• The Journal of the Petrological Society of Korea
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• v.12 no.4
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• pp.196-206
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• 2003

The geochemical and mineralogical investigation on the rocks and repair material comprising of the Sungryemun (The 1st National Treasure) has been made. Rock of the Sungryemun is highly weathered coarse-grained calc-alkali granite. The rock consists mainly of quartz, perthite, plagioclase and biotite with small amounts of orthoclase, muscovite, chlorite and sericite, which are major weathering products from perthite. For obtaining informations about degree of weathering, mineral composition of the original rock calculated by CIPW norm and weathered rock composition determined by XRD quantitative analysis were plotted on a ternary diagram of quartz-potash feldspar-plagioclase. Original rock compositions are plotted on the central granite area. whereas weathered ones are plotted on the granite area close to quartz. The result means that quartz is more abundant in weathered rock, due to selective chemical weathering of potash feldspar and plagioclase over quartz. On the whole, surface of the rocks were black-coated, exfoliated and highly fractured due to the physical and chemical weathering and heavy load has made the cracks in the lower parts of the stone construction. Also, cement and nails, which was used as repair material, during the repair work in the early 1960's, has accelerated the weathering process. Furthermore, weathered conditions of repair materials are very severe. Therefore, it is very urgent to establish of the conservation plan for the Sungryemun.

• Magazine of the Korean Society of Agricultural Engineers
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• v.45 no.1
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• pp.83-90
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• 2003

In order to offer some fundamental data for recycling the excavated rocks, the component and mechanical characteristics was investigated for the excavated rocks, by means of X-ray diffraction analysis, strength test, slacking test and abrasion test were performed. It appeared that the unconfined compressive strength and the elastic wave velocity were the highest in the sound rock. The dissipation rate by stability tests was found to be high in the case of the slacking index of 98% because of more bedding and more clay minerals. The apparent specific gravity of some crushed aggregate was decreased because they included easily weathered minerals while both the absorption and the abrasion were increased. The results in this study were expected to be useful for recycling the excavated rocks as a concrete aggregate.

• 보존과학연구
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• s.13
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• pp.14-36
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• 1992

The investigation has been made on the rocks consisting the pagoda(12), Buddhist Statues(9) Buldaejwa and cakra(2, rewpectively), stele(5), and Flagpole wupport and stupa(6) which are stood in Weonju city, Weonju-gun, Hwoengseong-gun and Hongcheon-gun, Kangweondo. These rock-monuments range mostly in age from late Shilla Kingdom to middle Korye Kingdom. The geology around this region is mainly composed of Precambrian metamorphic rocks and mesozoic granitic rocks. The granitic rocks are largely divided into Jurassic and cretaceous ones which are slightly different in rock phase. The main rock phase consisting the monumentsare are coarse biotite granite with minor amount of hornblende in Jurassic age. Variation in rock phase is abserved even in part of the stone used in the monuments. Inclusions composed of biotite and hornblende, porphyritic texture with microcline phenocryst, igneous lineation and exfoliation according to weathering are observable in all rocks in these monuments. In the case of stele whose a body and a capstone is remained, one is composed of black slate and the other white limestone. But the turtle shaped pedestal is constituted of coarse biotite granite. These stone-monuments are strongly weathered and exfoliated out about 1∼2mm.In case of exfoliated weathering along igneous lineation, some are taken off about 3∼5mm thick. In some monuments, the degree of weathering is somewhat different according to position, grade of sculpture, and biological activity.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.4
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• pp.1499-1508
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• 2013

Freeze-thaw tests were performed on gneiss samples collected from Terra Nova Bay, Antarctica in order to examine the engineering properties of rocks with slightly weathered (SW) and moderately weathered (MW). The tests were conducted under temperature ranging from $20{\pm}2^{\circ}C$ to $-20{\pm}2^{\circ}C$. A cycle of test consisted of 5 hours of freezing followed by another 5 hours of thawing under full saturation. In this paper, total 200 cycles of freeze-thaw test were performed with measurements of porosity, absorption, ultrasonic velocity, and shore hardness per each 20 cycle and that of uniaxial compressive strength (UCS) per each 50 cycle. The UCS of the SW rocks approximately decreased 0.07 MPa per a single cycle, while that of MW rocks decreased around 0.2 MPa per a single cycle. During the 200 cycles of SW rocks, the absorption increased from 0.23% to 0.39%, the P-wave velocity decreased from 4,054 m/s to 3,227 m/s and S-wave velocity decreased from 2,519 m/s to 2,079 m/s. Similarly, those of MW rocks changed from 0.65% to 1.6%, 3,207 m/s to 2,133 m/s and 2,028 m/s to 1,357 m/s. In conclusion, it was inferred that the properties of SW rocks experienced approximately 200-300 cycles of freeze-thaw process become close to those of MW rocks.

• Proceedings of the Korean Geotechical Society Conference
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• 1997.10a
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• pp.399-408
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• 1997

• The Journal of Engineering Geology
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• v.24 no.2
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• pp.179-189
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• 2014

We analyzed the three-dimensional distribution of micropores and internal structures in both fresh and weathered granite using micro-focus X-ray computed tomography (micro-CT). Results show that the pore radius in fresh granite is mostly in the range of $17-50{\mu}m$, the throat radius is in the range of $5-25{\mu}m$, and the coordination number (CN) of pores is less than 10. In contrast, the pore radius in weathered granite is mostly in the range of $20-80{\mu}m$, the throat radius is in the range of $8-30{\mu}m$, and the CN is less than 12. In general, a positive linear relationship exists between pore radius and CN. In addition, both the size and the density of pores increase with an increasing degree of rock weathering. The size of the throats that connect the pores also increases with an increasing degree of weathering, which induces fracture propagation in rocks. Micro-CT is a powerful and versatile approach for investigating the three-dimensional distributions of pores and fracture structures in rocks, and for quantitatively assessing the degree of pore connectivity.

• Korean Journal of Soil Science and Fertilizer
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• v.27 no.3
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• pp.158-167
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• 1994

The various weathering products derived from andesitic rocks in the Guweol mountain area of Pusan have been studied in order to investigate the occurrence, characteristics and evolutional trend of clay minerals in the weathered rock and soil using mainly X-ray powder diffraction method. Kaolinite and halloysite are very abundant in the weathered rocks and soils derived from andesitic rocks of this area. Also, $12{\AA}$- and $14{\AA}$-minerals occur in the considerable amount. $12{\AA}$-minerals have been identified as mica/vermiculite interlayer minerals showing the $25{\AA}$ basal reflection. Their crystal sizes are relatively big showing more than 10 micron in diameter. Two types of $14{\AA}$-mineral, which are vermiculite/smectite interlayer mineral and Al-vermiculite, have been observed. Kaolin minerais consist of kaolinite, $10{\AA}$ and $7{\AA}$ halloysite. Kaolinite relatively dominates in the strongly weathered soil of the area. In contrast with kaolinite. $12{\AA}$- and $14{\AA}$-minerals such as vermiculite/smectite and mica/vermiculite interlayer minerals tend to occur in the weakly to intermediately weathered products. Based on their occurrences, it strongly suggests that they are intermediate products in the course of the weathering process from the parent materials into the kaolin mineral.

• Economic and Environmental Geology
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• v.8 no.4
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• pp.211-221
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• 1975

Weathering of granites has a geochemical role of great significance, because of their abundance and because of chemical instability near the surface of the earth, which is more pronounced than in most other rocks. On the other hand the granites are tectonically fragile and "react" to deformation with marked facility, giving rise to a whole gamut of deformed rocks. Therefore, the writer has studied on the weathering of granitic rocks at of Iri city and Jeonju city Jeollabukdo, Korea, The fresh and weathered rocks were used as material for the investigation. The results obtained by chemical analysis and observation are as follows. 1) The order of mobility in major elements was Ca, Na and K$H_2O$ was observed clearly and late stages of weathering processes. 3) The early stage of weathering is commenced by physical weathering and followed by chemical weathering. 4) The ratio of FeO/. $Fe_2O_3$, FeO/MgO, and $SiO_2/Al_2O_3 $ decreased uniformly from early to late stage of weathering processes. 5) It was proved that weathering potential of granite was larger than that of basaltic rocks.

• Journal of the Korean Geotechnical Society
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• v.23 no.8
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• pp.107-116
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• 2007

Load and Resistance Factor Design (LRFD) method is being used increasingly in geotechnical design practice worldwide, and is expected to completely replace the current Allowable Stress Design (ASD) method in the near future. LRFD has advantages over ASD in that it allows the design of superstructures and substructures at a consistent reliable level by quantification of failure probability based on reliability analysis. At present, resistance factors for cast-in-place piles embedded in rocks are determined by AASHTO only for the intact rock conditions. In Korea, however, most of the bedrocks in which piles are embedded are heavily weathered. Thus, this study will try to determine the resistance factors of heavily weathered rocks (so-called intermediate goo-materials). To this aim, reliability analysis was carried out to evaluate the resistance factors of cast-in-place piles embedded in intermediate geo-materials in Korea. Pile load test data of 21 cast-in-place piles of 4 construction sites were used for the analysis. Depending on the method which calculates the pile capacities, the resulting resistance factors ranged between 0.1 and 0.6.

• The Journal of Engineering Geology
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• v.20 no.4
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• pp.461-465
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• 2010

Weathering and permeability in rocks play a very important role in underground disposal of radioactive waste and their long-term management as well as stability security of rock structures. Weathering and permeability of rocks are largely controlled by the characters of inner structures of rocks. In other words, weathering rate can be accelerated depending on the quantity of pore and microcrack in rocks. Quantitative evaluation of inner structures of rocks can serve as a tool that can assess the degree of weathering of rocks. Therefore it can be said that the understanding of three dimensional distribution of the inner structure of rocks is important for long-term management of rock structures. This study was performed to analyze three dimensional distribution of pore in rocks using Micro Focus X-ray CT on fresh granite and weathered granite from Korea. Results of the analysis clearly show distribution of pore and porosity of the inner rock.