COOLING OF HOT-MIX ASPHALT LAID ON FROZEN SUBGRADE WITH DISCUSSION

THE DESCRIPTION AND SOLUTION OF THE TEMPERATURE DISTRIBUTION AND HEAT FLOW PROBLEM REQUIRES THAT AN ACCOUNT BE TAKEN, IN THE MATHEMATICAL FORMULATION, OF THE POSSIBILITY OF MULTIPLE PHASES IN THE SUBGRADE. ONE MUST CONSIDER A BASE WITH A THAWING REGION WHICH MOVES INTO THE BASE WITH TIME. FOR THE SAME AMOUNT OF HEAT LOSS FROM THE MAT, THE THERMAL WAVE (TEMPERATURE RISE) PROGRESSES FURTHER INTO THE UNFROZEN SUBGRADE THAN INTO THE FROZEN SUBGRADE. AS AN INCREMENT OF FROZEN SOIL REACHES 32 F, THE TEMPERATURE CHANGE "PAUSES" UNTIL THE MOISTURE HAS BEEN THAWED BEFORE THE TEMPERATURE AGAIN STARTS TO RISE. THIS PHENOMENA HAS THE EFFECT OF PRODUCING A SUBSTANTIAL TIME LAG IN THE THERMAL WAVE PENETRATION INTO FROZEN SOIL. COMPUTER RESULTS SHOW THAT THE SOLAR FLUX HAS LESSER EFFECT ON THE TEMPERATURE PROFILE IN THE UPPER HALF OF THE MAT THAN DOES THE WIND VELOCITY. NEITHER OF THESE EFFECTS IS IMPORTANT IN THE LOWER HALF OF THE ASPHALT MAT. COMPUTATIONS FOR VARIOUS MOISTURE CONTENTS OF FROZEN SUBGRADE SHOWED THE EFFECT OF MOISTURE CONTENT ON MAT TEMPERATURE PROFILE AND HEAT FLUX INTO SUBGRADE TO BE APPRECIABLE IN THE LOWER PORTION OF THE MAT. THIS EFFECT DECREASES IN IMPORTANCE WITH INCREASED DISTANCE FROM THE MAT-SUBGRADE INTERFACE. INCREASED MOISTURE CONTENT IN THE FROZEN SUBGRADE PRODUCES A LOWER INTERFACIAL TEMPERATURE AND REQUIRES A HIGHER LAYDOWN TEMPERATURE TO PROVIDE SUFFICIENT TIME TO COOL TO A SPECIFIED AVERAGE MAT TEMPERATURE. A DISCUSSION IS INCLUDED WHICH DEALS WITH VARIOUS QUESTIONS CONCERNING THIS STUDY.

• Authors:
  • Dickson, P F
  • Corlew, J S
• Conference:
  • Association of Asphalt Paving Technologists Proceedings
• Publication Date: 1972

Media Info

• Features: Figures; References; Tables;
• Pagination: p. 49-69
• Serial:
  • Volume: 41

Subject/Index Terms

• TRT Terms: Cold weather construction; Frozen soils; Heat flow; Heat sinks; Hot mix asphalt; Information processing; Interfaces; Mathematical analysis; Paving; Soil water; Solar energy; Solar power generation; Subgrade (Pavements); Temperature; Temperature gradients; Thaw; Time; Velocity; Wind
• Uncontrolled Terms: Temperature distribution
• Old TRIS Terms: Subgrade moisture; Time factor; Wind velocity
• Subject Areas: Highways; Materials;

Filing Info

• Accession Number: 00211818
• Record Type: Publication
• Files: TRIS
• Created Date: Sep 17 2002 12:00AM