Concrete bridge in Northern Ireland is first to use basalt fibre composite bars, which are corrosion-resistant

What is believed to be the world’s first bridge to use basalt fibre composite bars to reinforce the concrete is due to open this autumn in County Fermanagh, Northern Ireland.

Basalt was developed during the Russian space programme and as well as being a good insulator it is very strong - twice the tensile strength of steel reinforcement bar and a quarter of the weight. Crucially it is also corrosion resistant which led to it being specified on the project.

According to Ben Williams, managing director of MagmaTech who supplied the RockBar that replaces the traditional steel reinforcement, it’s estimated that over £500m is spent each year on the repair and rehabilitation of concrete infrastructure in the UK.

He said: “A large proportion of this is due to the corrosion of steel reinforcement embedded within the concrete. The aim of the project is to create an exemplar of a sustainable concrete bridge deck with excellent durability which will make the structure longer lasting with lower maintenance”.

The Thompson Bridge carries a two-lane A-road and replaces an existing structure. The single span bridge comprises of reinforced concrete abutments on piled foundations with a superstructure of ’W-shaped’ precast pre-stressed beams with a reinforced concrete slab bridge deck reinforced with RockBar.

The overall project management and design was provided by Amey while Queen’s University Belfast will be load testing the RockBar reinforced deck and in partnership with monitoring equipment specialist Sengenia conduct long term monitoring of the bridge deck using fibre optic strain sensors that are embedded in the bridge deck.

The bridge is one of the first structures to be built using basalt fibre composite reinforcement bars. The same material has also been used to replace stainless steel wall ties because of its low thermal conductivity.