• Journal of the Korea Concrete Institute
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• v.15 no.2
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• pp.280-287
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• 2003

To evaluate the practical application of oyster shells(OS) as construction materials, an experimental study was performed. More specifically, the long-term mechanical properties and durability of concrete blended with oyster shells were investigated. Test results indicate that long-term strength of concrete blended with 10% oyster shells is almost identical to that of normal concrete. However, the long-term strength of concrete blended with 20% oyster shells is appreciably lower than that of normal concrete. Thereby, concrete with higher oyster shell blend has the possibility of negatively influencing the concrete long-term strength. Elastic modulus of concrete blended with crushed oyster shells decreases as the blending mixture rate increases. Namely, the modulus is reduced to approximately 10∼15% when oyster shells are blended up to 20% as the fine aggregate. The drying shrinkage strain increases with an increasing crushed oyster shells substitution rate. In addition, the existing model code of drying shrinkage and creep do not coincide with the test results of this study. An adequate prediction equation needs to be developed. The utilization of oyster shells as the fine aggregate in concrete has an insignificant effect on fleering and thawing resistance, carbonation and chemical attack of concrete. However, water permeability is considerably improved.

• Korean Journal of Soil Science and Fertilizer
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• v.30 no.3
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• pp.242-247
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• 1997

This study was conducted to investigate the combined effects of oyster shell, fly ash and gypsum on rice yield and quality. The four treatments of soil amelioration were oyster shell 4, fly ash 80, fly ash 56 + gypsum 24 and oyster shell 0.8 + fly ash 40 + gypsum 24 ton/ha. Rice yield were in the order of oyster shell, fly ash and control plats. The pH, EC values and OM, Ca, $SO_4$, moisture contents of the top-soil after rice harvesting in soil amelioration treatments were increased, while Mg, Na, Fe, Zn and Al were decreased than those of control. Rice quality was the best in the fly ash plat due to lower T-N and higher Mg/K ratio.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.211-216
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• 2003

굴폐각은 굴양식 후 남는 것으로 남해안에서 주로 집중적으로 발생하는데 연간 28만톤의 발생량 중 상당양은 폐기물로 계속 누적되고 혹은 불법매립되어 환경오염 문제까지 발생시키고 있다. 본 연구에서는 산업폐기물로 분류되는 굴패각을 지반공학 분야에서 활용하기 위한 대안으로 해성점토와 혼합하여 매립재료로써의 적용성을 평가하기 위하여 대형 압밀기를 이용하여 실험을 실시하고 이를 토대로 기초자료를 획득하고자 하였다. 원형의 굴패각을 파쇄하여 입도별로 분류하고 이중 사질토 입경 크기의 재료에 대한 기본 물성치를 평가하고 지반 재료로써의 적용성를 분석하였다. 해성점토 내의 굴패각입자의 혼합비를 변화시켜 만들어진 혼합토에 대한 압밀 실험 결과 굴패각의 혼합율이 증가할수록 체적변화율이 작게 되고, 침하 속도는 빠르게 증가함을 알 수 있었다. 이는 압밀응력의 일부를 굴패각 입자의 골격구조가 부담함으로써 실제 점토부분에 작용하는 압밀응력은 굴패각 혼합율이 증가할수록 작아지는 것으로 판단된다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.2
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• pp.159-165
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• 2000

This study was investigated the environment of waste shells such as oyster, cockle and paphia on southern shore in korea and established the recycling method to prevent the environmental pollution, etc. The waste shells were reclaimed at public shore illegally or leaved on the surroundings of shore. The origin mechanism, XRD and TG-DTA analyses were performed to effective recycling of waste shells, and the optimal recycling method was preparation of the calcium carbonate. In this work, calcium carbonate and lime fertilizer of granular shape were prepared using the waste shell.

• Journal of the Korean Geotechnical Society
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• v.17 no.5
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• pp.51-60
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• 2001

연안역 굴양식장에서 발생하여 폐기물로 분류되어 불법으로 버려지는 굴패각을 파쇄하여 혼합한 모르타르 혼합토의 특성을 규명하고자 압축강도 시험을 포함한 다양한 실내시험을 수행하였다. 압축강도시험을 위하여 준비한 모르타르 공시체는 시멘트, 물, 모래 및 굴패각을 다양한 배합비로 혼합하여 제작하였다. 강도시험결과에 따르면 분쇄한 굴패각의 비율이 최대 모래중량의 40%까지 혼합한 경우에도 굴패각을 섞지 않은 일반 모르타르 혼합토에 비하여 압축강도가 크게 감소하지 않았다. 본 연구에서 수행한 압축강도실험을 분석한 결과, 다양한 크기로 파쇄한 굴패각을 적절한 혼합비의 모래 및 시멘트와 배합하여 사용한다면 건설재료로서의 재활용 가능성이 충분한 것으로 판단되었다.

• Journal of the Korea Organic Resources Recycling Association
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• v.15 no.1
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• pp.143-148
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• 2007

The objective of this study was to investigate the proper conditions of calcination and calcium extraction from powdered oyster shell. The physical characteristics such as particle size distribution, surface morphology, and thermal gravity were examined. The following result were obtained. As the powdered oyster shell was ignited in high temperature of $650^{\circ}C$ to $950^{\circ}C$, the calcination reactions was effectively progressed. The amount of weight loss during calcination would be matched with the generation of carbon dioxide gas. In the calcination of powdered oyster shell, the amount of weight loss increased according to the increased of calcination temperature and the decrease of mean particle size. It was founded that the proper temperature and retention time of calcination was $850^{\circ}C$ and 40 minute. In the extraction of calcium into liquid form using acid addition, the calcination oyster shell was more effective than the non-calcinated shell. The liquid calcium extraction technique using the calcinated oyster shell needed more researches considering cost evaluation.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.1
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• pp.82-88
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• 2007

The objective of this study is to examine the effect of the waste oyster shell powder as the addition agent in bulking sludge thickening of paper manufacturing plant using DAF(Dissolved Air Flotation) and gravitational sedimentation. The effect of parameters such as dosage and size distribution of oyster shell were examined. The results showed that the optimum dosage of mixed oyster shell(size range : $\sim250{\mu}m$) was 0.8 g/L. The oyster shell addition of 5.0 g/L in sedimentation process was increased thickening concentration of 3.25 times. When 5.0 g/L of oyster shell was added in DAF process, water content of sludge was decreased from 95.5% to 82.7% in dewatering process using Buchner funnel test device. When size of oyster shell was divided four ranges($\sim53{\mu}m$, $53\sim106{\mu}m$, $106\sim150{\mu}m$, $150\sim250{\mu}m$), optimum size range for the flotation and dewatering was $53\sim106{\mu}m$.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.3
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• pp.169-177
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• 2005

This study is to analyze the application of the oyster shells as a substitute fine aggregate of concrete. For this purpose, the fundamental experiments of the composed materials and the variations of the main factors on it were considered and then the variations of workability and strength properties of the specimens with each case were also studied. The experimental results on the properties as construction material showed that the use of oyster shells in concrete would not cause abnormal chemical reactions or lead to the formation of any new objects, the workability and strengths decreased with increase in proportion of oyster shells. The compressive strength of concrete with oyster shells is developed as much as that of normal concrete and the grain size of oyster shells is superior on 3.0~5.0mm and the percentage of substitution of them to fine aggregate about 30% from the properties of concrete with them. The relationship equation between compressive strength and tensile strength is ( ).

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.2
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• pp.196-202
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• 2018

In this study, we investigated phosphate removal efficiency according to pretreatment (pyrolysis temperature, pyrolysis time, particle size) of oyster shells as a basic study for their recycling. And XAFS analysis and isothermal adsorption experiments were performed to investigate the phosphate removal characteristics of oyster shells. As a result, the removal efficiency was good at $600^{\circ}C$ pyrolysis temperature with 6 hour pyrolysis time and 0.355 ~ 0.075 mm particle size. Isothermal adsorption experiments showed that the Langmuir model is suitable for adsorption of oyster shells. XAFS analysis showed that calcium phosphate formed on the oyster shell pyrolyzed at $600^{\circ}C$. In other words, it was confirmed that the formation of calcium phosphate by the calcium ion elution of the oyster shell contributes to the decrease of phosphate concentration.

• Journal of the Korean Geotechnical Society
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• v.19 no.5
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• pp.281-290
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• 2003

In order to investigate recycling possibility as a construction material of oyster-shells, the geotechnical characteristics including permeability, confined compression and shear strength of crushed oyster shell were quantitatively examined in terms of fineness modulus and relative density of crushed oyster-shell. Experimental results show that the crushed oyster-shells are lighter than sand in weight, and have similar characteristics on permeability and shear strength to sandy soils. The oyster-shell can be considered as highly crushable material but not much crushable with existing high loads. Based on the laboratory test results, it is highly fudged that the crushed oyster-shell can be a substitute of sand as SCP materials.