Asphalt Durability Tests and Their Relationship to Field Hardening

A total of 24 asphalts in 8 test sections are being evaluated relative to their change in viscosity with time. The test sections are located in different climatic areas in California. Statistical correlations are presented covering various laboratory test methods for predicting asphalt durability with 30 and 50 months of pavement service life. The laboratory test methods employed for predicting asphalt durability involve the concept whereby the asphalt is weathered by heat and air in a thin film. The amount of heat and thickness of the film varies, but the end result is basically volatization and oxidation to cause hardening of the asphalt. Additional correlations are presented using original voids and chemical procedures involving the Rostler analysis and Heithaus procedure. This report discusses the findings to date; additional pavement service life will be required before final conclusions can be drawn.