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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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The strength formation and hydration mechanism of the non-calcined cementitious binder were discussed by analyzing the X-ray diffraction (XRD), scanning electron microscope (SEM) and pH of the ...
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The anhydrite binder calcined with the addition of 5% ground glass exposes the best physical and mechanical properties: the setting duration up to 13-38 min, the compressive strength of the dry ...
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The analysis of the effect of the additives on the properties of the anhydrite binder (Tables 2, 3) shows that the binding of the calcined material with the additives of the dust from a cupola ...
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Anhydrite cement is widely utilized in the construction industry in many countries. It is gypsum calcined at high temperatures (600-700 °C) [14].Alum plaster is a product obtained by mixing ...
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The FT-IR spectrums of the anhydrite binder calcined at 800 and 900°C (with additives as well is without additives) are alike (Figure 5).
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297 Due to the reduced amount of calcined clay, the anhydrite content is also reduced from 5% to 3%. It is ... 411 binder system containing calcined clay and slag). 412 5.1 LC 3 with single …
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X-ray diffraction patterns of hydrated anhydrite binder: 1 - 1 mixture, 2 - 2, 3 mixtures, 3 - 4 mixture, 4 - 5 mixture. Composition of mixtures is reported in Table 1. Indexes: A - …
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Pastes with a water-to-binder (w/b) ratio of 0.50 were prepared using PC with 25% calcined clay substitution. These were sealed in small plastic vials immediately after mixing and stored at 20 °C. ... Although anhydrite content in clays calcined at above 800 °C was <5%, its presence can affect the cement hydration and stability of AFm and Aft ...
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Regarding the phases formed, higher anhydrite peaks were obtained for higher calcination temperatures and also for a longer period of thermal retention. The XRD spectra and thermograms showed that to obtain anhydrite II for use as a binder, a temperature higher than 450 °C is required.
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The effects of calcination and modification on the morphology (shapes and textures) and crystal structure of anhydrite powders were studied. The results show that, calcination at 100°C causes anhydrite to disintegrate into smaller crystals, accompanied by a slight increase in d-spacing. Without calcination and modification, the solidification …
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The anhydrite binder calcined with the addition of 5% ground glass exposes the best physical and mechanical properties: the setting duration up to 13-38 min, the compressive strength of the dry ...
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The results showed that the density of the anhydrite calcined at different temperatures increased gradually (Figure 2). The relationship between the density and the calcination temperature can be described with a linear regression function. ... The anhydrite binder obtained at the temperature of 500 °C was fully hydrated after 28 days (degree ...
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The anhydrite binder calcined with the addition of 5% ground glass exposes the best physical and mechanical properties: the setting duration up to 13-38 min, the compressive strength of the dry ...
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Results show that obvious defects appeared in anhydrite facets due to the formation of calcium pyrophosphate (Ca 2 P 2 O 7 ), calcium fluoride (CaF 2 ). …
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DOI: 10.1016/j.conbuildmat.2024.137546 Corpus ID: 271557508; Clinker-free cement based on calcined clay, slag, portlandite, anhydrite, and C-S-H seeding: An SCM-based low-carbon cementitious binder approach
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The phosphogypsum – dihydrate calcium sulphate is waste material of phosphoric acid production from the Kola apatites. The possibility of applying lime neutralized …
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Converted impurities could accelerate the hydration process of anhydrite. • PG calcined at 800 °C to prepare anhydrite showed the best performance. Abstract. The calcination of phosphogypsum (PG) was employed to produce gypsum plaster to achieve its recovery and utilization. ... Anhydrite binder calcined from phosphogypsum[J] …
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In CPB samples, the solid concentration and binder content (binder/solid by mass) are set at 77 % and 10 %, respectively. Five different contents of CA (0.5 %, 1 %, 2 %, 3 %, 5 % by weight of binder) were used as admixture to prepare CPB samples. For comparison, CPB samples utilizing pure OPC and ASAS as binder were also prepared.
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The phosphogypsum – dihydrate calcium sulphate is waste material of phosphoric acid production from the Kola apatites. The possibility of applying lime neutralized phosphogypsum as a raw material for obtaining anhydrite binder was investigated in …
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The paper deals with an investigation about the production of high strength plaster from the waste phosphogypsum and its use in making flooring tiles. To achieve this objective, phosphogypsum was calcined at 900–1000 °C to anhydrite which was mixed with suitable chemical activators (alkali/alkaline earth hydroxides, sulphates, …
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Combined action of calcined siltstone and lime leads to a 45% increase in strength due to the additional compaction by new hydration products formed in the course of metakaolin and lime interaction. ... minerals proves that finely ground siltstone can be used as a mineral additive in the composition of the anhydrite binder, accelerating ...
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It was determined that the phosphogypsum with additives calcined at the temperature 900°C, and the following grinding of it to the specific surface area 600 ± 10 m²/kg allow obtaining the fast setting anhydrite binder. The anhydrite binder calcined with the addition of 5% ground glass exposes the best physical and mechanical properties: the ...
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Other research experiments were performed to determine the effect of calcined phosphogypsum on the strength of fly ash–lime binders. ... Anhydrite binder calcined from phosphogypsum. Ceram. Silik. 54(2), 152–159 (2010) Google Scholar Leškevičienė, V., Nizevičienė, D.: Influence of the setting activators on the physical …
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The dependence of the anhydrite binder strength on the phosphate activators content: a -with sodium phosphate; b -with ammonium phosphate 0 3 5 7 10 Na PO additive content, % 3 4
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The calcined PG produced was designated according to the temperature at which it was calcined, and the SG mixtures were prepared in accordance with Table 3. A fixed water to binder ratio of 0.7 was used throughout the experiment to …
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The dehydration process consists of two stages: first, one with a hemihydrate formation (25.4) CaSO 4 · 2 H 2 O → CaSO 4 · 0.5 H 2 O + 1.5 H 2 O and, second, one with an anhydrite formation (25.5) CaSO 4 · 0.5 H 2 O → CaSO 4 + 0.5 H 2 O. All the reactions are endothermic (energy-absorbing). Depending on the equipment applied and …
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The calcined clay and anhydrite contents were kept constant at 30 wt% and 5 wt%, respectively. An equivalent amount of OPC was replaced by more limestone. The strength of the pure OPC reference at the corresponding ages is indicated with a blue dashed line. ... LC 3-53 with 2 wt% anhydrite: binder mix made of 53 wt% OPC, 30 …
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Figure 8. X-ray diffraction patterns of hydrated anhydrite binder: 1 - 1 mixture, 2 - 2, 3 mixtures, 3 - 4 mixture, 4 - 5 mixture. Composition of mixtures is reported in Table 1. Indexes: A - anhydrite CaSO4; G - gypsum CaSO4·2H2O; E - gismondite CaAl2Si2O8·4H2O; H - calcium aluminium silicate hydrate Ca2Al2SiO7·8H2O - …
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In addition, the effect of small amounts of uncalcined gypsum or insoluble anhydrite II calcined at 800 °C (i.e., 1, 5, 10, and 20 wt%) on the hydration of pure bassanite (obtained by calcining gypsum at 200 °C for 6 h) was studied using pastes with a 1:1 water/solid ratio. ... causing a local disruption of the plaster matrix as it does not ...
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