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https://nap.nationalacademies.org/catalog/27432/critical-issues-in-transportation-for-2024-and-beyond

Performance Evaluation of Glass Fiber Reinforced Polymer (GFRP) Reinforcing Bars Embedded in Concrete Under Aggressive Environments

In this research project, Glass Fiber Reinforced Polymer (GFRP) rebar products from three major composite rebar producers were extensively and comprehensively tested to characterize these materials and to evaluate the usability of these products under current Florida Department of Transportation (FDOT) guideline constraints. Three manufacturers were chosen to capture a variety of different physical rebar features (various fiber types, different resins, dissimilar surface enhancements and forms, etc.) and to test commonly available products, which are produced in various locations via individual and proprietary methods. For each product type, three rebar sizes were selected to evaluate the current, most typical GFRP rebar diameters and a suitable size range for FDOT construction projects. Specifically, rebar sizes # 3, # 5, and # 6 or # 8 (diameters 10 mm, 15 mm, and 19 mm or 25 mm) were tested in pristine condition (as received from the manufacturer) and after exposure to saltwater. First, each rebar type and size was characterized in its virgin state to define reference values for four physical properties and four strength characteristics. Physical rebar analyses included density measurements or measurement of cross-sectional dimensions, fiber content, moisture absorption, and scanning electron microscopy imaging, while strength measurements were conducted to determine the transverse shear strength, horizontal shear strength, tensile strength including elastic modulus properties, as well as the bond-to-concrete characteristics. As these virgin properties were determined, companion specimens were exposed to saltwater (representative of conditions generally expected in Florida seawater) at three different elevated temperatures for accelerated aging. Only # 3 (10 mm) were conditioned because aggressive environments were expected to impact small-size rebars more severely as the percentage of degradation effects is intensified for smaller cross sections. Aging temperatures ranged from 73 ◦F (23 ◦C), through 105 ◦F (40 ◦C), to 140 ◦F (60 ◦C) and the specimens were conditioned inside the storage solutions for 60 days, 120 days, 240 days, and 365 days. At the end of each aging period, the needed material was removed from the conditioning solutions, dried, and tested. Except for cross-section and fiber content measurements, the same experiments that were conducted for the virgin materials were conducted for the aged specimens. Based on the experimental measurements and an in-depth comparison between the virgin and the aged material properties, the retention of each tested property was determined throughout the four aging periods. All test data were statistically reduced and compared to the prevailing material specifications or acceptance criteria for FRP rebars (AC454, ASTM D 7957, etc.) with a special focus on FDOT Developmental Specification Section 932 (Florida Department of Transportation, 2017). The analyzed and statistically evaluated test data were used to predict the durability behavior of GFRP rebars in saltwater based on a multi-parameter Arrhenius approach. Finally, the findings made throughout the experimental phase and the theoretical analyses provided a foundation for recommendations toward future implementation of GFRP rebars in FDOT construction projects and adjustments or refinements for FDOT Developmental Specification Section 932 (Florida Department of Transportation, 2017) were proposed.

Language

  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Appendices; Figures; Maps; Photos; References; Tables;
  • Pagination: 244p

Subject/Index Terms

Filing Info

  • Accession Number: 01703106
  • Record Type: Publication
  • Contract Numbers: BDV30-977-18; 038558
  • Files: NTL, TRIS, ATRI, STATEDOT
  • Created Date: Apr 26 2019 4:58PM