Properties of FRC with Carbon Fibres from Recycled Wind Turbine Blades

This paper investigates the use of recycled carbon fibre (rCF) from wind turbine blades in fibre-reinforced concrete (FRC). The research demonstrates the combined effects of fibre length (25 mm, 35 mm, and 45 mm) and fibre content (0.29%, 0.58%, and 0.87% by volume). The experimental programme included the investigation of compressive and tensile splitting strengths, as well as the determination of the Brittleness Index and fracture energy. The transfer of tensile forces through fibres was assessed based on the surface area of split samples. Tensile strength was determined for two loading directions: parallel and perpendicular to the direction of concreting. It was found that the maximum fibre addition reduced the compressive strength by up to 9% and that the tensile strength was significantly dependent on the fibre orientation, which was determined by the direction of concreting. The tensile strength perpendicular to the direction of concreting increased by a maximum of 11.8% and parallel to the direction of concreting by a maximum of 66% compared to plain concrete, depending on the fibre content and length. The research also demonstrated the synergy of pull-out and rupture of fibres in transmitting tensile forces. These studies provide important insights into the applicability of rCF as a dispersed reinforcement in concrete and have important implications for sustainability in the construction sector.