THE DESCRIPTION OF THE DEFORMATION RESISTANCE OF ASPHALTS WITH THE AID OF A CREEP TEST

ON VARIOUS SECTIONS OF SWISS MOTORWAY WITH HEAVY TRAFFICKING, WHICH WERE BUILT BETWEEN 1965 AND THE BEGINNING OF THE SEVENTIES, HEAVY DEFORMATIONS IN THE BITUMINOUS COURSES HAVE APPEARED. ON SOME SECTIONS COMPREHENSIVE INVESTIGATIONS WERE CARRIED OUT. FOR THIS SECTIONS OF THE CONSTRUCTION OVER THE TOTAL LANE WIDTHS WERE TAKEN AND INVESTIGATED IN A LABORATORY, WHERE THE USUAL LABORATORY TESTS WERE COMPLEMENTED BY CREEP TESTS. THE SEQUENCE OF BITUMINOUS COURSES IN CROSS SECTION AND GRAPHICAL REPRESENTATIONS OF THE MEASURED THICKNESS OF EACH COURSE, COMMENCING IN EACH CASE WITH A BASE COURSE, SHOW THAT THE MAIN PART OF THE DEFORMATION OCCURRED IN THE REGION OF THE UPPER 15 CM. IN THE SECTIONS INVESTIGATED WEAK TO MEDIUM-HARD BITUMINOUS BINDER MATERIAL WAS USED. IN ONE SECTION HOWEVER IN WHICH THE MIX OF THE WEARING AND BINDING COURSE WAS PRODUCED WITH AIR-BLOWN BITUMEN (PENETRATION INDEX +2.5), BOTH CONSIDERABLY LOWER GROOVE DEPTHS WERE OBSERVED AND ALSO UNDESIRABLE CRACK FORMATIONS. IT IS RECOMMENDED THAT ROAD CONSTRUCTION BITUMEN B40/50 BE USED MORE IN FUTURE, IN ORDER TO PRODUCE A STABLE ROAD SURFACE.