Evaluation of Warm-Mix Asphalt Produced with the Double Barrel Green Process

During the past 3 years, warm-mix asphalt (WMA) technologies from European countries have entered the North American market. European experiences with WMA technologies have indicated that a significant reduction in mixture temperature, mixture viscosity, energy consumption, and environmental emissions during asphalt mix production and placement can be achieved in comparison with traditional hot-mix asphalt (HMA). On the basis of North American experiences with these technologies to date, transportation agencies and HMA producers are unlikely to adopt WMA technologies solely for the reduction in manufacturing energy costs and environmental emissions, because these benefits do not cover the associated increase in investment and additive costs of WMA over HMA, even in the most expensive North American energy markets. This paper presents an evaluation of the economic, environmental, and mixture performance factors to assess the sustainability of WMA in North America. The paper examines the benefits, risks, investment and material costs, and sustainability associated with the different WMA technologies and specifically the Double Barrel Green process. Included is a mixture performance evaluation of WMA mixes containing reclaimed asphalt pavement and Manufactured Shingle Modifier produced with the Double Barrel Green System during field trials in Vancouver, British Columbia, Canada.