Comparison of Methods for Determining the Water Absorption of Glazed Porcelain Stoneware Ceramic Tiles

This work evaluated the water absorption of glazed porcelain stoneware ceramic tiles using three different methods. Two methods were based on a procedure of boiling in water, specified by standards ISO 10545 and ASTM C373, and the third was the vacuum method proposed by the standard ISO 10545. The three products produced under the three different firing conditions were tested according to a 22 factorial design, with intervening factors of the boiling time and immersion time for the methods involving boiling, and of pressure and immersion time for the vacuum method. The maximum saturation of the plates was evaluated by helium gas pycnometry testing. The results showed that no sample saturation occurs in the boiling water absorption test performed according to the conditions established by standards ISO 10545 and ASTM C373. The values of open porosity, using the method of helium gas picnometry, showed absolute values of saturation higher than those presented by the water absorption measured according to the current standards. Thus, the results showed that the current methods for determining the water absorption of glazed porcelain stoneware ceramic tiles do not guarantee the complete saturation of the plates and, therefore, they are not able to correctly measure this property.

本研究采用三种不同方法，对施釉炻瓷陶瓷砖的吸水率进行了评测。其中两种方法基于ISO 10545与ASTM C373标准规定的水煮流程，第三种则为ISO 10545标准提出的真空法。本研究针对三种不同烧成条件下制备的试样，采用2²析因设计开展测试：对于水煮类测试方法，干预因子为水煮时长与浸泡时长；对于真空法，干预因子则为压力与浸泡时长。采用氦气比重瓶法（helium gas pycnometry）测试了试样的最大饱和状态。结果显示，按照ISO 10545与ASTM C373标准规定的条件开展水煮吸水率测试时，试样未达到完全饱和状态。采用氦气比重瓶法测得的开口孔隙率对应的饱和绝对值，高于现行标准中吸水率的测试结果。由此可见，现行的施釉炻瓷陶瓷砖吸水率测定方法无法保证试样完全饱和，因此无法准确测得该性能指标。