Abstract
The purpose of this study is the development of permeability and density acceptance criteria for HMA pavements in Wisconsin. The work detailed in this report is Phase 1 or 2. Databases from the Pavement Management Unit of WisDOT were obtained for design, new construction reports, traffic, and performance data to assemble a profile of higher and lower performing pavements within a similar geographic region and truck traffic. Specific field tests on each project included water permeability with the NCAT device, air permeability with the ROMUS device, nuclear density, cores, and pavement distress surveys. Only fine-graded mixtures were tested.

In-service pavements were nearly impermeable, where water permeability rates ranged from 0 to 5 x 10E-5 cm/sec, and air permeability rates were a factor of 10 greater than water permeability. Water permeability between wheel paths were generally higher than in the wheel paths. In-service pavement density ranged from 92% to 99%. Air permeability trended downward with an increase in density, while water permeability had no discernible trend.

A methodology for developing design criteria for permeability and density based on preliminary findings was presented. Defining a specific criteria requires establishing a target PDI to yield an expected design permeability, which in turn specifies as-built density at construction. Similarly, the target PDI/year determines the as-built density, to achieve the target value. Based on limited data, it was not possible to establish definitive criteria for permiability and density. A work plan was proposed for Phase 2 of the study to produce performance models that will establish specific criteria. Phase 2 will require a long-term study of about 5 years. As-built construction data will be collected on projects throughout the state having varying density requirments, then performance data are collected and monitoring every other year until the pavement reaches 8 years of age.

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