Enhancing sustainability in high-performance concrete: The role of solid waste-based porous ceramsite aggregates in internal curing and early-age performance

The transition toward sustainable construction materials requires innovative solutions that reduce resource consumption while maintaining structural performance. This study investigates solid waste-based porous ceramsite coarse aggregates (SW-PCAs) as eco-friendly internal curing agents for mitigating early-age cracking in high-performance concrete (HPC), with particular emphasis on their water absorption–desorption behavior and influence on early-age mechanical properties. A multi-method experimental approach—including volumetric flask tests, desorption analysis, nuclear magnetic resonance (NMR), and isothermal calorimetry (ITC)—was employed to systematically evaluate hydration kinetics, porosity evolution, and compressive strength development. Results show that high-water-absorption SW-PCAs exhibit rapid initial moisture uptake and controlled release under high relative humidity, satisfying the functional requirements of internal curing materials. Prewetting treatment significantly enhances curing efficiency by promoting effective moisture migration within the cement matrix, leading to improved early-age mechanical performance. Although SW-PCA-modified concrete shows a slight reduction in 28-day compressive strength compared with conventional mixes, prewetted high-absorption aggregates achieve noticeable strength gains. Moreover, SW-PCAs promote secondary hydration of unreacted cement particles, resulting in refined pore structures, particularly in systems incorporating prewetted high-absorption aggregates. These findings demonstrate that properly treated SW-PCAs can effectively balance early-age performance and long-term strength, highlighting their potential for sustainable concrete design through the high-value utilization of solid waste.