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Production of Calcined Gypsum or Gypsum Plaster
Published in Manjit Singh, Gypsum & Gypsum Products, 2023
Gypsum is a naturally occurring crystal of calcium sulphate (CaSO4.2H2O). It can be quarried in different parts of the world in slightly different forms, but in this country the most commonly known form is alabaster. Plaster is made from gypsum by grinding it to powder and then gently heating it to drive off some, or all, of the water of crystallization.
Erosion by Water: Amendment Techniques
Published in Brian D. Fath, Sven E. Jørgensen, Megan Cole, Managing Soils and Terrestrial Systems, 2020
Overall, gypsum addition is effective in preventing clay dispersion, stabilizing soil aggregates and structure, reducing surface seal formation, increasing water infiltration, and reducing soil erosion by water.[3,10,11] It is well documented that gypsum can reduce soil erosion by (1) promoting water infiltration and reducing erosive power of runoff, (2) increasing soil resistance to erosion by increasing aggregate size and stability, and (3) enhancing flocculation and deposition of clay particles suspended in runoff.[13] Based on field experiment conducted in many countries, surface application of 3–10 Mg/ha of gypsum would considerably reduce surface runoff and soil erosion in most soils for several months after application or until mixed into soils by tillage.[14] If it is applied as a source of fertilizer calcium and sulfur, 0.1–0.5 Mg/ha is often adequate.
Materials
Published in Roy Chudley, Roger Greeno, Karl Kovac, Chudley and Greeno’s Building Construction Handbook, 2020
Roy Chudley, Roger Greeno, Karl Kovac
Gypsum is a crystalline combination of calcium sulphate and water. The raw material is crushed, screened and heated to dehydrate the gypsum and this process, together with various additives, defines its type as set out in BS EN 13279–1: Gypsum Binders and Gypsum Plasters.
Study of the Influence of Limewash on the Conservation of Islamic Plasterworks through Weathering Tests
Published in International Journal of Architectural Heritage, 2021
F.J. Alejandre, F.J. Blasco-López, V. Flores-Alés, R. Villegas, M.T. Freire
Gypsum is a very versatile material whose main properties — ability to reproduce forms by casting or carving, fast setting, whiteness and low density — make it suitable for several applications, such as statuary or building construction, both in walls and ceilings’ smooth surface coatings, as base for frescoes or in more elaborated decorative programmes. However, its drawback is its slight solubility when in contact with water (recrystallised calcium sulphate dihydrate — CaSO4 · 2H2O — solubility is 2,3 g/l at 20°C (Innorta, Rabbi, and Tomadin 1931–1936)). In addition, when humidity increases in its capillary network, it loses mechanical properties, even at low moisture contents (Coquard and Boistelle 1994; Reynaud et al. 2006; Wirsching 1985). It is consensual, however, that this effect is reversible, unless gypsum remains wet during long periods of time; in that case, it occurs the dissolution of part of the crystal structure, inducing structural changes that affect negatively the mechanical performance.
Vipulanandan failure models to predict the tensile strength, compressive modulus, fracture toughness and ultimate shear strength of calcium rocks
Published in International Journal of Geotechnical Engineering, 2021
Gypsum rock is a soft sulphate mineral composed of calcium sulphate dehydrate, with the chemical formula CaSO4 2H2O and its cover more than 20% of the earth crust, seven million square kilometres of gypsum rock covering by highly soluble gypsum-bearing rocks (Dreybrodt, Romanov, and Gabrovsek 2002). Gypsum is a soluble mineral that deposits from natural water because of evaporation. Gypsum can transform to anhydrite by losing its hydration water or anhydrite can transform to gypsum by the addition of water (Salih 2013). Several studies on gypsum rock showed that it experiences the various problems due to change in the physical and mechanical properties of gypsum rock due to the dissolution of gypsum, so there is a need for prediction the mechanical properties of such a problematic type of the rock such as gypsum rock (Klimchouk 1996; Johnson 2005; Salih and Mohammed 2017).
Characteristics of the marble processing powder waste at Shaq El-Thoaban industrial area, Egypt, and its suitability for cement manufacture
Published in HBRC Journal, 2018
Hamdy A. El-Sayed, A.B. Farag, A.M. Kandeel, Ahmed A. Younes, Mai M. Yousef
It is worth mentioning that, this result is also, in favor of the beneficial use of the marble dust waste in Portland cement industry. Natural gypsum is used in the cement industry to control the setting of the produced cement. The gypsum content to be ground with the clinker reaches about 7% of the clinker amount. Therefore, the marble dust waste could replace, at least, a portion of the used gypsum in Portland cement industry and attaining acceptable setting times. This conclusion could be confirmed by the work of Negro et al. [14] who indicated that the partial substitution of limestone for gypsum may be possible without harmful side effects. They came to the conclusion that, up to 50% replacement of gypsum was possible without adverse effects on the set, shrinkage and compressive strength properties of Portland cement. At these low levels, limestone, also, acts as an active component in the cement hydration reaction. Also, Puchyr and Taborsky [15] have shown that, cement ground with 2–5% limestone has no decrease in physical properties.