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Moisture transport and dehydration in heated gypsum, an NMR study



Title: Moisture transport and dehydration in heated gypsum, an NMR study
Author(s): G.H.A. van der Heijden, L. Pel and K. Kopinga
Paper category : conference
Book title: 2nd International RILEM Workshop on Concrete Spalling due to Fire Exposure
Editor(s): E.A.B. Koenders and F. Dehn
ISBN: 978-2-35158-118-6
e-ISBN: 978-2-35158-119-3
Publisher: RILEM Publications SARL
Publication year: 2011
Pages: 181 - 188
Total Pages: 8
Nb references: 13
Language: English


Abstract: Nuclear magnetic resonance (NMR) is used to non-destructively measure the moisture profiles in gypsum during one sided intense heating. Simultaneously with the moisture measurement the temperature profiles were recorded. Moreover, in gypsum it was possible to measure the degree of hydration, i.e., the hydration profiles.
The moisture content has a significant influence on the moisture transport processes taking place inside the gypsum. The dehydration reactions of gypsum are directly influenced by the partial vapour pressure under which the reaction takes place. With NMR we are able to separate the liquid and chemically bound moisture and to monitor the progression of the dehydration front in time.
To our knowledge we present the first quantitative time evolution of moisture, hydration, and temperature profiles. Furthermore, the existence of a moisture peak resulting from the vapour released by dehydration is presented. We will present a simple heat and mass transfer model including dehydration aiming to describe the NMR results. The NMR experiments presented in this paper can be used to evaluate and validate thermo-hygral models in the field of fire research on building materials.


Online publication: 2012-01-17
Publication type : full_text
Public price (Euros): 0.00