1. Scope
1.1 This Standard specifies a method for determining, by partial immersion with no temperature gradient, the short-term liquid water absorption coefficient. It is intended to assess the rate of absorption of water, by capillary action from continuous or driving rain during on site storage or construction, by insulating and other materials, which are normally protected. The method is suitable for renders or coatings tested in conjunction with the substrate on which they are normally mounted. It is not intended to assess the absorption of water by materials used under water or in overall contact with saturated ground, where a total immersion test is more appropriate. 1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard. However, derived results can be converted from one system to the other using appropriate conversion factors (see Table 1). TABLE 1 Metric Units and Conversion Factors MultiplybyTo Obtain (for the same test condition) Area m210.8 ft2 ft29.2910-2 m2 Mass kg2.22 lb lb0.45 kg Mass per Area kg/m20.206 lb/ft2 lb/ft24.86 kg/m2 Water Absorption Coefficient kg/(m2s)0.206 lb/(ft2s) lb/(ft2s)4.86 kg/(m2s) kg/(m2h)0.206 lb/(ft2h) lb/(ft2h)4.86 kg/(m2h) 1.3 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
Talking about numerical simulation of the combined heat and moisture transport and storage, most important material properties as well as their determination are covered by ASTM standards. The only important material property which is missing is the liquid water absorption coefficient. This material property is an integral property summarizing the capillary activity of all different pores sizes of a material. The determination of this material property is already covered by ISO 15148. I used this ISO standard as basis for the ASTM proposal, extended the units to be SI as well as IP. Furthermore I made one major change regarding the content as follow. In case the measurement does not result a constant slope (which is defined to be the absorption coefficient) the average slope within the 24 hours time span should be used for the absorption coefficient. I think there is no justification to use 24 hours. Furthermore, if this material property is used for hygrothermal simulation, a time span which represents an average rain incident is supposed to be much more appropriate. Therefore I replaced the 24 hour time span with a 4 hour time span. I should mention that this approach is state of the art at Fraunhofer IBP for many years when measurement results are used to create material properties for hygrothermal simulation.
Keywords
liquid water absorption, test method for, hygrothermal simulation.
The title and scope are in draft form and are under development within this ASTM Committee.
Citing ASTM Standards
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