Review of water desorption test methods

The water retaining ability of fresh mortar is described by a well-defined parameter, desorptivity. To date various methods have been developed and introduced to measure desorptivity. Desorptivity can be measured in four main ways; Capillary Suction Time (CTS), Suction Test, Filter Paper Plate, American Pertoleum Institute (API) Pressure Cell. All test methods for water desorption have the same working principle. The quantity of desorbed water at specified time intervals is measured by creating a potential difference in water pressure. This potential difference can be realised in different ways depending on the method. This paper investigates the four main test methods for desorptivity herein. The review of the test methods show that the desorptivity results of pressure cell is much more meaningful than the results of the CTS, paper plate and suction method as the pressure cell uses pressures equivalent to suction of brick.