Initial Assessment of TxDOT Binder Quality Assurance Program (0-4047-1)

Most state departments of transportation (DOT) maintain asphalt binder quality assurance (QA) programs to ensure that asphalt binders used in the construction of their road system meet specifications stipulated for each project. TxDOT samples and approves asphalt materials at the source and utilizes these materials in highway projects without consideration of possible changes in properties that may occur between production and use during construction. Historic concern and limited recent data indicate that binder properties do change, contributing to difficulties during construction operations and poor performance. The primary goal of this study is to evaluate the current TxDOT binder QA program and recommend revisions as necessary toward improving quality. This interim report documents an initial assessment of the current program based on (1) an extensive information search and review that included two detailed surveys of TxDOT districts and nine other state DOTS and (2) partial results from a comprehensive laboratory testing program that simulated factors that may affect changes in binder properties prior to use. Preliminary recommendations that will be evaluated as the project continues include performing a more detailed and comprehensive evaluation of the current binder QA program and implementing revisions in terms of a total binder quality system under the direction of a quality manager. In this system, the binder QA program would be one tool to improve material quality used during construction. Other recommended tools include mandated quality control (QC) plans for both suppliers and contractors that require special handling for binders, training programs for sampling and testing, general education seminars presenting the goals of the system to all involved, and a round-robin program to establish testing variability. Researchers also recommend development of a user-friendly database for storing binder QA data that includes storage times, storage temperatures, and pavement performance data. They suggest frequent analysis of this data, possibly to set frequency rates for field sampling by binder and supplier.