STUDYING SURFACE ROUGHNESS TO ENHANCE THE BOND PERFORMANCE OF RECYCLED FRP NEEDLES IN CONCRETE

The application of fibre-reinforced polymer (FRP) composites has substantially increased in recent years. Currently, the reuse and recycling of composite waste is minimal, with most waste being disposed of in landfills or incinerated. As an alternative recycling strategy, incorporating glass fibre-reinforced polymer (GFRP) waste into concrete has shown structural potential. This study investigates a new type of discrete reinforcing elements for concrete produced from GFRP wind blade waste material, defined as GFRP needles. The bond strength between the GFRP needles and the concrete is important to produce GFRP-reinforced concrete of satisfactory mechanical performance. The bond performance between commercial GFRP bars and concrete is achieved through their sand coating layer and surface deformations. However, in this study, the cutting process results in a smooth surface on the GFRP needles, therefore sand and glass blasting techniques were employed to create a rougher surface to address this issue. The surface roughness was measured using an Alicona microscope machine, and the bond strength was assessed using pull-out tests and a 50 mm bonded length. The results showed that glass blasting leads to higher bond strength than sandblasting. However, a higher scatter was observed in the glass blasted GFRP needles due to the randomised nature of the blasting method.