Impacts of WMA additives on rutting resistance and moisture susceptibility

The implementation of warm-mix asphalt (WMA) is becoming more widespread in the United States of America with a growing number of contractors choosing to utilize various WMA technologies. WMA technologies were developed in order to reduce mixing and compaction temperatures of hot mix asphalt (HMA) without affecting the quality of the pavement. Research into the effects of WMA additives suggests that it may be more susceptible to rutting and moisture damage than traditional HMA pavements. The objective of this research is to evaluate the effects of a single WMA additive on resistance to rutting and moisture damage on lab mixed and field mixed pavements. This objective was completed by conducting extensive laboratory experiments to determine and assess the performance of both WMA and HMA mixtures produced using Iowa aggregates. The conclusions of this study are as follow: · Reduced mixing and compaction temperatures were achieved using the selected additive. · The selected WMA additive was successfully used and samples were taken during a local resurfacing project. · Moisture sensitivity of both field mixed WMA and field mixed HMA were comparable although both failed to meet Iowa DOT standards. · Dry Indirect Tensile Strength values of lab mixed WMA and HMA samples were nearly the same. · TSR values of lab mixed HMA surpassed those of lab mixed WMA although both failed to meet Iowa DOT standards. · The aged field mixed HMA successfully passed the Hamburg Wheel Tracker Test and provided the best creep and stripping values compared to all other field mixed specimens. · Lab mixed HMA using a PG 64-22 binder performed the best compared to all other lab mixed specimens although none of the lab mixed specimens successfully passed the Hamburg Wheel Tracker Test.