USE OF PLANT MIX SEALS IN LOUISIANA

A policy has been adopted which stipulates that all new asphaltic concrete construction projects on highways serving average daily traffic volumes of 1000 vehicles per lane and greater shall be provided with a plant mix seal (PMS) surface. The PMS performance is determined by choice and quality of aggregates. Porous, polish-resistant aggregates posess the most desirable skid resistance characteristics. The skid characteristics of native Louisiana aggregates are compared with that obtained from a typical dense graded hot mix. Study data have prompted regulations which require that a slag, expanded clay or gravel PMS be placed on all new asphaltic concrete surfaces serving between 1000 and 2000 vehicles per lane per day. On roadways where the ADT per lane exceeds 2000 vehicles, only slag and expanded clay plant mix seals are permitted. The policy is applicable only to roadways with posted speed limits of 40 mph or higher. However, when the speed limit is less than 40 mph, a number of pre-established guidelines determine the need for a PMS riding surface. Inspection of several installations with PMS surfaces reveal the importance of the source of aggregate, and the fact that PMS surfaces that contain excessive fines seemed to yield lower skid numbers.

Media Info

  • Features: Figures;
  • Pagination: p. 4-6
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00096890
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Sep 10 1975 12:00AM