Reclaimed GFRP Sandwich Laminate from Decommissioned Wind Turbine Blades as a Road Noise Barrier Material: Full-Scale Acoustic Characterisation

Glass-fibre-reinforced polymer (GFRP) sandwich laminate recovered intact from decommissioned wind turbine blades is a candidate construction material: it is available in large panel sizes, requires no thermal or chemical processing, and has a documented structural performance. However, no acoustic characterisation of it has been reported. This study provides that characterisation for the road noise barrier application. A full-scale 4 × 4 m barrier panel was built from segments cut from decommissioned blades. A solid spar-cap laminate forms the lowest 1.2 m, and the sandwich shell forms the remainder, giving a mean surface mass of 39.6 kg/m2. Sound reflection and airborne sound insulation were measured in situ according to EN 1793-5 and 1793-6. The as-installed prototype reached DLSI,E (200–5000 Hz) = 29.6 ± 2.1 dB and DLRI = 0.1 ± 1.4 dB. It meets the 24–28 dB tender threshold most common among European road administrations, at one-fifth of the concrete’s surface mass. At 2000 Hz, positions facing the panel base fell 17.5 dB below their mass-based expectation, identifying a 5 cm mounting gap, not the material itself, as the origin of spatial variation. Away from the gap, per-band SIE reached 38–47 dB between 2500 and 5000 Hz, of the same order as values reported for purpose-made GFRP sandwich panels. These results form a prototype-level verification that a road noise barrier made of reclaimed blade laminate can meet the airborne sound insulation levels required in Europe.