Improving Fracture Resistance Measurement in Asphalt Binder Specification with Verification on Asphalt Mixtures Cracking
Record Type: DOT
The current performance grading (PG) specification for asphalt binders was developed during the Strategic Highway Research Program (SHRP), it is based primarily on the study of unmodified asphalt binders. Over the years experience has proven that the PG grading system, while good for ensuring overall quality, fails in some cases to guarantee good rutting and cracking performance, particularly as it applies to modified binders. Specifically, recent studies on mixes with highly modified binders from out of state (Minnesota) found that the MnRoad mixes have substantially improved cold weather cracking properties than mixes currently used in Texas, while still passing Texas Department of Transportation's (TxDOT’s) Hamburg rutting requirements. To eliminate this type of apparent discrepancy AASHTO has adopted a new PG grading system based on the Multiple Stress Creep and Recovery (MSCR) test which is claimed to encourage the adoption of binders which are softer but still retain the required rut resistant. The benefits of the new grading system have not been verified for Texas asphalt binders and mixes. The major objectives of project 0-6674 are: (1) Determine if the new AASHTO MSCR-based binder grading system is superior to the current TxDOT binder grading system; (2) Identify/develop a simple test method or methods to characterize fracture and adhesive properties of asphalt binders and associated tentative specification limits; (3) Determine if the asphalt binders not currently used in Texas would potentially improve overlay performance, if so conduct an associated cost-benefit analysis; (4) Identify optimal asphalt binder/aggregate combinations for different environmental zones in Texas; (5) Develop and initially populate a catalogue of all these measured (binder, binder/fine aggregate mastic, and asphalt mix) properties with relevant information that can be used to track the field performance of pavements constructed using these asphalt binders.
Start date: 2011/9/1
End date: 2014/8/31
Status: Active
Contract/Grant Number: 0-6674
Total Dollars: 503940
Source Organization: Texas Department of Transportation
Date Added: 05/02/2012
Index Terms: Fracture mechanics, Binders, Asphalt, Multiple Stress Creep Recovery, Rut resistance, Texas, Pavements,
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