Nondestructive Test Methods for Improved Quality of Recycled Pavement

MaineDOT is using recycling techniques such as foamed asphalt full depth reclamation and plant mix recycled asphalt pavement (PMRAP) as a primary highway improvement technique. Although we have learned much about the material and processes over the past few years there is still much more to learn in order to improve the quality and longevity of our highways. The structural capacity or "layer coefficient" for foamed asphalt and PMRAP is being determined based on limited laboratory work, FWD analysis and engineering judgment. The work to date concludes that layer coefficients and performance can vary greatly depending on presence of larger aggregates, in-situ moisture, material uniformity and layer thickness. Given the relatively high values being used to determine overall pavement thickness (1" recycled layer = ½" hot mix asphalt pavement) it is critical to improve the quality of these layers.