Cyclicity estimation of superabsorbent polymer in concretes based on similarity principles

Abstract

The cyclicity of superabsorbent polymers (SAP) significantly impact the efficiency and sustainability of crack self-healing for concretes. This study proposed a method to assess the cyclic absorption-release ability of SAP in concretes based on the similarity principles of materials and geometry. The evolution of its properties during cycling was characterized using the tea-bag method. Microstructure, elemental composition, content, and functional groups were analyzed through field emission scanning electron microscope, energy dispersive spectrometry, and Fourier transform infrared spectroscopy. Results demonstrate that the absorption capacity of SAP with different particle sizes showed a rapid then a slow decrease with the increasing wet/dry cycles. The increased swellable volume accelerated the attenuation process, exacerbating ion complexation, and ageing. Despite these changes, SAP exhibited excellent cyclicity owing to its high molecular stability with minor changes in functional groups. It is necessary to consider the matrix space limitation in the estimation process, which can enhance the reliability and availability of SAP durability tests in concretes.