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Table 2 Ion concentrations and maximum ionic strength for three Swiss tunnels in Gypsum Keuper. Full size table. ... Anhydrite appears in natural rocks either in the form of particles or of layers of different ... Bock E (1961) On the solubility of anhydrous calcium sulfate and of gypsum in concentrated solutions of sodium chloride at 25 °C ...
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2.3.. Experimental methodAll tests were carried out based on Korean Standards (KS). Molds of dimensions 50. × 50 × 50 mm for compressive strength, 40 × 40 × 160 mm for drying shrinkage, and 80 × 100 × 200 mm for carbonation were prepared.. The samples were cured at 20 ± 2 °C in water after 1-day standard room and kept cured …
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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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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 …
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The addition of 10% anhydrous gypsum showed a considerable improvement in the mechanical strength including flexure and compression. Because preparing MK is costly, of which it consumes high energy during kaolin calcination, it is better to replace it by any suitable waste or by-product material.
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Moreover, compressive strength was higher when anhydrous gypsum, CS, was added to mix proportion in comparison with a mix containing di-hydrate gypsum, CSH 2, which can be attributed to the faster solubility rate of anhydrous gypsum, which promotes quick reaction of tricalcium silicates that facilitates strength enhancement.
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At calcination temperatures above 350℃, type III anhydrous gypsum transforms into type II anhydrous gypsum or natural anhydrite characterized by dense and stable crystalline phase with...
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In this context, a complete characterization of the physical properties of Moroccan natural gypsum materials was carried out. Basic information on the mineralogical, microstructure, thermal, mechanical, …
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Anhydrous gypsum, also called dead-burnt gypsum, can be used as an exterior plaster that lasts over 100 years, and historically it was fairly commonly used in France and Belgium. In North America gypsum is hardly used by natural builders, however it could certainly play a greater role as an interior plaster, either on its own or mixed into ...
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Gypsum (CaSO 4 2H 2 O) and anhydrite (CaSO 4) are the most common sulfate minerals.The predominant part of gypsum and anhydrite is used as raw materials for the production of gypsum binders (construction gypsum) and additives in various types of cements, to a lesser extent–for the production of hard-burnt, high-strength, molding …
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Nearly 95% of the Brazilian production of natural gypsum comes from the state of Pernambuco, from the Araripe Gypsum Center. Of the 95%, that is to say, of the 1.3 million ton/year production, 61% is allotted to the making of blocks and plates, 35% for coverings, 3% for ceramic moulding, and 1% for other uses.
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Anhydrous gypsum was added as a chemical activator in varying proportions of 0, 2.5, 5, 7.5 and 10% by weight of the binder. The mortar was prepared using a binder:sand ratio was of 1:1.5 mass% and a water/binder ratio of 0.50. ... silica fume, fly ashes) and the natural resources (natural pozzolan, limestone and ...
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Natural Gypsum 1 Mineral Planning Factsheet Gypsum Continuous miner, Barrow-upon-Soar Mine, Leicestershire. This factsheet pro-vides an overview of the gypsum sup-ply in the UK. It is one of a series on economically important minerals that are extracted in Britain and it is primarily intended to inform the land-use planning process. January ...
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Figure 6 b shows the compressive strength experiments, where both DG and natural gypsum were mixed and used together. The compressive strength of the mortar with 2.1% DG and 1.4% natural gypsum was greater than that of the other mixes. The performance of cement prepared by mixing DG and natural gypsum was better …
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With natural anhydrite (type II anhydrous gypsum) from Hanshan Country of Anhui Province as major raw materials, the preparation and application of anhydrous plaster gypsum are investigated.
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Activation treatment of natural and chemical anhydrous gypsum can make it adhesive and strong. So as to be suitable for the production of gypsum dry-mixed building materials. Acidic activators can accelerate the early hydration rate of anhydrous gypsum, shorten the setting time, and improve the early strength of gypsum hardened …
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According to the "Test method of cement mortar strength (ISO method)" (Chinese standard GB/T 17671–2021) and the mix proportion in Table 2, anhydrous phosphogypsum, carbide slag, and water-reducing agent were weighed and poured into a cement mortar mixer for pre-mixing for 30 s.Then, according to the mass ratio of dry …
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According to the amount of crystalline water, gypsum can also be categorised into dihydrate gypsum, hemihydrate gypsum, and anhydrous gypsum. Hemihydrate gypsum can be further classified as alpha-gypsum and beta-gypsum [26], which are considerably different in physical performance. The alpha-gypsum is well …
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Gypsums played a vital role in the building materials, and gypsum whiskers were fiber-like crystals with small diameters and high aspect ratios, which performed lightweight, high strength, and green. The traditional methods of anhydrous gypsum whiskers through high temperature mostly involve high energy consumption and have …
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Zhou et al. [22] conducted uniaxial and triaxial compression tests under natural and water saturated conditions for fresh gypsum rocks retained as pillars in Jinghua gypsum mine in Jingmen city in ...
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The results show that the main components of natural gypsum minerals were gypsum dihydrate (71%), dolomite (27%) and potassium chloride (2%). The hydration of …
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• High-strength gypsum cement specially formulated for use with glass fiber for fabricating glass-reinforced architectural details • Exceptionally quick setting; accepts most coatings and finishes • Low water requirements result in high-strength, high-density glass fiber-reinforced gypsum pieces • Ideal for producing lightweight, thin-cast,
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The chemical compositions of clinker and natural dihydrate gypsum as well as the mineral phases of clinker calculated by Bogue's equations are shown in Table ... Hemihydrate gypsum reduces compressive strength at early ages and promotes strength after 28 days. Anhydrous gypsum decreases the compressive strength of cement paste.
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The swelling of clay-sulfate rocks is a well-known phenomenon often causing threats to the success of various geotechnical projects, including tunneling, road and bridge construction, and geothermal drilling. The origin of clay-sulfate swelling is usually explained by physical swelling due to clay expansion combined with chemical swelling associated …
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After high-strength gypsum powder was used to make the remolded sample, the calcium sulfate disappeared, the water content increased, and the main mineral components of the natural and...
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natural gypsum. In addition, anhydrite reacts more slowly, assisting concrete to achieve full strength over 30 days. Anhydrite was formerly mined on a large scale in England as …
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Although many scholars have carried out a series of research and discussion on the physical and mechanical properties of gypsum rock, the use of A-class α-high …
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mechanical strength by using the atmospheric pressure CaCl 2 solution method, and found that high strength gypsum with 95% purity could be prepared aˇer 6 cycles 32. In the preparation of α-HH ...
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The study revealed that a combination of 30% lime, 50% FA, 20% ceramic waste powder and 10% anhydrous gypsum developed a strength greater than 25 MPa at 28 days of curing. ...
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The strength of fly ash mixture often needs to be enhanced for its better utilization in geotechnical and environmental applications. Many fly ashes often improve their strength with lime but may not meet the requirements. Gypsum, which reduces the lime leachability, further improves the strength. An attempt is made in this paper to …
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Gypsum raw materials are available in two forms: as a natural gypsum stone (or anhydrite—anhydrous calcium sulfate) and as a byproduct of many industrial …
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Gypsum, a naturally occurring mineral with the chemical formula CaSO4·2H2O, exhibits several important chemical properties that contribute to its versatility and usefulness in …
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Anhydrous gypsum, also called dead-burnt gypsum, can be used as an exterior plaster that lasts over 100 years, and historically it was fairly commonly used in France and Belgium. In North America …
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Ground granulated blast-furnace slag (GGBFS) was supplied by the Wuhan GangHua Co., Ltd. in China. Its chemical composition was tested by XRF and given in Table 1.The phosphogypsum (PG) and the natural gypsum (NG) were used in this study, and their chemical compositions were given in Table 1.The mineral compositions of …
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The β-type hemihydrate gypsum is formed through the dehydration of dihydrate gypsum in a dry environment, but its products feature low mechanical strength, vulnerability to temperature, and poor ...
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This work has investigated the possibility of two common minerals (silica flour and talc powder) in modifying composite gypsum's physical and mechanical …
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