Detection of Stripping in Hot-Mix Asphalt

Abstract

Damage mechanisms that lead to stripping significantly affect the dynamic modulus and tensile strength of hot-mix asphalt (HMA). When stripped HMA is unexpectedly encountered below the planned milling depth during routine mill and overlay rehabilitation projects, it must be removed and replaced; this causes significant cost overruns and delays. A procedure was developed to identify the extent and depth of stripping in in-place HMA pavement sections. Several nondestructive survey methods were analyzed to determine their capability to locate areas of stripping, either by themselves or in various combinations. Cores were extracted and used to calibrate the methods. Visual inspections of the cores and laboratory tests on selected cores were used to validate the results. The procedure involved observation of surface distresses, complete ground penetrating radar survey, seismic testing of selected areas, limited coring, and laboratory testing of selected cores. With these procedures, areas with stripping can be distinguished so that effective rehabilitation strategies can be developed.