Field Evaluation of Low-Temperature Cracking Performance of Highly Elastic Asphalt Mixtures Under Extreme Cold Conditions in Alaska

Extreme thermal expansion–contraction cycles in cold regions can cause significant thermal stresses in asphalt mixtures and result in thermal cracking. The current study focuses on evaluating the in-situ thermal cracking resistance of pavement test sections made using highly elastic asphalt binders (HEBs) under extreme cold conditions. Four pavement test sections prepared with one control binder (PG 52-28) and three HEBs were constructed in Fairbanks, Alaska. The HEB mixtures were prepared using binders modified with 7.5% styrene-butadiene-styrene polymer and two softening agents, namely hydrolene oil (7%) and corn oil (7%, and 14%), respectively. Asphalt strain gauges (ASGs) and thermocouples were installed in the hot mix asphalt (HMA) layers to monitor field-induced thermal strains from August 2024 to July 2025. Daily and seasonal temperatures and respective HMA strain variations were recorded to understand the criticality of strain amplitudes under field conditions. Results showed that HMA mix temperatures were warmer throughout the monitoring period and exhibited a nonlinear relationship with ambient air temperatures. HMA mixtures exhibited positive tensile strains and negative compressive strains during the day–night thermal expansion–contraction cycles. HEBs showed higher strain recovery capacity during both summer and winter seasons because of their enhanced flexibility by softening agents. Interestingly, HEB mixtures showed higher and lower cyclic strain variations during winter and summer seasons, respectively. HEB mixtures exhibited higher coefficient of thermal expansion and contraction (CTE and CTC) values during winter, but lower CTE and CTC values during the summer season, respectively.