Investigation into fibre composites jacket with an innovative joining system

• A new type of FRP jacket with an innovative mechanical joining system was developed.
• The materials used in the joint have a significant effect on the capacity of the FRP jacket.
• An interlocking key with GFRP rod has a better joint performance.
• Theoretical evaluation showed a good agreement with full-scale experimental results.
• The performance of jacket exceeds the industry standard for a permanent concrete formwork.

The effectiveness of fibre reinforced polymer (FRP) composites jacket for pile rehabilitation relies mostly on the continuity of repair system. This paper presents the development of a new type of FRP jacket with an innovative, easy-fit and self-locking mechanical joining system and the evaluation of the suitability of this composite repair system for pile rehabilitation and concrete formwork. An intensive characterisation of the mechanical properties of the composite resin for the interlocking teeth and locking key of the jacket was conducted. Similarly, finite element (FE) simulation on the behaviour of the FRP jacket subjected to internal pressure was performed and verified through full-scale experimental testing. The results showed that the use of a microfibre composite resin provide the highest capacity joint. Further, the embedment of an FRP rod in the locking key resulted in an FRP jacket with a better joint performance. The results of the FE simulations showed a good agreement with the experimental results in predicting the lateral expansion in the elastic stage, capacity and failure behaviour of the FRP jacket.