The Colas Repave recycling process is an alternative solution
for airport pavement rehabilitation projects which will reduce time
and cost and has significant sustainability benefits.
Our Repave process is a hot in-situ recycling method that is used extensively on the UK road network and is approved under Clause 926 of the Specification for Highway Works. However, the process has been used successfully during the past ten years within the airport sector at the airfields listed below, including commercial airport runways, with a variety of overlay materials and is currently being drafted for inclusion in a forthcoming Defence Estates publication covering recycling of airfield pavements.
|Location||Airfield Site Area||Year||Site Dimension||Overlay Material||Depth of Overlay|
Heavy Duty Macadam
Isle of Man
|RAF Kemble||Aprons and
DWFS HRA Design
|Duxford Aerodrome||Runway||2007||54,000m2||Porous Friction Course||20mm|
|RAF Valley||Taxiway adjacent ASP1||2004||3,000m2||Marshall Asphalt Surface Course||35mm|
|RNAS Yeovilton||14/32 Disused runway shoulders||2004||8,000m2||DWFS HRA Design Type A||25mm|
|RNAS Merryfield||34 Thresfold to 03 Thresfold||2002||10,000m2||DWFS HRA Design Type A||25mm|
|ATC Lasham||Runway||2002||81,000m2||Porous Friction Course||25mm|
The key benefits the Repave process would bring to a project are:
- Greater potential seasonal working windows. The heat generated by the process drives off moisture and frost whilst the recycled underlying surface retains heat, ensuring that the new overlay is laid on a hot surface. Surfacing operations are therefore not as susceptible to adverse conditions as conventional operations.
- An asphaltic thermal weld is produced when the new hotmix is laid and compacted over the underlying heat treated existing asphalt. Guaranteed certainty that the new overlay is bonded to the existing surface and a homogenous pavement is formed which will provide greater whole life cost benefits throughout the pavement life.
- There is no need for a tack coat with this operation and hence no waiting for tack coats to break in cold or damp conditions plus cost saving of material.
- All cracks (subject to inspection) in the underlying surface are treated.
- The heat generated by the Repave process ensures that longitudinal joints are heat welded to successive lanes. There are clear whole life cost benefits here owing to reduced potential for future joint failure, a particular feature when asphalt is laid in colder conditions by conventional means.
- Areas of runway that require improved PCN or regulating can be reconstructed to binder course level prior to the Repave process. Once the new profile has been achieved through conventional regulating the surface is Repaved and overlaid with a thinner new asphalt layer.
- Repave is a sustainable construction process, a growing requirement in Government procurement programmes.
- Reduced thickness of overlay means that a lower (40%) daily tonnage is required to cover the equivalent surface area compared to the conventional 50mm overlay. Therefore shorter working hours can be accommodated without loss of m2 per day productivity.
- Any recognised airfield surface course material (Marshall Asphalt, SMA, HRA, PFC or BBA Asphalt) can be combined with the Repave process.
- A typical runway measuring 1800m length by 45m wide incorporating a 30mm surface course with Repave would save approximately 3,750t of new asphalt.
In addition to considerable cost savings there would be a reduction of nearly 200 lorry movements on site and on local roads. In addition to the environmental and social impact of this saving there is a reduced interface with day to day airport customers and neighbouring stakeholders particularly at night when truck movements can be socially unacceptable.