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https://nap.nationalacademies.org/catalog/27432/critical-issues-in-transportation-for-2024-and-beyond

COMPUTER ANALYSIS FOR MODIFICATION OF BASE ENVIRONMENTAL CONDITIONS TO PERMIT COLD WEATHER PAVING

THE PURPOSE OF THIS STUDY WAS TO DEVELOP METHODS FOR PREDICTING THE EXPECTED TIME FOR AN ASPHALT CONCRETE MIX TO COOL TO SPECIFIED TEMPERATURES WHEN LAID ON PREHEATED BASE MATERIAL. THESE TIMES ARE COMPARED TO THOSE FOR SIMILAR UNHEATED BASE SITUATIONS. ALSO CONSIDERED WAS THE QUESTION OF FUEL COSTS ASSOCIATED WITH ANY BASE PREHEATING OPERATION. A FINITE DIFFERENCE SOLUTION WAS USED AS THE BASIS FOR A COMPUTER PROGRAM FOR CALCULATING TEMPERATURES AS A FUNCTION OF TIME, PLACE IN THE BASE, PLACE IN THEMIX, DURATION AND MAGNITUDE OF HEATING, TIME BETWEEN HEATER INPUT AND ASPHALT LAYDOWN (CALLED STALL), AND THE VARYING ENVIRONMENTAL CONDITIONS. RESULTS OF THIS STUDY INDICATE THAT PREHEATING THE BASE MATERIAL HAS A PRONOUNCED EFFECT ON THE TIME FOR THE MIX TO COOL TO A SPECIFIED TEMPERATURE AND THAT THE FUEL COST OF PREHEATING APPEARS TO BE ECONOMICALLY FEASIBLE. IN ADDITION, WITH NO BASE PREHEAT, THE HEAT FLUX INTO THE BASE IS INITIALLY GREATER THAN THE HEAT FLUX TO THE ATMOSPHERE AND, THEREFORE, THE LOWER PORTION OF THE MAT IS COOLED MORE RAPIDLY. WITH PREHEATING, THE HEAT FLUX GOES INTO THE LOWER PORTION OF THE MAT INITIALLY, A REVERSAL IN THE DIRECTION OF HEAT FLUX AT THE BOTTOM SURFACE OF THE MAT. THIS IS PARTICULARLY SIGNIFICANT WHEN COUPLED WITH THE FACT THAT THE COMPACTIVE EFFORT IS LESS NEAR THE BOTTOM OF THE MAT THAN AT THE PLACE OF APPLICATION ON THE SURFACE OF THE MATERIAL BEING COMPACTED. /AUTHOR/

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 487-508
  • Serial:
    • Volume: 40

Subject/Index Terms

Filing Info

  • Accession Number: 00215530
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Oct 15 1972 12:00AM