Evolution of the Surface Performance-Graded Specification for Chip Seal Binders

Over the past 15 years, a surface performance-graded (SPG) specification for chip seal binders has been developed by the Texas Department of Transportation and has been validated with laboratory measurements and the visual field performance of 120 highway sections. The SPG specification was established in an effort to extend the service life of chip seals by providing a binder grading system and an associated selection method that (a) accounted for differences in climate and (b) used existing equipment and performance-based properties that precluded bleeding and aggregate loss in the critical first year of service after construction. A multiyear implementation effort of this specification is ongoing. This paper describes the motivation and evolution of the SPG specification, including a summary of the validation effort and a round robin testing program with the Texas Department of Transportation and suppliers of chip seal binders. Binder selection guidelines that use this specification are provided.