Use of Fuel Resistant Asphalt for Aircraft Pavement Surfaces in Australia

Many regional and smaller airport aprons in Australia and provided with an asphalt surface course. In areas where fuel spills from venting aircraft tanks and refueling operations are unavoidable, the surface is exposed to hydrocarbons on a regular basis. Bitumen binders are softened by these hydrocarbons and the surface can be damaged. Such damage can lead to increased maintenance effort being required and increased loose material on the apron surface which, can be ingested and damage aircraft engines. Traditionally in Australia aircraft parking aprons were treated with a fuel resistant membrane. These membranes are sprayed onto the surface some weeks after asphalt finishing. Such membranes, generally tar-based products, result in top-down cracking of the asphalt and require re-treatment every two to three years. Shell Bitumen has developed a fuel resistant asphalt binder, Mexphalte Fuelsafe. This material is a proprietary product which blends a mix of polymer products into conventional bitumen. This fuel resistant binder offers the advantages of not resulting in top down cracking and being more economical than fuel resistant membrane treatments. The resulting asphalt has a stiffness that exceeds that from conventional binders and is easily manufactured. A field trial at an Australian Defence airfield demonstrated that the fuel resistant asphalt was manufactured, placed, compacted and finished like conventional asphalt. The only noticeable difference being that the asphalt had a slightly sticky feel which caused some adhesion to the screed at the rear of the asphalt paver. Twelve months after construction and following significant fuel exposure, the apron surface is performing well. Otherwise identical cores of asphalt containing conventional and fuel resistant binders were taken from the trial and assessed. Based on surface exposure and submersion in diesel fuel for 10 days, it was concluded that the fuel resistant binder resisted hydrocarbons for a few days. However, after prolonged exposure the hydrocarbons were absorbed by the asphalt. Once hydrocarbons were absorbed, the fuel resistant binder softened in a similar manner to the conventional bitumen. It was concluded that the fuel resistant binder was therefore effective in resisting short term fuel spills but would be less effective under prolonged or continuous spills in an isolated area