• 산업기술연구
• /
• 제20권A호
• /
• pp.239-245
• /
• 2000

Sintered $Al_2TiO_5$ has a very low thermal expansion and an infrared radiative selectively emitting large amounts of far infrared rays. However, it is week in mechanical strength. Spectral infrared emittance, thermal expansion coefficient, and mechanical strength of $Al_2TiO_5$-clay composites were studied to develop a material for far infrared radiators. The composites containing 10~50 mass% Jungsan clay had high emittance in the range of 2,000~500cm-1. The bending strength of the $Al_2TiO_5$-clay composites increased with increasing clay content. The $Al_2TiO_5$-clay composites with a clay content of 50mass% and heat-treated at $1,200^{\circ}C$ had a large strength for infrared radiators ; 86MPa. The average linear thermal expansion coefficient from $200{\sim}1,000^{\circ}C$ of the 50mass% jungsan clay containing compo sited heat-treated at $1,200^{\circ}C$ was lower than $3.87{\times}10-6/^{\circ}C$.

• Macromolecular Research
• /
• 제15권1호
• /
• pp.51-58
• /
• 2007

The approach studied in the present work produced an exfoliated state of clay layers via confinement of the charged nano-sized polystyrene (PS) beads within the gallery of swollen pristine clay. It was demonstrated that adsorption of the polymer nanobeads dramatically promotes expansion of the clay gallery. A comparative study of incorporation was conducted by employing organo-modified clay along with two different colloid polymer systems: electrostatically stabilized PS nanobeads and cationic monomer-grafted PS nanobeads. The mechanism of adsorption of the monomer-grafted polymer beads onto clay via cationic exchange between the alkyl ammonium group of the polymer nanobeads and the interlayer sodium cation of the layered silicate was verified by using several techniques. As distinct from the polymer nanobeads formed using conventional miniemulsion polymerization method, competitive adsorption of stabilizing surfactant molecules was be prevented by grafting the surface functional groups into the polymer chain, thereby supporting the observed effective adsorption of the polymer beads. The presence of surface functional groups that support the establishment of strong polymer-clay interactions was suggested to improve the compatibility of the clay with the polymer matrix and eventually play a crucial role in the performance of the final nanocomposites.

• 한국해양공학회지
• /
• 제25권6호
• /
• pp.110-115
• /
• 2011

Numerouslong-term consolidation and secondary compression settlements may occur in Busan clay, which is astructured soft clay and consists of a thick clay deposit. As a surcharge load is applied to soils, soils experience different stress paths with depth. Therefore, it is necessary to study the long-term consolidation behavior of Busan clay considering stress conditions such as OC or NC states. In this study, a series of long-term consolidation tests were performed to investigate the consolidation characteristics of Busan clay for 20 days. The undisturbed clay samples were taken from 3 sites located in the Nakdong River estuary. The results showed that the creep rate of the Busan clay gradually decreased with time, which indicated that the secondary compression settlement decreased with time. In addition, the experimental results for 3 samples showed that the ratios were about 0.0363 and 0.051, respectively.

• Geomechanics and Engineering
• /
• 제15권2호
• /
• pp.729-738
• /
• 2018

Soft clay soils due to their various geotechnical problems, stabilized with different additives. Traditional additives such as cement and lime will not able to increase the soil strength properties significantly. So, it seems necessary to use new additives for increasing strength parameters of soft clay soils significantly. Among the new additives, epoxy resins have excellent physical and mechanical properties, low shrinkage, excellent resistance to chemicals and corrosive materials, etc. So, in this research, epoxy resin used for stabilization of soft clay soils. For comprehensive study, three clay soil samples with different PI and various clay mineral types were studied. A series of uniaxial tests, SEM and XRD analysis conducted on the samples. The results show that using epoxy resin increases the strength parameters such as UCS, elastic modulus and material toughness about 100 to 500 times which the increase was dependent on the type of clay minerals type in the soil. Also, In addition to water conservation, the best efficiency in the weakest and most sensitive soils is the prominent results of stabilization by epoxy resin which can be used in different climatic zones, especially in hot and dry and equatorial climate which will be faced with water scarcity.

• 한국조경학회지
• /
• 제27권3호
• /
• pp.109-113
• /
• 1999

The objective of this research was to develop growth media for artificial ground by blending calcined clay and coconut peat. To achieve this, aggregates of clay particles were mixed with disel oil and heated to high temperature(1150~120$0^{\circ}C$) to expand clays. The particle sizes of expanded clay were controlled to 2~5mm in diameter. Then expanded clayes were mixed with coconut peat and changes of soil physicochemical properties and their effect on plant growth of Hedera L. were determined. The infiltration rate of calcined clay was very high, but the water holding capacity, the cation exchange capacity(CEC), and the nutrient contents were low. The characteritics of coconut peat was vice verse to calcined clay. This indicates that the mixture of calcined clay and coconut peat have the better characteristics than each material. As compared to mineral soil, the infiltration rate, the water holding capacity, the CEC and the nutrient contents increased, but bulk density decreased to about 1/4. And, Hedera L. grown in the mixture of calcined clay and coconut peat(6:4, v/v) had higher plant height, longer leaf length, more total number of leaves per plant and fresh weight than that grown in mineral soil, but statistical differences were not observed between two treatments.

• 농업과학연구
• /
• 제44권2호
• /
• pp.181-187
• /
• 2017

The use of practical management factors to maximize pig health improvement cannot guarantee freedom from diseases. Moreover, because of health safety concerns, the use of antibiotics has been restricted in livestock, including pigs. Therefore, the swine industry has been looking for various alternatives to antibiotics to improve pig's health and performance. Clay is a dietary factor generally accepted for improving pig health. It is a naturally occurring material and is primarily composed of fine-grained minerals. It has a specific structure with polar attraction. Because of this structure, clay has the ability to lose or gain water reversibly. In addition, clay has beneficial physiological activities. First, clay has anti-diarrheic and antibacterial effects by penetrating the cell wall of bacteria or inhibiting their metabolism. Second, it can protect the intestinal tract by absorbing toxins, bacteria, or even viruses. When added to the diet, clay has also been known to bind some mycotoxins, which are toxic secondary metabolites produced by fungi, namely in cereal grains. Those beneficial effects of clay can improve pigs' health and performance by reducing pathogenic bacteria, especially pathogenic Escherichia coli, in the intestinal tract. Therefore, it is suggested that clay has a remarkable potential as an antibiotics alternative.

• Nuclear Engineering and Technology
• /
• 제48권5호
• /
• pp.1230-1236
• /
• 2016

This study aims to determine the effect of fly ash with a high replacing ratio of clay on the radiation shielding properties of bricks. Some interaction parameters (mass attenuation coefficients, half value layer, effective atomic number, effective electron density, and absorption efficiency) of clay fly ash bricks were measured with a NaI(Tl) detector at 661.6 keV, 1,173.2 keV, and 1,332.5 keV. For the investigation of their shielding behavior, fly ash bricks were molded using an admixture to clay. A narrow beam transmission geometry condition was used for the measurements. The measured values of these parameters were found in good agreement with the theoretical calculations. The elemental compositions of the clay fly ash bricks were analyzed by using an energy dispersive X-ray fluorescence spectrometer. At selected energies the values of the effective atomic numbers and effective electron densities showed a very modest variation with the composition of the fly ash. This seems to be due to the similarity of their elemental compositions. The obtained results were also compared with concrete, in order to study the effect of fly ash content on the radiation shielding properties of clay fly ash bricks. The clay fly ash bricks showed good shielding properties for moderate energy gamma rays. Therefore, these bricks are feasible and eco-friendly compared with traditional clay bricks used for construction.

• 광물과산업
• /
• 제29권
• /
• pp.56-66
• /
• 2016

열수변질대가 폭넓게 분포하고 있는 우리나라에서 자연사면이나 인공사면에서 열수변질대 내에 산출되는 점토맥이 산사태 발생에 중요한 역할을 할 수 있다. 점토맥이 존재하는 지반에 지표수가 침투되면 점토광물의 팽윤성 때문에 국지적으로 간극수압이 급격히 상승할 수 있다. 간극수압의 상승으로 세립의 점토광물이 침식될 수 있다. 침식된 점토광물은 수두가 큰 곳에서 작은 곳으로 유동하면서 동수경사가 작은 부분에서 유속이 느려져 퇴적된다. 점토광물이 퇴적된 곳에서 국지적인 간극수압의 증가로 인한 지하수의 유출이 사면파괴를 일으킬 수 있다. 이에 본고에서는 열수변질 점토맥과 산사태와 관련한 국내외 자료를 소개하고자 한다.

• 대한건축학회논문집:구조계
• /
• 제35권10호
• /
• pp.199-206
• /
• 2019

This study aims to recycle redmud which is a byproduct in the alumina industry. Redmud ceramics were prepared according to the type of raw materials by blending redmud with the raw materials used in the conventional clay bricks. In this paper, the compressive strength, water absorption ratio, and shrinkage of redmud ceramics prepared by mixing clay bricks were evaluated. Compressive strength and absorption ratio of redmud ceramics were compared with the clay brick criteria of KS L 4201. At the firing temperature of $1200^{\circ}C$, the specimens containing redmud only and the redmud with sandy loam and black clay were found to satisfy the 1st class of clay brick. The quality standard of compressive strength and absorption ratio was obtained by firing redmud with black clay and sandy loam at $1200^{\circ}C$. Also, when the redmud was mixed with black clay and feldspar, the 2nd class was satisfied when the sample was fired at $1100^{\circ}C$.

• 한국작물학회지
• /
• 제53권3호
• /
• pp.292-296
• /
• 2008

Clay-coated rice seeds (clay-coated seeds A and B) were directly sown on dry paddy and their growth and yield were compared with the normal drill-sown seeds on dry flat paddy. In clay-coated seeds, germination was 1 day earlier and the emergence rate was higher up to 5% than that of normal drill-sown seeds. But the apparent number of seedling stand per $m^2$ was lower than that of normal drill-sown seeds, which is due to the smaller amount of seeding in clay-coated seeds. At the early growth stage, the plant height of clay-coated seeds A was taller than that of drill-sown seeds, while the plant height of clay-coated seeds B was 0.7 cm shorter than that of drill-sown seeds. At the late growth stage, however, the difference was insignificant in both cases. The maximum tillering stage was 10 days earlier in drill-sown seeds. Lodging index was the lowest in clay-coated seeds B and there was no difference between clay-coated seeds A and drill-sown seeds. The ratio of stem base weight, culm diameter and culm wall thickness were higher in clay-coated seeds, while the lower internodes (4th, 5th and 6th) length was shorter in claycoated seeds than in drill-sown seeds. In clay-coated seeds, the number of panicle per $m^2$ was smaller, while the number of spikelet per panicle was a little larger than in drill-sown seeds. The rate of ripened grain and brown rice 1,000 grain weight were lower in the clay-coated seeds, thus the yield was $98{\sim}99%$ level of drill-sown seeds. Considering that the amount of seeding in clay-coated seeds was two-thirds of that in drill-sown seeds, it is expected that clay coating method could become an additional technique for direct seeding cultivation.