Validation of the Maximum Allowable Amounts of Recycled Binder, RAP & RAS Using Accelerated Pavement Testing
Record Type: DOT
The Texas Department of Transportation's (TxDOT's) current special provisions have permitted the use of both reclaimed asphalt pavement (RAP) and recycled asphalt shingles (RAS), but there is little evidence that these mixes give comparable performance to those mixes that do not incorporate any recycled materials. Concerns have been raised about mixes which are now "drier", more difficult to compact and more susceptible to both reflection and fatigue cracking. Several studies are currently underway either in Universities or in the Construction Division and field tests sections are being constructed and monitored around Texas. There is an urgent need to conduct a rapid evaluation of these materials and this can readily be performed using accelerated pavement testing (APT) technology. APT is not currently available in Texas. The University of Texas at Arlington (UTA) will establish an APT center which can be used for a range of rapid pavement evaluations. Funds have been obtained from the UTA system and ground has been acquired to house and operate the APT device. A series of flexible pavement test sections using Texas mixes in typical TxDOT pavement structures will be constructed. These mixes will have different levels of RAP and RAS; the goal is to validate the cracking and rutting potential of both control and RAP/RAS modified mixes within a controlled APT program. The key issues to be evaluated in this project include: (1) Validation that poor results on lab prepared RAP/RAS samples translates to poor field performance under load. (Industry groups claim the lab studies do not simulate plant produced mixes); (2) Validation of overlay design tools that have recently been developed by the Texas Transportation Institute (TTl) to predict mix cracking and rutting of new overlays; these models need to be validated and calibrated for RAP and RAS mixes. Having a validated design system will then permit TxDOT designers to predict the performance of mixes containing different RAP/RAS levels for a range of existing pavement types with different pavement structures and different pre-existing cracking levels; and (3) To determine if the proposed balanced mix design procedures which incorporate both a cracking and rutting evaluation in the lab design phase can be used to design RAP/RAS mixes with performances comparable to virgin mixes.
Start date: 2012/4/11
End date: 2014/4/30
Status: Active
Contract/Grant Number: 0-6682
Source Organization: Texas Department of Transportation
Date Added: 07/30/2012
Index Terms: Recycled materials, Fatigue cracking, Reflection cracking, Reclaimed asphalt pavements, Flexible pavements, Binders, Texas, Mix design,
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University of Texas, Arlington
P.O. Box 4089
Arlington, TX 76010
USA
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Romanoschi, Stefan A.
Phone: (785) 532-1594
Fax: (785) 532-7717
Email: sromano@ksu.edu
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