AEMA’s International Technical Committee presents New Concept on Pavement Preservation Materials Specifications – NCHRP 9-50
Special ITC Session at Annual Meeting – Friday, February 26, at 8:00 – 11:00 am
Dr. Y. Richard Kim, North Carolina State University
Dr. Amy Epps-Martin, Texas A & M University
The Asphalt Emulsion Manufacturers Association (AEMA) and AEMA’s International Technical Committee have secured Dr. Y. Richard Kim and Dr. Amy Epps-Martin to present a new concept on Pavement Preservation Materials Specifications. These presentations will cover the National Cooperative Highway Research Programs research initiative to bring the Performance Specifications to Pavement Preservation Applications and the implementation of a Surface Performance Grade standard specification in Texas. The primary researchers will present the methods that were used to guide their research and how the new standards were developed and refined. Many agencies and DOT’s have expressed interest in implementing these new specifications or specifications like them and these new specs may be coming to your market sooner rather than later.
Dr. Y. Richard Kim, North Carolina State University, will present on the subject of the NCHRP 9-50 and its findings. As listed by TRB, the properties of asphaltic binders used in preservation surface treatments are very important to the performance of the treatment in which they are used. However, asphaltic binders used in such treatments are often selected based on availability and other factors that are not necessarily related to the performance of the final product. Often distress, such as stripping and raveling of these treatments, can be traced directly to improper binder selection and use. Clearly, proper binder selection is necessary for attaining desired performance. Performance-related specifications (PRS) that specify quality in terms related to long-term performance will help in the selection of the proper binder for a specific application. Although such PRS have been developed for the constituents of hot-mix asphalt mixtures used in pavements, PRS are not readily available for binders used in preservation surface treatments. Therefore, research is needed to (1) evaluate existing binder tests and, if necessary, identify new tests that relate to performance and (2) develop PRS for preservation surface treatments that provide a direct relationship between key quality characteristics of asphaltic binders and performance. These specifications will help highway agencies specify binder characteristics that will provide the desired performance of preservation treatments.
The objective of this research is to develop recommended performance-related specifications (PRS) for asphaltic binders used in preservation surface treatments. For the purpose of this research, preservation surface treatments are treatments that are applied to a large surface area of an existing roadway to slow future deterioration and maintain or improve its functional condition (without increasing structural capacity) such as chip seals, microsurfacing, and slurry seals.
More information is available at http://apps.trb.org/cmsfeed/TRBNetProjectDisplay.asp?ProjectID=2962
Dr Amy Epps-Martin, Texas A & M University, will present on the implementation of Surface Performance Grade Specifications for the Pavement Preservation applications. It will, essentially, be the implementation of the NCHRP 9-50 findings, except with TTI and TXDOT input. The TTI’s research proposal abstract to TXDOT (with link for validation) follows: 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, finally, 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.
More information is available at http://d2dtl5nnlpfr0r.cloudfront.net/tti.tamu.edu/documents/0-1710-2.pdf