Award of Merit: Longevity Category
Silver Jubilee Bridge Approach Viaducts Repair
Runcorn, United Kingdom
Submitted by Mott MacDonald
Halton Borough Council
Runcorn, United Kindgom
Altrincham, United Kingdom
Various UK-based contractors including Makers UK, Concrete Repairs, Ltd., and Balvac Whitley Moran
Hertfordshire, United Kingdom
The Silver Jubilee Bridge in Runcorn, United Kingdom, was constructed in the 1960s. It is the third-largest bridge of its type in the world and is part of a major highway route in North West England, carrying 90,000 vehicles per day on four lanes. Any closure results in a 40-mile diversion; the integrity and durability of this structure are critical.
Reinforced concrete is probably the world’s most successful and cost-effective structural material. Problems are frequently encountered, however, with the corrosion of the reinforcement causing the concrete to delaminate and spall. Tensile forces are produced when expansive corrosion products are formed, which causes the concrete to crack and delaminate. The corrosion of the reinforcing steel is most often due to the effects of aggressive chloride ions or the carbonation of concrete. This form of degradation can be seen on many types of structures, including car parks, steel frame buildings, and bridges.
Over the years, the reinforced concrete approach viaducts of this bridge complex have suffered from both carbonation and chloride attack. In 1992, a phased repair strategy was initiated that has incorporated advancing repair technology as appropriate. Techniques used include conventional concrete repair, cathodic protection, corrosion inhibitors, and reinforced polymer-modified cementitious coatings.
The durability of the phased remedial measures has resulted in a cost-effective repair strategy that could be tailored to the client’s funding, which means that this vital part of infrastructure remains in use.