Determination of the Water Absorption Coefficient by Partial Immersion

The purpose of these tests is to obtain, by means of simple apparatus, reliable and easy-to-determine values of liquid water transport for capillary active materials expressed in suitable units. These values are for use as part of the material properties in hygrothermal analysis tools for building envelope design and forensic studies. As the topic of liquid transport phenomena in porous materials is very complex, Appendix X1 in ISO 15148 shows some more detailed background information. This test method defines a procedure to determine the water absorption coefficient of a material by partial submersion. The scope is to evaluate the rate of absorption of water due to capillary forces for building materials in contact with normal or driving rain above grade. The procedure is typically suitable mainly for masonry material, plaster, or a coating in combination with a substrate; but it can also be used for insulation materials. This test method is designed to be used only on homogeneous materials and does not apply to materials that are composites or non-homogeneous (for example, faced rigid closed-cell Insulation). It is not within the scope of this standard to determine liquid uptake phenomena in below-grade applications. The water absorption coefficient is mainly used as an input datum for numerical simulation of the combined heat and moisture transport in building envelopes for design and forensic investigation purposes.