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South Dakota Department of Transportation
Request for Research Proposal

Project SD2011-09

TITLE: Tolerances for Placement of Tie Bars in Portland Cement Concrete Pavements

Problem Description:Tie bars are used in jointed portland cement concrete pavements to provide load transfer between longitudinal slabs and to prevent lane separation. Tie bars are located within the middle third of the pavement and span the longitudinal joint of two slabs. Tie bars are placed by staking or baskets prior to the placement of the concrete or during paving via automatic inserters. Inspection of South Dakota pavements after construction using ground penetrating radar (GPR) has revealed that many bars were misaligned or missing. More bars were reported missing or misaligned when automatic inserters were used. Many states, including South Dakota, have banned the use of automatic inserters based on a lack of confidence regarding the placement of tie bars. The long-term effect on the pavement from misaligned or missing bars is unknown, but it can be assumed that additional maintenance costs and reduced pavement life are both possible. While tie bars are considered necessary for long-lasting pavements, only a few states have set tolerances for placement. Specifications that have been established may lack engineering or economic basis, making it is impossible to know whether they are too lax or too stringent. Specifications may be unrealistically difficult to construct or verify. In the absence of an engineering or economic basis for the specifications, it is difficult to judge what corrective actions are warranted when they are not met.
Urgency:   Due to the apparent lack of engineering or economic basis for tie bar placement tolerances among states, research results to support these tolerances are needed as soon as possible.

Literature Summary:   Minimal literature exists on this topic. The Colorado Department of Transportation has performed a preliminary study encompassing tie bar performance and recommends additional research to develop allowable placement tolerances.

Are Research results already available? False  
If so, how can SDDOT use these results?

In summary, is research needed? True  
Explain: Many states do not have tie bar placement tolerances and those that have tolerances cannot support them with any literature.

Implementation:   Valuable knowledge would be gained towards the validation of current tie bar tolerances. From the results of the test matrix a general idea of tie bar performance would be gained. Based on the performance of test setups, specification tolerances of tie bar placement could either be verified or adjusted accordingly. This study would be the first step towards a model specification for PCC paving projects. The model specification would provide guidance to states for more rational and effective specifications and would establish a common level of expectation in the concrete paving industry for tie bar placement by any method.

Funds Available:   $150,000.00

Contract Period:   24 months

SDDOT Involvement:   The SDDOT would provide guidance while creating the test matrix and oversee all research conducted.

General Information:  The Office of Research of the South Dakota Department of Transportation (SDDOT) solicits proposals from colleges, universities, research institutes, foundations, engineering or other consultants, federal/state/local agencies or others who possess extensive, demonstrated capability and experience in the subject area.

Proposal Deadline:  Proposals are due at the following address by 5:00 pm on 11/30/2015:
South Dakota Department of Transportation
Office of Research Room 164
700 East Broadway Avenue
Pierre, South Dakota  57501-2586

Proposers will be notified of the results of the selection in writing no later than .

Anticipated Start Date:  

The proposal deadline is firm. Extensions will not be granted. 10 copies of the proposal must be submitted.

Project Management:   Aaron Breyfogle has responsibility for management of this project, and can be reached at 773-3871.

Research Objectives:
1  Characterize specifications currently used regarding tie bar placement tolerances in PCCP.
2  Develop structural analysis of tie bars that provides a basis for design and placement tolerances.
3  Develop recommendations for tie bar placement tolerances based on current specifications.

Research Tasks:
1  Meet with the technical panel to review project scope and work plan.
2  Review literature regarding tie bar placement specifications.
3  Based on literature review develop a load testing test matrix and procedure for individual or group tie bar configurations.
4  Meet with technical panel to review test matrix and testing procedure.
5  With technical panel approval of the test matrix and testing procedure, construct appropriate specimens.
6  Perform structural load testing as described in the testing procedure approved by the technical panel.
7  Meet with technical panel to discuss load testing results and decide if any additional testing is needed.
8  Prepare a final report and executive summary of the research methodology, findings, conclusions, and recommendations.
9  Make an executive presentation to the SDDOT Research Review Board at the completion of the project.

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