Evaluation of Concrete Bridge Rail Cracking - Phase I

Cracking of newly cast concrete bridge rails has been an ongoing problem throughout the State of Vermont, one that has been observed to be severe and rapidly occurring upon curing in some cases. Cracking in concrete allows for the penetration of chlorides and other corrosives resulting in deterioration of reinforcing. Additionally, moisture may also penetrate more readily resulting in accelerated damage from freeze thaw cycles in the form of scaling and spalling. These stressors lead to decreased strength and safety of the rails, which means increased maintenance to ensure safety and durability, a reduction in the overall aesthetics of the structures and decrease in public confidence and support. The ability to greatly reduce or eliminate the majority of the concrete bridge rail cracking is of utmost importance to alleviate these concerns. The objective of this research initiative is to examine the potential causations for cracking in aesthetic bridge rails. This will be accomplished by documenting current practices with respect to mix designs, casting and curing methods. Photographs and written documentation of the current state of recently cast rails will be collected. Particular attention will be focused on the phenomena of cracking including the attributes of size, pattern, placement and occurrence (temporal appearance). In addition, surrounding New England states will be surveyed and methods summarized. Corollary statistics will be utilized to determine if certain variables, such as aggregate size, water cement ratio, strength gain, contractor operations and pour conditions have an effect on the onset and rate of shrinkage cracking. Analysis of this data will lead to the pinpointing and detailing of the factors that contribute to increased shrinkage cracking in the structures. Excessive cracking due to other factors (other than shrinkage), if found, shall also be examined for causations and contributing elements, such as excessive 28 day concrete strengths that lead to high moduli of elasticity and very stiff bridge rails. This project will lead into future research to possibly consider alternate mix designs if positive correlations are identified, which may improve upon the current state of the rails. Solutions other than mix design may present themselves during the study, such as admixtures, placement or construction practices or excessive 28 day strength, and will also be taken into consideration. The alternatives should take into consideration cost, long term durability, quality assurance, construction feasibility and probability of success.

    Language

    • English

    Project

    • Status: Active
    • Funding: $35000.00
    • Contract Numbers:

      SPR 701

    • Sponsor Organizations:

      Vermont Agency of Transportation

      Materials and Research Section
      1 National Life Drive, Drawer 33
      Montpelier, VT  United States  05633
    • Project Managers:

      Tremblay, Jason

    • Performing Organizations:

      Vermont Agency of Transportation

      Materials and Research Section
      1 National Life Drive, Drawer 33
      Montpelier, VT  United States  05633
    • Principal Investigators:

      Tremblay, Jason

    • Start Date: 20071030
    • Expected Completion Date: 0
    • Actual Completion Date: 20101001
    • Source Data: RiP Project 14724

    Subject/Index Terms

    Filing Info

    • Accession Number: 01462802
    • Record Type: Research project
    • Source Agency: Vermont Agency of Transportation
    • Contract Numbers: SPR 701
    • Files: RiP, STATEDOT
    • Created Date: Jan 3 2013 2:10PM