Briefing: Introduction of French asphalts into UK airfield design

Abstract

French asphalt mixtures have been shown to provide viable alternatives to conventional UK airfield materials. This paper introduces an analytical design methodology for using French asphalt materials and quantifies the thickness benefits compared with conventional materials for new and rehabilitated airfield flexible pavements. The use of a stress-absorbing membrane interlayer (Sami) to mitigate the risk of reflective cracking in composite pavements is also considered. An assessment of materials presents similarities in performance properties between UK and French asphalt surfacing, resulting in the recommendation for using bétons bitumineux pour chaussées aéronautiques (BBA) as a direct replacement for Marshall asphalt surfacing. A direct replacement of UK materials with the same thickness of BBA/grave bitume (GB3) asphalt surface and base is proposed, whereas a thickness reduction of 20% is recommended through use of enrobé à module elévé (EME2) base material. Overlay thicknesses are proposed for reduction using either EME2 material or a Sami, dependent on specific design cases. Material equivalency factors have been proposed for inclusion of French asphalts in UK pavement design.