DILATOMETRIC ANALYSIS OF CERAMIC ROOF TILES FOR DETERMINING IRREVERSIBLE MOISTURE EXPANSION

Porous clay ceramic materials are subject to an ageing process which leads to moisture expansion. The irreversible moisture expansion value is usually determined with the use of time-consuming standard tests that require samples 20 cm in length. An advantage of a dilatometric method is that samples...

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Bibliographic Details
Published in:Ceramics (Praha) 2009-01, Vol.53 (4), p.303-309
Main Authors: Vokac, M, Klouzkova, A, Hanykyr, V, Bouska, P
Format: Article
Language:English
Online Access:Get full text
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Summary:Porous clay ceramic materials are subject to an ageing process which leads to moisture expansion. The irreversible moisture expansion value is usually determined with the use of time-consuming standard tests that require samples 20 cm in length. An advantage of a dilatometric method is that samples 2.5 cm in size can be measured. Using this method, the irreversible moisture expansion values of samples of historical roof tiles of various ages were determined. The procedure analysed the course and the shape of the curves and revealed whether volume changes resulted from the moisture expansion process. Rehydrated water was evolved within the interval 150-500 C. In addition, the correlation between the mineralogical composition and the irreversible expansion value was studied. Materials containing mullite fired at temperatures above 1000 C showed low values while samples with high porosity and containing no mullite fired at temperatures below 1000 C showed high values. Material containing gypsum exhibited the opposite effect - the tested fragments shrank, rather than expanded.
ISSN:0862-5468