• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.198-198
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• 2019

2011년 동일본 지역에서 발생한 지진으로 인하여 후쿠시마 다이이치에 위치한 원자력 발전소에서 다양한 방사성 물질들이 바다, 하천 그리고 대기와 같은 자연환경 속으로 유출되었다. 방사성 세슘(Cesuim, $Cs^{137}$)은 다양한 방사성 물질들 가운데 반감기(Half-life)가 30.17년으로 가장 긴 물질이다. 방사성 세슘이 환경 생태계로 한번 유출될 경우 긴 반감기과 널리 퍼지는 성질로 인하여 오랜 시간동안 넓은 지역에 막심한 피해를 초래하므로 효과적인 처리방법을 통해 안전하게 처리하는 것이 아주 중요하다. 세슘을 제거하기 위하여 물리적, 화학적, 생물학적 등 다양한 방법들을 통해 연구를 진행하고 있으며, 특히 세슘을 제거하는 아주 효과적인 방법 중 하나인 프러시안 블루(Prussian Blue, PB) 흡착제를 적용하는 방법이 많이 주목받고 있다. 그러나 프러시안 블루는 미세한 분말입자로서 수처리에 사용하게 되면 처리 후 발생되는 슬러지들을 수중으로 부터 분리하기 어려운 한계점을 가지고 있다. 최근 연구에서는 프러시안 블루의 적용 한계점를 극복하기 위하여 자성체(Magnetic substance)를 물리적 지지체로 이용하여 외부 자기장을 통해 수중으로 분리하는 방법들이 연구되고 있다. 자성체란 외부 자기장이 주어지게 되면 입자들 표면에 자성력을 띄는 물질들을 말한다. 본 연구에서는 자성체 종류들 가운데 가장 높은 자성력을 지닌 강자성체(Ferromagnetic Substance)를 물리적 지지체로 하여 산화과정, 실란과정, 합성과정을 거쳐 강자성체 입자의 표면에 프러시안 블루를 합성한 새로운 형태에 합성체를 제조하고, 제조된 합성체를 이용하여 수중에 존재하는 세슘 제거 능력을 평가하였다. 제조된 합성체의 물리적 특성을 분석하기 위하여 SEM, XRD를 이용하여 합성체 입자의 표면 분석을 진행하였다. 합성체의 세슘 제거 능력을 평가하기 위하여 임의 제조된 0.5mg/L의 세슘 농도를 가진 원수 100ml에 제조된 새로운 형태의 합성체 1g을 투입한 뒤 1분간의 반응시간 동안 반응한 이후 잔류 세슘을 측정한 결과 수중의 존재하는 세슘에 대해 99.9%의 세슘 제거율을 기록하였다. 자가분리(Magnetic Seperate)의 원리를 이용하여 수중으로부터 회수율을 측정한 결과, 99%의 합성체 회수율을 얻었다. 실험결과를 통해 외부자기장이 주어지게 되면 수중으로부터 합성체를 대부분 분리하여 회수할 수 있다고 판단된다. 본 연구를 통해 개발된 새로운 형태의 합성체는 수중의 세슘 처리 공정에서 사용자가 직접 접촉하지 않고 세슘제거 및 외부자기장을 통해 수중으로부터 분리가 가능한 합성체라고 판단된다.

• 레미콘
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• no.10 s.69
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• pp.19-26
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• 2001

• Journal of the Korean Geosynthetics Society
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• v.12 no.2
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• pp.25-33
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• 2013

This study introduces strength characteristics of the anti-washout grouting material using viscous modifiers and its characteristics mixed with coarse materials. Especially, this study focused on the strength characteristics of the grouts mixed with sea water. It is found that the anti-washout grout mixed with sea water has enough strength and good resistance to segregation just like that with fresh water. Also, a small scale test was performed to evaluate the solidification characteristic of the anti-washout grout mixed with coarse fill materials. It is also found that the strength of anti-washout grout mixed with coarse fill materials is greater and better segregation resistance than those of conventional grout with fill materials.

• Journal of the Korean Ceramic Society
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• v.39 no.10
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• pp.970-976
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• 2002

In this paper, the slump flow of the concrete, suspension, pH, corrosion effect, bleeding and the characteristics of coompressive strength were analyzed using antiwashout underwater admixture and antiwashout underwater agent+corrosion inhibitor mixed admixtures(1type). The results showed that there were no rare difference in physical properties but in the results of rapid corrosion tests there were lots of corrosion inhibitor ratio differences between concrete using only antiwashout underwater admixture and the corrosion inhibitor mixed(1type). In the case of only antiwashout underwater admixture 5.4%, the case corrosion inhibitor mixed(1type) 0.07%, the Antiseawater of the concrete which uses the Corrosion Inibitor Mixed(1type) appeared highly.

• Magazine of the Korean Society of Agricultural Engineers
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• v.43 no.3
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• pp.66-76
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• 2001

Recently the use of the antiwashout underwater concrete with the antiwashout admixture is increased considerably. Antiwashout underwater concrete is quite different in concept from conventional underwater concrete. By mixing an antiwashout admixture with concrete, the viscosity of the concrete is increased and its resistance to segregation under the washing action of water is enhanced. The aims of this research is statistically evaluated to mix proportion factor of antiwashout underwater concrete. Experiment was performed to analyze the influence variables(cement, water, and antiwashout admixture) on fundamental characteristics of antiwashout underwater concrete. The influence variables can be considered for use in a wide range of underwater work where their have statistically significant effect on the characteristics(fluidity, filling ability, resistance to washout, etc.) of antiwashout underwater concrete.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.3
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• pp.57-62
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• 2020

Among the sewage pipes installed in Korea, the length of concrete pipes exceeding 20 years is 66,334 km (42.5%). Deteriorated concrete sewer pipes need to be repaired due to the leakage of internal sewage, which causes problems such as sink holes by expanding the cavity around the pipeline. In this study, we tried to apply anti-washout underwater mortar with ultra rapid hardening cement and segregation reducing agent to sewage pipe repair. As a result of the setting time test, the final set time was delayed by up to 172% by incorporating segregation reducing agent. In the test for measuring the degree of mortar segregation in water, it was measured at pH 12 or less under all mixing conditions. In addition, the suspension amount was measured to be 50 mg / l or less to satisfy the KCI-AD102 standard by incorporating a segregation reducing agent. In terms of the average value of mortar compressive strength, by incorporating segregation reducing agent, the strength of the specimens produced in air was more than 80% of that of the specimens produced in water. Conversely, the bond strengths of the specimens produced in water were measured to be higher than those of the specimens produced in air. Water resistance was evaluated by measuring water absorption and water permeability. Water absorption and water permeability were reduced by 42.6% and 36.6%, respectively, by mixing segregation reducing agent.

• Journal of the Korea Concrete Institute
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• v.17 no.3 s.87
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• pp.455-464
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• 2005

Today the application of antiwashout underwater concrete to the construction sites is increasing steadily, while its reliability is in issue. Particularly, antiwashout underwater concrete is known to have very weak durability on frost attack, and hence Japan society of civil engineers(JSCE) regulated that not to use of antiwashout underwater concrete where the freezing and thawing is suspected. This study aims the improvement of the freezing and thawing resistance for antiwashout underwater concrete. From the results of fundamental test, FA20 and SG50 showed good performance in fluidity and long term compressive strength than control concrete. Meanwhile, MK10 marked the highest compressive strength through the whole curing age but a defect on fluidity was discovered. The results from the repeated freezing and thawing test show that the large volumes of air entrapped by cellulose based antiwashout underwater admixture gave bad effects to frost durability and hence not much benefits were confirmed from the use of mineral admixtures. However there were some increasing effects on frost durability of MK10 and SG50 by securing $6{\pm}0.5\%$ of entraining air. In the meantime, there was a increasing tendency of frost durability by increasing blame's fineness of ground granulated blast furnace slag.

• Resources Recycling
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• v.27 no.6
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• pp.30-37
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• 2018

A series of experiment was conducted to evaluate basic performances of low-pH, anti-washing grouts incorporating gypsum which applied for reinforcing underwater cavities in limestone- grounds. Various types of mix proportions were designed and the fluidity, strength and environmental impact of these mixtures were evaluated. The flowability was evaluated under two conditions, i.e., flows without and with pressing, respectively. Strength was measured for the hardened mixtures fabricated under conditions of air and water injections. The environmental impacts including the pH of the suspension and the suspended solids concentration for the mixtures were evaluated. The low pH of fresh mixture suspension, below than 10, was achieved by incorporation of gypsum. The mix proportions of cement-quartz powder-gypsum binders and chemical agents resulted in mortar natural flow 7-10 cm and uniaxial compressive strength 4 MPa were derived.

• Explosives and Blasting
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• v.38 no.4
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• pp.46-52
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• 2020

Although anti-washout grouts are used extensively in underwater targets, major constraints continue to be associated with their use. These include poor bonding strength, poor pumpability, and loss of high strength in everyday engineering applications. In this study, based on the literature pertaining to self-compacted, non-dispersive, anti-washout grouts, a review of research trends in anti-washout grouts for underwater construction and sealing of karst cavities was carried out in order to determine the problems faced in this field. Grouts used under water suffer a loss of strength and bonding strength in comparison to grouts cast in air. Researchers are designing high-viscosity grouts to overcome the inrush of water and seal karst cavities; however, in doing so, they have inadvertently caused serious problems pertaining to the pumpability of these grouts and concretes in deep target locations. Thus, the majority of the anti-washout grouts and concretes that have been developed are not applicable to deep target environments, instead being suitable for only near-surface targets.

• Journal of the Korean GEO-environmental Society
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• v.15 no.9
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• pp.59-67
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• 2014

With increasing underwater structure construction, there is high interest in offshore foundation and underwater grout and various study has been done in this area. For grout materials constructed underwater, it may be washed away by water or easily disturbed and material separation phenomenon during curing period always happens. As a result, it is difficult to ensure construction quality and this has a significant influence on the design strength of structure. In this study, to understand application effects of anti-washout admixture for the preplaced construction method, where grout is injected in monopile after filled with aggregates, laboratory tests on bleeding and compressive strength of anti-washout admixture were performed under various test conditions varying size of aggregate, water and cement ratio and admixture, and test results were compared and evaluated.