Material adsorption, the reverse process of evaporation diffusion, directly reflects the wettability of materials.
Wettability is one of the main factors that affect the drying shrinkage of materials. A device that measures the wettability
of recycled aggregate concrete (RAC) with fly ash is proposed in this study based on pore structure theory. The isothermal
absorption curve of RAC is examined with different fly ash contents. Results show that as the recycled aggregate
replacement rate increases, the moisture absorption capacity of RAC gradually increases. The addition of fly ash improves
the porosity of RAC structures and reduces material wettability.