PREDICTION OF AC MAT TEMPERATURES FOR ROUTINE LOAD/DEFLECTION MEASUREMENTS

An asphalt layer is highly viscoelastic, with a changing modulus, or stiffness, as a function of mat temperature. When conducting routine load/deflection measurements, for example with a Falling Weight Deflectometer (FWD), it is very important that the representative or "weighted average" mat temperature is known, so the modulus derived for the AC layer is correctly related to the temperature of the layer when the FWD tests were conducted. This paper summarizes the results of the most recent research on the subject, also using the conclusions from a companion paper entitled "Temperature Correction of Asphalt Moduli for FWD Measurements". Based on this work, together with Southgate's data and results from SHRP's LTPP studies, a new relationship is developed which uses a series of readily available time, air temperature, and AC thickness data, plus the AC surface temperature only as measured by an automatic infrared sensing device mounted on the FWD. This new method is called "BELLS", whereby a very close approximation of the weighted average AC mat temperature at the time of testing is easily obtainable using a relatively simple, computerized relationship. The BELLS mat temperature calculation method thus allows the engineer to adjust the derived (backcalculated) AC modulus to, eg, seasonal or standard values at any other appropriate mat temerature(s).

Language

  • English

Media Info

  • Features: Figures; Tables;
  • Pagination: p. 401-412
  • Serial:
    • Volume: 1

Subject/Index Terms

Filing Info

  • Accession Number: 00730066
  • Record Type: Publication
  • Files: TRIS, STATEDOT
  • Created Date: Nov 27 1997 12:00AM