OPEN-GRADED PLANT-MIXED SEALS

THE OPEN-GRADED PLANT-MIX SEAL IS A CHIP-SEAL AGGREGATE CONTAINING SOME SAND-SIZED MATERIAL, WHICH IS PREMIXED IN A PLANT AND HAS RELATIVELY HIGH ASPHALT CONTENT. THIS TYPE OF SEAL PROVIDES A SMOOTH RIDING SURFACE. A DURABLE SEAL IS PRODUCED WHICH HAS GOOD SKID RESISTANCE QUALITIES. A NUMBER OF WESTERN STATES ARE CONSTRUCTING OPEN-GRADED, PLANT-MIXED SEALS AS A STANDARD ON ALL HIGH-QUALITY ASPHALT PAVEMENTS. GRADATION USED AND ASPHALT CONTENT ARE DISCUSSED. AGGREGATE PARTICLES ARE COATED WITH A FILM OF ASPHALT 3 TO 4 TIMES THICKER THAN THAT FOR A DENSE-GRADED MIX. THIS PROVIDES DURABILITY AND RESISTANCE TO MOISTURE IN SPITE OF THE HIGH VOID RATIO. IN CONTRAST TO THE EXTREMELY WIDE RANGE OF SKID RESISTANCE VALUES OF CHIP-SEAL SURFACES, A UNIFORMLY GOOD SKID-RESISTANCE SURFACE IS PRODUCED. THE LOSS OF SKID NUMBER WITH SPEED IS RELATIVELY SMALL BECAUSE OF THE VOIDS AT THE SURFACE. THE OPEN-GRADED PLANT-MIXED SEAL REDUCES ROUGHNESS, WHILE A CHIP-SEAL ADDS ROUGHNESS TO A SMOOTH PAVEMENT. WITH AN OPEN-GRADED PLANT-MIXED SEAL THERE IS PRACTICALLY NO LOSS OF MATERIAL AND NO FINE PARTICLES TO DAMAGE WINDSHIELDS. SURFACE WATER CAN ESCAPE THROUGH THE VOIDS INSTEAD OF FLOWING OVER THE SURFACE. PAINTED STRIPES ARE MORE VISIBLE AND DURABLE BECAUSE OF THE SURFACE VOIDS. NO CURING TIME IS REQUIRED SO THAT THE ROAD CAN BE OPEN TO TRAFFIC IMMEDIATELY FOLLOWING ROLLING. COST IS LARGELY DEPENDENT ON AGGREGATE AVAILABILITY. CONSTRUCTION PROCEDURES ARE DESCRIBED AND IT IS POINTED OUT THAT THE SEAL CANNOT BE EXPECTED TO CORRECT LARGE UNDERLYING STRUCTURAL DEFICIENCIES OF A POOR PAVEMENT. ONE OBJECTION TO THE USE OF THE SEAL IS ITS SUSCEPTIBILITY TO OIL DRIPPINGS AT AN EARLY AGE.

  • Digital Copy:
  • Supplemental Notes:
    • Paper sponsored by Committee on Salvaging Old Pavements by Resurfacing, Maintenance of Bituminous Pavements, and Maintenance of Portland Cement Concrete Pavements and presented at the 48th Annual Meeting.
  • Authors:
    • Hewett, J W
  • Publication Date: 1969

Media Info

  • Media Type: Print
  • Features: Figures; References;
  • Pagination: pp 52-57
  • Monograph Title: Design of overlays and pavement rehabilitation
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00218573
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Feb 16 1970 12:00AM