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Long-Term Field Performance of Cold In-Place Recycled Roads in Iowa |
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| Authors: | Jungyong “Joe” Kim Hosin “David” Lee Charles T Jahren Michael Heitzman Don Chen |
| Affiliation: | 1Graduate Engineer, Fugro Consultants, Inc., 8613 Cross Park Dr., Austin, TX 78754. E-mail: jkim@fugro.com 2Associate Professor, Dept. of Civil and Environmental Engineering, Public Policy Center, 227 South Quad, Univ. of Iowa, Iowa City, IA 52242. E-mail: hlee@engr.uiowa.edu 3Associate Professor, Dept. of Civil, Construction, and Environmental Engineering, Iowa State Univ., 456 Town Engineering Bldg., Ames, IA 50011 (corresponding author). E-mail: cjahren@iastate.edu 4Assistant Director, National Center for Asphalt Technology, 277 Technology Pkwy., Auburn, AL 36830. E-mail: mah0016@auburn.edu 5Assistant Professor, Dept. of Engineering Technology, William States Lee College of Engineering, Univ. of North Carolina at Charlotte, 237 Smith Bldg., Charlotte, NC 28223-0001. E-mail: dchen9@uncc.edu |
| Abstract: | Cold in-place recycling (CIR) is one of the most effective methods to rehabilitate asphalt pavements. In fact, most CIR roads have performed well at low cost in Iowa since the first CIR road was constructed in 1986. However, some CIR roads have reached failures earlier than their expected design lives because there is no design standard for designing CIR roads with a limited amount of past performance information. Some of the most prominent problems seemed to have come from selecting CIR in areas where there are poor subgrades. Therefore, it is critical to collect CIR performance data along with falling weight deflectometer (FWD) data in order to develop performance models. The main purpose of this paper is to document that effort. The performance models were developed on the basis of historical data collected from CIR roads in Iowa. First, an inventory of CIR roads was created which includes construction information, subgrade and base characteristics, and traffic levels. In consideration of pavement age, level of traffic, and subgrade condition, 26 test sections were selected from the inventory of CIR roads and pavement surface distress surveys were conducted on these roads using an automated image collection system. Distress data were then compiled to compute pavement condition index (PCI) for each test section. FWD data were collected from each test section to determine its relative soil support condition. Finally, to determine their long-term performance, the PCI values were plotted against the pavement age for each group of pavements categorized by their soil support conditions and traffic levels. Overall, it can be concluded that the CIR roads in Iowa, all under traffic level of annual average daily traffic of 2,000, have performed very well and predicted to last up to 25 years before reaching the poor condition (PCI = 40) when the pavements are to be rehabilitated. The CIR roads with a good subgrade support, however, are predicted to last up to 35 years. |
| Keywords: | Asphalt pavements Recycling Service life Stress Measurement Iowa |