Use of fiber reinforced concrete in bridge approach slabs.

Details

• Creators:
  Ostertag, C.P. ; Blunt, J.
• Corporate Creators:
  University of California, Berkeley. Department of Civil and Environmental Engineering
• Subject/TRT Terms:
  • Bridge approaches
  • California
  • Fiber-reinforced concrete
• Publication/ Report Number:
  CA09-0632
• Resource Type:
  Tech Report
• Geographical Coverage:
  California
• Corporate Publisher:
  California. Dept. of Transportation. Division of Research and Innovation
• Abstract:
  Bridge approach slabs are deteriorating at a much faster rate than expected resulting in a massive need for repairs and premature replacement ; costing millions of dollars annually. Both environmental and traffic loading causes the concrete to worsen which accelerates the deterioration ; process by allowing deleterious agents to enter the concrete. In order to enhance the service life of bridge approach slabs the material needs to ; comply with certain performance criteria such as crack resistance, durability enhancement and post crack flexural stiffness. A Hybrid Fiber ; Reinforced Concrete (HyFRC) was developed for the use in bridge approach slabs in Area III jurisdiction which are exposed to severe ; environmental conditions. Deflection hardening was used as a performance goal in the design of the HyFRC composite. ; The research program consisted of four parts. First (1), a performance based materials approach to bridge approach slabs was developed. The ; fiber reinforced composite was designed to exhibit deflection hardening through an average measure of ductility exceeding the yield strain of steel ; rebar (i.e. > 0.002). Four point flexure tests on 6 in. (152 mm) deep beam specimens were conducted in order to quantify the material flexure ; performance. Second (2), the existing California Department of Transportation (Caltrans) bridge approach slab design was used as the basis for ; element sizing and reinforcement ratios. Four-point flexure tests (1/2 scale models of an existing bridge approach slabs) were conducted and ; HyFRC beams were compared against plain concrete control beams with and without conventional steel reinforcement. Third (3), an extensive ; durability study was conducted on how the crack resistance provided by the HyFRC mitigates durability problems associated with frost action and ; corrosion. The bridge approach slab is highly susceptible to deterioration from freeze-thaw cycling and reinforcement corrosion due to the ; anticipated location (i.e. Area III jurisdiction). Compared to the plain concrete specimens the HyFRC exhibited improved performance in regards to ; both freeze/thaw resistance and scaling resistance. To study the effect of cracking/crack resistance on corrosion behavior, cyclic flexure tests were ; conducted on reinforced beam elements composed of HyFRC and a comparable plain concrete in order to induce surface cracking. For a specified ; load demand in excess of the plain concrete fr and below the yield strength of the rebar, the HyFRC flexural specimens showed a high propensity ; for crack resistance (no surface cracks were visible as opposed to the reinforced plain concrete). Corrosion behavior was then monitored by ; ponding salt solution on the cracked surface and higher corrosion rates icorr (measured by polarization resistance) by nearly 1 order magnitude were ; observed in the reinforced plain concrete specimens. The observed increased corrosion rates were confirmed by direct gravimetric analysis of the ; bars after removal. The study concludes (4) with a discussion of how the observed improvements in flexural performance in the presence of the ; fibers can be used for a new design detail for bridge approach slabs.
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• Format:
  PDF
• Funding:
  DRI Research Task No. 0632 ; 65A0201
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/27626/dot_27626_DS1.pdf
• File Type:
  [PDF - 2.00 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha256:d03e05dd60c48920ea4a839c94450c9bee0fb92231dbb30326f19928975fdd19