The experimental data conclude that natural anhydrite can be a very efficient retarder of the setting of cement, with no significant change in the physicomechanical properties of the hardened pastes. (C) 2004 Elsevier Ltd.
Heat released during the hydration measured by the isothermal calorimetry of pastes. Pure clinker in the top row, cement with 10 % of anhydrite in the bottom row.
DOI: 10.1016/j.conbuildmat.2022.127630 Corpus ID: 248445855; Modification of phosphogypsum using circulating fluidized bed fly ash and carbide slag for use as cement retarder @article{Li2022ModificationOP, title={Modification of phosphogypsum using circulating fluidized bed fly ash and carbide slag for use as cement retarder}, …
Two different Italian SCMs, namely S (in accordance with EN 15167-1) and FA (according to EN 450-1), together with hydrated lime CL90-S class (CH: according to EN 459-1) and a natural anhydrite (A) were employed. TA additive, as a setting time retarder, and room temperature tap water were also used for obtaining pastes and mortars.
Cement pastes with hemihydrates also present a higher amount of hydrated sulfoaluminate phases, mainly monosulfoaluminate formations, than those with dihydrates [27]. The use of natural anhydrite as set retarder has been also studied, and the reduction of strengths in the first three days was the main difference found [7].
In China, more and more cement factories are trying to use the chemical gypsums as a cement retarder instead of natural gypsum (NG). Cement is the most massive man-made material, 0.04–0.08 ton of gypsum is needed to produce 1 ton of cement, and there were around 1.5 billion tons of cement produced in China in 2008.
DOI: 10.1016/J.CEMCONRES.2004.03.020 Corpus ID: 135769840; Alternative calcium sulfate-bearing materials as cement retarders: Part I. Anhydrite @article{Tzouvalas2004AlternativeCS, title={Alternative calcium sulfate-bearing materials as cement retarders: Part I. Anhydrite}, author={G. Tzouvalas and N. Dermatas and …
Cement Milling, Natural anhydrite may also be added to discourage ... which in turn has a higher solubility than either gypsum or Natural anhydrite. Cement mills need to be cooled to ... Go to Product Center. specification of gypsum used in cement industry, Up to 5% gypsum and/or natural anhydrite is ... to give Portland cement.
1. Introduction. Role of cement retarders is to prevent C 3 A and water fast reaction, that's why natural gypsum is grinded and blended with clinker in cement mills with the different additives according to the cement type. Gypsum hemihydrate and anhydrite exists in nature same as gypsum and can replace gypsum partially or completely in …
HS Code Of Chapter 2520, List Of Hs Codes For GYPSUM; ANHYDRITE; PLASTERS (CONSISTING OF CALCINED GYPSUM OR CALCIUM SULPHATE) WHETHER OR NOT COLOURED, WITH OR WITHOUT SMALL QUANTITIES OF ACCELERATES OR RETARDERS, Free Search Indian HS Classifications
The comparative investigations of gypsum cement pozzolana binding materials (GCPB) and anhydrite cement pozzolana binding materials (ACPB) with not burned natural anhydrite were performed ...
The constant use of natural gypsum as setting retarder in cement has led to the reduction of its high purity stock in Greece. The aim of this project was to investigate the possible displacement of natural gypsum (CaSO4·2H2O) in cement (CEM I and CEM II types) with alternative setting retarders such as: i) anhydrite, ii) phosphogypsum and …
The comparative investigations of gypsum cement pozzolana binding materials (GCPB) and anhydrite cement pozzolana binding materials (ACPB) with not burned natural anhydrite were performed ...
any chemical external attack to mass concrete. Concrete with FGD as setting retarder shows less capillary sorptivity for all additions in cement (Figure 5). The results of the resistance of concrete with different CSBMs in sulfate attack are presented in Figure 6. Concrete with FGD gypsum show a more vigorous resistance com-pared with natural ...
The anhydrite produced at 800°C, 900°C, and 1000°C (Fig. 2d–f) shows appearance of euhedral to anhedral prismatic and rhombic shaped crystals of platy structure binding the smaller anhydrite grains. The pseudoamorphous gypsum crystals break down into microcrystals with the increase in calcination temperature.
The utilization of citro- and desulphogypsum in the cement industry as set retarders was tested and compared with natural gypsum. Chemical gypsums were used in two different forms, powder and ...
and does not retard cement setting time of the cements. Most of this variety of gypsum is used by cement plants to advantage. Experience with this anhydrite gypsum has also resulted in import of natural anhydrite gypsum by many Cement plants so to have the indicated advantages in cement properties. Phosphogypsum: Phosphogypsum is a by …
Demand for cement in China exceeded 1.2 billion tons in 2010, which results in the increase of the demand for natural gypsum [4−6]. To exploit and use fluorgypsum as a substitute for natural gypsum reasonably and efficiently can not only save the resources of natural gypsum and lower the cost of gypsum mining, but also benefit the environment ...
The rapid hardening of cement pastes due to the vivid reaction of C3A with water is usually prevented by adding a substance that acts as a retarder of the setting of cement. This article reports on a study of the displacement of natural gypsum (CaSO4-2H2O) in cement with an alternative setting retarder, such as the industrial by-product derived ...
The hydration process of cement pastes is of great importance to the physicomechanical properties of the hardened material. Thus, substances that regulate the setting of cement, such as natural anhydrite, have attracted significant scientific interest during the past years. This paper briefly describes the results of utilization of natural anhydrite in …
Abstract. The aim of this paper is to investigate the possible displacement of natural gypsum (CaSO4·2H2O) in cement with an alternative setting retarder, such as the industrial by-product ...
protogenetic anhydrite in cement, and protogenetic anhydrite could not make the bigger volume ... In Portland cement, usually the added gypsum is natural dihydrate gypsum, but mixed gypsum and chemical gypsum are also used in cement [4,5]. In fact, in addi- ... as cement setting retarder instead of added gypsum. Our previous works [8,9] showed ...
The effect is harmless to volume stability of cement paste with appropriate anhydrite addition. Compared with natural gypsum, anhydrite in CFBC ash makes ettringite formation slower and more ...
The experimental data conclude that natural anhydrite can be a very efficient retarder of the setting of cement, with no significant change in the physicomechanical properties of the hardened ...
Natural anhydrous anhydrite ore belongs to natural anhydrous calcium sulfate (CaSO4), with high grade and stable quality. randall@acacem ... As a cement retarder and compound mineralizer, it is especially suitable for the production of concrete expansion agent, low alkalinity special expansion cement, stucco gypsum cementing materials and …
Portland cement typeII 52.5R and calcium aluminate cement CA50 used in this study were obtained from JinYang Cement Co. and Changchen Cement Co. respectively, and a commercial natural anhydrite was from Nanjing. The chemical compositions and mineralogical compositions of the cements provided by the …
Gypsum has been widely known for its use such as retarder in Portland cement and primary raw material for plaster of Paris (POP) and plaster ceiling materials . Extensive research has been carried out to ascertain the rehydration process for crystallizing gypsum from various natural anhydrite.
The present study is focused on clarifying the influence of waste gypsum (WG) in replacing natural gypsum (NG) in the production of ordinary Portland cement (OPC). WG taken from slip casting moulds in a ceramic factory was formed from the hydration of plaster of paris. Clinker and 3–5 wt% of WG was ground in a laboratory ball …
Influence of the gypsum dehydration temperature and alkali additives on the properties of anhydrite cement. V. Leskeviciene I. Sarlauskaite D. Nizevičienė N. Kybartienė. Materials Science. 2010. While dehydrating gypsum with additives at the temperatures of 800°C and 900°C the influence of alkali additives on both the crystalline structure ...
natural anhydrite to replace Portland cement in certain fields of application. As a sulphate retarder of setting, anhy- As a sulphate retarder of setting, anhy- drite can be used for production of ...
1. Introduction. In the process of cement production a certain amount of gypsum is added in order to adjust setting time of cement, contribute for strength acceleration in early stage and reduce drying shrinkage of hardened cement paste [1], [2], [3].In Portland cement, usually the added gypsum is natural dihydrate gypsum, but …
clinker blended with 10 wt.-% of the natural anhydrite (labelled CAH). ... were tested at a single addition rate of 0.5 % by cement weight. The impact of retarders was evaluated by measuring the ...
Fachinformationsdienst BAUdigital A platform for research: civil engineering, architecture and urbanism
Effect of Portland cement on strength development of Phosphoanhydrite-Pozzolana cement. A. Jarosiński C. Ostrowski. Materials Science, Engineering. 1997. The paper is a part of the research on a complex alternative technology of apatite phosphogypsum (PG) obtained during the production of phosphoric acid from Kola apatite, on rare earth ...
Flue gas desulfurization (FGD) gypsum was evaluated as a setting time retarder to replace the natural gypsum in the production of Portland cement (CP II E-32).
The cements with SPG had a similar setting time and strength as cement made with natural gypsum (NG). ... It can also be used as a cement retarder [26] [27 ... heating to hemihydrate-anhydrite ...
tive in specialty chemicals. Our local presence worldwide links us directly with customers and ensures the succ. ss of Sika and its partners. Every day highly motivated people strive to provi. er service.Sika Services AGBusiness Unit Concrete Tüffenwies 16 CH-8048 Zürich Switzerland Phone +41 58 436 40 40 Fax +41 58 436 47 29 Our ...
Use of inorganic setting retarders in cement industry. A J Papageorgiou. 2005, Cement and Concrete Composites. See Full PDF Download PDF. See Full PDF Download PDF. Related Papers. Cement and Concrete Research. Alternative calcium sulfate-bearing materials as cement retarders ...
Borax has positive impact on the later strength particularly on the cement containing addition of anhydrite. At 2 days, CAH-B sample is characterized by strength of 40 MPa at 2 days, i.e. 8 MPa ...
