Composite piles: A review

• Research findings on construction and applications of composite piles are discussed.
• SRP and hollow FRP piles have significant potential for load bearing applications.
• Composite piles materials show superior freeze-thawing properties.
• Construction issues such as core–shell debonding are discussed with solutions.
• Applicability of analytical design approaches for composite piles is discussed.

Traditional piling in the form of steel, concrete or timber is susceptible to hazards within harsh marine environments. The deterioration of wood, corrosion of steel and degradation of reinforced/prestressed concrete piles in deep foundations has led researchers to experiment with methods to overcome these problems. Composite material piles, such as fibre-reinforced polymers (FRP) and structurally reinforced plastics (SRP), are a unique solution to the problems faced by traditional piling in marine environments. Their resistance to corrosion and long service life make them an economical and environmentally viable solution to traditional piling. Although a few manufacturers have begun to adopt some form of composite piling for fender applications, barriers remain that prevent their widespread use as load bearing piles. These barriers include the lack of specific driving and installation guidelines, limited full-scale geotechnical design data, long-term durability studies and in-depth environmental impact studies. To facilitate research in the aforementioned areas, this review paper details the historical use of composite piles, the structural and geotechnical design of several types of load bearing composite piles, the durability of piles, and, lastly, the construction and manufacturing processes involved. The findings show that there is a general consensus amongst researchers that fibre-reinforced piles (FRP) are structurally and geotechnically suitable for a range of load bearing applications, and that SRP piles, with adequate reinforcement, can potentially be used in deep foundations. More full-scale field research is still needed to develop sufficient driving guidelines, and durability tests emulating saline marine conditions should be carried out to assess the effectiveness of epoxies, and, lastly, reinforcing arrangements should be tested to prevent lateral deflection.