EXPERIENCE OF DISTRICT 11 IN THE USE OF PLANT MIX SEAL COURSES

A TEST PROGRAM WAS DEVISED TO COMBAT THE PROBLEM OF SLICK PAVEMENTS. PRIOR RESEARCH AND EXPERIENCE IN WESTERN STATES HAD INDICATED THAT PLANT MIX SEAL, A TYPE OF OPEN-GRADED ASPHALTIC CONCRETE SURFACE, PROVIDED THE PAVEMENT STRUCTURE A DURABLE, UNIFORM, SKID-RESISTANT SURFACE THAT WAS OPEN-TEXTURED AND HENCE REDUCED THE HYDROPLANING POTENTIAL. THE AGGREGATES TESTED WERE TRAP ROCK, SANDSTONE, AND LIGHTWEIGHT AGGREGATE. TWO SEPARATE PROCEDURES WERE USED TO DETERMINE THE AMOUNT OF ASPHALT FOR THE THREE MATERIALS. PLANT OPERATIONS, INCLUDING TESTING AND INSPECTION, ARE DESCRIBED. BEFORE THE PLANT MIX SEAL WAS PLACED ON THE ROADWAY, A CUTBACK ASPHALT WAS USED, IN VARIOUS APPLICATION RATES, TO TACK THE SURFACE. IT WAS NOT POSSIBLE WITHIN THE TEST PERIOD TO EVALUATE ITS EFFECT, BUT THERE APPEARED TO BE NO SIGNIFICANT DIFFERENCE IN PLACING THE MIXTURE WITH OR WITHOUT TACK. THE OTHER LAYDOWN OPERATIONS, INCLUDING THE PROBLEMS ENCOUNTERED, ARE DESCRIBED IN DETAIL. SKID VALUES DETERMINED ON THE TEST SURFACE IMMEDIATELY AFTER COMPLETION AND AFTER OPENING TO TRAFFIC FELL INTO A RANGE FROM 0.28 TO 0.39. THE SEAL PROVIDED A SMOOTH RIDING SURFACE WITHOUT ANY NOTICEABLE CHANGES IN NOISE LEVELS FOR THE VARIOUS AGGREGATE SIZES. NO REVELLING OR FLUSHING HAS BEEN OBSERVED TO DATE. THE SEAL PROVIDES AN ADEQUATE VOID SYSTEM THAT PERMITS RAIN WATER TRAVEL THROUGH THE MIX RATHER THAN SHEET ACROSS THE SURFACE, WHICH TENDS TO ALLEVIATE THE PROBLEM OF HYDROPLANING.

• Supplemental Notes:
  • APP
• Corporate Authors:

  Texas State Department of Highways & Public Transp

  11th and Brazos Streets
  Austin, TX  United States  78701
• Authors:
  • Beaird, J L
• Publication Date: 1972-2

Media Info

• Features: References;
• Pagination: 21 p.

Subject/Index Terms

• TRT Terms: Asphalt concrete; Hydroplaning; Noise; Open graded aggregates; Permeability; Plant mix; Seal coats; Skid resistance tests; Surface treating
• Subject Areas: Construction; Environment; Highways;

Filing Info

• Accession Number: 00215527
• Record Type: Publication
• Report/Paper Numbers: No 55-15.5
• Files: TRIS, STATEDOT
• Created Date: Apr 2 1973 12:00AM