Influence of RAP Content on the e Air Void Distribution, Permeability and Modulus of the Base Layer in Recycled Asphalt Pavements

摘要

The use of recycled materials for construction is beneficial to both the environment and theeconomy. Recycled asphalt pavement (RAP) is one of the most commonly used recycledmaterials. Different state departments of transportation allow the use of RAP in unbound basematerials at different percentages. The modulus and permeability are recognized as importantparameters for base course materials due to their effect on pavement service life. Determinationof the effects of the percentage of RAP on the modulus and permeability of base materials thatcontain RAP is important for proper pavement design. This study evaluates the effects of RAPpercentage on the resilient modulus and permeability of unbound base materials. It is found thatincreasing the RAP percentage increases the resilient modulus. Constant-head permeability testresults indicate that increasing the RAP percentage decreases the coefficient of permeability.High resolution X-ray computed tomography (X-ray CT) is used to study the internal structure ofthe test specimens. It is found that RAP mixtures have lower void ratios than virgin crushedaggregate, which explains the high resilient modulus and low permeability of RAP mixtures.