Diffusion vs. concentration of chloride ions in concrete.

Details

• Creators:
  Presuel-Moreno, Francisco J. ; Arias, Wendy ; Echevarria, Victor ; Shill, Scott ; Wu, Yu-You
• Corporate Creators:
  Florida Atlantic University. Dept. of Ocean Engineering
• Subject/TRT Terms:
  • Reinforced concrete
  • Durability
  • Chlorides
  • Seawater
  • Bridge substructures
  • Concentration (Chemistry)
  • Ions
  • Thermal diffusion
  • Underwater structures
  • Cement
• Publication/ Report Number:
  BDK79-977-03
• Resource Type:
  Tech Report
• Geographical Coverage:
  Florida
• Corporate Publisher:
  Florida. Dept. of Transportation. Research Center
• Abstract:
  This investigation was performed to gain insight and assist in determining the long-term durability of ; reinforced concrete structures where the external chloride concentrations are different than those typically ; observed at the permanently immersed, tidal, and splash zones of partially immersed bridges. Insight into ; the diffusion properties of the concrete at these locations may lead to changes in the state’s policy on ; corrosion control of reinforced concrete structures. Structures at locations where the external chloride ; concentrations may have spatial, let alone time, variation are of interest. Additionally, at elevations above ; the splash zone, the amount of chlorides deposited would be lower, and the concrete close to the surface not ; saturated. Similarly, the section of structures that extend inland would be subjected to seawater spray and ; the concrete close to the surface would usually not be water saturated. ; The performance in regard to chloride penetration of specimens made with three base compositions (the ; supplementary cementitious materials were: 20% fly ash; 20% fly ash + 8% silica fume; and 50% slag), ; and water-to-cementitious ratios of 0.35, 0.41, or 0.47 were investigated here. Experiments investigated ; the diffusion of chloride ions into concrete samples that were exposed in scenarios that simulated the ; splash, tidal, and immersed portions of a marine structure, with the solution ranging from brackish water to ; 10% seawater, to seawater. Bulk diffusion experiments were conducted in solutions that contained 0.6%, ; 3%, and 16.5% NaCl. Rapid migration tests and resistivity measurements were also performed several ; times over two years, and the non-saturated migration coefficient vs. resistivity values were correlated. The ; apparent diffusion values from the bulk diffusion tests were correlated to corresponding equivalent ; resistivity values. Samples exposed for over 18 years, simulating tidal exposure were also part of this ; investigation. The field component investigated the chloride concentration as a function of elevation. Other ; experiments were conducted which involved controlling the degree of saturation and exposing a designated ; surface to finely ground salt. These apparent diffusion results were compared to the apparent diffusion ; results from specimens in which the chloride transport was due to natural marine atmosphere.
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• Format:
  PDF
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/27339/dot_27339_DS1.pdf
• File Type:
  [PDF - 22.44 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha256:f2d60dd5b03f017d955c825eb1ede6b833ef6ff142e548ae347d9c7b5396e48b