Axial compressive behavior of phosphogypsum-filled fiber-reinforced polymer tube short columns: Test and theoretical analysis

To overcome the high brittleness, water absorption tendency, and acidity of phosphogypsum (PG), a novel type of phosphogypsum-filled fiber-reinforced polymer (FRP) tube short column is proposed. The effect of the inner diameter, fiber winding angle, and thickness of the FRP tube on the axial compression performance of phosphogypsum-filled FRP tube specimens was investigated through experimental and theoretical research. Compared to unconfined PG short columns, phosphogypsum-filled FRP tube short columns exhibit a 326.0 %–822.0 % increase in ultimate bearing capacity, a 1336.6 %–2638.5 % increase in ultimate axial deformation, and a 954.7 %–1911.1 % increase in ductility coefficient. The compressive strength of confined PG increases as the inner diameter, the thickness and the fiber winding angle increase of the FRP tube. A theoretical model based on Samaan et al. for the axial stress-axial strain curve of phosphogypsum-filled FRP tube specimens was developed. Using this model, a parametric analysis was conducted, highlighting the significant impact of FRP tube inner diameter, thickness, fiber winding angle, and hoop tensile strength on the axial stress-axial strain curve of phosphogypsum-filled FRP tube specimens. The innovative method proposed in this paper improves the axial compressive performance of PG, expanding its potential for engineering applications.