THE DURABILITY OF BITUMINOUS OVERLAYS AND WEARING COURSES IN TROPICAL ENVIRONMENTS . THIRD INTERNATIONAL CONFERENCE ON BEARING CAPACITY OF ROADS AND AIRFIELDS. PROCEEDINGS, NORWEGIAN INSTITUTE OF TECHNOLOGY, TRONDHEIM, NORWAY, JULY 3-5 1990. VOLUMES 1-2

This paper describes an investigation into the durability of a range of asphalt wearing courses and overlays on the main road network of Kenya together with the results of a much wider range of mixes prepared in the laboratory. The results show that large increases in bitumen viscosity occur quite rapidly in the top few millimeters of all asphalt surfaces. Where air voids were interconnected bitumen hardening occurred throughout the layer and relationships were derived between bitumen viscosity, age and mix properties. However for all mixes large increases in viscosity occurred in the top 3 millimeters. For this thin surface layer, age was the dominant factor. The mix properties were statistically significant but only of second order. The application of a surface dressing to the premix layer was found to be the most successful method of reducing the rate of age hardening in the surface of the asphalt and preventing the formation of cracks. The complex nature of age-dependant effects and the changing susceptibility to cracking from traffic and temperature induced stresses makes the development of precise predictive 'life models' extremely difficult. However, for circumstances similar to those of the study experiments, knowledge of the critical degree of hardening at which cracking occurs and of the rate at which ageing takes place for the different surfacings will allow rational rehabilitation and maintenance strategies to be adopted. (Author/TRRL)

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  • Corporate Authors:

    Tapir

    Trondheim University, Gloeshaugen
    Trondheim-NTH,   Norway 
  • Authors:
    • Smith, H R
    • Rolf, J
    • Wambura, JHG
  • Publication Date: 1990

Language

  • English

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Filing Info

  • Accession Number: 00612248
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • ISBN: 82-519-1033-1
  • Files: ITRD, TRIS
  • Created Date: Aug 31 1991 12:00AM