GENERAL REPORT: DRAINAGE AND PERMEABILITY. UNBOUND AGGREGATES IN ROADS. PROCEEDINGS OF THE 3RD INTERNATIONAL SYMPOSIUM, UNIVERSITY OF NOTTINGHAM, APRIL 11-13, 1989

This article assumes that aggregate layers in roads do have a drainage function, and discusses how to assess the adequacy of such a function. The first point that is emphasized is that the coefficient of permeability, k, has no meaning unless the water flow obeys Darcy's law. For sub-base materials this means hydraulic gradients of less than about 0.05. The second point that is emphasized is that the specification of permeability itself is not easy. Permeability is a function of aggregate grading, moisture content, compaction, and flow direction as well as particle size. Three possible ways of establishing the values of k for design purposes are suggested. These are: (a) to carry out a laboratory test for each sample. A number of such tests need to be carried out for each sample to obtain a consistent average; (b) to carry out an extensive series of parametric tests on a large number of samples, with systematic variations of grading, compaction, moisture content etc, to produce an emphirical correlation that can be used in design; and (c) to derive a theoretical framework for the problem, and then to use the relatively few available results to validate this theory and to determine the free parameters that appear. For the covering abstract of the conference see IRRD 827698.

  • Availability:
  • Corporate Authors:

    Butterworths and Company Publishers, Limited

    Borough Green
    Sevenoaks, Kent TN15 8PH,   England 
  • Authors:
    • Baker, C J
  • Publication Date: 1989-8

Language

  • English

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00604599
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • ISBN: 0-408-04355-5
  • Files: ITRD, TRIS
  • Created Date: Feb 28 1991 12:00AM