• Journal of the Korea Concrete Institute
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• v.11 no.6
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• pp.89-100
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• 1999

Service life of concrete structures that are exposed to the environmental attack is largely influenced by the corrosion of reinforcing bare due to the chloride contamination. Chloride ions penetrate continuously into concrete from the environment, and chloride diffusion velocity is governed by a mechanical steady stage. In this study, a method is developed to predict corrosion initiation of reinforcing bars in the sea-shore structures, based on governing equations that take into account the diffusing of chloride ions and a mechanical steady state. As a result of this study, Corrosion Prediction System (CPS) is developed, and it can be used to determine an optimal time for repair and rehabilitation actions need to be taken. Futhermore, CPS assists the concrete mixing structures by predicting of chloride concentrations in concrete mixture, exposed to salt concentrations and service environment.

• International Journal of Concrete Structures and Materials
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• v.4 no.2
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• pp.71-75
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• 2010

The chloride ion attack on the passive iron oxide layer of reinforcement steel embedded in concrete under variable temperature environment is influenced by several parameters and some of them still need to be further investigated in more detail. Different school of thoughts exist between past researchers and the data is limited in the high temperature and high chloride concentration range which is necessary with regards to setting boundary conditions for enhancement of tafel diagram model presented in this research. The objective of this paper is to investigate the detrimental coupled effects of chloride and temperature on corrosion of reinforced concrete structures in the high range by incorporating classical Tafel diagram chloride induced corrosion model and laboratory controlled experimental non-linear effect of temperature on corrosion of rebar embedded in concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.106-110
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• 1995

Chloride ion is considered one of the most common culprits in the corrosion of steel in concrete. It breaks down the passive film and allows the steel to corrode actively at a high rate. The main objective of this study is to determine the critical chloride ion concentrations in the pore solutions and chloride binding effect of cement pastes made with and without fly ash. Cement pastes with water-ratio of 0.5 allowed to hydrate in sealed containers for 28 days and to express poresolution. T도 expressed pore fluids were analyzed for chloride and hydroxyl ion concentrations. It was found that the replaced cement with fly ash have little effect on Chloride binding capacity ratio.

• Computers and Concrete
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• v.9 no.5
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• pp.375-387
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• 2012

The objective of this investigation was to develop rules for automatic categorization of concrete quality using selected artificial intelligence methods based on machine learning. The range of tested materials included concrete containing a new waste material - solid residue from coal combustion in fluidized bed boilers (CFBC fly ash) used as additive. The rapid chloride permeability test - Nordtest Method BUILD 492 method was used for determining chloride ions penetration in concrete. Performed experimental tests on obtained chloride migration provided data for learning and testing of rules discovered by machine learning techniques. It has been found that machine learning is a tool which can be applied to determine concrete durability. The rules generated by computer programs AQ21 and WEKA using J48 algorithm provided means for adequate categorization of plain concrete and concrete modified with CFBC fly ash as materials of good and acceptable resistance to chloride penetration.

• Computers and Concrete
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• v.6 no.5
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• pp.421-435
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• 2009

Chloride induced corrosion is a concern that governs the durability of concrete structures in marine environments, especially in tidal environments. During the service lives of concrete structures, internal cracks in the concrete cover may appear due to imposed loads, accelerating chloride penetration because of the simultaneous action of environmental and service structural loads. This paper investigated the effects of cyclic flexural loads on chloride diffusion characteristics of plain concretes, and proposed a model to predict the chloride penetration into plain concretes subjected to both tidal environments and different cyclic flexural load levels. Further, a new experiment was performed to verify the model. Results of the model using Finite Difference Method (FDM) showed that the durability of concretes in tidal environments was reduced as cyclic flexural load levels, SR, increased, and the modeling results fitted well with the experimental results.

• Journal of Institute of Convergence Technology
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• v.6 no.2
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• pp.25-28
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• 2016

Recently, due to the climate change by global warming, the amount of snow has increased. The situations were demanded to use many snow removal materials. The snow removal materials that used in Korea were solid chloride deicing material. That is calcium chloride($CaCl_2$) and sodium chloride(NaCl). Solid chloride baesd snow removal materials have various property, for example good freezing point depression, deliquescence and economical solvents. However, there are problems such as water pollution, high corrosiveness and ecocide. For such reason, development of eco-friendly deicer was required obligatorily. This study investigated development situation of eco-friendly deicer materials.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.475-478
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• 2005

Deicing salt has been generally used for traffic safety in winter, and the amount is increasing every year. However, deicing salt may induce the decrease of bond strength, surface scaling, and environmental pollution, etc. the purpose of this paper is to suggest the fundamental data on safety and durability for concrete structures through the estimation of chloride concentration profile and chloride diffusion coefficient. According to the test results, the critical chloride concentration($0.9\~1.2kg/m^3$)was measured at depth $23\~30mm$, and the limit chloride concentration($0.3kg/m^3$)was reached to depth 40mm. Also the surface chloride amount indicates 3.45kg per concrete unit weight, and the results showed the possibility of corrosion by deicing salt penetration.

• Journal of the Korea Concrete Institute
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• v.12 no.1
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• pp.33-44
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• 2000

Since the mechanism of chloride diffusion and its ratio in concrete depend on structural conditions and concrete as a micro-structure, if these are analyzed quantitatively, the long-term ageing of structures can be predicted. Although, a quantitative analysis of concrete micro-structure, in which the results are affected by various parameters, is very difficult, this can be done indirectly by the durability test of concrete. In this study, the compressive strength, void ratio and air permeability of concrete. In this study, the compressive strength, void ratio and air permeability of concrete are chosen as the parameters in concrete durability test, and these effects on test results are analysed according to changes of mixing properties. The relationships between parameters and chloride diffusion velocity is used for prediction models of chloride diffusion. The developed prediction models for the chloride diffusion according to mixing and physical properties, can be used to estimate the service life and corrosion initiation of reinforcing bars in marine structures.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.269-272
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• 2006

Chloride ion diffusion is the most important thing of occuring deterioration in RC structure. So it is important to decide the precise chloride ion diffusion coefficient in order to predict the durability life in RC structure. The purpose of this study is to analyze the established data, which are restricted by chloride diffusion coefficient, and to calculate chloride ion diffusion coefficient using RCPT test. To examine the prediction of the concrete structure durability by an FEM analysis and the chloride diffusion coefficient as a variable. Each surface finishing materials were effective on the increment of chloride penetration resistance, but showed a little different effect depending on the type of surface finishing material.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.489-492
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• 2006

A chloride is an important deteriorating factor which governs the durability of the reinforced-concrete structures under marine environments. Also, the main penetration mechanism of chloride ion into concrete is a diffusion phenomenon and numerous methods have been proposed to determine the diffusion coefficient of chloride ion quickly. In this study, electrically accelerated experiments were carried out in order to evaluate diffusion coefficient of the chloride ion into concrete. The methods were diffusion cell test method in which the voltage of 15V(DC) was applied. The type of cement is blended cement in which the admixtures of blast-furnace slag and fly ash were used. In conclusion, the diffusion coefficient of chloride ion is much affected according to mineral admixtures and the diffusion coefficient of ternary blended cement showed very low values. it is presumably said that this result is due to highly densified pore structures by the aid of slag substitution and pozzolanic activity of fly ash.