During the past 40 years, the Norwegian Civil Aviation Administration (NCAA) has constructed some 50 flexible pavement runways with bituminous surfacing. Experience indicates that flexible pavement distresses such as cracking and ravelling are occuring prematurely, resulting in shortened pavement life. Since only a minority of Norwegian airfields are exposed to large volumes of traffic, the early deterioration of bituminous airfield surfaces is presumed to be caused by extreme climatic influences. One of the near term thrusts of the NCAA is to prolong asphalt airfield pavement life by developing more weather resistant asphalt mixes.