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CONSTRUCTION AND MAINTENANCE OF FLEXIBLE PAVEMENTS. REPORT FROM FINLAND --PIARC XVIII WORLD ROAD CONGRESS, BRUSSELS, BELGIUM, SEPTEMBER 13-19, 1987

This report discusses the following aspects: (1) practical design -equivalent loads of different axle configurations, tyres and tyre pressures were measured under test road conditions. The strains at the bottom of the bituminous layers and the stresses in the base and subbase courses were measured. The equivalences of different configurations are given; (2) pavement performance -pavement management systems -a Finnish pavement management system which uses performance models of ruts and cracking index is described. The system has been tested using data collected over a five year period, and the conditions at different budget levels are calculated; (3) bituminous binders -tall oil pitch, sulphite lignin modificate, fatty acid pitch and rubber powder were tested as additives in bitumen. The wearing resistance of the asphalt mixes was simulated in a circular test track with studded tyres. The mixes with additives showed some better wearing resistance in the wet conditions; (4) traditional and non-traditional bituminous materials - the effects of the road conditions and the road construction on the transverse cracking of the pavement were studied. The material consisted of 150 observation roads. The following results were received: the pavement age and the annual frost amount had significant effect on cracking. From the structural point of view the most significant factor was the tensile strength of the pavement, which was governed by the penetration and the viscosity of the binder and the shape index of the aggregate; (6) non-conventional materials -the Finnish guidelines for the use of slags in the road constructions are described; (9) techniques for severe climate areas -the mechanism of the wear caused by studded tyres and the effect of temperature on the pavement wear were studied in the test track. Wear had its minimum at the temperature between 0 deg c and -5 deg c and it increased about three times when the temperature dropped to -15 deg C. The components of the wearing forces, both dynamic and static, were measured and their dependence on different factors are discussed. The test roads show that the influence of bitumen hardness on wear is not linear but the wear has its minimum when the penetration is 80-120. The harder bitumen is more brittle at the low temperatures and the wear increases. Adhesion properties had also effect on wearing. The ruts caused by wear are repaired using a special rut filling method, which is described.(a) for the covering abstracts of the congress see IRRD 812115 and 812116.

  • Corporate Authors:

    Permanent International Assoc of Road Congresses

    27 rue Guenegaud
    Paris,   France 
  • Authors:
    • Blomberg, T
  • Publication Date: 0

Language

  • English

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00481236
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Files: ITRD, TRIS
  • Created Date: Apr 30 1989 12:00AM