Early-age shrinkage and hydration of concrete incorporating a mutually reinforcing systems of super absorbent polymers and MgO expansive agent under low humidity conditions

This study centers on evaluating the mechanical properties, autogenous and drying shrinkage kinetics, and crack propagation behavior in concrete samples internally cured with SAP and integrated with MgO-based expansive agents. A comprehensive material characterization was performed using state-of-the-art analytical methods such as Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and Mercury Intrusion Porosimetry (MIP), aiming to shed light on the microstructural transformations, phase composition shifts, and evolution of the pore network. Our findings reveal that SAP's moisture-release mechanism effectively mitigates water competition between the MgO expansive agents and the cement hydration process. Moreover, MgO's delayed expansive behavior serves as a beneficial factor in curtailing localized high-porosity zones in internally cured concrete. The knowledge gleaned from this investigation offers a robust framework for the design of concrete structures that need to withstand challenging environmental conditions marked by low ambient humidity and significant temperature fluctuations.