Influence of Sustainable Recycled Asphalt Technologies on Pavement Construction Cooling Predictions

Abstract

Adequate control of temperatures during compaction is a critical factor in the achievement of proper densification of asphalt concrete (AC) layers. As the mat cools down, the viscosity of the asphalt binder increases; this increased viscosity reduces the compaction capability of the asphalt mixture. To assist paving contractors in their estimation of the cooling rate of asphalt pavements, the MultiCool program uses a heat transfer model that predicts the time window for successful compaction. Although this program has been validated for a variety of hot- and warm-mix asphalt technologies, further validation is needed on additional sustainable asphalt mixture technology. Pavement sections built in 2012 at the National Center for Asphalt Technology Pavement Test Track were used to perform a validation study to assess the effect of sustainable technologies [e.g., reclaimed asphalt pavements, recycled asphalt shingles (RAS), ground tire rubber (GTR) modified binders, and foamed cold-mix (FCM) bases] on the cooling rate of AC and the time available for compaction. Results revealed that the MultiCool model was a fair predictor of the measured temperatures. However, the use of RAS, GTR-modified binders, and a FCM base had a direct effect on the temperature predictions. This effect warrants further investigation of the possible effects of RAS, GTR-modified binders, and FCM base on the thermal properties of asphalt mixtures.