PERFORMANCE AND DURABILITY OF BITUMINOUS MATERIALS. 2: AGGREGATE GRADING DESIGN FOR POROUS ASPHALT

Porous asphalt consists predominantly of coarse aggregate, its open porous structure is advantageous for eliminating splash and spray, improving skid resistance, reducing aquaplaning potential and lowering noise level and binder content requirement. A well designed porous asphalt exhibits high porosity where pores are continuous and form a network of drainage channels. Current literature on the development of aggregate gradings show that the overriding design considerations are to produce blends that give maximum density or minimum porosity. Most of porous asphalt gradings currently specified are based on empirical studies and do not deal directly with the packing behaviour of the aggregate mass. This paper proposes a grading for porous asphalt which is obtained by applying the theory of packing currently used to design dense bituminous mixtures. The packing behaviour of dry aggregate blends is studied using a vibratory compactor. The grading for porous asphalt is developed by applying the concept of designing to a target porosity starting with the minimum porosity of the coarse aggregate matrix. Fine aggregate gradings are varied to achieve the same target porosity. Mixes made with the gradation proposed exhibits slightly superior permeability and resistance to disintegration and overcompaction than the equivalent mix specified in BS 4987. Other gradations to achieve any desired porosity values can be easily established from a set of experimental curves developed using the vibratory compactor. (A) For the covering abstract see IRRD 875331.

Language

  • English

Media Info

  • Features: References;
  • Pagination: p. 10-22

Subject/Index Terms

Filing Info

  • Accession Number: 00720717
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • ISBN: 0-419-19730-3
  • Files: ITRD
  • Created Date: May 24 1996 12:00AM