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THE ASPHALT WEARING COURSE - YEAR 2000 --BITUMEN, FLEXIBLE AND DURABLE. 3RD EUROBITUME SYMPOSIUM 1985, THE HAGUE, NETHERLANDS, SEPTEMBER 11-13, 1985

In the production of asphalt wearing courses the aim is to use materials which, after being exposed to traffic loads, have sufficient stability and durability -and which, during their life span, retain an amount of surface qualities satisfactory enough to secure an optimum economy - operational as well as social. During the 1950's and at the beginning of the 1960's Danish roads were paved with a thin layer (2-3 cm) of a soft pavement material, fine cold asphalt. It was paved on various base courses of gravel and stone. Throughout the 1960's and 1970's the base courses were made with gravel aggregate and paved with a 2-4 cm wearing course of asphalt concrete which had to meet some very strict demands of friction. This resulted in relatively lean and open wearing course pavements. During the same period a large number of pavements was made in England with hot-rolled asphalt, and in Germany dense asphalt concrete pavements were used. Characteristic of both of these two types of pavements is that the erosion has been a lot slower, but on the other hand there have been problems with an adequate stability. During the last few years there has been a number of incidents in Denmark with dense-graded wearing courses of asphalt concrete being heavily eroded already after 5-7 years -which notoriously should have had a satisfactory durability (10-12 years). The Danish asphalt industry has made a lot of efforts in order to find the reasons for this, but so far it has not been possible to find a simple and valid explanation for the reduced life span. This paper states the types of damages which have been characteristic of the Danish roads over the last years. The main causes of these damages are: (1) strains in the upper asphalt courses because of an increase in axle load from 8-10 tons and a rise in tyre pressure from 7 to 9 kg/cm2, and (2) a change in adhesion power of bitumen to the most commonly used stone materials. Analysing the various reasons of erosion has now resulted in expectations in Denmark that similar problems can be avoided in the future. The report outlines a concept for renovation of asphalt pavements on primary roads. It contains suggestions for construction of wearing course pavements with a life span of minimum 15 years, maybe with recycling of the existing pavements. For the covering abstract of the symposium see IRRD 815173.

  • Corporate Authors:

    EUROBITUME

    BD EMILE BOCKSTAEL 351
    Bruxelles, ZZ Belgique   
  • Authors:
    • La COUR, J
    • Gormsen, H
    • Kirk, J M
  • Publication Date: 1985

Language

  • Undetermined

Media Info

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Filing Info

  • Accession Number: 00482088
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Files: ITRD, TRIS
  • Created Date: Apr 30 1989 12:00AM