Recyclable thermoplastic FRP bars for reinforced concrete structures: Current status and future opportunities

Replacing steel reinforcing bars in reinforcing concrete (RC) structures with fibre-reinforced polymer (FRP) bars is an effective approach to avoid problems associated with corrosion of steel bars due to external chloride ions and humid environments. Recently, thermoplastic FRP bar has attracted much attention due to its advantages such as recyclability and on-site workability. In particular, bendable FRP threaded bars made of thermoplastic composites are very easy to be processed on-site due to their flexibility when heated. A number of studies have been conducted on recyclable thermoplastic FRP bars for reinforced concrete structures. This article provides a comprehensive overview of the benefits associated with thermoplastic FRP bars. The basic properties of thermoplastic FRP bars (including mechanical properties, durability properties and creep properties, etc.) are reviewed and summarized, and the comparisons between them and thermosetting FRP bars are conducted. Opportunities for further research on thermoplastic FRP bars in terms of material properties and structural engineering applications are finally identified.