A test method for measuring chloride diffusion coefficients through nonsaturated concrete: Part I. The instantaneous plane source diffusion case

A test method is proposed for measuring chloride diffusion coefficients through nonsaturated concrete specimens with controlled water contents. The experimental setup used allows one to supply an initial limited amount of Cl⁻ to the tested concrete surface. The procedure consists of submitting the surface of concrete specimens to interaction with the products of combustion of PVC, which contain mainly gaseous hydrogen chloride. This interaction yields a limited Cl⁻ contamination of the concrete surface. After returning the specimens to their controlled humidity exposure conditions, the kinetics of Cl⁻ transport from the surface inwards may be studied. The experimental Cl⁻ concentration profiles determined at selected time intervals have been adjusted to a diffusion model of “instantaneous plane source,” which takes into account the particular initial and boundary conditions of the experimental procedure, for obtaining the corresponding diffusion coefficients.     

A novel method for describing chloride ion transport due to an electrical gradient in concrete: Part 2. Experimental study

This paper is the second of a set of two that develops a novel method for describing the transport of chloride ions in concrete under an electrical gradient. In Part 1, the development of a method to predict the movement of chloride ions under an electrical gradient is outlined. This new theory is designed to correct some deficiencies of the current state of the art. Namely, it considers the effect of concrete being a porous media rather than considering concrete as an aqueous solution as is done with the standard laws, e.g., the Nernst-Planck equation. In this part, experimental evidence is presented to support the theory.     

A novel method for describing chloride ion transport due to an electrical gradient in concrete: Part 1. Theoretical description

This paper is the first of two reporting the development of a novel method for describing the transport of chloride ions in concrete under an electrical gradient. In this part, the theory is described and developed. In the second paper, experimental evidence to support the proposed theory is provided. This new theory is designed to correct some deficiencies of the current state of the art. Namely, it considers the effect of concrete being a porous media rather than considering concrete as an aqueous solution as is done with the standard laws; for example, the Nernst-Planck equation.     

Development of a galvanic sensor system for detecting the corrosion damage of the steel embedded in concrete structures: Part 1. Laboratory tests to correlate galvanic current with actual damage

The correlation between sensor output and corrosion rate of reinforcing steel was evaluated by laboratory electrochemical tests in saturated Ca(OH)₂ with 3.5 wt.% NaCl. In this paper, two types of electrochemical probes were developed: galvanic cells containing of steel/copper and steel/stainless steel couples. The corrosion behavior in saturated Ca(OH)₂ solution with and without 3.5 wt.% NaCl addition for the different electrodes was investigated by potentiodynamic test. Weight loss measurement and galvanic corrosion test were conducted to obtain the corrosion rate of reinforcing steel and the charge of sensor in saturated Ca(OH)₂ solution with 3.5 wt.% NaCl addition, respectively.

The results of the potentiodynamic test indicated the possibility of detecting an ingress point of chlorides by measuring the galvanic current. In galvanic corrosion tests, the galvanic current of steel/copper couple was higher than that of steel/stainless steel couple, i.e., the steel/copper sensor is more suitable for high resistance environment. The steel/stainless sensor showed a better linear correlation than the steel/copper sensor. Through the relationship between the sensor system output and the weight loss (mg/cm²) of steel, real corrosion damage of the steel embedded in concrete can be detected.