It replaces its 250-year-old stone predecessor, which was destroyed during severe flooding as a result of Storm Desmond in 2015. The new single-span bridge has been designed to withstand extreme weather conditions and is in keeping with its location in Ullswater on the edge of the Lake District National Park.
Hanson UK worked with contractor Eric Wright Civil Engineering Ltd to create a bespoke concrete mix for the lower arch of the steel bridge, designed and constructed to provide structural strength, and also supplied and laid the asphalt to complete the project.
The steelwork for the new bridge was manufactured off-site in two sections, fabricated and welded on an adjacent piece of land, where the concrete lower arch was installed to allow the whole structure to be lifted into place over the River Eamont.
The high early strength concrete mix included Hanson Regen GGBS (ground granulated blast furnace slag), a cement replacement product which enhances the durability of the concrete while adding to its sustainability credentials. It is a by-product and using it to replace one tonne of Portland cement reduces the embodied CO2 of the concrete by around 780kg. Its use in large pours also helps minimise the production of heat, reducing the risk of thermal cracking.
In total 1,200m3 of concrete containing Regen have been supplied by Hanson’s nearby Penrith concrete plant to create the lower arch, bridge deck, bridge abutment and walls, highway approach retaining walls and several temporary works.
“Concrete supply to this project was always going to be a challenge due to the location, unique characteristics of the bridge and the tight deadline,” said Nick Graham, technical sales officer at Hanson Concrete.
Technical services manager Terry Balmer added: “Our technical team was involved early in the design stage due to the complex concrete requirements, especially for the high-quality visual concrete that makes up the deck composite, and this partnership working was fundamental to the success of the project.”
To complete the project, Hanson supplied 275 tonnes of asphalt from its nearby plant at Shap, which was laid by the company’s specialist contracting team. This included 130 tonnes of Tufflex, chosen for its durability and high resistance to cracking, for the surface course.
In addition to the complex nature of the bridge, the final abutment work, concrete arch and composite deck – as well as the asphalt – were all supplied under the added pressure of the COVID-19 pandemic and the associated issues entailed with furloughed staff and social distancing protocols.
