Recent research by Anusha Toshikhani and Solomon Debbarma has unveiled a significant advancement in the performance of roller-compacted concrete (RCC) pavements through the use of internal curing. Unlike traditional concrete, RCC often suffers from a weakened interfacial transition zone (ITZ) due to its low-paste composition and limited early-age moisture, making it highly susceptible to environmental stress. By replacing 20% of fine aggregates with pre-soaked expanded clay, the study demonstrated a substantial improvement in the microstructure of the concrete. This internal reservoir of water directly addresses the hydration limitations found in low water-cement ratio mixtures, particularly in challenging semi-arid and tropical humid environments where external curing often fails to penetrate the dense material effectively.
The study employed advanced 4D X-ray microscopy and nanoindentation to reveal that internal curing significantly reduces both the porosity and the thickness of the ITZ. Higher water-cement ratios typically lead to a more porous and fragile structure due to the wall effect, but the introduction of internal moisture promoted the development of high-density calcium silicate hydrate, creating a much tougher bond between the cement and the aggregates. These micro-level enhancements translated into impressive macroscopic results, with compressive strengths increasing by nearly a quarter and flexural strengths rising by over 18%. This discovery provides engineers with a robust strategy to extend the service life of sustainable pavement infrastructure by tailoring hydration at the molecular level.
Read more here: https://www.tandfonline.com/doi/full/10.1080/10298436.2026.2634953