Analyze Existing Fog Seal Asphalts and Additives

This project summary report summarizes the research performed in Texas Department of Transportation (TxDOT) Project 0-5091. The purpose of this two-year project was to assess the effectiveness of fog seal treatments as an aid to highway maintenance managers in making sound decisions for fog seal treatments. The project investigated asphalt emulsions and coal-tar type materials and evaluated the physical and durability properties of fog seal binders. Researchers found that the fog seal does not penetrate into the pavement to a detectable level. The project investigated the effects of the fog seal treatments on the in situ binder, specifically the possible rejuvenation of the binder and possible effects to retard binder aging. The project also reviewed data to assess the effects of air voids or binder content on binder aging in pavements and determined that the aging rates of asphalt binders are decreased by very low accessible air voids. The effects of fog seals on pavement durability appear to be minimal with respect to binder rejuvenation or sealing. Cosmetic effects or possible protection against shelling or raveling remain as possible benefits although they were not assessed by this project.