Study on the Method of Measuring the Chloride Threshold Value of Corrosion and Estimation of the Values in Durability Design of Concrete Structures

Abstract

In this study, a method was developed to estimate accurately the chloride threshold value for corrosion initiation in reinforced concrete. In this method, chlorides are supplied through a part of the specimen surface, and half-cell potential between the rebar and reference electrode embedded in a concrete specimen was measured in every ten minutes. A sudden drop of half-cell potential was observed as the continuation of the measurement. At that time, the specimen was broken and corrosion of rebar on its narrow surface was confirmed. The chloride threshold value can be estimated by determining the chloride concentration at the time of the potential drop. The estimated chloride threshold values for normal Portland cement concrete with cement content between 254 and 446 kg/m 3 are in the range of 1.6 to 3.6 kg/m 3. This paper is an English translation from the authors' previous work [Horiguchi, K., Yamaguchi, T., Maruya, T. and Takewaka, K., (2015). "A study on the method of measuring the chloride threshold value of corrosion and on the estimation of the values."

Variation in Service Life on RC Structure According to Concrete Binder Type

“…This is because as the replacement rate of GGBFS or FA increases, the Ca(OH)2 produced by hydrated OPC stimulates a latent hydraulic reaction or is consumed by the pozzolanic reaction, so the total amount of Ca(OH)2 in the concrete decreases and the pH of concrete decreases accordingly. The reduced amount of Ettringite and Ca(OH)2 produced by the decrease in the absolute quantity of cement also has a direct effect [27][28][29][30][31][32][33][34][35]. Particularly when using FA, its effect was greater than that of using GGBFS.…”

“…This study evaluated the service life against chloride attack for reinforced concrete structures with 40 mm concrete cover using the results of assessing the concrete chloride ion diffusion coefficient according to the admixture replacement rate and admixture type measured in Section 4.2 and the critical chloride content in the Korean concrete standard specification (1.2 kg/m 3 ), and the results are This is because as the replacement rate of GGBFS or FA increases, the Ca(OH) 2 produced by hydrated OPC stimulates a latent hydraulic reaction or is consumed by the pozzolanic reaction, so the total amount of Ca(OH) 2 in the concrete decreases and the pH of concrete decreases accordingly. The reduced amount of Ettringite and Ca(OH) 2 produced by the decrease in the absolute quantity of cement also has a direct effect [27][28][29][30][31][32][33][34][35]. Particularly when using FA, its effect was greater than that of using GGBFS.…”

“…However, studies have shown that replacing the cement used in concrete with admixtures such as GGBFS and fly ash can reduce the critical chloride content of rebars embedded in the concrete [26][27][28][29][30][31][32][33][34]. It is critically important to correctly determine the critical chloride content of rebars in order to ensure the durability of reinforced concrete structures, as an incorrect estimation of critical chloride contents can cause errors in the design for durability against chloride attack [35][36][37][38][39].…”

Updating Durability Models for Concrete Structures in Chlorine Environment Based on Detection Information

“…Matsushima et al [32] advised cr C as the mean of 3.07 kg/m 3 and a COV (coefficient of variation) of 0.41. The Japanese Civil Society criteria [33] considered cr C with 0.3~2.4 kg/m 3 when predicting the service life. For reinforced concrete with high durability requirements, the chloride ion mass of cr C does not exceed 0.3 kg/m 3 .…”

Hydrophobic Polyurethane Coating against Corrosion of Reinforced Concrete Structures Exposed to Marine Environment

“…The rapid chloride permeability test measures the electric charges passing through the sliced concrete specimens [2,6,13,15,17]. Both sides of the specimen were in contact with a sodium hydroxide solution.…”