by Graham Black | Wed 06 Feb 2019
Smart Concrete Bridge Repair
The bridge over the River Nene in Peterborough was built in the 1970s and features an iconic V-shaped pier. Inspections of the bridge revealed signs of structural weakness in its bearings and cracking to the saddles of the piers. Traditional methods of replacing the bearings were not possible because of the ornate design of the piers, which did not allow space for jacks to be positioned beneath the superstructure, nor were jacking points provided within the box girders.
Skanska was awarded the £5m refurbishment project and came up with an innovative solution to this challenging project, to encase the piers in reinforced concrete jackets, which would provide jacking platforms to allow the superstructure to be lifted.
For this plan to work, the concrete used had to be lightweight to minimise the additional load on the foundations, yet strong enough to strengthen the piers and to carry the jacking loads. In addition, it had to be self-compacting and flow easily around the dense reinforcement.
The solution was Aggregate Industries’ Lytacrete concrete mix, which uses a secondary aggregate called Lytag, a lightweight material that offers the same structural performance as more common concrete mixes. It is the first bridge repair of its kind in the UK to use this solution.