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