• Geomechanics and Engineering
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• v.20 no.6
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• pp.537-546
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• 2020

Oil and natural gas reserves have been recognised abundantly in clayey rich rock formations in deep costal reservoirs. It is necessary to understand the sedimentary history of those reservoir rocks to well explore these natural resources. This work designs a group of laboratory experiments to mimic the physical process of the sedimentary clay-rich rock formation. It presents characterisation results of the physical properties of the artificial clayey rocks synthesized from illite clay, quartz sand and brine water by high-pressure consolidation tests. Special focus is given on the effects of illite clay content and high-stress consolidation on the physical properties. Multi-step loaded consolidation experiments were carried out with stress up to 35 MPa on mixtures constituting of the illite clay, quartz sand and brine water with five initial illite clay contents (w=85%, 70%, 55%, 40% and 25%). Compressibility and void ratio were characterised throughout the physical compaction process of the mixtures constituting of five illite clay contents and their water permeability was measured as well. Results show that the applied stress induces a great reduction of clayey rock void ratio. Illite clay contents has a significant influence on the compressibility, void ratio and the permeability of the physically synthesized clayey rocks. There is a critical illite clay content w=70% that induces the minimum void ratio in the physically synthesised clayey rocks. The SEM study indicates, in the high-pressure synthesised clayey rocks with high illite clay contents, the illite clay minerals are located in layers and serve as the material matrix, and the quartz minerals fill in the inter-mineral pores or are embedded in the illite clay matrix. The arrangements of the minerals in microscale originate the structural anisotropy of the high-pressure synthesised clayey rock. The test findings can give an intuitive physical understanding of the deep-buried clayey rock basins in energy reservoirs.

• Korean Journal of Environmental Agriculture
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• v.19 no.1
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• pp.38-43
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• 2000

This study was conducted to examine the effects of cow manure originated from the clay mineral (porphyrite, zeolite and bentonite) feeding on the growth of Zea mays GK729. CEC of the manure after bentonite, zeolite, and porphyrite feeding were 147.5, 137.0, and 114.0 cmol/Kg, respectively. These values were higher than that of non-mineral treated manure, 107.5 cmol/Kg. After 3 month growing, there was significant difference among treatment in the biomass prodcution and the content of minerals in plant tissue of Z. mays, but the physico-chemical properties of soils were not showed significant difference. For these results suggested that the clay mineral enhanced the grwoth of Z. mays according to the unknown mechanism, the further studies on the physiological changes will be needed.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.1
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• pp.22-28
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• 2011

With the increasing cultivation of acid-loving plants such as blueberries, the artificial acidification of soils is frequently required. This research was conducted to determine the application rates of elemental sulfur (S) required in the soil acidification for blueberry cultivation. Laboratory incubation experiment was conducted to acidify three arable soils (pH 6-7) of different texture to pH 4.5-5.0 by the addition of varying amounts of elemental S. All rates of elemental S addition reduced soil pH, although the efficacy of acidification was related to the application rate and soil characteristics. pH reduction was slow in sandy loam soil, and the final equilibrium pH was obtained after 60, 43, and 30 days of incubation in sandy loam, loam, and silty clay, respectively. Although the final pHs obtained after 93 days of incubation were not significantly different among the three soils, the equilibrium pH was relatively higher in soil of higher clay content in the application rates of 1.5-2.0 g S $kg^{-1}$ soil. The estimated amounts of elemental S required in lowering pH to 4.5-5.0 were 0.59-1.01, 0.67-1.03, and 0.53-0.88 g S $kg^{-1}$ for sandy loam, loam, and silty clay, respectively. The lowest estimated amount of elemental S in the acidification of silty clay soil was attributable to the low organic matter content. For clay soils containing optimum level of organic matter, the application rates of elemental S should be much higher than those values estimated in this research. Soil acidification did not significantly increase the available concentrations of Ca, Mg and K. Extractable Cu and Zn was not greatly affected by the acidification, but extractable Fe, Mn, and Al in the acidified soils were higher than those found in non-acidified soils. Such increases in solubility are attributable to the dissolution of oxides and hydroxides of the elements.

• Journal of the Korean earth science society
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• v.23 no.7
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• pp.575-586
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• 2002

Authigenic minerals found in sandstones and mudrocks of the Lower Hayang Group (Cretaceous) in the central part of the Kyungsang Basin are carbonate minerals (calcite, dolomite), clay minerals (illite, chlorite, C/S, I/S and kaolinite), albite, quartz and hematite. Characteristic diagenetic mineral assemblages are as follows: albite-chlorite (including C/S)-hematite in the Chilgog Formation, albite-illite-calcite in the Silla Conglomerate, illite-chlorite-hematite in the Haman Formation and albite-chlorite-dolomite in the Panyawol Formation, respectively. Among clay minerals reflecting the physical and chemical change of the diagenetic process, illite, the dominant clay mineral, occurs in every formation in the study area. Chlorite occurs mainly in green or gray sandstones and mudrocks, or in sandstones and mudrocks of the Chilogok Formation which contains a high content of volcanic materials. Based on the mineral assemblage, diagenetic minerals are strongly related with source rocks. Judging from the illite crystallinity, diagenesis of sandstones and mudrocks in the study area reached the late diagenetic stage or low grade metamorphisim. The diagenetic process was much influenced by intrusion of the Bulguksa granite, content of organic materials, grain size, and depositional environment rather than burial depth.

• 한국해양학회지
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• v.24 no.1
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• pp.39-51
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• 1989

A total of 139 surface sediment samples, collected from the continental shelf and slope off the southeastern coast of Korea, were analyzed in order to understand their grain-size, mineral composition and organic carbon content. Based on the grain-size characteristics, five surface sedimentary facies were distinguished: sand, clay, mud, sand-mud mixed, and sand-clay mixed facies. The sand facies appears to be composed mostly of relict sand. For mud, most of which seem to be of recent origin, two different sources were suggested, based principally on their areal distribution pattern and the local hydrographic conditions. Heavy mineral composition of the fine-sand size fraction allowed us to distinguish different sand populations from the study area. On the whole, the Hupo Bank sediments showed a high content of garnet, while the sediments from the northern part of the continental shelf were characterized by a relatively high content of metamorphic minerals (kyanite, sillimanite, andalusite, staurolite). Among clay minerals, the most abundant was illite, with chlorite, kaolinite and smectite following in decreasing order. Organic carbon contents in the sediments of the study area were generally high and showed an average value of 1.94%. The sediment grain-size exerted a strong influence on the organic carbon content. The highest organic carbon content, on the other hand, was found in the continental slope sediments.

• Applied Microscopy
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• v.52
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• pp.12.1-12.8
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• 2022

The microstructure of diatom frustules found in mud sediments along the coast of Boryeong- city, South Korea, was observed using a scanning electron microscopy (SEM), and the constituent elements of diatoms were analyzed using energy-dispersive X-ray spectroscopy (EDS). Diatom frustules and clay minerals were present in the SEM images of the mud powder. High-magnification SEM images revealed that the surface of the frustules contained identically shaped circular pores, measuring 1 ㎛ in diameter, arranged at regular intervals. This study revealed that the diatom shell fragments in the mud powder ranged in size from 3 to 30 ㎛, with an average thickness of approximately 2.5 ㎛. The elements Si, Al, Fe, K, Na, Mg, and Ti were detected while analyzing the frustule constituents, with Si being the primary component with the highest content.

• Journal of the Korean Geotechnical Society
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• v.31 no.12
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• pp.17-27
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• 2015

In this study, we tried to precipitate calcium carbonate with carbonate ions decomposed from urea by plant extract and calcium ions dissolved in water. The clay particles carry a net negative charge on their surfaces. Such clay mineral was additionally mixed as a medium to improve soil strength and durability with environmentally-friendly way. The $1^{st}$ solution (plant extracts and urea) and the $2^{nd}$ solution (calcium chloride and clay) were mixed together with clean Nakdong River sand. Then, this mixed soil was compacted into a small cylindrical specimen and then air cured for 7 days in laboratory. The molar concentration of urea and calcium chloride was tested for three different conditions, 1, 5, and 7 mol. Three different clay contents (0, 1, and 3% per total weight) were mixed with sand. For each specimen, a series of unconfined compression test, a durability test, SEM, EDX and XRD analyses were carried out to evaluate its cementation and structure. As the molar concentration of the solution and clay content increased, the unconfined compressive strength and durability increased. The results of SEM, EDX and XRD analyses showed that calcite was precipitated around clay mineral. The thermogravimetry analysis indicated that calcium carbonate precipitated about 1~2% per total weight of the sample.

• Journal of the Korean Ceramic Society
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• v.44 no.9
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• pp.483-488
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• 2007

The influence of $P_2O_5$ on clinker mineral composition and the cement quality was investigated. When the sewage sludge was used as a raw material in place of clay, the presence of $P_2O_5$ in sewage sludge affects the mineral composition and the clinker quality. As the $P_2O_5$ concentration in raw mix increases, the burnability of clinker becomes worse and the alite decomposes into belite and free-CaO, so belite increases with the decrease of alite. The early strength of mortar decreases with the increase of $P_2O_5$ concentration. On the other hand, later-age strength increases with the increase of belite content. The setting time of cement was delayed with the $P_2O_5$ concentration above 0.6 wt%.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.6
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• pp.399-407
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• 2008

Importance of climate change and its impact on agriculture and environment has increased with a rise of greenhouse gases (GHGs) concentration in Earth's atmosphere, which had caused an increase of temperature in Earth. Greenhouse gas emissions such as methane($CH_4$) and nitrous oxide($N_2O$) in the field need to be assessed. GHGs fluxes using chamber systems in the fields(2004~2005) with pepper cultivation were monitored at the experimental plots of National Academy of Agricultural Science(NAAS), Rural Development Administration(RDA) located in Suwon city. $N_2O$ emission during pepper growing period was reduced to 74.0~82.1% in sandy loam soil compared with those in clay loam soil. Evaluating $N_2O$ emission at different levels of soil water conditions, $N_2O$ emission at -50 kPa were lowered to 13.2% in clay loam soil and 40.2% in sandy loam soil compared with those at -30 kPa. $CH_4$ emission was reduced to 45.7~61.6% in sandy loam soil compared with those in clay loam soil. Evaluating $CH_4$ at different levels of soil water conditions, $CH_4$ emission at -50 kPa was lowered to 69.6% in clay loam soil and 55.8% in sandy loam soil compared with those at -30 kPa. It implied that -50 kPa of soil water potential was effective for saving water and reducing GHG emissions. From the path analysis as to contribution factors for $N_2O$ emission, it appeared that contribution rate was in the order of mineral N(51.2%), soil temperature (25.8%), and soil moisture content(23.0%) in clay loam soil and soil moisture content(39.3%), soil temperature (36.4%), and mineral N(24.3%) in sandy loam soil.

• Journal of the Korean Geosynthetics Society
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• v.9 no.1
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• pp.1-11
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• 2010

The soil mechanical characteristics according to geologic conditions were investigated in the study area. The geology of study area was consisted of Ingok Tuff, Yuchi Conglomerate and Dado Tuff. Yuchi Tuff covered about 80% of the study area. The disturbed and undisturbed soils were sampled from the conglomerate area, Tuff area and Shale area, and then a series of the laboratory soil tests was performed. The soils sampled from the conglomerate area have a large dry unit weight and a low permeability relatively, while the soils sampled from tuff and shale areas have a small dry unit weight and a high permeability. It is proven that the soil permeability is highly affected by the effective grain size and the silt and clay content. That is, the soil permeability is increased with increasing the effective grain size, and the soil permeability is decreased with increasing the silt and clay content.