Design and Performance Enhancement of Permeable Pavement Materials: Material Selection, Composition, Structural Design, and Multifunctional Integration in Sponge City Applications - Part 1

Part 1 establishes the material and sustainability foundations of permeable pavements (PPs) within the Sponge City paradigm. It consolidates hydrological-mechanical requirements and embeds them in international and domestic standards that govern infiltration, storage, and structural reliability. The core analysis links composition to pore-scale architecture and durability: gap-graded and stone-on-stone aggregate frameworks to raise connected porosity and stabilize load paths; binder families (cement, porous asphalt, polymer/hybrids) modified with supplementary cementitious materials (SCMs), nanosilica, polymer reinforcement, and surface densifiers to mitigate carbonation, freeze-thaw damage, and aging; and functional additives (hydrophobic agents, adsorptive biochar/layered double hydroxide (LDH), photocatalytic TiO₂) that deliver pollutant attenuation, de-icing resilience, and self-cleaning without sealing macropores. Valorization of industrial by-products and recycled aggregates (RCA, RAP, steel slag) is assessed for carbon reduction and resource efficiency, alongside performance trade-offs and quality-control routes. X-ray CT-informed packing models and pore metrics (connectivity, throat size, tortuosity) are highlighted as practical levers to reconcile hydraulic conductivity with mechanical resilience. Collectively, Part 1 provides a materials-centric framework that primes the structural design, multiscale modeling, and multifunctional integration developed in Part 2.