Relative humidity evolution in recycled aggregate concrete with glazed hollow beads internal curing: Self-desiccation and moisture diffusion

Internal relative humidity plays a critical role in the durability of recycled aggregate concrete (RAC), particularly under self-desiccation and moisture diffusion conditions. This study investigates the internal humidity evolution of RAC incorporating glazed hollow beads (GHB) as an internal curing agent. Experimental results demonstrate that the water absorption and release properties of GHB effectively enhance internal curing, regulate humidity loss at different depths, and mitigate the effects of self-desiccation and moisture diffusion. The relationship between GHB content and the internal humidity gradient in RAC was established. Furthermore, a quantitative assessment of self-desiccation and moisture diffusion revealed that moisture diffusion primarily drives humidity reduction at shallow depths, while self-desiccation has a greater influence at greater depths. Comparisons with other internal curing materials highlight the superior long-term moisture regulation effects of GHB under low dosages. The findings provide valuable insights into moisture regulation mechanisms and offer guidance for designing more durable and sustainable concrete.