Permeability of recycled aggregate concrete containing fly ash and clay brick waste

The quantity of construction and demolition waste is continually increasing throughout the world, and recycling this waste is beneficial and necessary for environmental preservation. Because the permeability of concrete materials is closely related to their durability, this paper predominately discusses the permeability of recycled concretes composed of fly ash and clay brick waste. Various proportions of recycled coarse aggregates obtained from clay brick waste were used to replace natural coarse aggregates. The properties of natural aggregates and recycled aggregates were studied, and recycled aggregates exhibited a higher porosity. Additionally, the strength of the recycled concrete decreased because of the incorporation of recycled coarse aggregates. The permeability of water, air and chloride ions was evaluated through water absorption, water permeability, air permeability and chloride ion diffusion tests. The results indicated that the permeability of water, air and chloride ions increased when recycled coarse aggregates were used. Additionally, the recycled concrete containing clay brick waste had increased porosity and exhibited a loose paste matrix, which may be the reason for the increased permeability.