Measurement of permeability in horizontal direction of open-graded friction course with rutting

Abstract

Although the permeability of open-graded friction course (OGFC) materials in the transverse direction and the reduction in permeability associated with long-term traffic loading are important issues, they have remained under researched thus far. In this study, testing equipment and procedure were developed to evaluate the permeability of an OGFC specimen along the horizontal direction and its reduction due to rutting. Horizontal permeability tests were conducted by varying the hydraulic gradient of specimens with porosities of 19.6%, 15.6%, and 10.3%. The reduction in cross-section due to traffic loading was simulated via a wheel tracking test, and the permeability was subsequently evaluated. The reliability of test methodology was successfully verified; the tendency of the relationship between discharge velocity and hydraulic gradient was in good agreement with existing research results. The reduction in cross-sectional flow area due to rutting decreased and the horizontal permeability. The test results using developed testing equipment will enable efficient OGFC design.