A novel phosphogypsum aggregate vegetated concrete with tunable properties and enhanced ecological compatibility

To address the dual challenges of solid waste management and the performance limitations of conventional vegetated concrete, this study develops a novel cleaner material strategy for the large-scale valorization of phosphogypsum (PG). A synergistic innovation is proposed by utilizing narrowly graded, high-sphericity phosphogypsum aggregates (PGA) as the sole coarse aggregate, coupled with a novel mix design methodology for phosphogypsum aggregate vegetated concrete (PGAVC). Systematic experiments were conducted to investigate the individual effects of water-to-binder ratio (W/B), aggregate-to-binder ratio (A/B), and silica fume (SF) content on pore structure, permeability, and compressive strength, thereby enabling precise regulation of key performance parameters. Under optimized mix proportions, PGAVC achieves a balanced performance portfolio: Connected porosity of 9.7%–27.8%, permeability coefficient of 0.94–22.56 mm/s, compressive strength of 4.2–15.1 MPa, 28 day vegetation coverage of 98%, and effective pH self-regulation to near-neutrality (≈7.5). Leaching tests validate that the release of soluble phosphorus (P), fluorine (F), and heavy metals is effectively immobilized, fully complying with environmental safety criteria. This work not only establishes a sustainable and cleaner production pathway for large-scale PG recycling but also provides critical theoretical and technical support for advancing eco-friendly slope protection and green infrastructure development