• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.361-366
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• 2002

The deterioration of concrete structure due to corrosion of the reinforcement has created big financial losses on the overall industries. The volume expansion of the corrosion products causes internal pressure to concrete wall around reinforcing bar. If the maximum principal stress induced by internal pressure exceeds the tensile strength of the concrete at any point of time, a crack forms at any point of material. Therefore, in terms of life assessment of concrete structure, it is very important to predict the amount of corrosion products which induces initial concrete cracking. With this objective, this paper proposes the critical amount of corrosion products at interface between reinforcement and concrete using finite element analysis. If an actual survey of corrosion rates could be made, the model might supply information for condition assessment of existing concrete structure. As the mechanical properties of corrosion product and instantaneous geometry of corroded steel are considered in the analysis, the value obtained will be more realistic.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2010.05a
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• pp.73-76
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• 2010

This study deals with the properties of polymer-modified mortars with a nitrite-type hydrocalumite, which are effectively used as intelligent patch materials for deteriorated reinforced concrete structures. The calumite is a material that can adsorb the chloride ions (Cl-) causing the corrosion of reinforcing bars and liberate the nitrite ions (NO2-) inhibiting the corrosion in reinforced concrete, and can provide a self-corrosion inhibition function to the reinforced concrete. Polymer-modified mortars using hydrocalumite and terpolymer powders are prepared with various calumite contents and polymer-binder ratios, and tested for corrosion inhibition. Subsequently, regardless of the polymer-binder ratio, the replacement of ordinary portland cement with the calumite has a marked effect on the corrosion-inhibiting property of the polymer-modified mortars.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.1
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• pp.84-94
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• 2007

As a reactor coolant pump(RCP) is operated in the nuclear power system for a long time. so its surface is continuously contaminated by radioactive scales. In order to perform regular or emergency repair about RCP internals a special decontamination process should be used to reduce the radiation from the RCP surface by means of chemical cleaning. In this study, applicable possibility in chemical decontamination for RCP was investigated on the various materials. The STS 304 showed the best electrochemical properties for corrosion resistance than other materials. However, the pitting corrosion was slightly generated in both STS 415 and STS 431 with the increasing numbers of cycle and intergranular corrosion were sporadically observed. The size of their pitting corrosion and intergranular corrosion were also increased with increasing cycle numbers.

• Journal of the Korea Concrete Institute
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• v.12 no.5
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• pp.69-80
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• 2000

This paper presents the prediction of remaining service life of the concrete due to steel corrosion caused by the following three cases; carbonation, using sea sand and using deicing salts. The assessment of initiation period was generalized considering the existing perdiction models in the literature, corrosion experiment and field assessment. To evaluate the prediction equation of rust growth, the corrosion accelerating experiments was performed. The polarization resistance was measured by potentiostat and the conversion coefficient of polarzation resistance to corrosion rate was determined by the measurement of real mass loss. Chloride content, carbonation, cover depth, relative humidity, water-cement ratio(W/C), and the use of deicing salts were taken into account and the resulting prediction equation of rust growth was proposed on the basis of these properties. The proposed equation is to predict the rust growth during any specified period of time and be effective in particular for predicting service life of concrete in the case of using sea sand.

• Corrosion Science and Technology
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• v.10 no.6
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• pp.218-224
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• 2011

The fresh water and sea water in present ships is used as cooling water for marine engine. Therefore, corrosion damage in seawater system is frequently occurred. In particular, in the impeller of pump, the performance and material span due to the corrosion and cavitation erosion has adverse effects. Most of the pump impellers in vessels are used Cu-Al alloy. Cu-Al alloy which having the excellent mechanical properties and corrosion resistance is widely used in marine environments. However, despite the excellent characteristics, the periodic replacement parts due to the cavitation damage in seawater is vulnerable to economic viewpoint. In this study, Cu-Al alloy used with impeller for centrifugal pump were conducted various experiments to evaluate its characteristics in seawater and fresh water solutions. As an electrochemical result, the dynamic conditions that exposed to the cavitation environment presented high corrosion current density with collapse of the cavity compared with the static conditions. Cavitation test results, the weightloss and weightloss rate in fresh water are observed more than those of seawater.

• Corrosion Science and Technology
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• v.8 no.4
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• pp.139-142
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• 2009

Recently, quaternary titanium alloys of the system Ti-Nb-Ta-Zr received considerable research interest as potential implant materials because of their excellent mechanical properties and biocompatibility. However, only few reported works were available on the corrosion behavior of such alloys. Hence, in the present work, electrochemical corrosion of Ti-35Nb-5Ta-7Zr alloy, which has been fabricated by arc melting and heat treatment, was studied in 0.9 wt% NaCl at $37\pm1^{\circ}C$, along with biomedical grade Ti-6Al-4V and CP-Ti. The phase and microstructure of the alloys were investigated employing XRD and SEM. The results of electrochemical studies indicated that the corrosion resistance of the quaternary alloy was inferior to that of Ti-6Al-4V and CP Ti.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.04a
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• pp.241-247
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• 1997

Reinforced concrete is in general known as high durability construction material under normal enviroments due to strong alkalinity of cement. Marine and harbour concrete as well as concrete mixed with seasand for fine aggregate are exposed to detrimental saltwater wich cause to accel-eate corrosion of reinforcing steel in concrete. If corrosion resistance of concrete gets to weaken due to carbonation and crack in cover concrete, concrete durability rapidly decrease by corrosion of reinforcement steel embedded in concrete. This research is to investigate basic physical properties of various corrosion inhibitors and to evaluate their corrosion resistance in concrete mixed with seasand. The object of this study is develop appropriate corrosion protection systems so as to enhance the durability of concrete.

• Journal of the Korea Concrete Institute
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• v.17 no.6 s.90
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• pp.1045-1051
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• 2005

For critical structures and application, where a given reliability must be met, it is necessary to account for uncertainties and variability in material properties, structural parameters affecting the corrosion process, in addition to the statistical and decision uncertainties. This paper presents an approach to the fuzzy arithmetic based modeling of the chloride-induced corrosion of reinforcement in concrete structures that takes into account the uncertainties in the physical models of chloride penetration into concrete and corrosion of steel reinforcement, as well as the uncertainties in the governing parameters, including concrete diffusivity, concrete cover depth, surface chloride concentration and critical chloride level for corrosion initiation. The parameters of the models are regarded as fuzzy numbers with proper membership function adapted to statistical data of the governing parameters and the fuzziness of the corrosion time is determined by the fuzzy arithmetic of interval arithmetic and extension principle

• Computers and Concrete
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• v.19 no.2
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• pp.161-169
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• 2017

Chloride induced reinforcement corrosion is widely accepted to be the most frequent mechanism causing premature degradation of reinforced concrete structures. The electrochemical impedance of reinforcing steel in diatomite- and zeolite-containing concrete exposed to sodium chloride was assessed. Chemical, physical and mineralogical properties of three concrete samples (20% diatomite, 20% zeolite, and a reference containing neither) were correlated with corrosion investigations. The steel-reinforced samples were exposed to 3.5% NaCl solution for 500 days, and measured every 15 days via EIS method. Results indicated that porosity and capillary spaces increase the diffusion rate of water and electrolytes throughout the concrete, making it more susceptible to cracking. Reinforcement in the reference concrete was the most corroded compare to the zeolite and the diatomite samples.

• Journal of the Korean institute of surface engineering
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• v.51 no.6
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• pp.372-380
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• 2018

Anodization techniques are widely used in the area of surface treatment of aluminum alloys because of its simplicity, low-cost and good corrosion resistance. In this study, we investigated the relationship between the properties (porosity and thickness) of anodic aluminum oxide (AAO) and its corrosion behavior. Aluminum 5052 alloy was anodized in 0.3 M oxalic acid at $0^{\circ}C$. The anodizing of aluminum 5052 was performed at 20 V, 40 V and 60 V for various durations. The corrosion behavior was studied in 3.5 wt % NaCl using potentiodynamic polarization method. Results showed that the pore diameter and thickness increased as voltage and anodization time increased. The relatively thick oxide film revealed a lower corrosion current density and a higher corrosion potential value.