Corrosion performance of prestressing strands in contact with dissimilar grouts.

Details

• Creators:
  O’Reilly, Matthew ; Darwin, David ; Browning, JoAnn
• Corporate Creators:
  University of Kansas. Dept. of Civil, Environmental and Architectural Engineering
• Subject/TRT Terms:
  Cement Grouts Chlorides Concrete--Deterioration--Research Corrosion Corrosion Tests Deterioration By Environmental Action Grout (Mortar)--Testing Portland Cement Post-tensioned Prestressed Concrete--Corrosion Prestressing
• Publication/ Report Number:
  KS-12-4
• Resource Type:
  Tech Report
• Geographical Coverage:
  United States
• Edition:
  Final report.
• Corporate Publisher:
  Kansas. Dept. of Transportation
• Abstract:
  To improve the corrosion protection provided to prestressing strands, anti-bleed grouts are used to fill voids in post-tensioning
  
  ducts that result from bleeding and shrinkage of older Portland Cement grouts. Environmental differences caused by exposing the
  
  strands to dissimilar grouts, however, have the potential to cause rapid corrosion. Portland Cement grout, gypsum grout, and four
  
  commercially available prepackaged grouts were analyzed to determine the chemical composition of the resulting pore solutions
  
  and tested to determine if using a second grout will provide improved corrosion protection for prestressing strands or result in
  
  accelerated corrosion. The potential consequences of leaving the voids unfilled were also evaluated. Pore solutions were analyzed
  
  for pH and sodium, potassium, fluoride, chloride, nitrite, sulfate, carbonate, nitrate, and phosphate ion content. The analyses were
  
  used to develop simulated pore solutions. Selected grouts and simulated pore solutions were paired to evaluate their potential to
  
  cause corrosion of, respectively, grout-wrapped and bare stress-relieved seven-wire prestressing strands using the rapid macrocell
  
  test. Strands were also evaluated in simulated pore solutions containing chlorides and in deionized water. Because exposure of
  
  strands to water or chlorides has the potential to cause rapid corrosion, filling voids in post-tensioning ducts with an anti-bleed
  
  grout is recommended. Gypsum grout, with its low pH and high sulfate content, will cause accelerated corrosion of strands when
  
  used in conjunction with Portland Cement grout or any of the commercially prepackaged grouts tested. When paired with Portland
  
  Cement grout, the prepackaged anti-bleed grouts evaluated in this study resulted in corrosion losses significantly below those
  
  observed for strands exposed to salt or water. The highest corrosion measured for a prepackaged grout occurred for the grout with
  
  the highest pore solution sulfate content.
  
  
• Format:
  PDF
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha256:394d02e60333293c90b2b5d0cac881a43d8e7e552f0ad871c45ac03777886db4
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/25456/dot_25456_DS1.pdf
• File Type:
  [PDF - 2.25 MB ]