Client
Graham Group
Value
£58k
Sectors & Services
Highway Structures Structural Strengthening Projects Projects
Concrete Repairs Ltd (CRL) was commissioned by the Graham Group to undertake a Carbon Fibre Reinforcement (CFRP) strengthening programme on the rail crossing bridge at Coolderry, near Ballymoney, County Antrim. The bridge, over 50 years old, features exposed steel beams requiring structural reinforcement to extend service life and support ongoing rail operations.
The contract was strategically scheduled over a weekend possession in May 2021 to minimise disruption to rail traffic. CRL’s involvement was essential to deliver a rapid, technically precise solution, utilising advanced CFRP technology for structural strengthening while demonstrating best practice in asset management and structural repairs UK.
Services undertaken
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Preparation and mechanical cleaning of steel beams
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Pull-off testing of steel substrate
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Solvent wipe-down and preparation of CFRP plates
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Application of Mapei Adesilex PG1 adhesive
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Installation of CFRP plates to steel beams
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Temporary securing of plates using magnetic brackets and aluminium straps
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Removal of temporary fixing system after adhesive curing
The project involved the installation of two CFRP plates measuring 8.5m x 150mm x 15mm to the underside of the steel beams. CRL’s methodical approach began with mechanical cleaning of the beams using aluminium towers and a mobile elevating work platform (MEWP) supplied by the client. Pull-off tests were conducted using “Dollies” to confirm the adhesion performance and integrity of the steel substrate.
On the second night of possession, a fixed scaffold spanning the bridge length was erected, providing safe and complete access to the beams. CRL applied Mapei Adesilex PG1 adhesive to both the steel flange and the CFRP plates following a solvent wipe-down to ensure optimal adhesion. The five-person installation team lifted the plates into position sequentially, ensuring a continuous 2–3mm adhesive bed while expelling trapped air.
A bespoke arrangement of magnetic brackets and aluminium straps, designed with a pull force of 105.6kg per bracket and spaced at 1m centres, temporarily secured the plates until the adhesive had set. This innovative system reduced reliance on prolonged possessions, accelerated the installation process, and eliminated additional site visits. After approximately six hours, the brackets were removed, leaving the plates securely bonded. CRL’s expertise in precision structural repairs and its innovative use of temporary fixing solutions ensured efficiency, safety, and adherence to client timelines.
"The installation and use of the innovative bracket system saved CRL and the client possession time and a site visit leaving a very happy client and a tired workforce ready to sail back to Scotland."
Murray Soutar | Regional Director (Scotland & Northern Ireland) | CRL
The application of CFRP plates provides a high-strength, lightweight reinforcement solution that significantly enhances the load-carrying capacity of the existing steel beams while maintaining minimal additional deadweight. The use of a carefully selected adhesive and controlled installation ensures durable bonding, resistance to environmental degradation, and long-term performance. The temporary magnetic bracket system not only safeguarded the integrity of the installation during curing but also minimised handling stress and the potential for misalignment.
CRL’s integrated approach combines advanced materials, specialist techniques, and practical on-site innovation to deliver resilient, low-maintenance strengthening solutions. The works extend the service life of the bridge, reduce the need for future interventions, and support the long-term asset management strategy for this critical rail infrastructure.
