Low Temperature Cracking of Modified AC Mixes in Alaska Author(s): Raad, Lutfi; Saboundjian, Stephan; Sebaaly, Peter; Epps, Jon; Camilli, Bob & Bush, David Origin: Alaska Date: March, 1997 Categories: Performance Key Words: Asphalt mixes, pavement cracking, modified polymer asphalts, superpave Summary: 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 used.