• Explosives and Blasting
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• v.23 no.1
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• pp.9-17
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• 2005

This study is to clarify the comparative relationship and mechanical anisotropy of granite distributed in the Nam-weon on the subject of weathered rock mass sea water surroundings. Artificial weathering test is defined as a test, which controls the weathering rate and agents by controlling the weathering rate and agents by artificial environmental of salt water. Increased weathering degree is large indicated by weathering salt water, such as apparent specific gravity, absorption, porosity, uniaxial compression strength, P-wave velocity, slake durability, shore hardness, indirect tensile strength(brazilian test) and cohesion were measured. As the Weathering salt water proceeds, cracks develope increasingly. A number the cracks affect the rock deformation. Therefore, stress-strain curve of weathered salt water rock in one confined state are quite differ from weathered fresh water rock those. A reason of their deformation type is the formation of micro-cracks and potential porosity caused by artificial weathering test.

• Tunnel and Underground Space
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• v.13 no.3
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• pp.215-224
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• 2003

Weathering in nature was simulated by freeze-thaw cyclic test which represents mechanical weathering. Measured physical properties were elastic wave velocities, absorption rate, volume change and weight change. Uniaxial compression tests were also conducted before and after the weathering tests. The change in weight and volume of the specimens were not clearly related to the weathering process, but P, S wave velocities, uniaxial compression strength and Young's modulus were clearly decreased as weathering progresses. Test result can be used for the assessment of long-term stability of rock slopes.

• Corrosion Science and Technology
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• v.7 no.2
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• pp.119-124
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• 2008

Steel is generally not corrosion resistant to water with formation of non protective rusts on its surface. Rusts are composed of iron oxides such as $Fe_3O_4$, $\alpha-$, $\beta-$, $\gamma-$and ${\delta}-FeOOH$. However, steel, particularly weathering steel containing small amounts of Cu, Ni and Cr etc., shows good corrosion resistance against rural, industrial or marine environment. Its corrosion rate is exceedingly small as compared with that of carbon steel. According to the exposure test results undertaken in outdoor environments, the atmospheric corrosion rate for weathering steel is only 1 mm for a century. Atmospheric corrosion for steels proceeds under alternate dry and wet conditions. Dry condition is encountered on steel surface on fine or cloudy days, and wet condition is on rainy or snowy days. The reason why weathering steel shows superior atmospheric corrosion resistance is due to formation of corrosion protective rusts on its surface under very thin water layer. The protective rusts are usually composed of two layer rusts; the upper layer is ${\gamma}-FeOOH$ termed as lepidocrocite, and inner layer is nano-particle ${\alpha}-FeOOH$ termed as goethite. This paper is aimed at elucidating the atmospheric corrosion mechanism for steel in comparison with corrosion in bulky water environment by use of empirical data.The summary is as follows: 1. No corrosion protective rusts are formed on steel in bulky water. 2. Atmospheric corrosion for steel is the corrosion under wetting and drying conditions. Corrosion and passivation occur alternately on steel surface. Steel, particularly weathering steel with small amounts of alloying elements such as Cu, Ni and Cr etc. enhances forming corrosion protective rusts by passivation.

• Journal of the Korean earth science society
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• v.36 no.6
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• pp.543-552
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• 2015

This study examines the processes of rock weathering and tafoni formation targeting tafoni at Mt. Cheonsaeng, Gumi-si, Gyeongsangbuk-do. In the study area, a frequency of tafoni is high in conglomerate and conglomeratic sandstone among regional sedimentary rocks, which means that an initial stage of the formation begins a breakaway of gravel from bedrock and also exfoliation from rock surface. Geomorphologically tafoni have intensively been developed at the southfacing slope with exposed rocks, which means that its formation was favorably controlled by environmental conditions including strong influences of mechanical weathering in winter and chemical weathering in summer times. The results of measuring water content at a tafoni-bearing rock surface using GIS interpolation analysis indicate that moisture rate in/around tafoni is higher than the periphery. Thus, it is considered that moisture distribution at a rock surface plays a role in its formation. Analysis of percipitation and secondary minerals induced by chemical weathering is in progress.

• Journal of the Korean Geographical Society
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• v.46 no.2
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• pp.134-151
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• 2011

The types of gnamma at the summit area of Mt. Geum, Sangju-ri, Namhae-gun, Gyeongsangnam-do are classified and geomorphic developments are investigated. The rocks facing the coast show high distributional density of gnamma due to the salt supply from the coast. The water content rate of gnamma distributed in flat rocks at the summit is highest in the bottom area and lowest in the outside area. Moreover, the quartz grains are fallen due to the weathering of feldspar in the crystalline rocks such as granites and the gnamma are merged and expanded as they develop. The average weathering rate of gnamma is 0.04mm/y and it slowed with time. The results on rate indicate that the gnamma are formed and developed at the present rather than the fossil landform or by subsurface weathering.

• 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 Korean GEO-environmental Society
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• v.18 no.8
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• pp.23-32
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• 2017

For exposed slopes, the weathering degree over time has a major effect on the engineering properties of rocks and the slope stability. Rocks are gradually changed by weathering into soil over time, and the resulting physical, chemical and mechanical changes of rocks affect the engineering stability of the slope. However, there are not many ways to objectively evaluate the weathering degree of a slope. In this study, therefore, to investigate the weathering characteristics of rocks, granite, gneiss and shale distributed in the Chungbuk region were sampled by weathering stage and changes in their component minerals and tissues were investigated. Furthermore, artificial weathering was induced using the freezing and thawing test and quantitatively investigated through porosity and absorption rate. In addition, the changes of microcracks due to artificial weathering were evaluated through box fractal dimension ($D_B$). Through mineralogical study the phase change of constituting minerals, the growth of secondary minerals, the development of micro-cracks and the fabric changes due to weathering were observed. The mineralogical, chemical and engineering evaluations of the weathering degree through the experimental results in this study are expected to be useful for analyzing the weathering characteristics and causes by rock type and for proposing a methodology to evaluate the degradation of physical properties comparatively and quantitatively.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.2
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• pp.232-237
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• 2010

Fault rate of RCD is increasing due to deterioration and long period usage in domestic. According to Korean standards, the RCDs are installed in panel boards. When RCDs are installed at outdoor, the RCDs must be protected from uv, water etc. by using the housing. However, many RCDs are exposed to the external environment. As a results, many RCDs have malfunctions so that cause the electrical accidents. The RCDs manufactured by four makes were used as the sample to weathering test. Futhermore, those were analyzed the ingredients of RCD'S using SEM, EDX and FT-IR/TAR before and after weathering test.

• Tunnel and Underground Space
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• v.21 no.2
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• pp.145-150
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• 2011

Variations of physical properties such as weight loss rate, wave velocity and uniaxial compressive strength after performing freeze-thaw cyclic test were measured in order to define weathering characteristics of sandstone and andesite. Weight change in specimens of the two rocks decreased with increasing the repetition number of freeze-thaw cyclic test. In particular, weight loss of andesite specimens was very irregular. P-wave velocity of sandstone specimens decreased more than 5%. On the other hand, P-wave velocity of andesite specimens do not vary up to 500 cycles and decreased more than 5% after 1000 cycles. This implies that the sandstone are easily weakened and loosened by weathering processes, while the andesite are relatively strong. In addition, the wave velocity changes of the andesite specimens coincident with the weight change. Uniaxial compressive strengths of the sandstone specimens slightly decreased at the early stage of the freezing-thawing cyclic test, then tended to be irregular after 64 cycles. In conclusion, the rock specimens showed smaller weight loss, less had lower strength reduction rate.

• Economic and Environmental Geology
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• v.26 no.1
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• pp.67-81
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• 1993

This dissertation is a basic research on the degradation of rocks and aims at clarifying the relations between the progression of degree of weathering and the variation of chemical composition. The author wants to make clear the degradation of rocks and the process of formation of sedimentary rocks from a standpoint of elucidation of migration of elements. This study is considered to be significant not only as a part of research on the distribution of earth crust materials but as the petrogenesis of rocks. The chemical studies on the weathered rocks have been started relatively early and there are not a few researches on them: Goldich, 1938; Harris, et al., 1966; Ruxton, 1968; Berner, et al., 1982; Kanuss, 1983; Lasaga, 1984; Siagel, 1984. The degree of migration of elements in weathering is the composite result of various factors. Because, at the present time, it is difficult to clarify the individual and composite effects of each factor theoretically and quanititatively, we must accumulate empirical data and use them relatively. In such consideration the author acquired some data of chemical weathering from the chemical analysis of granitic and basaltic rocks in and around Fukuoka city, Japan and granitic rocks in and around Chonju and Iri cities, Korea. Because both rock types studied can be considered as representative materials of acidic and basic rocks compsing the earth crust, it is significant to examine the phenomena of weathering of both rock types. The following results are obtained from the analysis and examinations of chemical compositions of the original and weathered rocks. The loss rate of major elements has no uniformity, but the following relation holds in general; Ca, Na> K, Si> Mg> Fe, Al. As weathering proceeds, the ratio of $Al_2O_3/CaO$ shows increasing phenomena, and that of $Na_2O/CaO$ decreasing. The range of migration of composition is broad in basaltic rocks but narrow in granitic rocks. The reason is that the chemical weathering of basaltic rocks progresses more easily than that of granitic rocks. The chemical weathering potenitial index of basaltic rocks in larger than that of granitic rocks. The reason is that the chemical weathering of basaltic rocks proceeds more easily than that of granitic rocks. In weathering, the decrease of mobile cations such as $Ca^{2+}$, $Na^{2+}$, $Mg^{2+}$ and the increase of $H_2O$ in basaltic rocks are more obvious than in granitic rocks.