OPEN-GRADED DRAINAGE LAYERS: PERFORMANCE PROBLEMS UNDER CONTINUOUSLY REINFORCED CONCRETE PAVEMENTS IN ILLINOIS

Abstract

Illinois has constructed fourteen pavement sections that contain open-graded drainage layers (OGDLs) in the past few years. The pavement types include continuously reinforced concrete pavements (CRCPs), jointed concrete pavements, and full-depth asphalt concrete pavements. Three of the CRCPs have begun to show a higher level of distress than would be expected from pavements of that cross section and age. An in-depth investigation into the cause of the distress has begun. The investigation to date has included: visual distress surveys; core analysis; analysis of Shelby tube samples; analysis of OGDL gradations, separation layer gradations; and subgrade gradations; deflection tests; and inspection of slabs removed in patching operations. The state placed a moratorium on the construction of new OGDLs pending the outcome of the investigation. The distresses evident on these pavements may be related to the characteristics of the OGDL, separation layer, and subgrade. The bonding of the CRCP to the OGDL, as well as crack spacing, may have contributed to the poor performance of these pavements. The current maintenance plan includes patching and undersealing of problem areas. Until the investigation is concluded, ODGLs should not be constructed under CRCPs.