engleski

Adsorption of calciumhydroxide on polyacrilonitrile, cellulose and chrysotile fibres

Asbestos fibres are being eliminated from use because of their their danger to human. health; equivalent substitute fibres are being introduced for manufacturing fibre-cement products. Asbestos fibres have a series of extraordinary properties; one of these is a pronounced surface activity which intensifies cement hydration. This paper presents results obtained for the surface activity of two types of polyacrylonitrile (PAN) fibres and for treated cellulose fibres as compared to chrysotile asbestos, by determining the adsorption of Ca(OH)_2 onto the fibres. The Ca(OH)_2 concentration was determined before and after contact with the fibres by titration with HCl. The results indicate that the adsorption isotherms obtained are multistep isotherms characteristic of the formation of multimolecular layers. The measurements have shown that the polyacrylonitrile and cellulose fibres have a surface activity similar to that of asbestos fibres. Therefore it may be expected that they will have a similar effect on cement hydration.

Surface-properties; Asbestos

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