Surface performance grading and grade selection process for surface treatment binders

Abstract

Surface treatments have been used by many government agencies as part of their maintenance and rehabilitation programs to improve surface quality and extend the service life of pavements. Traditional specifications for asphalt binders failed to characterize materials across the entire spectrum of temperatures experienced during production and construction and in-service and required properties that were not directly related to performance. The Superior Performing Asphalt Pavements (Superpave) or performance-graded (PG) asphalt binder specification was developed in the 1990's to measure binder properties directly related to hot mix asphalt concrete (HMAC) performance and included material characterization at low, intermediate, and high temperatures. Direct application of the PG binder specification to binders used in surface treatments is not appropriate due to differences between surface treatments and HMAC in terms of distress types, construction methods, and exposure to environmental conditions. The objective of this study conducted for the Texas Department of Transportation was to develop a performance-based specification system for surface treatment binders that maximizes the use of existing equipment required in the PG system for HMAC binders. This new surface performance grading (SPG) specification assumes appropriate design and construction practices and considers only binder properties after construction. The SPG was developed based on the identification of common distresses and analysis of physical properties of surface treatment binders measured at multiple temperatures and corresponding performance in specific environmental conditions. The final SPG includes suggested limiting values for high and low surface pavement design temperatures. Implementation of the SPG is recommended after results from the suggested validation experiment are obtained.