INSIDE THE DOT
South Dakota Department of Transportation
Fiber Reinforced Concrete for Structure Components
Traditional concrete structures experience cracking and spalling, corrosion of imbedded reinforcement, failure under severe loading, and lack of durability. Transportation departments are challenged to extend the service life of portland cement concrete (PCC) structural components such as columns, bridge decks, and abutments in light of budget constraints. Technological advancements in fiber reinforced concrete (FRC) offer possible solutions to many problems. Fibers have been used in concrete to control plastic shrinkage cracking and drying shrinkage cracking. Some types of fibers (micro fibers) are designed to produce greater impact, abrasion and shatter resistance in concrete. There is some evidence that fibers increase the flexural strength and ductility (ability to deform under tensile stress) of concrete, thereby enhancing moment resisting of structural steel reinforcement. The improved material properties of FRC tend to enhance the flexural and shear behavior of structures making it an attractive material for numerous highway infrastructure component applications such as support beams, slabs-on-grade, bridge decks, and elevated metal composite slabs. Fibers come in many varieties. Micro-synthetic or larger (macro) fibers are manufactured from polypropylene, polyethylene, polyester, nylon and other synthetic materials such as carbon, aramid and other acrylics. Depending on fiber type and application, dosage rates may range from 0.03 to 0.2% by volume of concrete (0.5 to 3.0 lb/y3). Engineers find it challenging to interpret performance claims by manufacturers based on unstandardized testing procedures and what seem to be high fiber dosage recommendations. The sheer volume of relevant FRC literature, research and case studies is overwhelming, spanning a period of more than 45 years. Moreover, it has been nearly 20 years since SDDOT has delved into the topic. Many of the fiber materials used in SDDOT projects have been phased out or discontinued, and many more new products have been developed. What little guidance that is available on the proper specification and use of FRC comes from the American Concrete Institute (ACI)) and is generic in nature. Research is needed to investigate recent product development, evaluate fiber products currently on the market, and generate guidance for use, testing, and potential application of FRC.
1 Identify and describe prevailing and best practices for design and construction of fiber reinforced concrete structural components in South Dakota and nationally.
2 Assess potential application, performance, costs, benefits, drawbacks, and constructability of fiber reinforced concrete structural components.
3 Develop guidance for design, material selection, construction, testing, and application of fiber reinforced concrete structures in South Dakota.
1 Meet with the project technical panel to review project scope and work plan.
2 Review and summarize existing literature pertaining to prevailing and best practices in structural applications of fiber reinforced concrete regionally and nationally—including design, materials selection, construction, and laboratory and field testing.
3 Interview SDDOT personnel to assess performance of previous FRC structural projects and describe current FRC specifications and practices in South Dakota.
4 Prepare a draft interview guide and a list of candidates for interviews of state transportation agencies with experience and expertise in structural applications of FRC.
5 Meet with the project’s technical panel to present findings of tasks 2 & 3 and to secure approval of the draft interview guide and list of interview candidates.
6 6) in structural applications of FRC to assess agency specifications, practices, and experience with cost and performance.
7 Prepare a laboratory testing plan to verify material properties, determine optimal fiber dosage, and assess the performance of a select list of candidate fibers with high potential for success based on evidence of superior performance in structural applications
8 Meet with the project’s technical panel to review results of agency interviews and the proposed testing plan.
9 Develop concise but comprehensive guidance for design, materials selection, construction, and laboratory and field testing of FRC for structural applications.
10 Prepare a final report and executive summary of the research methodology, findings, conclusions, and recommendations.
11 Make an executive presentation to the SDDOT Research Review Board.
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