Posttraffic Testing On Medium-Strength Subgrade Flexible Pavements At The National Airport Pavement Test Facility

摘要

During the first series of traffic tests, two flexible pavement test items on medium-strength subgrade (MFC & MFS) exhibited severe rutting, with upheaval outside the traffic lanes, and asphalt surface (AC) cracking in the wander path. Four trenches were opened perpendicular to the centerline of the test items to conduct posttraffic investigation into the failure mechanism of the pavement structure. The trenching involved removal of the P-401 AC layer, the P-209 base, and the P-154 subbase layer to reveal the subgrade interface and subsequent subgrade layers below. Tests conducted on the pavement component layers included CBR's, in situ densities and moisture contents, and dynamic cone penetrometer tests. Elevation profiles of the interfaces show clear evidence of shear flow in the subgrade, with vertical movement of the subgrade material in the upheaval areas.