When the M3 Hawley Lane Bridge started to show signs of excessive deflection under heavy traffic, engineers at Enterprise Mouchel devised a repair solution that included the installation of a new central bridge pier to support two existing outer piers. To counteract changes to the deck’s dynamics and reinforce the bridge between the three structural piers, Sika CarboDur rods and Sika CarboDur plates were used – marking one of Europe’s largest applications of composite reinforcement systems.

Built in the 1960s, the concrete bridge had been under-designed to withstand the traffic volumes and live loads under which it is now subjected every day. With the span between two original outer structural piers proving insufficient to cope with the loading forces of constant and heavy traffic, a third pier proved the most suitable reinforcement solution to meet the increasing capacity demands.

However, as the initial bridge construction had not accounted for a third structural pier, further strengthening was required to accommodate changes in the structure. Approached early in the design process, Sika worked closely with the consulting engineers to advise material selection and properties required for a performance-based specification – in-line with Highways Agency best practice.

To achieve the required performance, carbon fibre plates and rods were specified as part of a complex repair and concrete protection solution. The use of carbon fibre offered an accelerated application process and enhanced performance properties when compared to traditional steel reinforcement. Set to be delivered by main contractor Birse Civils and specialist contractor Structural Systems UK Ltd, the £5 million project will see a total of 1,000mtr of Sika CarboDur Rods and 5,000mtr of Sika CarboDur Plates installed.

Sika CarboDur is a Carbon Fibre Reinforced Polymer (CFRP) system, designed to provide high performance structural stability in the most demanding reinforcement applications. Each plate, measuring 100mm wide and 1.4mm thick, was supplied by Sika in a variety of lengths of up to 13 metres to deliver exceptional reinforcing capability across the entire application area.

Utilising a team of skilled applicators, Structural Systems UK Ltd is completing the installation of the carbon reinforcement within a strict two month period.

Using the company’s extensive experience of structural strengthening – including in 2011 the UK’s largest application of ultra high modulus composite reinforcement at Embankment Tube Station – Sika will be closely involved at Hawley Bridge from initial specification to project completion. The company’s full range of structural strengthening systems are suitable for increased loading, change of use, column wrapping, as well as applications in the nuclear industry for protection against seismic activity.

On track to be delivered within a two month period, the project will be successfully finished to the highest standard thanks to a well-organised, detailed application process and with minimal effect on the road’s users – above and below the M3 Hawley Lane Bridge.

Composite reinforcement bridge strengthening

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