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South Dakota Department of Transportation
Project Synopsis
SD2005-11


Title: Evaluation of Crack Free Bridge Decks
Project Researcher: UNKNOWN,
Project Manager: Dan Johnston
Research Period: 7/13/2005 - 8/31/2009
Status: Approved
Cost: $70,000.00

Problem Statement:SDDOT submitted a successful application for funding as part of the TEA-21 Innovative Bridge, Research and Construction Program (IBRC). This research is designed to evaluate the proposed draft specifications for low-cracking high-performance concrete (LC-HPC) for bridge decks, being developed as part of Pooled Fund TPF-5(051), Construction of Crack-Free Concrete Bridge Decks. This research is designed to reduce shrinkage cracking that occurs in bridge decks as the concrete cures by using a mix design that has less cement paste, dense graded aggregate, and increased air content. Extended moist curing and stringent control of evaporation during placement are also used to reduce cracking. Two pairs of new bridges have been selected for the research. One bridge in each pair will be built using the LC-HPC specification and the other will use existing specifications. The research bridges have the following design details:

  • two single-span composite steel girder bridge, 208 x 40 roadway (structure numbers 52-435-289 and 52-435-288) as part of project IM90-2(134)59 PCN 4259, I-90 over East North Street in Pennington County;

  • two three-span composite prestressed concrete girder bridges, both 173.35 x 40 roadway, (structure numbers 08-230-130 and 08-230-131) as part of IM-90-6(37)281 PCN 1245, I-90 over a county road in Brule County.

  • The intent is to use low alkali Type I/II Portland cement with lower cement content and dense graded aggregate to achieve a compressive strength equal to conventional bridge deck concrete with fly ash and higher cement content. Bridge decks on both steel and prestressed concrete girders will be included in the research. This will be in conjunction with optimized gradation concrete for the decks.

    It may be necessary to mitigate for ASR susceptible aggregates as some aggregates in South Dakota are known to be alkali-silica reactive (ASR). The reduced cement content mixes should have less shrinkage which should result in fewer cracks and increased protection for reinforcing steel from deicing chemicals. All the recommended procedures in the draft specifications for controlling concrete temperatures, slump, protection from evaporation and rapid water loss and curing will be adhered to. Surface texture will be cut into the hardened concrete on all decks after the curing period is over. Appropriate data will be collected to support Pooled Fund TPF-5(051) Construction of Crack-Free Concrete Bridge Decks.



    Findings:

    Research Objectives:
    1  Evaluate the constructability of the bridge decks with proposed Low-Cracking High Performance Concrete material and construction specifications proposed by Pooled Fund project TPF-5(051) as implemented by SDDOT special provisions.
    2  Evaluate the performance of the bridge decks with respect to crack width and frequency.
    3  Evaluate the suitability of the draft Pooled Fund material and construction specifications for construction of crack-free bridge decks in South Dakota.

    Research Tasks:
    1  Meet with the technical panel to review project scope, discuss construction issues, and present tentative work plan.
    2  Conduct a literature search and compare the results of bridge construction practices and specifications in SDDOT with other states as they relate to crack-free bridge deck construction.
    3  Finalize a work plan incorporating previous SDDOT and other research results for monitoring construction and evaluating performance of the experimental bridges.
    4  Conduct shrinkage tests using SDDOT standard mix designs with fly ash and mix designs with reduced cement content and no fly ash, using South Dakota materials, and compare the results.
    5  Document the concrete physical properties (seven, fourteen, and twenty-eight day compressive strengths, air content, slump, and temperature) of SDDOT-furnished mix designs, for the control bridges and the LC-HPC concrete used on this project in the f
    6  Monitor construction of the control bridge decks and the LC-HPC bridge decks, including test slabs, and document the results. Submit an interim report, after construction of each of the four bridges, detailing constructability issues and suggestions
    7  Conduct an extensive crack survey of each of the four bridges prior to its being opened to traffic and annually for three years after opening to traffic. The crack surveys will be conducted according to the protocol developed as part of Pooled Fund T
    8  Conduct crack surveys on a minimum of two of each type of South Dakota bridges constructed prior to this research using: old mix design without addition of fly ash; more recent mix design with fly ash but without optimized aggregate; and current mix
    9  Compare current SDDOT materials and construction specifications to the draft Pooled Fund material and construction specifications being developed for crack-free bridge decks with respect to constructability, South Dakota materials, and concrete plant
    10  Prepare a final report and executive summary of the prior research, research methodology, findings, conclusions and recommendations.
    11  Make an executive presentation to the SDDOT Research Review Board at the conclusion of the project.

    Documents Available:
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