Hygric properties of porous building materials (III): Impact factors and data processing methods of the capillary absorption test

The capillary absorption test is one of the most frequently performed material characterization tests. It provides the capillary absorption coefficient and the capillary moisture content, both are important material properties. Currently, full consensus concerning the experimental protocol and data processing of the capillary absorption test has not been reached yet. This paper studies the potential impact factors during the test and compares different methods for processing the raw data. Measurements on calcium silicate, ceramic brick, sintered glass and autoclaved aerated concrete are carried out, and published literature results are reviewed. The impact of sample size, sealing method, initial moisture content, temperature and personnel have been thoroughly analyzed, and proper recommendations are provided accordingly. Moreover, a new data processing model with a solid physical background for calculating the capillary absorption coefficient and the capillary moisture content has been proposed. It shows obvious advantages over other published models and is applicable for both ideal and irregular capillary absorption patterns.