4.1 This test method provides a laboratory procedure for determining the relative water absorption properties over time of mortars used for masonry construction. Because the specimens are made under laboratory conditions and do not take into account the effect of the masonry substrate or field mixing procedures, this method is not intended for field use. Data generated from this test method may be useful for determining the relative effectiveness of water repellent admixtures or the effect of other admixtures or mortar components on the water repellency of a mortar. However, use caution in interpreting the results. While the resistance of masonry to water penetration may be related to the water absorption of the mortar, it also depends on other factors, such as the workmanship, extent of bond, and the properties of the masonry units and mortar.

Note 1: This test method is specified in Specification C1384 for demonstrating compliance of mortar admixtures classified as Water Repellent. In this compliance testing, the admixed mortar is compared to a reference mortar made with the same mortar materials except that it does not include the admixture. For quality control testing of water repellent preblended dry mortar mixes, the reference mortar is not typically available since the water repellent additive is added during the manufacturing process prior to bagging the final product. In these cases, the procedure in Annex A1 can be used to determine the relative resistance of the mortar to absorption by capillary uptake.