answers to many of these questions are found in an Association document revised in 2019, GA-231 Assessing Water Damage to …
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 hydration of high-temperature dehydration samples was an extremely complex physical and chemical process. Hydration had a significant strengthening effect …
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 …
The production of flue gas desulfurization gypsum poses a serious threat to the environment. Thus, utilizing gypsum-based self-leveling mortar (GSLM) stands out as a promising and effective approach to address the issue. β-hemihydrate gypsum, cement, polycarboxylate superplasticizer, hydroxypropyl methyl cellulose ether (HPMC), retarder, …
Gypsum modification is an effective strategy to improve the water resistance of magnesium oxychloride cement paste (MOCP), but its early-ages performance evolution has not received much attention. The exothermic characteristics and hydration kinetic parameters of MOCP with different contents and types of gypsum are investigated. The …
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 …
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 …
Influence of one macromolecule-type retarder bone glue on the setting time,strength,ion concentration in liquid phase and supersaturation degree,crystal morphology of dehydrate and microstructure of hardened paste of building gypsum is investigated.Furthermore,internal cause of strength loss of building gypsum with …
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 …
The present paper addresses the gypsum hydration study with the theoretical and experimental method. The microstructure of gypsum changes during the hydration …
According to the hydration products and micro-morphological analysis in Section 3.5 and Section 3.6, the hydration reaction process of gypsum-based composite cementitious materials was elucidated, as …
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
Figure 1: a: Gypsum crystals produced from sodium sulphate and calcium chloride; b: Natural gypsum cut along black lines; c: Gypsum crystals from a, with directions from Figure 2 marked with arrows, on side from Figure 3 marked with yellow, on cleavage plane with red; d: Crystal from a) along c-axis marked in black.