Refining Volumetric Boundaries for Balanced Mix Design (BMD) Approaches
Volumetric parameters have played a foundational role in asphalt mix design, acceptance, and quality assurance (QA). In both the Marshall and the Superpave mix design methods, volumetric criteria guide the selection of materials, aggregate gradation, and binder content. In more recent balanced mix design (BMD) approaches, particularly Approaches A and B, the initial mix design still relies on traditional volumetric properties. However, the integration of performance-related testing in BMD has raised questions about the continued relevance and appropriate limits of volumetric criteria. Modern asphalt mixtures increasingly incorporate modified binders, additives, reclaimed asphalt pavement (RAP), and other recycled or innovative materials that may result in volumetric properties that differ from conventional hot mix asphalt. Strictly enforcing conventional volumetric criteria may unnecessarily restrict the design flexibility that BMD seeks to promote. At the same time, volumetric properties are relatively easy to measure, monitor, and adjust during mix design, production, and QA, and they provide an additional layer of assurance in mix consistency and constructability. There is currently no consensus on how volumetric boundaries should be defined to appropriately reflect mixture performance and support effective mix design within the BMD framework. As transportation agencies transition toward performance-related mix design specifications, there is a need to revise current volumetric boundaries to better align with modern materials, performance objectives, and QA practices. The objective of this research is to investigate the impact of variations in volumetric parameters on modern asphalt mixtures and determine the volumetric boundaries that are suitable for BMD approaches and QA. The research should include, but not be limited to: Conducting a detailed review of practices, feedback, and experience in implementing and revising volumetric criteria in mix design and QA at state departments of transportation. Identifying the key volumetric parameters that can effectively control mix performance or provide mix design guidance in BMD. Evaluating the effect of changes in the identified volumetric parameters on mix performance. Defining appropriate volumetric boundaries and recommending necessary adjustments to Superpave volumetric criteria for various asphalt mixture types within the BMD framework. Demonstrating the application and effectiveness of the recommended volumetric boundaries within the BMD framework. Developing guidelines and draft revised specifications for BMD that incorporate the recommended volumetric boundaries.
- Record URL:
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Supplemental Notes:
- Contract to a Performing Organization has not yet been awarded.
Language
- English
Project
- Status: Proposed
- Funding: $900,000.00
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Contract Numbers:
Project 09-78
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Sponsor Organizations:
American Association of State Highway Transportation Officials (AASHTO)
444 North Capitol Street, NW
Washington, DC United States 20001Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC United States 20590 -
Managing Organizations:
National Cooperative Highway Research Program (NCHRP)
Transportation Research Board
500 Fifth Street, NW
Washington, DC United States 20001 -
Project Managers:
Khosravifar, Sadaf
- Start Date: 20261005
- Expected Completion Date: 0
- Actual Completion Date: 0
Subject/Index Terms
- TRT Terms: Asphalt mixtures; Mix design; Quality assurance; Volume
- Subject Areas: Design; Highways; Materials; Pavements;
Filing Info
- Accession Number: 01992222
- Record Type: Research project
- Source Agency: Transportation Research Board
- Contract Numbers: Project 09-78
- Files: TRB, RIP
- Created Date: Jun 10 2026 11:05AM