A Novel Method to Optimize N-design for Balanced Performance and Compactability
The Superpave gyratory compaction number, N-design, represents the number of gyrations a hot mix asphalt is subjected to in a gyratory compactor to simulate field compaction and achieve desired volumetric properties. However, currently specified gyration levels have recently come into question as being rather excessive. High N-design values can reduce voids in mineral aggregates, lower the design asphalt binder content, and ultimately compromise the compactibility and durability of the asphalt mixture. Quite a few state departments of transportation (DOTs) have resorted to modifying their design specifications to lower N-design values, but these adjustments mostly rely on a trial-and-error approach and lack a strong correlation with field compaction behavior and long-term performance. A method with scientific basis would be more appropriate for optimizing N-design, particularly in alignment with the Balanced Mixed Design concept to ensure an optimal trade-off between rutting resistance and cracking performance. For NCHRP 20-30/IDEA 267, the research team will conduct research based on the theory that particle rotation under compacting effort serves as a fundamental parameter linking laboratory and field compaction. The method employs the rotation parameter and wireless sensors along with artificial intelligence to bridge the gap between laboratory and field compaction and establishes a scientifically sound approach to determine N-design criterion for balanced performance and improved field compactibility. It also enables laboratory compaction to serve as an effective tool for mix design optimization, specimen preparation for field performance evaluation, and field compaction guidance. With a focus on optimizing N-design criteria and evaluating performance, Superpave gyratory compaction tests with wireless sensors will be conducted along with performance tests for rutting and cracking. Laboratory and field compactibility will be evaluated along with volumetric properties and performance. Using the obtained results, N-design for balanced performance and compactibility will be optimized. Next, the optimized N-design and compaction will be validated. Designed mixtures with reduced N-design numbers will be verified and their field compactibility analyzed. Field pavement performance will be monitored, and the reasonableness of the reduced N-design numbers will be confirmed. To facilitate transfer to practice, an implementation plan will be developed, including an Excel-based tool and a training module with a video.
Language
- English
Project
- Status: Active
- Funding: $149,954.00
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Contract Numbers:
Project 20-30, IDEA 267
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Sponsor Organizations:
National Cooperative Highway Research Program
Transportation Research Board
500 Fifth Street, NW
Washington, DC United States 20001American Association of State Highway and 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 -
Project Managers:
Jawed, Inam
- Performing Organizations: Altoona, PA United States
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Principal Investigators:
Shen, Shihui
- Start Date: 20250101
- Expected Completion Date: 0
- Actual Completion Date: 0
Subject/Index Terms
- TRT Terms: Compaction; Cracking; Hot mix asphalt; Mix design; Pavement design; Rutting
- Subject Areas: Design; Highways; Pavements;
Filing Info
- Accession Number: 01993204
- Record Type: Research project
- Source Agency: Transportation Research Board
- Contract Numbers: Project 20-30, IDEA 267
- Files: TRB, RIP
- Created Date: Jun 23 2026 1:22PM