Abstract
When an additive is used to replace a certain amount of cement, a concrete pore structure becomes dense. Thus, it results in inhibiting the penetration of chlorine ions and suppressing corrosion of reinforcing bars. However, the pH level of the concrete decreases, and it deteriorates the performance of the passive film formed on the surface of the rebars embedded in the concrete. Therefore, in this study, the service lives of reinforced concrete containing different types of concrete binders were predicted and compared. The chloride ion diffusion coefficients of concretes with various binders were measured, and the critical chloride content of the rebar was assessed by the real-time monitoring on the corrosion initiation time of the rebar embedded in concrete. Moreover, Fick’s 2nd law was applied to predict when the chloride content at the 40 mm depth of cover reached the critical chloride content based on the chloride ion diffusion coefficient. It was observed that the service life of S6 (OPC 40% + GGBFS 60%) was the highest, followed by TBC (OPC 40% + GGBFS 40% + FA 20%), S3 (OPC 70% + GGBFS 30%), and OPC (OPC 100%).
Highlights
With the durability of concrete emerging as a social issue, the need to develop concrete with high durability has been coming to the fore
This study evaluated the service life against chloride attack for reinforced concrete structures hydrated OPC stimulates a latent hydraulic reaction or is consumed by the pozzolanic reaction, so with 40 mm concrete cover using the results of assessing the concrete chloride ion diffusion coefficient the total amount of Ca(OH)2 in the concrete decreases and the pH of concrete decreases
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/m3), and the results are shown in the table below
Summary
With the durability of concrete emerging as a social issue, the need to develop concrete with high durability has been coming to the fore. The demand to construct concrete structures around port facilities has increased due to the increase of goods transported by sea, so it is becoming important to build concrete structures with excellent resistance to marine environments both in terms of structural stability and in terms of economics [3,4,5] Methods using such admixtures as ground granulated blast furnace slag (GGBFS) and fly ash have been proposed to improve the durability of concrete exposed to chloride attack [6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25]. The penetration rate of chloride ions was calculated using Fick’s 2nd law, and the time when the chloride content at the 40 mm depth of cover reached critical chloride content was considered as the point at which the service life of concrete terminated
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