Mitigating early age shrinkage in internally cured concrete under extreme dry conditions with MEA and SRA

While internal curing technology has proven effective in mitigating shrinkage and cracking in concrete, its limitations under extremely arid conditions remain a significant challenge. To address this gap, this study investigates the effects of internal curing and shrinkage-reducing materials on the shrinkage behavior of concrete under harsh conditions, systematically evaluating the synergistic interactions of superabsorbent polymer (SAP), MgO expansive agent (MEA), and shrinkage-reducing agent (SRA) on drying shrinkage, autogenous shrinkage, and crack resistance of concrete. The results demonstrated that SAP effectively delays autogenous shrinkage by maintaining internal humidity, but increases drying shrinkage due to pore coarsening. MEA counteracted the strength loss induced by SAP through the formation of expansive products, which enhanced control over autogenous shrinkage, while also consuming internal water. Conversely, SRA reduced capillary pressure, alleviating long-term drying shrinkage while promoting hydration synchronization. Microscopic analysis revealed that SAP enhanced hydration efficiency but resulted in residual porosity, MEA densified the matrix through Mg(OH) 2 crystallization, and SRA improved water retention. The combined application of MEA and SRA exhibited optimal performance, achieving superior shrinkage reduction and crack resistance by delaying shrinkage progression and minimizing harmful pores. Numerical modeling corroborated the experimental findings, quantifying the contributions of SAP, MEA, and SRA to shrinkage behavior and highlighting their synergistic effects. The results derived from present study offer a substantive foundation of data and theoretical frameworks to advance structural design as well as operational maintenance in regions characterized by extreme aridity.