Durability performance of recycled aggregate porous concrete for pavement base applications under acid and sulphate exposure

The long-term durability of Recycled Concrete Aggregate (RCA)-based Porous Concrete (PC) remains a key limitation for its use in sustainable pavements, particularly under acid and sulphate exposure, and is insufficiently addressed in the existing literature. To address this gap, this study aims to optimise RCA-based PC through a systematic multi-parameter mix design considering RCA–Virgin Aggregate (VA) blending, fibre reinforcement (PET and steel), silica fume, and fine aggregate inclusion. Twenty-eight mixes were evaluated for density, void content, compressive strength, permeability, and durability under exposure to sulphuric acid (3% and 5% H 2 SO 4 ) and magnesium sulphate (3% and 5% MgSO 4 ). Results show that PC produced solely with RCA exhibits higher porosity, lower strength, and greater mass loss, due to a weak aggregate packing and a highly connected pore structure. The novelty of this study lies in the combined use of RCA–VA blending and supplementary fine materials to refine pore connectivity and enhance matrix densification. The optimised mix (M28) achieved a density of 1790 kg/m³ , a void content of 17%, a compressive strength of 7.45 MPa, a permeability of 0.574 cm/s, and a mass loss of less than 5%, demonstrating its suitability for pavement base and sub-base applications. • Durability-driven optimisation of PC with high RCA content. • RCA-VA blending refined pore connectivity and improved chemical resistance. • Optimised mix achieved 7.45 MPa strength with 0.574 cm/s permeability. • Sustainable PC suitable for pavement base and sub-base applications.