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  4. iCCL DSR Asphalt Testing: A Surrogate Test for BBR

iCCL DSR Asphalt Testing: A Surrogate Test for BBR

The low-temperature PG of bitumen is determined using a device called Bending Beam Rheometer (BBR) and the procedure is outlined in AASHTO T 313 and ASTM D6648.  However, the BBR test is time consuming and laborious and involves several hazardous liquids as listed in Section 8 of D6648.

The Incremental Creep for Cracking at Low Temperature (iCCL) test is for determining the low-temperature properties of binder equivalent to those of BBR.  The iCCL test is performed using a Dynamic Shear Rheometer (DSR), which is significantly more advanced, in terms of load and temperature control, than the BBR device.  It provides properties using RTFO as well as PAV aged binder without use of any chemicals. The iCCL test is significantly faster, safer, more reliable, and less costly than BBR and provides continuous low-temperature grade, as well as m-value, S, and ΔTc equivalent to those of BBR.

The test takes about 30 minutes and has better precision than BBR. AASHTO has recognized iCCL as a surrogate test for the BBR in the Standard Practice PP 112 (2021). This presentation outlines comparison of thousands of iCCL and BBR test results from over 30 U.S. laboratories. The results show that iCCL provides low-temperature properties within the allowable limits of the BBR test in AASHTO T 313.

Key Learning Objectives:

  • Faster, safer, higher precision, and less costly determination of low-temperature properties than BBR
  • Surrogate test for the BBR in the Standard Practice PP 112 (2021)
  • Implementation of iCCL in State DOTs and other labs
  • Precision estimates of iCCL versus BBR

Dr. Ala Mohseni (Langues: English)
Ala Mohseni

Dr. Mohseni, Vice President of Pavement Systems LLC, has been involved in the SHRP/Superpave projects since 1992 and has made a major contribution to the development of Superpave PG asphalt binder grading system. 

Since 2005, Dr. Mohseni has been working on the development of several new asphalt test methods, namely UPTiM.  These tests include Asphalt Mixture Rutting, Fatigue Cracking, and Moisture Damage. Since 2010, he has been working on the iCCL test, for binder low-temperature PG.  He has contributed to the development of AASHTO T 410 and AASHTO PP 112 standards.

Dr. Mohseni earned a Ph.D. in Civil Engineering (Pavements) from University of Illinois at Urbana-Champaign (1990), an M.S. in Civil Engineering (Transportation) from Oregon State University (1986), and a B.S. in Civil Engineering from the University of Washington in Seattle (1979).