A Logical Extension of the ASTM Standard E96 to Determine the Dependence of Water Vapour Transmission on Relative Humidity

Abstract

/npsi/ctrl?lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?lang=fr Access and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. Special Technical Publication, 1320, pp. 456-470, 1997 A Logical extension of the ASTM standard E96 to determine the dependence of water vapour transmission on relative humidity Lackey, J. C.; Marchand, R. G.; Kumaran, M. K. ASTMhttp://www.nrc-cnrc.gc.ca/irc A Logic a l e x t e nsion of t he AST M st a nda rd E9 6 t o de t e rm ine t he de pe nde nc e of w a t e r va pour t ra nsm ission on re la t ive hum idit y NRCC-40105Lackey, J.C.; Marchand, R.G.; Kumaran, M.K. April 1997A version of this document is published in / Une version de ce document se trouve dans: Special Technical Publication, 1320, pp. 456-470, April 01, 1997 The material in this document is covered by the provisions of the Copyright Act, by Canadian laws, policies, regulations and international agreements. Such provisions serve to identify the information source and, in specific instances, to prohibit reproduction of materials without written permission. For more information visit http://laws.justice.gc.ca/en/showtdm/cs/C-42 ASTMLes renseignements dans ce document sont protégés par la Loi sur le droit d'auteur, par les lois, les politiques et les règlements du Canada et des accords internationaux. Ces dispositions permettent d'identifier la source de l'information et, dans certains cas, d'interdire la copie de documents sans permission écrite. Pour obtenir de plus amples renseignements : http://lois.justice.gc.ca/fr/showtdm/cs/C-42 It is well koowo that the water vapour transmission properties of hygroscopic building materials depend on the local relative humidities(rh). Traditionally, the ASTM Standard E96 specifies only two conditions of rho The dry cup method in the standard corresponds to a mean rh of 25 % and the wet cup to 75 %. This information is not enough to describe the behaviour of the material through the entire range of rho European standards have already proposed an extension of the existing standard to address this issue. ASTM standard should follow this change. A logical extension of the E96 standard to include the effect of rh on water vapour transmission properties has been proposed and is being discussed by one of the C16 Committee Task Groups. This paper presents the application of the proposed extension to several common building materials. The details include the operating principles of a constant temperaturerh chamber and the effects on the test results, of the vapour resistance offered by still air inside the cup, the surface resistanc...

An Alternative Procedure for the Analysis of Data from the Cup Method Measurements for Determination of Water Vapor Transmission Properties

“…Otherwise the corrections towards the resistances offered by the air layer complicate the data analysis. All assemblies are then placed in a chamber [5] maintained at 23°C and initially at approximately 30% RH. The assemblies are periodically weighed, as usual for the E 96 procedure, to confirm the steady state, and then the steady rate of mass change is recorded.…”

“…The penneance so calculated should be correcled [5,11] for the surface resistances and the resistance offered by the still air inside the cups, common to all measurements. (This is why it is necessary to keep the thickness of the still air the same in all assemblies.…”

Water Vapor Transmission Measurement and Significance of Corrections

“…The following equation [16] The density of air can be calculated using the ideal gas law for the measured atmospheric pressure and ambient temperature. The buoyancy correction is important [15] when measured mass changes are in the range of 0 to 100 mg.…”

Moisture Transport Across Interfaces Between Autoclaved Aerated Concrete and Mortar

“…Since water vapor pressure is significantly lower than the atmospheric pressure, the water vapor can be treated as ideal gas (Lackey et al 1997). Therefore, based on the assumption (2), water vapor transport can be expressed as the well-known equation:…”

“…The water vapor permeability of air under room temperature was 2×10 -10 kg·m -1 · s -1 ·Pa -1 (Lackey et al 1997). The constant convection mass transfer coefficient, β, can be estimated using Lewis relation (Pedersen 1990):…”