Using recycled asphalt pavement in construction of transportation infrastructure: Alaska experience

Due to its enormous environmental and economic benefits, recycled asphalt pavement (RAP) has been widely used in construction of transportation infrastructure. In Alaska, the use of RAP has been reported for decades. However, materials containing RAP used in transportation infrastructure in Alaska have not been fully characterized yet. The current experience is generally empirical and little documented. This paper provided a comprehensive study to characterize Alaska's construction materials containing RAP. Three most commonly-used applications were included, which were hot mix asphalt (HMA) containing RAP for both highway and airfield construction, and RAP treated base (RAP-TB) containing 50% RAP and 50% granular materials. The study developed dynamic modulus (|E*|) of HMA containing RAP and resilient modulus (MR) of RAP-TB using representative Alaskan materials, and provided predictive models to estimate their modulus. The performance evaluation showed that the incorporation of RAP increased the rutting resistance of HMA in Alaska, and caused limited effects on HMA's fatigue. RAP's effects on low-temperature performance of Alaska's HMA should be further evaluated. Field practices from Alaska Department of Transportation & Public Facilities (ADOT&PF)'s all three Regions were also summarized regarding RAP use in Alaska. The successful use of RAP and the tendency of using more RAP in Alaska's transportation infrastructure were both confirmed. A preliminary cost analysis reasonably estimated a saving of $13.3/ton in materials cost when 25% RAP was used in typical Alaska HMA in DOT's Northern Region. However, it seems that RAP is still not preferred when construction is needed, which means that further efforts should be made to promote its wider use in Alaska from which more confidence will be gained.