Chloride Diffusion Constant for Concretes

by Richard E. Weyers, Richard E. Weyers Assoc, United States,
David G. Smith, Richard E. Weyers Assoc, United States,



Document Type: Proceeding Paper

Part of: Structural Materials

Abstract:

Reinforced concrete exposed to chloride ions rapidly deteriorates once the chloride concentration level exceeds the corrosion threshold limit. The diffusion of the chloride ion through concrete follows Fick's Law, which is a function of time, the chloride concentration at the surface, and a diffusion constant. The study presented here examines the effect of water to cement ratio, pozzolan and temperature on the diffusion constant for portland cement concrete. Water to cement ratios of 0.35, 0.40, 0.45 and 0.50 by weight were included in the study. One set of specimens were exposed to a laboratory environment and another set was placed in an outdoor exposure site. In addition, silica fume and Type F fly ash replaced 15 percent of the cement by weight at a water to cementitious ratio of 0.45. A relationship of the diffusion constant as a function of water to cement ratio was developed for each exposure condition.

Subject Headings: Diffusion (porous media) | Diffusion (chemical) | Chloride | Concrete admixtures | Reinforced concrete | Cement | Hydration

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