Comparison of Different Approaches for Testing Sorption by a Superabsorbent Polymer to Be Used in Cement-Based Materials

The absorption and desorption behavior of superabsorbent polymer (SAP) can influence various properties of cementitious materials. Therefore, it is essential to know these performances of SAP prior to implementation in cement-based materials. In this paper, two types of SAP with different chemical compositions were tested in free liquid (deionized water and cement filtrate) and cement paste. Five absorption test methods were considered, including the tea-bag method, the filtration method, the centrifuge method, the suction filtration method, and the slump flow method. The results show that the absorptivity of SAP A73 and SAP N in cement paste by the slump flow method are about 21 g/g and 7 g/g, respectively. In addition, the centrifuge method and suction filtration method give more accurate absorption values when compared to the tea-bag method and filtration method due to their effectiveness in removing inter-particle liquid. Though the absorptivity obtained by the tea-bag method is higher than the centrifuge method and suction filtration method, it is still a good pre-test method to reveal the performance of SAP used in cementitious materials due to time-saving and simple setups.