Coolderry Bridge CFRP

Innovative Use of Bracket System ...

Our Falkirk office recently undertook a Carbon Fibre Reinforcement Strengthening contract for the Graham Group in Northern Ireland over a weekend in May 2021. The contract involved the placing of 2 no. 8.5m x 150 x 15 plates to the underside of the of the exposed steel beams on the rail crossing bridge at Coolderry, nr Ballymoney, County Antrim.

The works were programmed over a 5-night rail possession, consisting of preparation of the exposed steel work, pull off tests and the placing/installation of the plates.

In consultation with the client, this program was reduced to 2 nights over the Friday and Saturday. The client provided the aluminium towers and a MEWP on the first possession to access the beams. This allowed us to mechanically clean the beams, ready for the pull off “Dollies” to be fixed. The steel on this bridge was in remarkably good condition, considering it was over 50 years old.

On the second nights possession the client built a fixed scaffold spanning the length of the bridge to allow us complete access. After successful pull off tests, the process of applying the Mapei Adesilex PG1 adhesive and the  CFRP plates began with the solvent wipe down of the steel beams and the CFRP plates. The adhesive was applied to both the steel flange and the plates. The 5-man team then lifted the plates into place, starting at one end and moving along the length of the plate. At the same time the excess adhesive was pushed out, removing any trapped air, leaving a 2-3mm bed of adhesive.
While moving along the plate an initiative design of magnetic brackets and aluminium straps (with a pull force of 105.6kg per bracket) were placed in position at 1m centres to keep the plate secure and in position until the adhesive had sufficiently set.

Before the end of the shift (approximately 6 hours) and once the adhesive had sufficiently set the brackets were removed. This 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.