Impact of air exposure post-steam curing on the internal curing efficiency of porous ceramic roof-tile waste fine aggregate in steam-cured fly ash concrete

•Porous ceramic roof-tile waste fine aggregate was used as internal curing material.•Air exposure post-steam curing adversely affects the internal curing efficiency.•Air exposure post-steam curing made coarse pore structures on the concrete surface.•The internal curing mitigated this coarse pore structure zone of fly ash concrete.•The internal curing decreased the surface air permeability of steam-cured concrete. This study aims to elucidate the impact of drying on the internal curing effect of fine aggregates derived from roof-tile waste in steam-cured fly ash concrete. The research examines the compressive strength, mass loss, surface moisture content, and surface air permeability of the concrete under two conditions: conventional steam curing (followed by exposure to air) and six-day sealed curing post-steam curing. Additionally, pore size distributions were exclusively evaluated for concrete exposed to air post-steam curing. Results indicate that drying after steam curing negatively affects the internal curing by porous ceramic roof-tile waste. Nonetheless, internal curing effectively mitigated the negative impact of drying on the surface layer of steam-cured concrete.