Accelerated laboratory tests are being used to evaluate the “adhesivity” of an asphalt, that is, its resistance to displacement from aggregate surfaces by water. These methods generally involve an evaluation of the coated aggregate after static immersion in water. To establish whether a correlation exists with field performance, comparisons have been made of a static immersion test with circular track tests and with the behavior of pavements under normal traffic conditions.

The study included paving grade and cutback asphalts, with and without adhesion promoters, used in surface treatment, road mix, and plant mix construction.

The static immersion test usually predicted the initial ability of cutback asphalt to coat and adhere to damp or wet aggregate. However, no correlation with pavement service performance was evident in the 12-yr period of field observations. The various adhesion promoters did not exhibit the life improvement indicated possible by the circular track tests. Thus, new laboratory methods must be developed based on satisfactory correlation with longtime observations of actual pavements exposed to traffic.