Constructing and maintaining pavements require a dependable and abundant supply of quality aggregates. Aggregates encompass a wide range of materials including quarried rock, sand and gravel, and materials such as slag, reclaimed asphalt pavement (RAP) and recycled concrete aggregate (RCA). Identifying and qualifying sources in terms of material availability is important although usage may be limited by specifications and other considerations. Moreover, the availability of quality aggregate material is decreasing due to depletion or loss to other land uses.
Aggregate type and quality are important factors for determining use and placement within the different layers of the pavement structure. There are wide variations in what transportation agencies consider suitable aggregates for specific applications. Under certain conditions, agencies have modified their specifications to allow the use of a wider range of materials. Optimizing the use of available materials can yield significant economic and environmental benefits.
The objective of this synthesis is to document and summarize transportation agency requirements for the quality of aggregates used for various pavement types.
Information to be gathered for different pavement types and applications includes (but is not limited to):
• Material properties
• Test methods (e.g., AASHTO, ASTM, agency specific methods, etc.)
• Typical ranges of test results
• Acceptance criteria and methods
• Modifications and innovations to optimize the use of available aggregates or allow a wider range of materials
• Links to or copies of agency specifications
• Documented performance metrics (e.g., impact of using recycled materials, importing aggregates, changing acceptance criteria, environmental and economic impacts)
Information will be gathered by literature review, survey of state DOTs and Canadian provincial transportation agencies. Follow up interviews with selected agencies will be conducted to illustrate examples of the optimization of aggregate use for different applications. The survey will be directed to the voting members of the AASHTO Subcommittee on Materials.
Information Sources (Partial):
• NCHRP 9-35, Aggregate Properties and Their Relationship to the Performance of Superpave-Designed HMA: A Critical Review
• NCHRP Project 4-19(2), Validation of Performance-Related Tests of Aggregates for Use in Hot-Mix Asphalt Pavements
• P. S. Kandhal and F. Parker, NCHRP 4-19, Aggregate Tests Related to Asphalt Concrete Performance in Pavements
• A. Saeed et al., NCHRP 4-23, Performance-Related Tests of Aggregates for Use in Unbound Pavement Layers
• E. Masad et al., NCHRP 4-30A, Test Methods for Characterizing Aggregate Shape, Texture, and Angularity
• L. Wang et al., NCHRP 4-34, Application of LADAR in the Analysis of Aggregate Characteristics
• D. W. Christensen and R. F. Bonaquist, NCHRP 9-25, Requirements for Voids in Mineral Aggregate for Superpave Mixtures
• NCHRP Synthesis 445, Practices of Unbound Aggregate Pavement Layers
• Volz et al, RCA for infrastructure Elements, MoDOT Report 14-014, June 2014
• Wen et al, Evaluation of Recycled Concrete as Aggregate in new Concrete Pavements, WSDOT Report WA-RD 826.1, April 2014
• NCHRP 4-20A
• NCHRP 4-31
Jo Allen Gause
First Panel: September 21, 2016, Washington, DC
Teleconference with Consultant: October 5, 2016, 1:00 p.m., EST
Second Panel: June 15, 2017, Washington, DC
Sheila Beshears, Illinois DOT
Michael Dawidczik, Texas DOT
Larry Ilg, Oregon DOT
Thomas J. Kazmierowski, Golder Associates Ltd.
Leslie A. McCarthy, Villanova University
Derek J. Nener-Plante, Maine DOT
Roger C. Olson, Minnesota Department of Transportation (Ret)
John P. Shoucair, Florida DOT
Michael Arasteh, Federal Highway Administration
Richard C. Meininger, Federal Highway Administration
Amir N. Hanna, Transportation Research Board
Nancy M. Whiting, Transportation Research Board