• Journal of the Korean Ceramic Society
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• v.38 no.3
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• pp.231-237
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• 2001

NaOH 용액 처리로 제조한 개질 굴 패각 미분말은 98.7 wt%의 CaCO$_3$와 1.3 wt%의 chitosan으로 구성되어 있으며, chitosan의 탈아세틸화는 74.9%이었다. 개질화함으로서 입경은 작아지고 비표면적은 증가하였으며, 밀도는 감소하는 경향을 나타냈다. 입자 형상은 모서리가 각지고 매끄러운 형태에서 모서리가 침식되고 표면이 다공성인 환상의 형태로 변화되었다. 개질 굴 패각 미분말을 시멘트 대신 5.0 wt%까지 치환했을 때의 모르터의 압축강도는 치환량이 증가할수록 증가하였고, 흡수율은 치환량이 증가할수록 감소하는 경향을 나타냈다. 굴 패각 미분말은 대장균 및 황색포도상구균에 대해 항균력이 나타나지 않았으나, 개질 굴 패각 미분말은 5.0 wt% 첨가했을 때 99.8-99.9%의 항균력을 나타냈다. 또한 KS M 5000에 의한 항곰팡이 시험은 피막이 변색이나 변형이 전혀 없는 10등급으로 판정되었다.

• The Korean Journal of Malacology
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• v.30 no.2
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• pp.165-168
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• 2014

Shell of oyster has a function of shelter from predator as well as growth potential. We investigated the physicochemical characteristics of oyster shells from three difference oyster farms. The shells from Wando waters characterized high stability of nanostructure, ticker nacreous layer, high thermal decomposition temperature and low content of sulphur as well. These results represent that Wando coast is pristine water for oyster farming.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.4
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• pp.265-273
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• 2004

As a result of compressive strength experiment, rupture compressive strength showed more increases in specimens of 15% and 20% of Cockle shells in those of non-mixture. The specimen which was used general aggregate showed the highest value and ductility capacity was getting decreased as the amount of cockle shell was getting increased in the ductility capacity of specimen. We might conclude that the reason of the yield strength's decline was the lack of the bond strength which was caused by the amount of cockle shell.

• Journal of the Korean GEO-environmental Society
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• v.2 no.2
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• pp.33-39
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• 2001

In order to utilize mass of oyster shells for a partial substitute material for reclamation, the shear characteristics of two-phase mixture soil with oyster shells were investigated with $\overline{CU}$ test. From various experiments, it was found that the increase of mixed ratio of oyster shells causes the shear strength of mixed soil. And this phenomenon not only depends on friction due to confining pressure such as pure clay but also is influenced by shaping skeleton of oyster shells. Also, it was discovered that there were many influences by clay-oyster shell mixture from the study of the secant modulus and dilatancy characteristics of mixed soil. In addition, variation of oyster shell skeleton during shearing stage is examined applying modifying coefficient concept.

• Journal of the Korean GEO-environmental Society
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• v.8 no.1
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• pp.27-32
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• 2007

Trafficability for construction equipments in soft ground should be secured by improving the surface course. For this situation, the ground improvement technique has been used with stiffening agent, but the improvement cement has been mostly used so far. However, oyster shell has been developed and used as the stiffening agent to expand the chance of recycling oyster shell, which is regarded as solid waste. In this research, it was confirmed mechanical characteristics of oyster shell as stiffening agent by analyzing the strength characteristic such as mixing rates, water contents, and curing days of that to the dredging soil.

• Clean Technology
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• v.19 no.4
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• pp.423-429
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• 2013

This study aimed to develop flowable backfill material using oyster shell, coal ash, and surplus soil. The high temperature (> $800^{\circ}C$) reaction was required to convert $CaCO_3$ to CaO. The solid specimens formed by pozzlanic reaction between CaO and coal ash showed low unconfined compressive strength. The effect of kaolin and blast furnace slag was also examined. It was found that CaO and coal ash could not be utilized due to high cost and low performance. The use of oyster shell without calcination ($CaCO_3$) was evaluated. The specimens composing of oyster shell and cement showed the higher unconfined compressive strength than that composing of coal ash and cement. However, use of oyster shell is limited in mortar due to the presence of salt. Addition of soil into oyster shell-coal ash-cement mixture satisfied the specification of flowable backfill material by optimizing their ratio.

• Economic and Environmental Geology
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• v.51 no.6
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• pp.485-492
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• 2018

About 300 thousand tones of oyster shells are produced annually and, thus, their massive recycling methods are required. Recently, a method, utilizing them as wet desulfurization materials after removal of organic matters and changing $CaCO_3$ phase into CaO through calcination, is under consideration. This study investigates the mineralogical changes (specific surface area, phase changes, surface state, etc.) of oyster shells by calcination and their characteristics were compared with those of limestone. Uncalcined oyster shells showed the higher specific surface area than limestone because the former are composed of platy and columnar structures. In contrast, investigated limestone showed a dense structure. The phase change of oyster shells occurred at lower temperature than that of limestone. The specific surface area of oyster shell decreased significantly after calcination while limestone depicted a drastic increase. Small amount of Na contained in oyster shell was suggested as the cause of this phenomenon; in that, it acted as a flux causing melting and sintering of oyster materials at lower temperature. Because of this, an additional phenomenon was observed that a part of shell materials remained untransformed even at higher calcination temperature and after longer treatment period due to the sintered surface, which covers the rest parts. Further studies investigating the effect of this phenomena from the perspective of desulfurization is required.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.37 no.1
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• pp.33-40
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• 2024

The volume of shells, a prominent form of marine waste, is steadily increasing each year. However, a significant portion of these shells is either discarded or left near coastlines, posing environmental and social concerns. Utilizing shells as a substitute for traditional aggregates presents a potential solution, especially considering the diminishing availability of natural aggregates. This approach could effectively reduce transportation logistics costs, thereby promoting resource recycling. In this study, we explore the feasibility of employing wasted shell aggregates in 3D concrete printing technology for marine structures. Despite the advantages, it is observed that 3D printing concrete with wasted shells as aggregates results in lower strength compared to ordinary concrete, attributed to pores at the interface of shells and cement paste. Microstructure characterization becomes essential for evaluating mechanical properties. We conduct an analysis of the mechanical properties and microstructure of 3D printing concrete specimens incorporating wasted shells. Additionally, a mix design is proposed, taking into account flowability, extrudability, and buildability. To assess mechanical properties, compression and bonding strength specimens are fabricated using a 3D printer, and subsequent strength tests are conducted. Microstructure characteristics are analyzed through scanning electron microscope tests, providing high-resolution images. A histogram-based segmentation method is applied to segment pores, and porosity is compared based on the type of wasted shell. Pore characteristics are quantified using a probability function, establishing a correlation between the mechanical properties and microstructure characteristics of the specimens according to the type of wasted shell.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.12
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• pp.3971-3976
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• 2009

In this study, we secured wasted oyster shells as raw materials in order to applicate it to corrosion preventive ceramic coating reagent in the drinking water pipeline. Then, we investigated physicochemical properties in terms of basic calcination processing. Oyster shell was composed with 92.08% of $CaCO_3$ and the shapes of the pulverized particles were mostly oval. The calcined oyster shell showed increasing tendency of weight loss and of calcium content with the lapse of time and increase of temperature. The result indicates that the higher calcination processing temperature and the uniformly smaller particle size give more efficiency during calcination process. Therefore it is anticipated to be a good ceramic material to protect a surface of cleaning bed and inside of a tap water pipes from corrosion.

• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.7-14
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• 2003

In this study, undrained shear test was performed$K_o$ consolidation in order to study the shear strength characteristics of oysters-marine clay mixtures for three mixed ratios(0%, 25% and 50%). And, in order to study shear strength characteristics of oysters-marine clay mixtures, three different effective vertical stresses(200, 300 and 400kPa) were applied for the $K_o$ consolidation tests. In addition three different axial strain rates(0.005%/min, 0.05%/min, 0.5%/min) were applied for the case of effective vertical stress, 300kPa. According to experimental results, the more mixed ratios were increased, the more deviator stress was increased by crushing effect of oysters particles. especially, when effective vertical stress is 300kPa and mixed ratio increase from 25% to 50%, Test shows the increase of shear strength. But axial strain rate was not effect on the undrained shear strength. In the comparison and analysis that are based on the values of tests on the oysters-marine clay mixtures and the Mayne & Bishop's empiric formula, the undrained shear strength ratio shows a similar pattern of the tests. But for the prediction of the coefficient of the pore water pressure, the value of empiric formula shows more overestimated than the values of the tests at 0%, mixture ratio.