Mechanical recycling of GFRP waste as short-fiber reinforcements in microconcrete

• Mechanical recycling of the GFRP waste for being used as short reinforcing fiber.
• Treatment effects in the properties of the GFRP recycled fiber reinforced concrete.
• Analysis of the internal structure of the GFRP recycled fiber reinforced concrete.
• Verification of the admissibility of the shrinkage and alkali-aggregate reaction.

The suitability of mechanically recycled glass fiber reinforced plastics (rGFRP) from different sources as short fibers is considered for precast microconcrete components. Shredding and screening processes were successively adjusted to obtain a high-fiber content product with fiber lengths optimized for flat microconcrete elements.The physical–mechanical properties of the concrete with rGFRP were characterized by compression and bending tests as well as shrinkage stability and alkali-aggregate reaction. Furthermore, the interaction between the rGFRP and the cementitious matrix was observed and characterized by scanning electron microscopy. It was found that when the rGFRP material obtained from an optimized milling process was used to prepare the microconcrete specimens (40 × 40 × 160 mm3), the flexural and compressive strength at 28 days increased by 16% and 22%, respectively, in comparison to the control specimens.