The use of steel dowel bars to transfer forces across sawed or formed transverse joints from one concrete pavement slab to another while permitting expansion and contraction movements of the concrete has been a basic design practice in most U.S. state departments of transportation for many decades.
A common problem is the corrosion of the steel dowels, especially in states which use salt for snow and ice control. Corrosion can lead to a reduction in the diameter of the dowel bar in the joint area to the point where the dowel bar will fail in shear when loaded, resulting in faulting of the pavement slab. The corrosion can also; the dowel bar into the concrete, preventing movement of the concrete during expansion and contraction, resulting in the transfer of stress to the concrete which cause the slab to crack. In the mid 1970s, state DOT began to require steel dowel bars be coated with epoxy or other materials to prevent corrosion. Epoxy coated dowels have become the standard for most states. Recently, alternative materials have been used to manufacture dowel bars. While the resistance of some alternative materials have been well documented in laboratory examinations, other performance characteristics affecting service life remain to be fully evaluated, particularly in representative field installations and over meaningful time periods.
A program to evaluate two alternative dowel bar materials, stainless steel and fiber reinforced polymer (FRP), was initiated in 1998 by the Highway Innovative Technology Evaluation Center (HITEC). Initial field installations of FRP and stainless steel dowel bars began in 1996 in conjunction with the FHWA High Performance Concrete Pavement (TE-30) project. Projects were completed in 4 States; Iowa, Illinois, Ohio, and Wisconsin, over a period of 4 years. The last project was completed in 2000. The projects were being evaluated under the May 9, 1998 HITEC evaluation plan. A draft interim report detailing the construction and early performance of the test sections was submitted March, 2005. However, prior to completion of the evaluation, the contract was terminated with the now defunct HITEC. This research shall complete the work initiated by HITEC.
The objectives of this study are:
o To assess the constructability, placement verification, environmental qualities and performance capabilities of FRP dowels and stainless steel dowels to perform the load transfer and joint movement requirements in concrete pavement joints for the full service life of the pavement without detrimental corrosion or deterioration; and
o To consider the comparative performance and service life costs of these alternative materials and epoxy coated mild steel for use in dowel bars.
Scope of Work
Task 1: Revise draft interim report to incorporation review comments and revise evaluation plan to reflect recommendations in the draft interim report. Update annotated literature review.
Task 2: Host initial Technical Panel Meeting in Chicago. Discuss the current status of the evaluation and the approach to close out the project.
Task 3: Execute the revised evaluation plan. Participating states with evaluation sites will be responsible for collecting data and cores identified in the revised evaluation plan.
Task 4: Provide quarterly progress reports until the completion of the evaluation.
Task 5: Prepare draft final report
Task 6: Host final technical panel meeting in Chicago. Present results of evaluation and discuss draft final report.
Task 7: Prepare final report
Ohio DOT along with a minimum of four other participating states are asked to contribute $10,800 in fiscal year 2008 to fund the research proposed in this pooled fund study.