Comparative study on the behaviour of different infill materials for pre-fabricated fibre composite repair systems

Prefabricated fibre-reinforced polymer (FRP) composite jacket is now becoming an effective repair system for deteriorating piles and columns exposed to marine environment. This system works by providing grout infills between the annulus of the existing structure and the composite jacket. Few studies are however available on the optimal grouting materials that can effectively transfer the stresses between the existing structure and the FRP jacket. This study is investigating the effect of cementitious, concrete and epoxy-based grout infills on the structural behaviour of pre-fabricated glass-FRP (GFRP) tubes. The considered grouts have compressive strength and modulus of elasticity ranging from 10 MPa to 70 MPa and from 10 GPa to 35 GPa, respectively. The experimental results showed that the behaviour of the composite repair system is highly dependent on the modulus of elasticity and the compressive strength of the grout infill. The brittle failure behaviour of the cementitious and epoxy grouts led to localised failure in the FRP repair system while the progressive cracking and crushing of the concrete infill resulted in effective utilisation of the high strength properties of the composite materials. Theoretical analysis of the overall compressive behaviour has also been conducted and showed very good agreement with the experimental results. (C) 2018 Elsevier Ltd. All rights reserved.