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South Dakota Department of Transportation
Project Synopsis

Title: The Determination of the Permeability, Density, and Bond Strength of Non-Metallic Fiber Reinforced Concrete in Bridge Deck Overlay Applications
Project Researcher: V Ramakrishnan, SDSM&T
Project Manager: Dan Strand
Research Period: 4/12/1999 - 7/31/2000
Cost: $15,000.00

Problem Statement: The South Dakota Department of Transportation (SDDOT) places a concrete overlay over older bridge decks to either protect the black steel in old decks and/or as a form of maintenance to extend the life of the deck to the service life of the bridge. The concrete that is used is considered to be a low-slump dense (LSD) structural concrete which creates an almost impermeable barrier between the surface of the overlay and the deck steel. When the LSD concrete is being placed the bridge deck overlay machine applies some compactive effort into the fresh overlay concrete to increase the concrete's density.

In 1994 a research project was initiated to study the use of 3M's Polyolefin Fibers (non-metallic fiber reinforced concrete (NMFRC)) in several applications. One application incorporated these fibers in the bridge deck overlay concrete for the structure at Exit 212 over I-90 (I-90/US83). A comparison of SDDOT's LSD concrete was made to the fiber overlay concrete. As a result of the 1994 study, it was found that the fiber deck overlay performed favorably. Therefore, because of the fibers' ability to greatly enhance the concrete's structural properties, the Department decided to include these fibers in the deck overlay concrete for the two severely deteriorated bridge decks at Exit 32 on I-90 (I-90/SD79). The Department hopes that these overlays will extend the life of these decks for seven years from the time of construction (to about 2004).

As a result of the study of the fiber concrete bridge deck overlays which were constructed in 1997, it was recommended that fiber concrete overlays be considered not only on badly deteriorated bridge decks, but on a case by case basis for all bridges. Although the performance of the fiber concrete deck overlays appears to be acceptable, some questions continue to be unanswered. How do the permeability, density, and bond strength of the NMFRC deck overlays compare to plain LSD concrete? Does the higher initial slump, prior to the addition of fiber, adversely affect the compactive effort of the deck overlay machine? What equipment and testing procedures are necessary for designing the NMFRC mix? Also, what equipment and testing procedures are necessary for quality control in the field? Therefore, research needs to be conducted to determine these properties and determine how they compare to South Dakota's (SD) plain LSD concrete. In addition, equipment and testing requirements need to be identified and recommended for mix design development and field testing.

Findings: A comparison of the results from the field and laboratory mixes had shown that there was good bond between the overlay concrete and the old concrete and the bond strength was greater than the tensile strength of the old concrete, The chloride permeability and density values of NMFRC were found to be similar to the values of the plain low slump dense concrete (LSDC). This was true in both the field and laboratory tests. The chloride permeability mainly depended on the cement content and compactive effort used in making the cylinders. The addition of fibers did not influence the chloride permeability or density of the concrete

Research Objectives:
1  To determine the permeability, density, and bond strength of bridge deck overlay NMFRC as compared to South Dakota’s plain LSD concrete.
2  To develop standard mix design and field testing procedures for bridge deck NMFRC.

Research Tasks:
1  Review and summarize literature related to equipment and testing requirements necessary for NMFRC.
2  Attend SDDOT’s coring operation of the selected sites to ensure that the samples obtained are acceptable for the testing to be conducted.
3  Perform permeability testing on the 3 or 4 cores taken from each of the following test sections: - Plain LSD concrete from the north bound lane of the Exit 212 interchange bridge over I-90 (I-90/US83) at Vivian. - Bridge deck overlay NMFRC with fi
4  Determine the density of the whitetopping and deck overlay concrete from the cores provided by SDDOT.
5  Determine the bond strength of the bridge deck overlay concrete to the original deck from the cores provided.
6  Using NMFRC laboratory mixes, make specimens and determine their density and permeability. The specimens should be made using different levels of compactive effort. The laboratory mixes should be similar to that used for the Vivian and Sturgis NMFRC
7  Compare the permeabilities and densities of the samples taken for Task 3 with those for Task 6.
8  Identify and recommend equipment and testing requirements necessary for the development of bridge deck overlay NMFRC mix designs.
9  Identify and recommend necessary equipment, tests, and procedures required for quality control testing in the field.
10  Submit a final report summarizing relevant literature, research methodology, test results, NMFRC mix design specifications, required testing equipment, laboratory and field testing procedures, conclusions, and recommendations.
11  Make an executive presentation to the SDDOT Research Review Board summarizing the findings and conclusions.

Documents Available:

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