A Surface Performance-Graded (SPG) Specification for Surface Treatment Binders: Development and Initial Validation (0-1710-2)

Presently, surface treatment design and material selection is based on traditional specifications and experience, which are not performance-based and sometimes result in inadequate performance of the surface treatment. In 2000 the first phase of a Texas Department of Transportation (TxDOT) research project developed a surface performance-graded (SPG) specification for the selection of surface treatment binders (Research Report 1710-1). The SPG specification is performance-based and utilizes binder properties directly related to surface treatment performance and associated distress. The specification takes into account environmental conditions, aging effects of the binder, visco-elastic behavior, and reliability. The objective of this second phase of the project was to investigate and establish the validity and applicability of the proposed SPG specification, make modifications where necessary, and, fmally, recommend the SPG specification for practical implementation. The research methodology involved highway section identification, laboratory testing including SPG 'grading, performance monitoring, and comparison of the SPG binder grades to actual field performance. Factors included in the experimental design were binder type and suppliers, environment, aggregates, and traffic. Analyses of the results showed that there is generally a good correlation between the proposed SPG specification and actual field performance. Overall, the results are indicative that the SPG specification is functional and if properly applied, the specification promises to be a relatively cost-effective method for selecting binders to ensure adequate surface treatment performance. However, further validation is recommended, possibly with controlled test sections to fully investigate the effects of design, construction, and quality control processes and address some of the deficiencies of the specification.