This study investigates the axial behavior of recycled aggregate concrete (RAC) cylinders (150 × 300 mm, 50 % recycled coarse aggregate) strengthened using external fibre-reinforced polymer (FRP) wraps: carbon (CFRP), basalt (BFRP), and glass (GFRP) combined with internal steel ties to form a hybrid confinement system. Nine mix configurations were tested to evaluate the influence of FRP type and tie spacing on compressive strength, ductility, and confinement efficiency. Recycled aggregates led to a 10-13 per cent decrease in the natural compressive strength at the base level owing mainly to their different microstructure and increased water absorption. The experimental results show that hybrid confinement markedly improves the mechanical performance of RAC. Compared with unconfined specimens (30.2 MPa), FRP-only systems increased compressive strength by 40-100 %, while the inclusion of three and four steel ties further enhanced it by 60-80 %. The ultimate axial strain rose by as much as twelve times (≈1200 %), indicating substantial gains in deformability and energy absorption. The strength hierarchy CFRP > BFRP > GFRP was consistent across all tie configurations, though the performance gap narrowed as tie spacing decreased, confirming that volumetric steel ratio becomes dominant in highly confined systems. Analytical predictions using the modified Lam–Teng bilinear model correlated strongly with experimental strengths (R² = 0.94) but over-predicted strain due to RAC heterogeneity and premature FRP–epoxy debonding. Cost analysis identified BFRP as the most efficient material, providing ≈ 90 % of CFRP’s performance at 50 % lower cost (₹ 24.5 / MPa vs ₹ 35 / MPa). The findings offer practical guidance for designing economical, high-ductility hybrid confinement systems for sustainable rehabilitation and retrofitting of structural members incorporating recycled aggregates.
