MAIN FINDINGS FROM THE EXPERIMENTAL RESEARCH IN MEXICO

Since 1962 the Secretaria de Obras Publicas sponsors a research program on flexible pavement design, which is conducted through the Institute of Engineering of the Universidad Nacional Autonoma de Mexico (UNAM). Main purpose of the program is to obtain better methods of design for roads with low traffic volume, taking into account regional conditions of the country of the country in such aspects as materials, traffic characteristics, climate environment, specifications, construction procedures, safety factors and investment policy. The experimental studies include three closely interrelated aspects: 1) Research on the performance of three test roads located on two Federal Highways. Project 1 is in a tropical zone; projects 2 and 3 are in a cold steppe region and they were constructed on the same road with only a short transition in between. There are 80 structural sections in the three projects, with pavements ranging from 10 to 50 cm in total thickness. After seven years to testing under actual traffic, 72 of the original sections are still in good condition, with present serviceability ratings of 2.5 or more. Each section is one-lane wide and it is 30 m long. 2) Study of the actual performance of existing pavements located in three climatic zones representative of the conditions of the country. Total length under study is of the order of 6000 km, from which 96 field sections will be studied in detail in a factorial experiment. Main variables of the study are climate, traffic, subgrade strength, composite strength and years in service. Length of each section will be 500 m. 3) Research on full-scale pavements tested in a 13 m diameter circular track, under the action of 10 Ton single axle loads applied through conventional 10.00-20 dual tires. The facility was especially designed as part of the program and it has been in operation since December 1970. Each test ring has three structural sections and it is possible to study four rings per year. After nine years of research, the following conclusions can be stated: a) There is an urgent need for developing fundamental parameters which can be used for pavement design. In the meantime, it would be convenient to standarize the methods of test to interchange information on an international basis; for the same reason a uniform climatic classification is suggested, in combination with other environmental studies such as water table level and moisture equilibrium. b) AASHO system of present serviceability rating has been found useful. Acceptance and rejection levels (2.5 and 2.0) have been found adequate for the conditions of the country. c) Deflection basins determined by use of Berkelman beam are close to Boussinesq's prediction, and maximum rebound deflections did not correlate clearly with pavement design but with the composite strength; this fact should be considered to predict performance or to design overlays. A tentative design chart is presented based on the experimentation conducted to date. AASHO load equivalence factors were applied; the track will be used in further stages to establish coefficients for other soil types. /Author/

  • Supplemental Notes:
    • Presented at the Third International Conference on the Structural Design of Asphalt Pavements, Grosvenor House, Park Lane, London, England, Sept. 11-15, 1972.
  • Corporate Authors:

    International Conf Struct Design Asph Pvmts (3rd)

    University of Michigan, Department of Civil Engineering
    Ann Arbor, MI  United States  48104

    International Conf Struct Design Asph Pvmts (3rd)

    University of Michigan, Department of Divil Engineering
    Ann Arbor, MI  United States  48104

    Interrational Conf Struct Design Asph Pvmts (3rd)

    University of Michigan, Department of Civil Engineering
    Ann Arbor, MI  United States  48104
  • Authors:
    • Santiago Corro, C
  • Conference:
  • Publication Date: 1972-9

Media Info

  • Features: Figures; References;
  • Pagination: p. 761-775
  • Serial:
    • Volume: 1

Subject/Index Terms

Filing Info

  • Accession Number: 00261922
  • Record Type: Publication
  • Report/Paper Numbers: Proceeding
  • Files: TRIS
  • Created Date: Oct 22 1974 12:00AM