Field Calibration and Implementation of the Performance-Based Chip Seals Mix Design Method
Record Type: DOT
A series of research projects has been funded by the North Carolina Department of Transportation (NCDOT) to investigate various ways to improve chip seal performance. During the course of conducting these research projects, existing chip seal test methods and design procedures were carefully reviewed and evaluated. The review of existing design procedures has revealed a clear need for a new chip seal design procedure that encompasses new materials and is based on performance. Specifically, the existing design methods do not take into consideration lightweight materials, which are used throughout the State, or the use of polymer-modified emulsion, which is gaining support in more Divisions.
In response to these urgent needs, the NCDOT funded a research project, HWY-2008-04, Development of a New Chip Seal Mix Design Method, which was conducted by North Carolina State University (NCSU). The findings from the HWY-2008-04 project clearly demonstrate the ability of the NCSU-developed chip seal mix design to help ensure effective and consistent performance with regard to the performance parameters that are important for chip seals. However, three primary research needs were identified at the end of the HWY-2008-04 project. First, the NCSU mix design procedure calls for adjustment of the design aggregate application rates (AARs) and emulsion application rates (EARs) based on the individual job conditions. Calibration of these parameters is needed to ensure the effectiveness of the mix design procedure in field situations. Secondly, the survey results from the HWY-2008-04 project reveal that the design rates used by some Divisions are much higher than the NCSU optimal mix design rates. Therefore, if the lower NCSU rates yield satisfactory performance in the field, significant cost savings could be realized by NCDOT and NC taxpayers. Thirdly, the NCSU mix design procedure for single seals needs to be extended to apply to the more commonly used multiple seals.
The proposed research herein describes a field and laboratory experimental program to meet these research needs so that the calibrated and validated NCSU performance-based mix design procedure can be implemented by the Divisions. Once the research products are implemented successfully, the Divisions will be able to use the mix design procedure to improve the consistency and performance of chip seals statewide. The performance-based chip seal mix design procedure will provide pavement preservation engineers with tools to design the appropriate mix for each job site, and help ensure better chip seal performance over time. These tools, when used in conjunction with field experience and effective construction techniques, will become the foundation for improving chip seal performance statewide. Additionally, the product will be adaptable as various regions make slight adjustments to the design to account for local environmental variables. It is expected that these benefits will result in long-term cost savings for the State and overall improvement in the condition of chip seal pavements in North Carolina.
Start date: 2012/8/16
End date: 2014/8/15
Contract/Grant Number: 2013-03
Total Dollars: $291,000
Source Organization: North Carolina Department of Transportation
Date Added: 06/12/2012
Index Terms: Chip seals, Mix design, Pavement performance, Aggregates, Field tests, Calibration, North Carolina,
North Carolina Department of Transportation
Research and Development
1549 Mail Service Center
Raleigh, NC 27699-1549
Phone: (919) 508-1790
Fax: (919) 715-0137
Kadibhai, Mustansir A.
Phone: (919) 508-1819
Fax: (919) 715-0137
North Carolina State University, Raleigh
Department of Civil Engineering, Campus Box 7908
Raleigh, NC 27695-7908
Kim, Y. Richard
Phone: (919) 515-7758
Fax: (919) 515-7908