Asphalt Rubber Technology Information Center
Low Temperature Cracking of Modified AC Mixes in Alaska
Raad, Lutfi; Saboundjian, Stephan; Sebaaly, Peter; Epps, Jon; Camilli, Bob & Bush, David  
March, 1997  
Key Words:
Asphalt mixes, pavement cracking, modified polymer asphalts, superpave  
Low temperature cracking is major distress mode in Alaskan pavements due to the extreme temperature conditions that
range, in some instances, from about –50 in winter to 40 degrees in summer.  The use of asphalt modifiers in Alaskan
pavements occurred over the past 15 years.  These modifiers include SBR polymers, SBS polymers, ULTRAPAVE and
CRM.  Field observations and laboratory studies in Alaska and elsewhere indicate that the use of these modifiers would
improve the low temperature cracking resistance of pavements.  The degree these modifiers provide for Alaskan
pavements needs to be evaluated.  The objectives of this research were 1) to characterize asphalt and polymer modified
asphalt mixes from a number of selected sites using SHRP Superpave PG grading system, thermal stress restrained
specimen test, and Superpave IDT laboratory tests on field specimens; 2) To compare low temperature cracking
performance using field surveys; 3) to verify the applicability of SHRP Superpave thermal cracking.  Results of this study
indicate in general significant improvement in the low temperature cracking resistance when polymer modifiers are
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