The 84-year old bridge, which is cared for by the Canal & River Trust charity, carries the busy A49 road over the River Weaver Navigation, north Cheshire. As part of a £1.5 million repair programme, the bridge recently underwent a complete refurbishment, including strengthening works to the underside of the bridge as well as improvements to its appearance.
Core to the project’s success was the ability to enhance the bridge’s structural integrity, in order to allow for heavier traffic, all without causing an increase of mass – given the required 2.5m allowance for boats passing underneath.
As such, Aggregate Industries’ Lytag secondary aggregate, being up to 50% lighter than normal weight aggregate, was the obvious choice for lead contractor, Kier Construction, working under the Canal & River Trust.
By using Lytag to replace the existing infill with the framework, the weight was effectively reduced from 2400kg/m3 to 1650kg/m3 giving increased flexibility and durability for Kier, whilst also ensuring an increased overall strength. This approach also negated the need for quarried aggregate, helping to reduce material requirements and ensure efficiencies.
With works now complete, the contract saw Aggregate Industries supply 100 tonne of 0/14mm Lytag; a tailored blend of aggregates specifically designed to offer a greater reduction in concrete density.
Steve Curley, general manager for Lytag at Aggregate Industries, said: “The design freedom afforded by Lytag is unparalleled in that it can offer the same level of structural performance as normal weight concrete however it is significantly lighter, thus reducing the dead load of a construction. In projects such as Acton Swing Bridge, where strengthening works need to be achieved without resulting in an increase to size or mass, this product can really make the otherwise infeasible achievable.”
Daniel Preston, principal engineer at the Canal & River Trust added: “Lytag is a fantastic product which enabled us to more easily meet our requirements, all while creating sustainable savings in concrete, foundations and other associated construction costs.”