Northam River Bridge, UK
Eliminator protection for Southampton's Northam River Bridge
The Northam River Bridge was originally constructed in 1799 and operated as a toll road. It was replaced in 1889 with an Iron bridge and was replaced again in 1954 with a pre-stressed concrete bridge, making it the first major pre-stressed concrete road bridge in the UK.
With the surfacing on this 148m long bridge deck very uneven and in increasingly poor condition, in January 2015 a significant bridge deck refurbishment programme was undertaken including the replacement of the waterproofing and surfacing, using Stirling Lloyd Polychem’s Eliminator system and Gussasphalt, at a cost of £1.2million.
Southampton City Council
Stirling Lloyd Construction & VolkerLaser
- Northam River Bridge, Southampton
Working on behalf of Southampton City Council, consultant engineers Capita specified the use of Stirling Lloyd’s Eliminator waterproofing membrane system in conjunction with Gussasphalt surfacing produced by Hanson UK on behalf of Aeschlimann AG – Stirling Lloyd’s partner for the promotion of Gussasphalt surfacing, for the main deck refurbishment.
Due to problems with the different types of surfacing previously used, and with the bridge providing a busy transport route into and out of Southampton, the proven combination of Eliminator and Gussasphalt were considered the ideal specification to provide a long life and enhanced in-situ performance before any first maintenance would be required, while their ease and speed of application would minimise traffic congestion and avoid costly road closures and diversions during the refurbishment. For the project 3,118m2 of Eliminator was spray applied to both the main deck and the sidewalk, 2,366m2 of Gussasphalt was used on the main deck.
Appointed to carry out all deck preparation, waterproofing and resurfacing, Stirling Lloyd Construction, working in partnership with VolkerLaser Ltd, two authorised contractors for the installation of the Eliminator system, initially planed off the existing asphalt which exposed the badly damaged deck. This was repaired using Metaset Resifilla Horizontal, a resin based rapid cure system manufactured by Stirling Lloyd Polychem.
Two coats of the Eliminator membrane were then spray-applied with a Flintag aggregate propagated into the second coat whilst the membrane was still wet to provide an enhanced shear key interface between the waterproofing and the surfacing which was to be 55mm thick.
Once the Eliminator had cured, which took less than an hour, a hot melt adhesive (Tack Coat No 2) was applied to further enhance the bond between the membrane and the Gussasphalt surfacing.
The strong bond that the tack coat helps achieve, enables the surfacing, waterproofing and deck to act as a composite significantly reducing stress within the structure.
Supplied by Hanson UK - providers of asphalt surfacing solutions for a wide range of civil engineering applications, Gussasphalt is a dense, machine-laid mastic asphalt that is self-levelling and self-compacting once laid. It comprises a high performance polymer-modified bitumen mixed with gritstone coarse and fine aggregate to provide the stiffness and durability needed for a bridge running surface. High PSV lightly coated chippings are embedded in the hot surface by rollers to provide surface texture.
The Gussasphalt was produced at Hanson’s asphalt plant in Brayford, North Devon and loaded into Aeschlimann’s mixers for the 130 mile trip to Southampton. To meet the tight programme at the site the plant was kept open for extended hours to enable the mixers to make two trips to site on each of the two production days.
Alongside the bridge deck re-surfacing, Stirling Lloyd Construction completed the project with the application of 750m² of Eliminator overcoated with the Safetrack SC coloured surfacing system, in asphalt grey, to provide slip resistant surfacing for the bridge’s walkways.
Due to Eliminators compatibility with Gussasphalt, the project was able to ensure the benefits of Gussasphalt were fully realised on the bridge, allowing for a strong bond to form between the two, reducing the stress within the structure and enhancing performance. The concrete structure now has a long term, low maintenance waterproofing and surfacing combination to protect this major transport route in Southampton for many years to come.