Absorption kinetics of superabsorbent polymers (SAP) in various cement-based solutions

A new modified tea-bag method with various cement-based solutions is used to investigate the absorption kinetics of superabsorbent polymer (SAP) in concrete with low water to cement ratio (W/C). It includes a centrifugal process to efficiently remove the excess solution that can cause inaccurate absorption measurements. Various cement-based artificial pore solutions are prepared by dissolving ions in cement filtrates and considering the influence of silica fumes and polycarboxylate-ether type superplasticizers. Depending on the monovalent ion concentrations under the given Ca concentration of the filtrate, the absorption kinetics is drastically altered. This result underlines the risk of underestimating the absorption capacity of SAP in concrete. The suggested method and prepared solutions can be used to reasonably and efficiently determine the amount of required extra water for internal curing. Furthermore, the investigated ion-dependent characteristics will enhance our understanding of the absorption kinetics and contribute to the development of hydrogel products for concrete.