Evaluation of the durability of structural concrete with low contents of Raw-Crushed Wind Turbine Blade

Abstract

The raw crushing of wind turbine blades that have reached the end of their service life has led to the emergence of a waste material known as Raw-Crushed Wind Turbine Blade (RCWTB). Its heterogeneous composition primarily consists of fibres of glass fibre-reinforced polymer (GFRP), polymeric and balsa wood particles. This study explores the incorporation of RCWTB at low contents in concrete mixes, with a focus on its effects on durability. To this end, four concrete mixes were prepared with RCWTB contents of 0 %, 0.5 %, 1.25 %, and 2.5 %. After fresh-state and strength characterization, the mixes were evaluated for water absorption, chloride penetration resistance, carbonation resistance, thermal conductivity and shrinkage. In terms of slump and compressive strength, the incorporation of RCWTB resulted in moderate reductions in both properties. Nonetheless, all mixes reached 28-day strength values widely exceeding 30 MPa, meeting structural performance criteria. Water absorption, chloride penetration, and carbonation depth increased with RCWTB content due to the presence of porous particles within RCWTB, reaching a maximum at 1.25 % RCWTB, then stabilizing for 2.5 % RCWTB. Conversely, thermal conductivity decreased with RCWTB content due to the low-density particles of balsa wood, also stabilizing beyond 1.25 % RCWTB. All these properties followed a logarithmic evolution with the RCWTB content. Finally, the stiffness provided by GFRP fibres when incorporating 1.25 % and 2.5 % of RCWTB slightly reduced concrete shrinkage. These durability findings allow identifying potential fields of application of concrete containing low RCWTB amounts, such as façade cladding elements, interior beams and columns of buildings, or pavements.