Exploring the evolution of superabsorbent polymer in cementitious materials: insights into testing methods and their impact on properties

The aim of this paper is to review the developments in the use of superabsorbent polymer (SAP) in cementitious materials. This review covers the classification, properties, and methods for testing SAP, along with its impact on concrete properties, and other noteworthy developments in SAP usage. Various methods can be used to test the water absorption by SAP. Among them, the tea bag method is considered a simple and time-saving test, while centrifuge and suction filtration methods are regarded as accurate because they remove inter-particle liquid. The water absorption by SAP is affected by factors such as SAP composition, method of preparation, physical characteristics, and properties of the fluid. Higher fluid temperature (e.g., 60 °C) leads to greater absorption and release distance, while higher pH levels (pH 13) result in lesser absorption. The optimal dosage of SAP varies between studies, generally ranging from 0.1% to 1.5%. Higher SAP content (0.3–8%) reduces workability and decreases slump. Results related to strength vary; some studies have reported increased strength due to SAP’s maintenance of higher internal relative humidity, while others have observed decreased strength due to increased porosity caused by SAP. The inclusion of SAP typically leads to a strength recovery of about 10% over time due to the continuous hydration process. Curing methods also influence strength, with sealed curing showing greater strength. Additionally, an increase in SAP dosage (0.1–0.6%) reduces shrinkage. Furthermore, the paper discusses the challenges encountered while using and testing SAP, as well as the explanations provided by researchers.