MPC
Research Projects (2009-10)

Identifying Number

MPC-316

Project Title

Mitigation of Corrosion in CRC Pavement, Year 1

University

South Dakota State University

Project Investigators

Dr. Nadim Wehbe, South Dakota State University Professor
Dr. Dana Medlin, South Dakota School of Mines and Technology Associate Professor

Description of Project Abstract

A recently completed research project by the South Dakota DOT, SD2004-07 Impact, Cause, and Remedies for Excessive Cracking in CRC Pavement involved condition surveys of CRC pavements built since 1995 using newer design standards and material requirements. One of the tasks for this project was to recommend cost-effective maintenance and rehabilitation strategies to maintain and extend the life of in-service CRC pavements exhibiting unexpected levels of cracking and distress.

The results of the surveys indicated a strong likelihood of potential future problems in the newer CRC with corrosion of the reinforcing steel, with several projects exhibiting rust staining on the pavement surface. The combination of relatively wide cracks and frequent small spalls along cracks led to a recommendation that this task would best be accomplished as a separate research project, as the scope was too broad to be adequately addressed as a single task.

The CRC pavements constructed as part of the original Interstate system in South Dakota have performed extremely well and exhibited virtually no problems with steel reinforcement corrosion. These pavements had typically tight surface cracks and no spalling and were subjected to a minimum of deicing chemicals over their lives. Comparable pavements in Minnesota, where the use of deicers was several orders of magnitude greater than in South Dakota, provides a cautionary tale of what can happen when corrosion occurs in CRC. Most of these Minnesota CRC pavements had to be replaced within a decade of construction as maintenance became impracticable. The demand for more aggressive winter maintenance, coupled with an increase in usage of solid sodium chloride and concentrated magnesium chloride deicers, means that the newer CRC pavements will be exposed to a much greater level of corrosion-inducing chloride than their predecessors.

This research project is necessary to determine the extent of the problem at present and develop strategies to mitigate any corrosion issues before they can result in a significant reduction in service life.

Project Objectives

1. Determine the character, extent, and severity of corrosion in CRC pavements constructed in South Dakota since 1995.
2. Identify factors and interactions among factors that contribute to observed levels of corrosion.
3. Develop cost effective maintenance and rehabilitation mitigation strategies for treatment of CRC pavements with corrosion problems to extend service life.

Project Approach/Methods

The project will include the following tasks:

1. Review literature pertaining to steel reinforcement corrosion in concrete, especially with regard to CRC pavements, with particular emphasis on mitigation using crack sealing and corrosion inhibitors.
2. Collect information on CRC projects, including results from the prior study, and conduct interviews with appropriate SDDOT personnel on particular projects using a questionnaire reviewed by the technical panel prior to use.
3. Develop a work plan for CRC project evaluation selection including factors such as geographic distribution, age, traffic, precipitation and deicing application rates, a sampling and testing site evaluation protocol including coring, chloride distribution levels, copper-copper sulfate half-cell potential measurements, cracking severity and spalling and crack width measurement and a laboratory testing matrix for evaluating the potential effectiveness of any mitigation measures.
4. Meet with the project's technical panel to discuss the project scope and work plan.
5. Conduct an initial CRC evaluation near Sioux Falls (projects north, south and east) and develop a preliminary assessment of the level of corrosion observed and the probable extent of any problems.
6. Meet with the technical panel via videoconference to discuss preliminary results, any desirable work plan modifications and the necessity of completing further work based on the magnitude of the problem.
7. Resume CRC project evaluation statewide based on the final work plan.
8. Conduct laboratory corrosion testing designed to demonstrate the effectiveness of various mitigation strategies including crack sealing, corrosion inhibitors and any other promising alternatives identified and develop a field test section matrix, including monitoring, for their application.
9. Meet with the technical panel to discuss interim results and finalize the field test sections
10. Obtain baseline measurements including half-cell potentials on proposed test section locations and install test sections using SDDOT maintenance forces with appropriate instrumentation for long term monitoring.
11. Evaluate the initial effectiveness of the mitigation strategies employed within a reasonable time after installation.
12. Provide a statewide assessment of CRC corrosion condition and potential based on the results of the project evaluations.
13. Develop recommendations for a future CRC corrosion mitigation evaluation research project including an estimated timeframe allowing sufficient time to provide clear verification of a given treatment's effectiveness.
14. Prepare a final report and executive summary of the research methodology, findings, conclusions, and recommendations.
15. Make an executive presentation to the SDDOT Research Review Board at the conclusion of the project.

MPC Critical Issues Addressed by the Research

1) #15 Improved Infrastructure Design

2) #16 Infrastructure Longevity

Contributions/Potential Applications of Research

If successful, this research will identify the magnitude of any potential corrosion problems in newer CRC pavements and possible strategies to mitigate these effects.

Technology Transfer Activities

At the end of the study, a comprehensive report will be published to document the research procedures and results. Technical presentations will be offered to DOT engineers and technicians in Region 8 to transfer the knowledge learnt from the research. Graduate and undergraduate students also will be trained to conduct research and apply procedures for the design of jointed plain concrete pavements.

Time Duration

July 1, 2009 through June 30, 2010

Total Project Cost

$49,478.00

MPC Funds Requested

$19,200.00

TRB Keywords

Continuously Reinforced Concrete Pavement, CRC Pavement, Portland Cement Concrete Pavement, PCCP, Reinforcement Corrosion.