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:
  • Prestressing
  • Chlorides
  • Corrosion
  • Cement grouts
  • Portland cement
  • Deterioration by environmental action
  • Corrosion tests
  • Post-tensioned prestressed concrete--Corrosion
  • Grout (Mortar)--Testing
  • Portland cement
  More +
• 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.
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• Format:
  PDF
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/25456/dot_25456_DS1.pdf
• File Type:
  [PDF - 2.25 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:1d94b0a6f68d6e21c4669d3fbe2a1dc6861b303b8a735b563bba6ef463843fcf84e5786201dcc864bbe948f7a852d6598cab43610c1a9301d53551fa74e6cdf5