• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.181-182
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• 2010

This study was performed to introduce advanced conditioning and test method to improve problems of the conventional approach for evaluation of durability of FRC.

• Magazine of the Korea Concrete Institute
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• v.14 no.1
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• pp.32-36
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• 2002

지식, 정보 및 문화의 시대인 21세기는 변화하는 환경에 얼마나 빨리 적응하고, 나아가 변화를 유도하느냐에 따라 기술인의 성공여부가 좌우될 것이다. 건설 시장에서도 WTO의 출범으로 무한 경쟁 시대를 맞이하고 있으며, 세계 경제의 통합이 점점 가속화되는 지금, 우리나라의 건설산업과 기술인이 생존하고 발전하기 위해서는 미래에 대한 예측과 대비, 그리고 세계화(globalization) 등 환경 변화에 대한 빠른 적응이 무엇보다 중요하다고 하겠다.(중략)

• Journal of the Korean GEO-environmental Society
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• v.24 no.12
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• pp.13-18
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• 2023

Cast-in-place concrete lining is commonly used in tunnel lining, but cast-in-place concrete lining has problems with construction and quality control. Precast segment lining is being used to solve these problems. In general, precast segment lining is known to have improved durability and easy maintenance such as rehabilitation of structures. This study compared the durability of 22 tunnel linings constructed with precast segments or cast-in-place reinforced concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.773-776
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• 2008

The corrosion of steel in concrete is significant in marine environment. Marine bridges are readily deteriorated due to the exposure to marine environment. Salt damage is one of the most detrimental causes to concrete bridges and port structures. Especially, the splash and tidal zones around water line are comparatively important in terms of safety and life-time point of view. During the last several decades, cathodic protection (cp) has been commonly accepted as an effective technique for corrosion control in concrete structures. Zn-mesh sacrificial anode has been recently developed and started to apply to the bridge column cp in marine condition. The detailed parameters regarding Zn-mesh cp technique, however, have not well understood. This study is to investigate how much Zn-mesh cp influences along the concrete column at elevated temperature. About 100cm column specimens with eight of 10cm segment rebars have been used to measure the variation of cp potential with the distance from Zn-mesh anode at both 10$^{\circ}$C and 40$^{\circ}$C in natural seawater. The cp potential change and current diminishment along the column specimens have been discussed for the optimum design of cp by Zn-mesh sacrificial anode

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.965-968
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• 2008

The KS F 2403 method used on domestic sites for checking the compressive strength of a structure, sets the compressive strength of the concrete used in structural specimens as the compressive strength of testing specimens. Under this regulation, the curing method used for testing the specimens must be the standard ponding curing method (20$\pm$2$^{\circ}$C). However, because in-placed concrete is exposed to open air and cured under the seasonal temperature changes, the compressive strength of a real structure is different from the tested compressive strength. (Therefore,) This thesis first identifies the distinct characteristics of the strength development by applying the curing method listed under the KS and used for testing specimens on compressive strength tests; the atmospheric curing method, the sealed curing method, and the structural specimen core strength testing methods used for the in-sites quality checks including reckoning of the compressive strength of the structural specimens and form-demolding period; and the curing method suggested in this research, which sets the internal conditions of the structural specimens as the conditions of the applied curing method. Then, the thesis suggests the specimen curing method that most closely reenacts the compressive strength of the concrete used on the structural specimens

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.4
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• pp.241-247
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• 2010

Corrosion of steel embedded in concrete is one of the foremost factors that affect the durability of concrete structures in marine environments. This paper presents an application technique of anode-ladder-system to evaluate corrosion behaviours of marine concrete structure. In order to investigate the behaviours quantitatively, the measurement of potential and current was performed on the concrete elements subjected to the penetration and diffusion of chloride ions. The main variable was the heights from seawater level; namely 3.7, 6.0 and 8.2 m. As a result of the monitoring, it was found that the corrosion characteristics differently behaved with the increasing height. Additionally, through migration test, the relationship between compressive strength of concrete and diffusivity of chloride ions was observed. It is suggested, ultimately, that in order to reduce or mitigate steel corrosion, both appropriate concrete cover depth and high-quality of concrete in early ages should be done.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.685-688
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• 2008

This study has examined the effect of bottom ash(BA) on the properties of low heat-blended cement(LHC) and concrete. A number of binders were prepared by the replacement of LHC with BA in range of 5$^{\sim}$20wt%. The results showed that the final setting time of cement paste were delayed when the BA replaced part of the cement. However, The heat of hydration increased narrowly with adding BA in a early hydration period. The results also showed the inclusion of BA at replacement levels of 5$^{\sim}$10wt% resulted in an increase in compressive strength of the specimens compared with that of the control concrete and improved a resistance of concrete against the sulfate and chlorine ion.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.1065-1068
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• 2008

Marine bridges are readily deteriorated due to the exposure to marine environment. The concrete deterioration occurred by corrosion of steel in concrete is mainly relevant to chloride in seawater. Chloride ions penetrate through porous concrete, and then reach to the reinforcing steel, and finally corroded them. The corrosion by-products(rusts) increase the volume as much as 6 to 10 times of origin steel. this creates expanding pressure and tensile stress, which cause the structures cracking and spalling. Sometimes the rebar corrosion is accelerated, and then collapsed catastrophically. In order to prevent corrosion damage, it is important to understand well regarding the reason of concrete corrosion, the quantification of its damage, and protection method/system to stop or to mitigate the corrosion. In this study, slab specimens were fabricated to evaluate the effect of cathodic protection which was simulated to marine bridges, and/or port structures. Zn-mesh sacrificial anode has been applied as a chathodic protection system and accelerated test conditions, i.e. temperature and salt concentration have been used in this study.

• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.1
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• pp.46-51
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• 2014

Increasing of waste FRP (fiber reinforced plastics) has caused environmental problems. Recently, the technology of making fibers from waste FRP, which can be used to reinforce the concrete, was developed and the reinforced concretes were tested to study the structural performance. The purpose of this study is to investigate the effect of the powder, obtained together with F-fiber from the waste FRP, on the compressive strength and the fire resistance performance as in the high strength concrete. Strength tests show that the use of recycled FRP powder does not reduce the compressive strength of high strength concrete if the volume fraction of FRP powder is less than 0.7%. Electric furnace test results also show that the use of recycled FRP powder may increase the fire resistance performance of high strength concrete significantly.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.2
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• pp.93-100
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• 2019

In this study, the mechanical properties of early-age concrete were evaluated by mixing the electric arc furnace oxidizing slag fine aggregate with 30% and 50% replacement ratio. Slump test, air content test and unit volume weight test were performed for fresh concrete, and compressive strength test and chloride penetration experiments were carried out in hardened concrete. The compressive strength increased up to 7 days of curing age with increasing replacement ratio of the electric furnace oxidizing slag, but the strength decreased to 90% level of OPC concrete at 28 days of age. Regarding the result of chloride penetration test, no significant differences from OPC concrete were evaluated, which shows a feasibility of application to concrete aggregate.