• Journal of Coastal Disaster Prevention
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• v.5 no.4
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• pp.163-172
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• 2018

To propose the design technique and the execution manual of the LWFS(Lightweight Foamed Soil) method using dredged soil, the operation system for the test-bed integrated management, and to establish an amendment for the domestic quantity per unit and specifications, and a strategy for its internationalization. In order to utilize the dredged soil from the coastal area as a construction material, we constructed the embankment with LWFS on soft ground and monitored its behavior. As a result, it can be expected that the use of LWFS as an embankment material on the soft ground can improve the economic efficiency by reducing the depth and period of soil improvement as well as the uses of nearby dredged soil. To verify the utilization of the dredged soil as a material for light-weighted roadbed, soft ground and foundation ground, and surface processing, perform an experimental construction for practical structures and analyze the behavior. It is expected to be able to improve the soft ground with dredged soil and develop technique codes and manuals of the dredged soil reclamation by constructing a test-bed in the same size of the fields, and establish the criteria and manual of effective dredged soil reclamation for practical use. The application technology of the dredged soil reclamation during harbor constructions and dredged soil reclamation constructions can be reflected during the working design stage. By using the materials immediately that occur from the reclamation during harbor and background land developments, the development time will decrease and an increase of economic feasibility will happen. It is expected to be able to apply the improved soil at dredged soil reclamation, harbor and shore protection construction, dredged soil purification projects etc. Future-work for develop the design criteria and guideline for the technology of field application of dredged soil reclamation is that review the proposed test-bed sites, consult with the institutions relevant with the test-bed, establish the space planning of the test-bed, licensing from the institutions relevant with the test-bed, select a test-bed for the dredged soil disposal area.

• Journal of Soil and Groundwater Environment
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• v.12 no.4
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• pp.8-15
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• 2007

Geotechnical and environmental properties of stone fillers are analyzed by several laboratory experiment to identify the possibility of recycling fillers and sewage dredged soils as construction materials. The result of geotechnjical test shows that the sewage dredged soil is a sandy soil which contains 70-80% sand and is useful as an aggregate of construction site. Stone filler has large fine content, which may disqualifies the use as construction materials. However, this material is still useful as a filler in stone quarries or finished mines. From the environmental test, the liquids leached from two types of materials have satisfied the standard of chemical substances in the soil environment law and no harmful effect in ground pollution is expected when recycling.

• Journal of the Korean Geotechnical Society
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• v.24 no.5
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• pp.5-13
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• 2008

This paper proposed an environmental standard far beneficial use of dredged materials currently considered as waste materials. In Korea, even though chemical analysis of sediments are carried out frequently, their analysis results were not interrelated with the effects of biological lives due to a shortage of data, which may result in difficulty to develope Korean standards for reusing dredged materials. For these, this paper first searched existing foreign standards, analyzed local contaminated sediment data, identified their main components of contaminations and then compared clean-up standards of sediments consisting of lower and higher level. From these analyses new environmental standards considering Korean domestic circumstances are proposed. It is judged that newly proposed standards are appropriate in terms of both Korean national sedimental environments and economical recycling aspects because environmental standard levels proposed are higher than background level of sediments in Korea and foreign country's standards, where many experiences and environmental monitoring works have been already performed.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.433-438
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• 2006

When we consider to develop a new harbor, the most important factor, we think, is the lowest water depth of waterway and approaching channel for safe navigation of vesse. The existing harbors have been being dredged to meet the international trend of jumbo sized vessels by adopting the new design criteria. As the dredged materials over the expected at the design level were common and there are still lack of land based reclamation area, we have no choice to discharge the dredged materials in open sea area. In this study, we analysed the behavior of discharged materials at the dumping area of offshore open sea, which were collected from the dredging work at the waterway in Busan New Port. We measured the tidal currents and analyzed the waters of dumping site after the dumping work. these were used to evaluate the numerical models. Suspended Solids(SS) were introduced to the diffusion model. Because of the characteristics of the dumping site, the speed of initial diffusion and settle down of the discharged materials was so fast. Therefore, we believe that the dumped materials do not cause a significant impact to the marine environment.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.4
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• pp.185-191
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• 2010

To effectively utilize resources of reject ash and dredged soil, globular shape-formed artificial lightweight aggregate were manufactured in 8~10 mm size. Starting materials were changed various grading and composition, sintered at $1050{\sim}1250^{\circ}C$. The specific gravity, water absorptance of artificial lightweight aggregates were measured on the basis of the KS. In this study could make a prediction about application of bloating mechanism by ferrous materials and alkali/alkali-earth oxide at high temperature.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.17 no.3
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• pp.133-137
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• 2007

Ecological lightweight aggregates were made in order to recycle the dredged soils from the seaside construction area and the bottom ashes from the power plant. Various physical and chemical analysis were performed on them to identify their possibility for applying lightweight concrete fields. Lightweight aggregates were made of bottom ashes and dredged soils from Yongheung Island which is located 20km west away from Seoul, and all the raw materials were milled before mixing. The physical and chemical properties such as density, absorption rate, stability, alkali latency reaction, heavy metal leaching of the lightweight aggregates were tested and analysed by following the KS standard procedures. From the size analysis, the coarse aggregates showed a suitable fit on standard particle ranges; however, the fine aggregates showed a large deviation from the standard. The absorption rates were increased with decreasing weight of the aggregates. All the aggregates were turned out to be safe by the stability and heavy metal leaching test; however, some of the aggregates were confirmed on the border of harmless and possibly harmful region through the alkali latency reactivity test.

• Geomechanics and Engineering
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• v.15 no.4
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• pp.1005-1016
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• 2018

This paper presents an investigation on the properties of two types of cement kiln dust (CKD)-stabilized dredged sediments, silt and clay with a comparison to hydrated lime stabilization. Unconfined compressive strength (UCS) and California bearing ratio (CBR) tests were conducted to examine the optimal stabilizer content and classify the type of highway material. A strength development model of treated dredged sediments was performed. The influences of various stabilizer types and sediment types on UCS were interpreted with the aid of microstructural observations, including X-ray diffraction and scanning electron microscopy analysis. The results of the tests revealed that 6% of lime by dry weight can be suggested as optimal content for the improvement of clay and silt as selected materials. For CKD-stabilized sediment as soil cement subbase material, the use of 8% CKD was suggested as optimal content for clay, whereas 6% CKD was recommended for silt; the overall CBR value agreed with the UCS test. The reaction products calcium silicate hydrate and ettringite are the controlling mechanisms for the mechanical performance of CKD-stabilized sediments, whereas calcium aluminate hydrate is the control for lime-stabilized sediments. These results will contribute to the use of CKD as a sustainable and novel stabilizer for lime in highway material applications.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.5
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• pp.199-204
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• 2015

In this study, prevention methods of radial cracks generated inside of artificial lightweight aggregate made of reject ash and dredged soil were investigated. The reject ash and dredged soil had mixed with weight ratio of 7 : 3 and formed to spheric shape of 5~20 mm diameter, then, the aggregates were manufactured using flash sintering method at $1200^{\circ}C$ for 10 min. The formation of radial cracks in the aggregates were suppressed as the size of specimen decreased. Also, the addition of silica to aggregates had prevented generation of the radial cracks. As the size and the amount of silica powder added increased, the development of radial cracks was constrained. Therefore the artificial lightweight aggregate manufactured in this study expected to be applicable to many fields such as construction and environmental usages. Also it is expected to contribute greatly to increase the recycling rate of reject ash and dredged soil.

• Korean Journal of Microbiology
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• v.51 no.4
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• pp.374-381
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• 2015

Occurrences of coastal dredged materials are ever increasing due to port construction, navigational course maintenance and dredging of polluted coastal sediments. Ocean dumping of the coastal dredged materials has become virtually prohibited as London Treaty will be enacted as of the year 2012. It will be necessary to treat and recycle the dredged materials that may carry organic pollutants and heavy metals in a reasonable and effective process: collection of the dredged materials, liquid and solid separation, and treatment of organic compounds and heavy metals. In this study we have developed a continuous bioreactor system that can treat a mixture of silt and particulate organic matter using a microbial consortium (BM-S-1). The steady-state operation conditions were: pH (7.4-7.5), temperature ($16^{\circ}C$), DO (7.5-7.9), and salt concentration (3.4-3.7%). The treatment efficiencies of SCOD, T-N and T-P of the mixture were 95-96%, 92-99%, and 79-97%. The system was also effective in removal of heavy metals such as Zn, Ni, and Cr. Levels of MLSS during three months operation period were 11,000-19,000 mg/L. Interestingly, there was little sludge generated during this period of operation. The augmented microbial consortium seemed to be quite active in the removal of the organic component (30%) present in the dredged material in association with indigenous bacteria. The dominant phyla in the treatment processes were Proteobacteria and Bacteroidetes while dominant genii were Marinobacterium, Flaviramulus, Formosa, Alteromonadaceae_uc, Flavobacteriaceae_uc. These results will contribute to a development of a successful bioremediation technology for various coastal and river sediments with a high content of organic matter, inorganic nutrients and heavy metals, leading to a successful reuse of the polluted dredged sediments.

• Proceedings of the Korean Geotechical Society Conference
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• 1992.10a
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• pp.61-64
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• 1992

Recently, by the lack of fill material, the dredg and fill(hydraulic fill) method is commonly used in reclamation projects. Hydraulic fill method dredges the soil and send it with water through the transportation pipe to the site. The intial state of the hydraulic fill material is accordingly the mixture of water and soil skeleton which settles with time forming a new soil layer. The properties of new soil layer is governed the size of the soil skeleton, the flow velocity of mixing water, salt concentration, the distance from the discharge pipe outlet, and other dredging conditions when settling process occur. In this study, the effects of gradation of derdged soil on the deposition properties (with emphasis on the optimum spacing of the discharge pipes) was investigated by field test. It was found that the soft fine graind soil was forme at 350m from the discharge pipe outlet when the dredged material was classified as CL, while the soft fine grained soil was not formed even at the distance farther than 400m from the diacharge pipe outlet when the dredged material was classified as SM.