Optimum Time for Application of Slurry Seal to Asphalt Concrete Pavements
This study evaluated the field performance of asphalt pavements with and without slurry seal applications, developed performance models for asphalt pavements without slurry seals and asphalt pavements receiving slurry seals at various times following construction, and identified the optimum time for the application of slurry seals on asphalt pavements within the Washoe County, Nevada region.
This was achieved by evaluating the long-term pavement performance data collected using the MicroPAVER system for the last 15 years and the cost-effectiveness of slurry seals applied to new and existing flexible pavements at years 0, 1, 3, 5, 7 and 9 after construction. This study found that the application of the slurry seal immediately after or 1 year after construction of the asphalt layer is not effective in terms of both the benefit to the users and the benefit cost ratio for the agency.
The optimum time of application of slurry seal depended on the type of the construction activity. For newly constructed pavements, the optimum time to apply slurry seal was three years after construction.
For pavements subjected to overlays, the optimum time to apply slurry seal was between three and five years after construction. However, for uniformity purposes, it was recommended that the agency applies slurry seal three years after the construction of the asphalt layer for both new and overlay constructions.
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Performance Evaluation of Terminal Blend Tire Rubber Asphalt Mixtures – Case Studies
A terminal blend tire-rubber (TR) modified asphalt binder is made using a finely ground crumb rubber modifier that is typically blended and digested into the binder at the asphalt refinery. TR with less than 10% rubber was initially introduced in hot mix applications during the mid 1980’s in California and Florida. Since then, it has been used in several other states with increasing amount of rubber up to 20% as a finished PG-TR binder in recent years. This paper summarizes the efforts undertaken in Nevada to assess and implement the use of TR binders in dense graded asphalt mixtures.
An extensive performance evaluation was conducted in the laboratory to assess and compare the TR binders to the standard polymer-modified asphalt binders used in Nevada. Subsequently, based on the findings, pilot demonstration projects were constructed in 2008 in Nevada and California with side by side sections of TR and polymer-modified asphalt mixtures.
Visual inspections conducted in 2011 of both projects revealed no visual distresses, with the pavement condition being excellent and uniformly the same along the total length of both test sections. Giving this promising field performance of TR mixes, a study was initiated in 2010 to evaluate the use of TR in warm-mix asphalt (WMA) mixes. The results for two types of warm-mix additives are presented in this paper: Advera® and Sasobit®. Mixture resistance to moisture damage was evaluated using the indirect tensile test and the dynamic modulus at multiple freeze-thaw cycles. The study specifically looked into the potential impact of aggregate residual moisture in the mix due to insufficient aggregate drying during production.
Overall, the impact of the evaluated warm-mix additives on the moisture resistance of the modified asphalt mixtures was similar for both the polymer-modified and terminal blend tire rubber modified asphalt binders.
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California Chip Seal Association 2011 Award Of Excellence In Contracting
- 96 Lane Miles of I-5 In Kern and Kings Counties
- 10,900 Tons of Type III Rubberized Slurry Seal
- CQS1h-TR Emulsion with Tire Rubber
- George Reed Table Mountain Type III Black Rock
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2012 Greenbook: Standard Specifications for Public Works Construction is Available Now!
- Utilization of tire rubber in emulsion reduces waste in landfills
- Tire rubber reduces road noise
- Use of black aggregate and tire rubber results in jet black appearance
The Standard Specifications for Public Works Construction, popularly known as the “Greenbook”, was originally published in 1967. The 2012 Edition is the 16th edition of this book, which is updated and republished every three years.
The Greenbook is designed to aid in furthering uniformity of plans and specifications accepted and used by those involved in public works construction and to take such other steps as are designed to promote more competitive bidding by private contractors. The Greenbook provides specifications that have general applicability to public works projects.
Many of the binder grades and emulsions that are listed in the Greenbook such as SS-1h, CQS-1h, PG58-22, PG64-10, PG64-16, PG70-10, MAC-10TR
are available at many of our terminal and refineries locations in California.
To order your copy of the Greenbook either by calling toll free (1-888-264-2665) or by clicking here: http://www.bnibooks.com/shopexd.asp?id=8363