Reusable and recyclable nonbonded composite tapes and ropes for concrete columns confinement

This paper investigates the use and efficiency of structural continuous tapes (laminates), fibre tapes and fibre ropes made of different materials (natural or not) in enhancing the axial strain ductility and stress of confined concrete. All used confining materials are non-impregnated, unbonded to concrete and thus easy to reuse and recycle. Concrete cylinders confined with polypropylene rope reached axial strain as high as 0.15 with no rope fracture. Wrapping of cylinders with ultra-high molecular weight polyethylene (UHMWPE) tape or aramid fibre tapes or basalt fibre tapes may provide concrete significantly enhanced mechanical properties under monotonic or cyclic load. Cylinders wrapped with basalt fiber tape presented gradual fibre fracture and ductile load drop after maximum bearing load. Vinylon fibre ropes and UHMWPE or basalt or aramid fibre tapes show interesting resilience features as they can reach high portion of their confining efficiency even after their fracture initiation. In addition, the study presents the test results of severely damaged reinforced concrete (RC) column, repaired with high strength mortar and externally wrapped with hybrid basalt – polypropylene confinement. The retrofitted column fully restored the original ever-increasing σ-ε behavior, revealing remarkable energy dissipation under cyclic loading. It reached 0.052 axial strain and then it was early terminated for safety reasons, despite having already sustained 0.058 strain during initial loading.