Case study on the strengthening of Routh Creek Bridge using externally bonded CFRP under adverse conditions

Managing bridges with substandard structural capacity presents an ongoing challenge for asset owners as infrastructure ages and vehicle loads increase. Many legacy structures do not conform to current design standards or adequately accommodate contemporary freight demands. Conventional strengthening techniques include externally bonded steel plates, concrete or steel jackets, and external post-tensioning. Since the early 2000s, fibre-reinforced polymer (FRP) systems, particularly carbon fibre-reinforced polymer (CFRP), have been adopted in Australia as an alternative strengthening method due to their high strength-to-weight ratio, corrosion resistance, and ease of installation. Recent advancements in research and material technology have led to increased industry recognition of CFRP systems. The Queensland Department of Transport and Main Roads (TMR) identified a portfolio of bridges requiring strengthening to accommodate current freight loads and selected CFRP as a potential solution. Given its limited prior application within TMR projects, a research-based pilot was initiated to evaluate feasibility, define performance criteria, and establish quality assurance protocols. This paper presents the pilot project’s implementation. The Routh Creek pilot project demonstrated the effectiveness of the CFRP strengthening in accordance with relevant standards. The field implementation demonstrated that vacuum-assisted installation and rigorous surface preparation procedures supported by robust quality assurance and environmental controls can ensure adequate bond performance despite environmental challenges. It also highlighted the significance of climate-adapted material handling, skilled workforce mobilisation and contingency planning. The technical challenges, mitigation strategies, and recommendations for future applications of CFRP in bridge strengthening are discussed.