Investigation of Test Methods, Pavements and Laboratory Design Related to Asphalt Permeability

About the report:

In this study, the permeability of Virginia's Superpave mixtures was tested. A constant head device and a falling head device under development were investigated as aids in measuring asphalt permeability. The effect on permeability of some of the variables associated with the falling head test was also investigated. Falling head permeability tests were performed on pavement cores to determine the general permeability of mixtures being placed, with an emphasis on Superpave mixtures. In addition, the permeability of pavement cores was compared with the permeability of specimens made in the laboratory using mixtures sampled during construction to determine whether laboratory specimens could be used to predict pavement permeability. The falling head test was found to be more suitable than the constant head test because of its simplicity and the inability of the latter to allow water flow at measurable pressure heads. Sealant was found to be necessary to prevent water flow along the sides of the specimen during the test, and sawing was found to decrease permeability. A large percentage of the field cores had excessive voids, resulting in excessive permeability. Each mixture had a unique voids-permeability relationship; a lower void content was required in mixtures having large aggregates to maintain an acceptable level of permeability. Permeability tests on specimens prepared in the laboratory predicted pavement permeability within acceptable limits in five of six cases. Limited repeat testing by different operators indicated differences among operators that require further investigation.

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