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2017 | 22 | 166 - 175
Article title

CHITOSAN APPLIED FOR GYPSUM MODIFICATION

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EN
Abstracts
EN
In order to improve the properties of gypsum materials, including workability, mechanical strength and ability to retain water, various admixtures (also polymers), known as plasticisers, have been applied. These polymers can be soluble in water, such as cellulose and starch ethers, or unsoluble applied in a form of dispersion up to 5% of weight fraction. The admixtures are added into initial water and mixed with hemihydrate calcium sulphate in a proper ratio. In the hydration process of the hemihydrate into dehydrate, a crystallisation process leading to gypsum setting occurs. In the present work, a chitosan sample of DD=85% in two forms was applied: dissolved in 1% acetic acid and as a water dispersion in the weight fraction up to 1% of the gypsum matrix. The water to gypsum ratios of 0.6 or 0.74 was applied. The influence of chitosan on the rate of setting and kinetics of crystallisation of gypsum was investigated and discussed. The morphological structure of the resulting gypsum sample was examined using SEM microscopy. In the presented results, chitosan in the form of a 1% dispersion was a setting retardant and it changed the morphological structure of gypsum. However, mechanical tests showed a decrease of bending strength. When chitosan was applied as a biomaterial, the chitosan content in the composite was equal to 10%, and thus a compressing strength increased. The presence of PVA (polyvinyl alcohol) in the gypsum matrix caused a small effect on gypsum setting in contrast to PVAc (polyvinyl acetate), which is a good admixture for both cement and gypsum [2,3].
Publisher

Year
Volume
22
Pages
166 - 175
Physical description
Contributors
author
  • Lodz University of Technology, Faculty of Process and Environmental Engineering, ul. Wolczanska 213, 90-924, Lodz, Poland, maria.mucha@p.lodz.pl
  • Lodz University of Technology, Faculty of Process and Environmental Engineering, ul. Wolczanska 213, 90-924, Lodz, Poland
  • Lodz University of Technology, Faculty of Process and Environmental Engineering, ul. Wolczanska 213, 90-924, Lodz, Poland
References
  • E. Knapen, D. Van Gemert, (2009) Cement hydration and microstructure formation in the presence of water soluble-polymers, Cement and Concrete Research 39, 6–13; DOI:10.1016/j.cemconres.2008.10.003
  • P. Mróz, M. Mucha, Hydration kinetics of calcium sulphate hemihydrate modified by water soluble polymers, International Journal of Concrete Structure and Materials – in press
  • M. Lasheras-Zubiate, I. Navarro-Blasco, J.M. Fernández, J.I. Álvarez, (2012) Effect of the addition of chitosan ethers on the fresh state properties of cement mortars, Cement and Concrete Composite 14, 964–973; DOI:/10.1016/j.cemconcomp.2012.04.010
  • Q.L. Yu, H.J.H. Brouwers, (2011) Microstructure and mechanical properties of β-hemihydrate produced gypsum: An insight from its hydration process, Construction and Building Materials 25, 3149–3157; DOI:10.1016/j.conbuildmat.2010.12.005
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  • V. E. Akhrimenkoa, N. V. Pashchevskayab, (2013) Russian Journal of Applied Chemistry 86(6), 942−944
  • A. Peschard, A. Govin, J. Pourchez, E. Fredon, L. Bertrand, S. Maximilien, B. Guilhot, (2006) Effect of polysaccharides on the hydration of cement suspension, Journal of the European Ceramic Society 26(8), 1439–1445; DOI:10.1016/j.jeurceramsoc.2005.02.005
  • J. Pourchez, A. Peschard, P. Grosseau, R. Guyonnet, B. Guilhot, F. Vallée, (2006) HPMC and HEMC influence on cement hydration, Cement and Concrete Research 36, 288–294; DOI:10.1016/j.cemconres.2005.08.003
  • D. Bülichen, J. Kainz, J. Plank, (2012) Working mechanism of methyl hydroxyethyl cellulose (MHEC) as water retention agent, Cement and Concrete Research 42, 953–959; DOI:10.1016/j.cemconres.2012.03.016
  • P. Mróz, M. Mucha, Calorimetric study of phase transition of gypsum with water soluble polymers, Journal of Thermal Analysis and Calorimetry – in press
  • A. Kocemba, M. Mucha, (2016) Water retention and setting in gypsum/polymers composites; Przemysł Chemiczny 95(5), 1003–1005; DOI:10.15199/62.2016.5.22
  • A. Low., (2015) Gypsum-based biomaterials: Evaluation of physical and mechanical properties, cellular effects and its potential as a pulp liner, Dental Material Journal 34, 522–528; DOI:10.4012/dmj.2015-029
Document Type
article
Publication order reference
Identifiers
YADDA identifier
bwmeta1.element.psjd-6d25e255-69e1-4cb0-96ef-1c533c85ed4e
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