Barrett Byrd Associates

Fuel resisting asphalt has been designed for two former military runways at Bristol International Airport, surfaced as part of an ambitious programme to expand aircraft operations. Mike Walter reports

Pressure to extend commercial services has led Bristol International Airport to rejuvenate two redundant runways and relocate private planes to a new facility away from the main terminal. Former runway areas will now provide two new taxiways, light aircraft parking, a new southern apron and two refuelling areas.

Both refuelling areas have been surfaced using a fuel resisting asphalt and marks the first UK use of the material on an airfield. The asphalt material is based on a product known as Bardon 10mm Forpave and has been produced using a fuel resisting binder known as Nyguard.

The binder is often used in asphalt designed to resurface motorway service areas and bus depots where fuel spillage is more likely. Surfacing for the Bristol contract was carried out by Bardon Aggregates and the binder has been designed by materials specialist Nynas Bitumen.

Bardon Aggregates’ regional technical manager Chris Mellor says: “We have specifically designed a material here that not only resists fuel spillage damage, but is highly durable and provides excellent deformation resistance.”

The binder’s ability to resist fuel lies in a special blend of polymer modified ingredients which also help give the asphalt added strength when it is put under pressure. Nynas Bitumen senior chemist Dr Ian Lancaster explains: “A high level of stiffness is afforded to asphalt containing Nyguard, which remains unaffected should fuel be spilled. The binder was first developed about five years ago and can withstand enormous point loads exerted on an airfield by aeroplane tyres.”

The Nyguard binder specified for the airport surfacing was mixed with a durable crushed quartzite aggregate at Bardon’s Westleigh asphalt plant in Devon. A total of 240t of the fuel resisting asphalt was laid at Bristol to a depth of 30mm by Bardon Contracting. The material represented a fairly small yet hugely significant part of a larger surfacing operation, which involved laying nearly 7,000t of asphalt.

The airport’s advisor Bristol Engineering Consultancy requested that three further types of surfacing material were specified for the airfield. The taxiways measure 500m and 300m in length respectively; one was surfaced with Bardon 6mm Smatex, the other with Bardon 10mm Smatex. Both stone mastic asphalt materials were produced using standard 50 penetration binder. Part of the new southern apron not designated for aircraft refuelling was surfaced using a Bardon 10mm Smatex Industrial surfacing, again produced with a straight run bitumen. Surfacing took place largely during the day, with night works required to tie in to the runway.

The two former runways, rejuvenated into taxiways, aprons and refuelling areas were used by fighter aircraft in the Second World War but fell into disrepair and have largely been unused ever since. Reinstatement and repair were carried out to much of the runways prior to them being resurfaced and extra carriageway strength was provided with use of a glass geomembrane rolled out beneath the binder course.

Resurfacing of the former runways has been carried out as part of a larger scheme headed up by main contractor Nuttall to develop airport facilities including a new aircraft hangar and offices for the Bristol Flying Club on the south side of the airport. The airport’s new light aircraft hangar stands around 13m high with a clear opening span of 50m by 30m and works on the hangar are soon to be completed.

Nuttall site agent John Hutton says: “The old runways were of very thin construction and unusable. We filled potholes, carried out patch repairs and strengthening before overlaying the existing construction with a 20mm sealing layer.” Glassmat geomembrane was then placed, after which binder and various surface courses were laid.

Taxiways and aprons have been reprofiled to allow the effective run off of surface water into newly installed, large capacity Gatic slot drains which take water through the drainage system to new interceptors and soakaways constructed on the perimeter.

Hutton adds: “Bristol International Airport is designated an environmental source protection zone by the Environment Agency and as such large interceptors, fuel stop chambers and soakaways have been incorporated into the scheme.”

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Bristol International Airport handles in excess of three million passengers every year and has seen a huge increase in recent years in the popularity of low cost airline carriers.

The need to accommodate future growth led the airport to look at relocating light aircraft – known as general aircraft – to the south side of the site, away from commercial services. It is hoped that this will allow the airport to extend its aprons for commercial aircraft.

Bristol International Airport’s head of engineering Carl Lapworth says: “This is the fastest growing regional airport in the UK and the largest in the south west of England. Future expansion of the airport’s commercial services depended on us taking the decision to move general aircraft to a new facility on the south side of the airport.”

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