Frictional Properties of Asphalt Concrete Pavements in Iowa, MLR-87-5, 1987

Friction testing of pavements has been a continuing effort by the Iowa Department of Transportation since 1969. This report details results of tests of asphaltic concrete pavements on the primary and interstate road systems. Both sprinkle treated and non-sprinkle treated pavements placed between 1975 - 1985 are included. A total of 1785 miles representing 216 separate paving projects were examined. The effect of fog sealing sprinkle treated pavements was studied by testing friction levels before and after the application of the fog seals. Conclusions of the report are: 1. Current aggregate selection criteria for a.c. pavement surface courses provides adequate friction levels through 10 years and should remain effective through a 15 year design life. 2. Sprinkle treatment of pavements has, for the most part, provided macrotexture in the pavement surface as evidenced by smooth tire testing. 3. Fog sealing sprinkle treated pavements does not significantly alter the friction properties.