Asphalt Binder Cracking Device

Research & Development


Without a reliable way to test the low temperature cracking potential of the asphalt binders, an innovative prototype of ABCD was developed through The National Cooperative Highway Research Program's Innovations Deserving Exploratory Analysis (NCHRP-IDEA) project. Dr. Kim and his team studied various test set-ups using different binder specimens, modified and unmodified, to develop the most convenient and reliable test device.

Two important findings of ABCD research with field and laboratory prepared samples are:

  • Good correlations with Field Performance

Asphalt binder samples from three well-known test road projects were used from ABCD testing and compared with crack severity of the pavement. ABCD provided consistently better correlations than the current AASHTO M320 Table 1 or 2 specifications.

Table 1.  Coefficient of Determination (R2) of Critical Temperature versus Cracking Index of Test Pavements using ABCD and standard AASHTO methods.

M320 Table 1
M320 Table 2
Elk Co, PA 0.94 0.21 0.95
Lamont 0.92 0.79 0.76
Highway 17 0.80 0.92 0.56
  • Effects of Polymer (SBS) Concentration

As SBS concentration in asphalt binders increased gradually from 0% to 5%, ABCD cracking temperature gradually decreased (better performing) and strength gradually increased. In BBR test results (AASHTO M320 Table 1 specification), the increase in SBS concentration caused no change in the estimated cracking temperature at low concentration and increased cracking temperatures (worse performing) at high concentrations. Field observations agree with ABCD results; polymer modified binders tend to perform better than unmodified binders in field trials.

Table 2.  Effects of SBS Concentration on Low Temperature Cracking Potential

Binder M320-Table 1 ABCD
PG Grade Tcr °C Strain Jump, me
Base 44.5 - 41.5 -44.2 21
Base+2% SBS 53.1 - 41.7 -46.5 36
Base+3% SBS 57.4 - 41.4 -48.0 40
Base+4% SBS 63.3 - 39.3 -51.1 43
Base+5% SBS 70.0 - 38.1 -54.1 53