Technical Bulletin on Design and Construction of Crack Attenuating Mixes (CAM)
The crack attenuating mix (CAM) is proposed as a thin, long-lasting, cost effective surface mix for pavement maintenance and preservation. Developed under Texas Department of Transportation (TxDOT) research study 0-5598, this very fine mix is designed to pass both the current Hamburg wheel test (HWTT) to ensure moisture susceptibility and good rut resistance and strict overlay tester (OT) requirements to ensure good crack resistance. It is typically placed as a 1-inch thick mat. This mix has been evaluated in several districts around Texas, and the performance to date has been very good. A new statewide specification is under preparation and will be available in 2009. This comprehensive specification includes all aspects of material selection, mix design, and construction. The design of the mix relies on the traditional volumetric approach. In this report a new mix design procedure is proposed that builds on the fact that in the CAM design the aggregates and asphalt are paid for separately. The proposed procedure attempts to define a window of asphalt contents where both cracking and rutting requirements are satisfied. The optimal asphalt content (OAC) is defined as the middle of the acceptable range. The volumetrics are then checked after the performance tests are satisfied. This procedure has several advantages. It will rapidly identify aggregate/asphalt combinations that will not work so that costly re-runs of the volumetric designs will be avoided. This new procedure can save money by identifying a window of asphalt content that will provide satisfactory performance.
- Record URL:
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Supplemental Notes:
- Project Title: Development of Very Thin Overlay Systems. Report Date: January 2009; Resubmitted: October 2009; Published: February 2010.
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Corporate Authors:
Texas Transportation Institute
Texas A&M University System, 3135 TAMU
College Station, TX United States 77843-3135Texas Department of Transportation
Research and Technology Implementation Office, P.O. Box 5080
Austin, TX United States 78763-5080Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC United States 20590 -
Authors:
- Scullion, Tom
- Publication Date: 2010-2
Language
- English
Media Info
- Media Type: Web
- Edition: Technical Bulletin
- Features: Figures; Photos; Tables;
- Pagination: 20p
Subject/Index Terms
- TRT Terms: Asphalt content; Bituminous overlays; Cost effectiveness; Cracking of asphalt concrete pavements; Mix design; Performance tests; Rutting; Volumetric analysis
- Subject Areas: Highways; Materials; Pavements; I31: Bituminous Binders and Materials;
Filing Info
- Accession Number: 01154198
- Record Type: Publication
- Report/Paper Numbers: Report 0-5598-P1
- Contract Numbers: Project 0-5598
- Files: TRIS, USDOT, STATEDOT
- Created Date: Apr 8 2010 4:29PM