Compressive behaviors of steel fiber‐reinforced geopolymer recycled aggregate concrete‐filled GFRP tube columns

This study introduced a novel composite component, the steel fiber-reinforced geopolymer recycled aggregate concrete-filled GFRP tube (CFFT) column, and conducted an axial compression test to assess its viability. The experimental variables encompassed specimen size, tube thickness, tube fiber winding angle, recycled coarse aggregate (RCA) replacement rate, and steel fiber volume content. The columns’ failure modes, stress-strain behaviors, dilatation behaviors, ultimate conditions, and hoop strain distribution were analyzed and discussed. Results indicated that geopolymer recycled concrete (GRC) was suitable for CFFT structures, exhibiting axial compression behavior akin to the conventional CFFT columns. The GFRP tube's properties emerged as the primary factor influencing the stress-strain behaviors of GRC-CFFT columns. Incorporating steel fibers helped counteract property degradation resulting from RCA, as the fibers effectively bridged cracks and mitigated stress concentration risks. Additionally, the study confirmed the applicability of an established unified model in predicting stress-strain behaviors of GRC-CFFT columns, proposing corresponding strength enhancement and strain enhancement models.