Repairs carried out to Forth Road Bridge

A £13.6 million project to repair and refurbish the Forth Road Bridge in Scotland has been completed.

Spanning the Firth of Forth in Scotland, the project for the Forth Estuary Transport Authority involved the replacement and refurbishment of the steel bearings on the north and south approach viaducts of the bridge, together with associated concrete repairs to the approach piers and strengthening to the steel box superstructure.

Appointed by main contractor Balfour Beatty to bring the structure up to 21^st century specifications, specialist contractor Freyssinet Makers turned to Sika for a long term, reliable and industry-proven concrete repair solution.

“The steel bearings sit on top of the approach viaducts and allow the deck to move and accommodate changes in temperature and traffic load,” commented Graham Stanford, business manager for Freyssinet Structural Repairs and CCSL. “During inspections and monitoring, the existing bearings were exhibiting little or no movement but were showing varying amounts of corrosion. Consequently the surrounding concrete and grout was beginning to show considerable wear and tear.”

Prior to the replacement of the bearings, action was required to repair the concrete pier tops with Sika’s unrivalled range of high performance repair mortars once again proving ideal to re-strengthen the approach viaduct piers and protect this iconic bridge for many years to come.

Approached early in the design process, Sika worked closely with the consulting engineers Atkins and main contractor Balfour Beatty to advise material selection and properties required for a performance-based specification.

Significant structures in their own right, the two approach viaducts at 252 metres and 438 metres on the north and south sides respectively, required around 100 tonnes of concrete repair products.

“Extensive flow trials were carried out on a specific test rig set up by Balfour Beatty and Atkins to prove the flowability and strength of these products,” adds Ronnie Turner of Sika. “Once testing was done Atkins signed off the specification and both were poured under gravity and allowed to cure while the bridge was still live and being used.”