Eco-friendly and mechanically reliable alternative to synthetic FRP in externally bonded strengthening of RC beams: Natural FRP.

The NFRP shows great advantages over synthetic FRP in terms of eco-friendliness, recyclability, cost per weight to resist tensile load and bio-degradability. In this study, the flexural performance of reinforced concrete beams strengthened with NFRP laminates is investigated. For the first time, this paper proves the advantages of NFRP over synthetic FRP in terms of strengthening effect and material cost. Two types of NFRP are selected for study: flax and jute. The mechanical properties of the NFRP laminates were first studied by standard coupon tests. A total of six reinforced concrete beams were externally bonded with NFRP laminates and tested under four-point bending. NFRP rupture and debonding were found to be the major failure modes of the strengthened specimen. The flexural performance was evaluated in terms of the load-deflection relationship, the load-strain relationship, the NFRP strain distribution, and the bond stress distribution. The test results showed that NFRP achieved strengthening effects similar to carbon FRP while its cost-efficiency was 20%–40% higher. The precision of current design codes to predict load-carrying capacity of NFRP-strengthened RC beam is evaluated, indicating further modifications to current design codes are needed for application to NFRP strengthening. [ABSTRACT FROM AUTHOR]