Effect of superabsorbent polymers on the shrinkage mitigation and pore structure characteristics of concrete with <scp>CaO</scp> ‐based expansive agent

Abstract CaO‐based expansive agents (CEA) can effectively compensate for the shrinkage of concrete. Considering that the hydration of CEA requires a significant amount of water, superabsorbent polymers (SAP) are used as internal curing agents. This study evaluates the influence of different SAP dosages and incorporation methods on the shrinkage mitigation and microstructure refinement of concrete containing different amounts of CEA. The results show that the incorporation of SAP can reduce drying shrinkage by extending the expansion period of CEA, thereby mitigating autogenous shrinkage. The addition of SAP refines the pore structure of the concrete, significantly increasing the number of harmless pores within 20 nm, but the macropores left by the desorption SAP particles adversely affect the compressive strength of concrete. The method of incorporating SAP also affects the curing effect; pre‐soaked SAP particles tend to form clusters, their higher water retention capacity enhances the internal curing efficiency. Among the results, the 0.3% dosage pre‐soaked SAP can effectively improve the pore structure of the concrete without compromising its compressive strength.