Assessment of moisture sensitivity of warm mix asphalt using advanced3-D imaging technique

Warm Mix Asphalt (WMA) is produced at lower temperature than Hot Mix Asphalt (HMA) and is more susceptible to adhesion failures at the binder-aggregate interface. An innovative approach was utilized to compute this failure in direct tension. Three levels of conditioning were used namely; unconditioned, 1 Freeze-Thaw (F-T) cycle and 3 F-T cycles prior to testing. The percentage of adhesion failure was initially estimated using a 2-D image analysis and then further quantified using the 3-D image analysis. The statistical paired t-test showed that there was a significant difference between the results of 2-D and 3-D analysis. This concluded that the use of 3-D technique is a more precise method to quantify the adhesion failure caused by moisture infiltration. The results from the image analysis also showed that adhesion failures for mixtures prepared with polymer modified binders were lower than unmodified binders. The extent of failure also increased with the number of F-T cycles.