Brick Kiln Bridge CFRP Strengthening

Interspan delivered the feasibility assessment, detailed design and installation of a carbon fibre reinforced polymer strengthening solution for prestressed bridge beams at Brick Kiln Bridge in Bloxwich. The soffit-mounted CFRP laminates were designed to accommodate up to 50% loss in prestress and were installed within two days.

Project Overview

Brick Kiln Bridge is a single-span road bridge comprising 14 internal inverted prestressed T-beams and external rectangular prestressed beams supported by two abutments. The bridge deck was replaced and widened during the 1960s, with the structure spanning approximately 7.5 metres.

CLM Construction was appointed main contractor to undertake concrete removal and repair works, including cleaning corrosion from the prestressing reinforcement and reinstating the concrete using a spray-applied repair system. Interspan Repair & Strengthening worked with Line Consulting Solutions to develop a strengthening solution that protected the existing prestressed beams throughout the repair process and restored the required flexural capacity.

Protecting Prestressed Beams During Concrete Repair

The repair works required local removal of concrete around the prestressing strands. This created the potential for reinforcement damage, local loss of prestress action while strands were exposed and reduced flexural capacity where corrosion had affected the pre-tensioned reinforcement.

Carbon fibre reinforced polymer laminates were selected to provide additional flexural reinforcement along the beam soffits. The CFRP system helped mitigate the structural risks associated with the concrete removal works while providing permanent strengthening to compensate for corrosion-related prestress losses.

Detailed Design for Up to 50% Prestress Loss

Interspan completed the carbon fibre strengthening feasibility assessment and detailed design based on the repair scope prepared by Line Consulting Solutions. The strengthening system was designed to accommodate up to 50% loss in prestress capacity within the affected beams.

The solution comprised externally bonded CFRP laminates installed to the beam soffits, coordinated with the concrete repair and strengthening procedure. This low-profile intervention provided the required structural capacity without materially changing the bridge geometry or adding substantial dead load.

Two-Day CFRP Installation

Following successful pull-off testing within the proposed strengthening zones, the CFRP laminates were installed within two days. The rapid installation demonstrated the programme efficiency of externally bonded carbon fibre strengthening for bridge repair and rehabilitation.

Compared with casting a reinforced concrete jacket to the soffits of the pre-tensioned beams, the CFRP solution reduced the extent of temporary works, wet trades, and curing time. It also provided a more practical approach for works that needed to be coordinated within a constrained infrastructure programme.

A More Efficient Strengthening Strategy

The Brick Kiln Bridge works demonstrate how targeted CFRP strengthening can support the repair and continued use of ageing prestressed infrastructure. By strengthening the existing beams rather than introducing a substantial concrete jacket, the solution minimised intervention, accelerated delivery and helped retain the existing structural asset.

Project-specific carbon savings were not quantified. However, extending the service life of the existing bridge and avoiding a more material-intensive concrete strengthening solution can reduce new material demand, site activity and associated disruption. Interspan’s infrastructure strengthening solutions can also be phased to suit short work windows across busy road and rail networks.

Interspan Scope

• CFRP strengthening feasibility assessment
• Detailed design of flexural strengthening to the prestressed beams
• CFRP laminate strengthening system designed for up to 50% prestress loss
• Coordination with the concrete repair designer and contractor
• Substrate pull-off testing and installation of soffit-mounted CFRP laminates
• Installation completed within two days