Alternate approach slab reinforcement.

Details

• Creators:
  Boisvert, Denis M.
• Corporate Creators:
  New Hampshire. Dept. of Transportation
• Corporate Contributors:
  United States. Federal Highway Administration
• Subject/TRT Terms:
  • Bridge decks
  • Slabs
  • Concrete bridges
  • Reinforcing steel
  • Corrosion resistant materials
  • Fiber reinforced concrete
  • Bridge approaches
  • Field tests
  • Laboratory tests
  • Freeze thaw tests
  More +
• Publication/ Report Number:
  FHWA-NH-RD-13733H
• Resource Type:
  Tech Report
• Geographical Coverage:
  New Hampshire
• Corporate Publisher:
  New Hampshire Department of Transportation
• Abstract:
  The upper mat of reinforcing steel, in exposed concrete bridge approach slabs, is prone to corrosion damage. Chlorides applied to the highways ; for winter maintenance can penetrate this concrete layer. Eventually chlorides reach the steel and begin the corrosion process. ; The objective of this research project was to investigate the performance of approach slabs constructed with structural fibers to replace the top ; mat of reinforcing steel. The research studied whether the performance of approach slabs reinforced with structural fibers would be equivalent ; to traditionally reinforced approach slabs. ; NHDOT Materials & Research Bureau technicians performed standard quality acceptance tests on the fresh concrete at the time of placement. ; Technicians also fabricated three freeze/thaw prisms for each mix. The specimens survived freeze/thaw testing with only minor physical ; deterioration, consisting of slight scaling and pitting. The Civil Engineering Department of the University of New Hampshire (UNH) was ; contracted to perform laboratory testing. The beam samples were tested for First Crack Strength and Average Residual Strength in accordance ; with ASTM C 1018 and C 1399, respectively. An independent testing laboratory extracted two cores from each approach slab to evaluate the ; air matrix within the concrete. Comparisons of the laboratory test results show that compressive and flexural strengths are similar for both ; mixes. The plots resulting from the residual strength testing show that the fiber-mix had greater strength after cracking than the normal mix. ; Periodic visual observations of the approach slabs were made to evaluate field performance by comparing crack size, frequency and scaling. ; After more than three and half years in service, the two approach slabs have performed similarly and well. The expected advantages of a thicker ; concrete cover over steel reinforcement will not be seen for many years. The epoxy-coated steel in the conventional slab construction should ; also delay damage from corrosion. ; Based on the performance observations to date, fiber-reinforced concrete is recommended for use in this and other applications where delaying ; the effects of steel corrosion is of interest. The NHDOT has implemented the use of fiber-reinforced concrete for all approach slabs as a result ; of this study.
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• Format:
  PDF
• Funding:
  13733H, X-A000(153)
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/25749/dot_25749_DS1.pdf
• File Type:
  [PDF - 4.00 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:bccd3a97dc82c93bd311f645171fbb92be57f3260cba2a2d5a522465969409db79ac29c584325b9f2f9762cbcf4686f9d8ee201b40b39fdd3d280278fde709c3