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Development of Performance-Based Specification for Asphalt Binders: Fatigue Characterization

Project Information

Project ID: 
FHWA-PROJ-03-0001
Project Status: 
Completed
Start Date: 
Wednesday, January 1, 2003
End Date: 
Wednesday, June 30, 2010
FHWA Program: 
Infrastructure
FHWA Subprogram: 
Pavement and Materials
FHWA Topics: 
Roads and Bridges--Design; Roads and Bridges--Pavement and Materials
TRT Terms: 
Bituminous Binders Falling Weight Deflectometers Fatigue cracking Infrastructure Mechanistic Design Pavement Design; Pavements; Performance; Tests; Research; Rutting; Superpave; Testing
FHWA Discipline: 
Pavement and Materials
TRB Subject Area: 
Design, Highways, Pavements, Research

Contact Information

First Name: 
Dave
Last Name: 
Mensching
Telephone: 
(202) 493-3232
Email Address: 
Team: 
Infrastructure Materials Team
Office:
Office of Infrastructure Research and Development
Office Code: 
HRDI-10

Project Details

Project Description: 

Test pavements were constructed with the primary variable being the binder type. Full-scale rutting and cracking performance were collected and compared to various candidate binder tests to identify the most discriminating element to replace the current specification for asphalt fatigue cracking and rutting.

Goals

The primary objective of this full-scale accelerated pavement testing was to evaluate the performance of unmodified and polymer-modified asphalt binders, and to recommend improved specification tests over existing Superpave (SUperior PERforming Asphalt PAVEments) performance-grading methodologies.

Partners and Other Sponsor/Managing/Performing Organizations: 
Organization Role: 
Partner: Advisory
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Other
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Partner: Advisory
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Partner: Advisory
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Partner: Advisory
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Partner: Advisory
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Partner: Advisory
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Partner: Advisory
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Partner: Advisory
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Partner: Advisory
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Partner: Advisory
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Partner: Advisory
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Other
Organization Role: 
Partner: Advisory
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Partner: Advisory
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Partner: Advisory
Organization Role: 
Partner: Advisory
Project Findings: 

Two fatigue cracking specification tests were identified as being more capable than others: binder yield energy and critical tip- opening displacement. Two rutting specification tests that quantify irrecoverable deformations exhibited the best strength to capture rutting: multiple stress creep, and recovery and oscillatory-based nonrecoverable stiffness. Based on the full-scale performance and laboratory tests, crumb rubber (recycled tires) modified asphalt (Arizona wet process) was shown to significantly slow or stop the growth of fatigue cracks in a composite asphalt pavementstructure. A hybrid technique to modify asphalt with a combination of crumb rubber and conventional polymers (terminally blended) exhibited good fatigue cracking resistance relative to the control binder without the special handling procedures needed for some crumb rubber modified asphalts. Also, a simple addition of polyester fibers-to-asphalt mix was shown to have high resistance to fatigue cracking without the use of polymer modification. The research study also quantified the capabilities of the National Cooperative Highway Research Program’s mechanistic-empirical pavement design and analysis methodologies to predict rutting and fatigue cracking of modified asphalts that were not captured in the calibration data from the Long-Term Pavement Performance program. Falling weight deflectometer, multidepth deflectometer, and strain gauge instrumentation were used to measure pavement response. The results illustrated that the globally calibrated mechanistic-empirical performance models could differentiate between structural asphalt thickness but had difficulty differentiating modified from unmodified asphalt binder performance. Nonetheless, the mechanistic-empirical performance ranking and predictions were enhanced and improved using mixture-specific performance tests currently being implemented using the Asphalt Mix Performance Tester.

Deliverables

Deliverable Name: 
Full-Scale Accelerated Performance Testing for Superpave and Structural Validation: Transportation Pooled Fund Study TPF-5(019) and SPR-2(174) Accelerated Pavement Testing of Crumb Rubber Modified Asphalt Pavements
Deliverable Type: 
Research report or guidelines
Deliverable Description: 
This final report provides the comprehensive findings from two Transportation Pooled Fund (TPF) research projects: TPF-5(019) Full-Scale Accelerated Performance Testing for Superpave (SUperior PERforming Asphalt PAVEments) and Structural Validation and SPR-2(174) Accelerated Pavement Testing of Crumb Rubber Modified Asphalt Pavements. The research identified candidate purchase specification tests for asphalt binder that better discriminate expected fatigue cracking and rutting performance than current Superpave tests. Full-scale accelerated pavement testing and laboratory characterization tests on mixtures and binders provided the basis for the recommendations.The report documents a historical review of the development of asphalt binder performance specifications, experimental design, test pavement construction and performance, and statistical methodology to rank and identify the strongest candidates, and all pertinent laboratory characterization of binders and mixtures that supplemented the recommendations. The research also provided a detailed case study of pavement evaluation using a falling weight deflectometer and objective means to evaluate two emerging technologies: the Asphalt Mixture Performance Tester and the Mechanistic-Empirical Pavement Design Guide.