• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.655-662
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• 2003

Slope stability is an important issue ill civil engineering works or in open pit mines where both economy and efficiency is required. These are the long-term stability problems which depend on the change of physical properties under a certain weather condition. These can also result in progress of weathering which can change mechanical or hydro-geological properties of rock mass considerably. In this study, weathering in nature was simulated by freeze-thaw test and Soxhlet test which represent mechanical and chemical weathering respectively. Measured were elastic wave velocities, absorption rate, volume change. Uniaxial compression strengths before and after the weathering tests were also measured. The change in weight and volume of the specimens were not clearly related to the weathering process, but P, S wave velocities were clearly decreased as weathering progresses. For some class of rocks, P-wave velocity was increased probably because of the saturation due to improved connectivity of the pre-existing pores. Based on the test results, stability of the slopes were analyzed using FLAC$\^$2D/. Due to the reduced strength parameters, the factors of safety were decreased for the selected sites.

• Journal of The Geomorphological Association of Korea
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• v.18 no.3
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• pp.21-36
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• 2011

Rock Weathering is a basic of geomorphological evolution as a preparation of materials. Of those, frost shattering has traditionally been considered as the operative process causing rock breakdown in cold regions as well as temperate zone. Each Granite(fresh rock, semi-weathered), Gneiss, Limestone, Dolomite was prepared slab specimens in ten, repeated freeze-thaw cycles of 180 under the -25℃~+30℃, and the changes was observed in physical properties and weathering aspect. Rock shattering was more active in waterlogging conditions rather than atmospheric and soil conditions. Limestone and Dolomite that high porosity are most severely crushed. Gneiss, regardless surface of the crack, joint, fissure and has a lowest rock strength(SHV), was even though no physical changes and their weathering product do not generate, has a very high resistance to weathering.

• Journal of the Korean institute of surface engineering
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• v.47 no.2
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• pp.57-62
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• 2014

The biogas holder is composed of an outer membrane and an inner membrane which are subject to outdoor exposure and gas exposure respectively. The influence of weathering conditions on the photo-degradation of a biogas holder was investigated. Tests were performed under three different methods - outdoor exposure tests (Seosan, Arizona), accelerated tests (Xenon-are lamp) with the outer-membrane of biogas. Moreover, the changes in the aging process were monitored using color difference, gloss, the contact angle and an optical microscope. Changes in physical properties, such as decrease reduction in gloss, decrease in the contact angle, increase in color difference were observed in the aging process. The comparison between membrane 3B, 4B and membrane 5B under xenon-arc were discussed. Membrane 5B was very sensitive to ultraviolet (UV) ray. There were many difficulties in the outdoor exposure test due to acid rain, dust, and stain resistance.

• Economic and Environmental Geology
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• v.22 no.1
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• pp.65-80
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• 1989

Strongly weathered granitic rocks are widely distributed in the south-eastern part of the Ganghwa island. Kaolinite developed during intense weathering on this granitic rocks have been studied mineralogically and chemically. Various weathering indexes were ca1culated on the basis of oxide. Those indexes are slightly varied with depth. It shows that the percentages of $Al_2O_3$ increase but that of $CaO+Na_2O+K_2O$ decrease as the weathering progress. These results indicate that day minerals, mainly kaolinite with the appreciable amount of halloysite, were formed by the weathering of feldspars in the granitic rocks. X-ray diffraction, differential thermal analysis, infrared spectrometry and electron microscopy were used to characterize and estimate crystallinity of the kaolinite. Generally, Kaolinite shows a less sharp basal reflection and relatively low dehydroxylation temperature, indicating disordered kaolinite. They usually occur aggregates as a vermicular kaolinites showing loose basal plane stacking arrangement.

• Journal of the Korean GEO-environmental Society
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• v.3 no.2
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• pp.49-60
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• 2002

A study on mineral composition and chemical component governing of weathering process is necessary to know the weathering characteristics of sedimentary rocks. In this study, a mineral and chemical component analysis, and physical and engineering characteristic tests were conducted to find out the characteristics of sedimentary rocks in Daegu, according to the weathering degree of sedimentary rock. Test results show that the mineral composition of rock, such as Albite (Ab), Muscovite (Ms), Magenetite (Mt) and the chemical composition of $A_2O_3$, CaO, $Na_2O$, $K_2O$, MgO and so on are closely related to the weathering. Based on the test results, we illustrated the quantitative application of weathering decision for the sedimentary rocks.

• 보존과학연구
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• s.29
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• pp.199-220
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• 2008

Hobun(Oyster shell White) is a traditional material used as extender and white pigment from ancient times. The production method of it, however, has been discontinued. We have studied the traditional production method of Hobun by weathering oyster shell, which is one of the traditional ways for preparing Hobun. Reproduction study of manufacturing method of the discontinued traditional material is an important accomplishment of our research. Also this study provides solid background knowledge to stabilize the production and supply of Hobun for the cultural asset repairing materials. The result can be summarized as follows: The production process of Hobun by weathering method takes 5 steps - (1) weathering shells ${\rightarrow}$ (2) washing ${\rightarrow}$ (3) pulverization ${\rightarrow}$ (4) separating fine powder by submerging in water ${\rightarrow}$ (5) drying. The major aim in step (1) is to eliminate organic impurities. In the step (4), the fine particles smaller than $25{\mu}m$ are separated by extracting the supernatant from stirred suspension after heavy particles are submerged. Also, the soluble inorganic impurities can be eliminated through the powder submerge in 15 times water and stirring the suspension 6 hours and changing the water 3~4 times. The final products have high quality with 94.03, 0.52, 2.05 for L, a, b, less than $25{\mu}m$ particle size, fine resistance for discoloration by light and environmental pollution and good workability.

• Economic and Environmental Geology
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• v.26 no.1
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• pp.29-40
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• 1993

Several vermiculite deposits occur as the alteration product from phlogopite in ultramafic rock, in the Hongseong and Cheongyang area, South Korea. Some quarries show well-defined weathering profile. Samples collected from those quarries were examined by XRD and chemistry to define a vertical variations in mineralogy and chemistry of the weathering profile developed on ultramafic rocks. The analysis by X-ray diffractometry showed that mineral compositions changed continuously as depth of profile increasing, the vermiculite-the phlogopite/vermiculite interstratified-the phlogopite. Chemical analysis of bulk samples in altered zone revealed that regardless of composition and kinds of mineral in the rock, there are significant increase of MgO, CaO and $H_2O$, and decrease of K as depth of profile decrease reflecting the characteristics in vermiculitization. Also, there was a tendency that weathering indicies of each sample horizon change gradually with increasing depth. This tendency can be explained as variations of degree of vermiculitization. The regular changes of mineralogical and chemical composition in vertical profile suggest that weathering is the most important process in vermiculitization in this area.

• Corrosion Science and Technology
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• v.23 no.1
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• pp.11-19
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• 2024

A Fe-Ni Bainitic steel as a weathering steel application was developed by combining its excellent mechanical properties and corrosion resistance in maritime environments. Nickel concentration (0.4-3 wt%) and inverted austempering multi-step (IAM) process were primary determinants of the microstructure of the Fe-Ni Bainitic steel. The initial austempering steel was performed at 300 ℃ for 600 seconds to obtain a partly bainitic transformation. The steel was heated again for 1800 s at 450 ℃. The microstructure was comprised of ferrite, a blocky martensite/austenite island, and a homogeneous lath-shape bainite structure with widths ranging from 4.67 to 6.89 ㎛. The maximum strength, 1480 MPa, was obtained with 3 wt% nickel. In this study, corrosion behavior was investigated utilizing potentiodynamic and electrochemical impedance spectroscopy (EIS) tests. A higher nickel content in Fe-Ni Bainitic steel refined the grain size, improved the bainite fraction, lowered the corrosion rate to 0.0257 mmpy, and increased the charge transfer of film resistance to 1369 Ω.

• The Journal of Engineering Geology
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• v.14 no.4 s.41
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• pp.381-390
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• 2004

This study was performed to relate the weathering properties of Oyaish tuff from Japan to mechanical properties of rocks in terms of mineralogical alteration and chemistry. The tuff is composed of clinoptilolite, quartz, feldspars, mordenite, opal C-T, and smectite. Since fresh tuff contains approximately $30\~50\%$ zeolite, it is expected that the rock is subjected to weathering process ascribed to water contents on earth surface, significantly reducing mechanical strength of tuff. It is also anticipated that weathering process and properties may be different even in the same rock mass, due to the differences in local mineralogy, chemistry and microtextures in tuff.

• Tunnel and Underground Space
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• v.19 no.3
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• pp.213-225
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• 2009

The purpose of the study is to evaluate the effects of chemical weathering on the granite and orthogneiss in Wonju area based on accelerated artificial chemical weathering. The rock samples were scrutinized the variation of index properties and ion exchanges caused by artificial chemical weathering which was implemented with leaching test for 170 days using double soxhlet extractor. The differential weathering and decrease of p wave velocity were obtained by weathering process without significant changes of porosity. In case of granite samples, the uniaxial compression strength was reduced by 20% and 16% for the F-grade and SW-grade, respectively. For MW-grade granite, however, was not able to examine the effect of strength reduction due to lack of sample number. Also, for orthogneiss, it is difficult to compare the values of uniaxial compressive strength between before and after the test because of its strong anisotropy.