- Topic Submission
- Discussion & Evaluation
- Development
- Project
Asset Management
Maintenance & Preservation
Pavements
Is this related to or a continuation of a previous Iowa DOT research project?
No
Does this idea include matching funds?
No
Anticipated Benefits
Development of strategies for maintaining lower volume highways that are near the end of their service life to a satisfactory level in order to delay the larger expense of rebuilding them.
Focus Area
Sustainability
Research Program
SPR / 774: Research & Technology Transfer
Project Title
Holding Strategies for Low Volume State Routes
Project Number
RB35-013
Contracted Agency
Iowa State University
Funding Program
State Planning and Research
Project Funding
$89,726
Project Funding Including External Sources
$89,726
Project Start Date
03/01/2013
Current Project End Date
12/31/2020
Project Abstract
The overall pavement condition of Iowa’s highway network has been deteriorating in the past decade due to aging facilities, increasing traffic, and lack of financial resources. Due to insufficient funding, rehabilitation or reconstruction is delayed for low volume roads in need of repairs. Some lower cost treatments, which may have shorter life expectancies in comparison to traditional rehabilitation or reconstruction methods, have been considered inappropriate for use with severely deteriorated pavements. However, these treatments could be applied to “hold” these pavements in an acceptable condition until funding for rehabilitation or reconstruction is available. Such holding strategies would likely increase the flexibility in allocating funds and improve the overall condition of the highway network in Iowa.
In order to develop treatments that can be used to fulfill the goal of a holding strategy, nine test sections were constructed on a 13 mile low-volume asphalt road segment in 2013. Proposed holding strategy treatments using various combinations of thin and ultrathin asphalt overlays, in-place recycling technologies, and chip seals were applied to remedy the poor surface conditions of the pavements. A series of pavement condition surveys, in situ and laboratory material tests, and surface characterizations were performed to evaluate the structural and functional performance of the test sections.
Based on the performance of the test sections, the life expectancies of the various treatments were estimated and lifecycle costs were analyzed. The lifecycle cost analysis results indicate that 8 of the 10 proposed treatments can be used as candidate holding strategy treatments to address conditions that are like the test. The other treatments had lower cost-effectiveness for these test sections compared to traditional pavement rehabilitation methods. However, they could be more cost effective in circumstances that are better matched to their advantages.
In order to develop treatments that can be used to fulfill the goal of a holding strategy, nine test sections were constructed on a 13 mile low-volume asphalt road segment in 2013. Proposed holding strategy treatments using various combinations of thin and ultrathin asphalt overlays, in-place recycling technologies, and chip seals were applied to remedy the poor surface conditions of the pavements. A series of pavement condition surveys, in situ and laboratory material tests, and surface characterizations were performed to evaluate the structural and functional performance of the test sections.
Based on the performance of the test sections, the life expectancies of the various treatments were estimated and lifecycle costs were analyzed. The lifecycle cost analysis results indicate that 8 of the 10 proposed treatments can be used as candidate holding strategy treatments to address conditions that are like the test. The other treatments had lower cost-effectiveness for these test sections compared to traditional pavement rehabilitation methods. However, they could be more cost effective in circumstances that are better matched to their advantages.
Project Complete Date
02/17/2021
Project Deliverables
Final Report Abstract
The Iowa Department of Transportation (DOT) sponsored a research project that involved constructing nine test sections on a 13-mile low-volume asphalt road in 2013. The aim of this research project was to develop holding strategies as a potential solution to a critical challenge facing the state.
The overall pavement condition of Iowa’s highway network has been deteriorating in the past decade, primarily due to aging facilities, increasing traffic, and lack of financial resources. Maintenance efforts for low-volume roads that are due for rehabilitation or reconstruction are sometimes postponed due to insufficient funding.
Some lower cost treatments, which may have shorter life expectancies in comparison to traditional rehabilitation or reconstruction methods, have been considered inappropriate for use with severely deteriorated pavement. However, these treatments could be applied to these pavements to “hold” them in an acceptable condition until funding for rehabilitation or reconstruction is available. Such holding strategies would likely increase the flexibility in allocating funds and improve the overall condition of the highway network in Iowa.
The holding strategy treatments described in this report include various combinations of thin and ultrathin asphalt overlays, in-place recycling technologies, and chip seals. This report documents the construction and six-year performance of the test sections. The performance was evaluated by pavement condition surveys, in situ nondestructive structural tests, laboratory material tests, and various surface characterizations.
The pavement condition surveys indicated that longitudinal cracking, rutting, raveling, edge breaks, and roughness in the existing pavements have been successfully corrected by the holding strategy treatments. The predominant distress type found in the test sections was reflective transverse cracking that developed from the cracking patterns that remained in the remaining layers of the original pavement sections.
Recycling technologies were the most effective treatments in preventing reflective cracking. A thin interlayer with an ultrathin asphalt overlay method and a two-inch asphalt overlay exhibited satisfactory performance against reflective transverse cracking. The sections that were scarified and covered with thin asphalt overlays developed more transverse cracking in comparison to the other test sections.
Applying chip seals over various treatments improved their ability to prevent reflective cracking. Loss of cover aggregate caused by snow plowing operations and traffic was observed with chip seals that were applied to rough surfaces, such as scarified pavements or full-depth reclamation (FDR) layers. The surface characteristics of the asphalt pavements and chip seals were evaluated using a dynamic friction tester (DFT) and the sand patch test (SPT). From a safety perspective, the functionality of chip seals is comparable to that of an asphalt surface. However, chip seals have higher macro-texture in comparison to an asphalt surface, which can lead to an increased noise level and faster tire wear. Some localized distress at bridge approaches was also observed where chip seals were the final surface over cold in-place recycling (CIR) and FDR.
The influences of the holding strategy treatments on the test sections’ structural capacity were investigated using a falling weight deflectometer (FWD) test and a dynamic modulus (E*) test. The structural evaluation indicated that the holding strategy treatments tend to temporarily decrease pavement structural capacity. The test sections regained their stiffness within two years after construction. The treatments involving a CIR or FDR layer exhibited the greatest decrease in pavement structural capacity shortly after construction, and pavements recovered to the original stiffness level that existed before construction within two years.
The lifecycle costs of the various holding strategy treatments were estimated and compared to those of a traditional 3-in. asphalt concrete overlay rehabilitation method. The lifecycle cost analysis (LCCA) results indicated that the equivalent annual cost (EAC) of the FDR and CIR with a double chip seal surface was projected to be higher than that of the 3-in. overlay strategy. The lifecycle costs of the other holding strategies are projected to be less than or equal to the lifecycle cost of the 3-in. overlay method.
The overall pavement condition of Iowa’s highway network has been deteriorating in the past decade, primarily due to aging facilities, increasing traffic, and lack of financial resources. Maintenance efforts for low-volume roads that are due for rehabilitation or reconstruction are sometimes postponed due to insufficient funding.
Some lower cost treatments, which may have shorter life expectancies in comparison to traditional rehabilitation or reconstruction methods, have been considered inappropriate for use with severely deteriorated pavement. However, these treatments could be applied to these pavements to “hold” them in an acceptable condition until funding for rehabilitation or reconstruction is available. Such holding strategies would likely increase the flexibility in allocating funds and improve the overall condition of the highway network in Iowa.
The holding strategy treatments described in this report include various combinations of thin and ultrathin asphalt overlays, in-place recycling technologies, and chip seals. This report documents the construction and six-year performance of the test sections. The performance was evaluated by pavement condition surveys, in situ nondestructive structural tests, laboratory material tests, and various surface characterizations.
The pavement condition surveys indicated that longitudinal cracking, rutting, raveling, edge breaks, and roughness in the existing pavements have been successfully corrected by the holding strategy treatments. The predominant distress type found in the test sections was reflective transverse cracking that developed from the cracking patterns that remained in the remaining layers of the original pavement sections.
Recycling technologies were the most effective treatments in preventing reflective cracking. A thin interlayer with an ultrathin asphalt overlay method and a two-inch asphalt overlay exhibited satisfactory performance against reflective transverse cracking. The sections that were scarified and covered with thin asphalt overlays developed more transverse cracking in comparison to the other test sections.
Applying chip seals over various treatments improved their ability to prevent reflective cracking. Loss of cover aggregate caused by snow plowing operations and traffic was observed with chip seals that were applied to rough surfaces, such as scarified pavements or full-depth reclamation (FDR) layers. The surface characteristics of the asphalt pavements and chip seals were evaluated using a dynamic friction tester (DFT) and the sand patch test (SPT). From a safety perspective, the functionality of chip seals is comparable to that of an asphalt surface. However, chip seals have higher macro-texture in comparison to an asphalt surface, which can lead to an increased noise level and faster tire wear. Some localized distress at bridge approaches was also observed where chip seals were the final surface over cold in-place recycling (CIR) and FDR.
The influences of the holding strategy treatments on the test sections’ structural capacity were investigated using a falling weight deflectometer (FWD) test and a dynamic modulus (E*) test. The structural evaluation indicated that the holding strategy treatments tend to temporarily decrease pavement structural capacity. The test sections regained their stiffness within two years after construction. The treatments involving a CIR or FDR layer exhibited the greatest decrease in pavement structural capacity shortly after construction, and pavements recovered to the original stiffness level that existed before construction within two years.
The lifecycle costs of the various holding strategy treatments were estimated and compared to those of a traditional 3-in. asphalt concrete overlay rehabilitation method. The lifecycle cost analysis (LCCA) results indicated that the equivalent annual cost (EAC) of the FDR and CIR with a double chip seal surface was projected to be higher than that of the 3-in. overlay strategy. The lifecycle costs of the other holding strategies are projected to be less than or equal to the lifecycle cost of the 3-in. overlay method.
Project Champion
Technical Advisory Committee
Project Manager
Delivering targeted solutions for Iowa's transportation future.
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