CEMENT-BASED MATERIALS |
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Study on Early Hydration Process of an Environmentally-friendly Gypsum-Cement-Pozzolan Binder System |
WANG Boyuan, YAO Wu
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Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education, School of Materials Science and Engineering, Tongji University, Shanghai 201804 |
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Abstract The effect of composition and hydration condition of an environmentally-friendly gypsum-cement-pozzolan binder system (GCP binder system) on its early hydration process was studied by means of X-ray diffraction (XRD) and heat flow calorimeter. It was found that the main hydration products of the GCP-slurry after the early hydration were ettringite, gypsum, portlandite, calcite and amorphous CSH phase. The content of ettringtie increased over time whereas the content of gypsum decreased. Results from heat flow calorimeter indicated the retarding effect of superplasticizer on the hydration process within the first 70 h of GCP bin-dersystem. Metakaolin could improve the formation of ettringite whereas microsilica could hinder it. Portlandite could only be mea-sured within the first week after hydration due to the pozzolanic reaction. The underwater hydration condition could promote the formation of ettringite and prevent the contact between the sample and carbon dioxide as well, which could lead to the reduction of calcite content.
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Published: 10 March 2017
Online: 2018-05-02
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1 Hendriks C A, Worrell E, De Jager D, et al. Emission reduction of greenhouse gases from the cement industry[C]// Proceedings of the Fourth International Conference on Greenhouse Gas Control Technologies.1998.
2 Pearce F. Green foundations[J]. New Sci, 2002,175(2351):39.
3 McLellan B C, Williams R P, Lay J, et al. Costs and carbon emissions for geopolymer pastes in comparison to ordinary Portland cement[J]. J Cleaner Production,2011,19(9):1080.
4 Altmann H D, Winkler K G. Einsatz von Anhydritbaustoffen im Bauwesen der DDR[J]. Baustoffindustrie,1984,4:99.
5 Escalante-García J I, Rios-Escobar M, Gorokhovsky A, et al. Fluo-rgypsum binders with OPC and PFA additions, strength and reactivity as a function of component proportioning and temperature[J]. Cem Concr Compos,2008,30(2):88.
6 Yan P,et al. Microstructure and properties of the binder of fly ash-fluorogypsum-Portland cement[J].Cem Concr Res,1999,29(3):349.
7 Zhvironaite J,Lasys A,et al.Investigations of composite anhydrite-cement pozzolana binding material[J].Tile Brick Int,1998,14(3):176.
8 Rietveld H M. A profile refinement method for nuclear and magnetic structure[J]. J Appl Crystallography,1969,2(2):65.
9 Ag D L T, Cabeza A, Calvente A, et al. Full phase analysis of Portland clinker by penetrating synchrotron powder diffraction[J]. Anal Chem,2001,73(2):151.
10 Taylor J C, Hinczak I, Matulis C E. Rietveld full-profile quantification of Portland cement clinker: The importance of including a full crystallography of the major phase polymorphs[J]. Zhurnal Vyssheǐ Nervnoǐ Deiatelnosti Imeni I P Pavlova,2000,15(1):7.
11 Neubauer J, et al. Quantification of a mixture of synthetic alite and belite by the Rietveld method[J]. Mater Sci Forum,1996,228-231:807.
12 Guirado F, et al. Quantitative Rietveld analysis of aluminous cement clinker phases[J]. Cem Concr Res,2000,30(7):1023.
13 Pajares I, Del T Á G, Martínez-Ramírez S, et al. Quantitative analysis of mineralized white Portland clinkers: The structure of fluorellestadite[J]. Powder Diffraction,2002, 17(4):281.
14 Schmidt R, et al. Quantification of calcium sulpho-aluminate cement by Rietveld analysis[J].Mater Sic Forum,2000,321-324:1022.
15 Saoût G L, Lothenbach B, Hori A, et al. Hydration of Portland cement with additions of calcium sulfoaluminates[J]. Cem Concr Res,2013,43(1):81.
16 Torre A G D L, Aranda M A G. Accuracy in Rietveld quantitative phase analysis of Portland cements[J]. J Appl Crystallography,2003,36(5):1169.
17 Scrivener K L, Füllmann T, et al. Quantitative study of Portland cement hydration by X-ray diffraction/Rietveld analysis and independent methods[J]. Cem Concr Res,2004,34(9):1541.
18 Saoût G L, et al. Quantitative study of cementitious materials by X-ray diffraction/Rietveld analysis using an external standard[C]// International Congress on the Chemistry of Cem.Montréal,2007.
19 Stepkowska E T, Aviles M A, Blanes J M, et al. Gradual transformation of Ca(OH)2, into CaCO3, on cement hydration[J]. J Thermal Anal Calorimetry,2007,46(1):4886.
20 Gallner M. Gips-zement-puzzolan-bindemittel, untersuchungen zur dauerhaftigkeit und festigkeitsentwicklung[D]. Munich: Technical University of Munich,2012. |
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