A new technology involving asphalt cement modified with HyperTherm was used to demonstrate that warm mix asphalt technology can be used to extend the paving season by facilitating paving in cold weather. HyperTherm was initially validated as an effective warm mix technology during an overlay project on Katimavik Road in the City of Ottawa. The job involved the City of Ottawa new 4.75 mm FC1 mix intended for traffic level C (3 to 10 million ESAL’s) placed at nominal 25mm thickness. PG 58-28 modified with HyperTherm was used as the asphalt cement. The warm-mix was produced at about 120o C at the plant and compacted at between 75o C – 90o C. This corresponds to reductions in mixing and compaction temperatures as compared to conventional hot mix using the same grade of asphalt cement. Visible emissions and odours during the production and placement of the mix were also reduced. Phase two of the study utilized the improved mix workability properties imparted by warm mix technology to extend the paving season in a cold weather application. Oxford Road 4 in the County of Oxford, Ontario was paved with PG 58-28 modified with HyperTherm during the month of December. By producing the mix at conventional hot mix temperatures, compaction targets were achieved despite the low ambient air temperature and frozen granular grade. The improved workability imparted by the warm mix additive counteracted the cold weather conditions.
