CONCEPTS FOR DEVELOPING AN NDT-BASED DESIGN PROCEDURE FOR DETERMINING ASPHALT CONCRETE OVERLAY THICKNESS

Preliminary flexible pavement asphalt concrete (AC) overlay design concepts using nondestructive testing (NDT) data are presented. The NDT data inputs are equivalent 9-kip wheel load deflections. The maximum deflection and a deflection basin parameter called AREA are used. Conventional pavements (surface treatment + granular base) and full-depth AC pavements (AC surface + AC base) are considered. Procedures for field evaluation and NDT testing, NDT data interpretation, and determination of overlay thickness are proposed. The ILLI-PAVE structural model and resilient materials and soils testing principles are used in the procedure.