Evaluation of fracture behaviour of modified warm mix asphalt containing vertical and angular cracks under freeze-thaw damage.

Freeze-Thaw Damage (FTD) is one of the most important factors that can reduce the Warm Mix Asphalt's (WMA) crack resistance. In this study, modified WMA and WMA mixtures' fracture behavior containing vertical and angular cracks was evaluated using semi-circular bend geometry (SCB). For this purpose, SCB samples containing vertical cracks (Pure mode II) and angular cracks (Pure mode I) were made first; Then, FTD conditions were applied to the samples to condition them. The results showed that all the mixtures modified with Calcium Lignosulfonate (CL) and polyester fibers (PE) had a better crack resistance than the base sample under FTD conditions. As a result, the fracture energy of WMA mixtures containing 6% CL increased by about 146, 141, 75, and 93%, respectively, while the fracture toughness of WMA mixtures containing 3% CL increased by about 103, 95, 97, and 92%, respectively. The results of the brittleness indices showed that mixtures containing 6% CL, 0.25% PE-6% CL, and 0.25% PE had a more flexible behavior than other mixtures under FTD conditions, respectively. Therefore, using these mixtures, in addition to improving the fracture performance, was also recommended for environmentally friendly purposes. [ABSTRACT FROM AUTHOR]