Bio-Based Carbon Fibre Reinforced Polymer Laminates for Strengthening of Concrete Structures: Material Characterization, Bond to Concrete and Structural Tests

This paper presents an overview of an on-going research project that aims at the development of bio-based pultruded carbon fibre reinforced polymer (CFRP) laminates for strengthening of reinforced concrete (RC) structures. The bio-based laminates were developed using a resin system that is partially derived from renewable resources, with a bio-based content of 50% (wt.%). The first part of the paper presents the material characterization tests performed on the bio-based CFRP laminates and on their conventional petrochemical-based counterparts, including tensile and interlaminar shear tests. The effects of hygrothermal ageing (immersion in water at different temperatures, up to 6 months) in those properties were also assessed. In the second part of the paper, the bond behaviour to concrete was assessed by means of direct pull-out tests, in which the effect of hygrothermal ageing was also evaluated. Finally, the third part of the paper comprises a proof of concept of the bio-based CFRP laminates – full-scale four-point bending tests were performed on RC beams strengthened in bending with CFRP laminates, providing the load vs. midspan deflection response, as well as the contribution of the CFRP strengthening system to the overall response of the beams. The results obtained in this study showed that the bio-based CFRP laminates present comparable mechanical, bond and structural performances when compared to their conventional counterparts; notwithstanding their overall good performance, they presented higher susceptibility to delamination failure and to hygrothermal ageing; further developments on the resin formulation and manufacturing process are ongoing to overcome these issues.