• Title/Summary/Keyword: Artificial weathering

Search Result 76, Processing Time 0.023 seconds

Salt Weathering Characteristics and Mechanism Interpretation of the Five-Storied Stone Pagoda in Tapri-ri, Uiseong (의성 탑리리 오층석탑의 염풍화 특성과 메커니즘 해석)

  • Lee, Mi Hey;Lee, Myeong Seong;Lee, Jae Man;Chun, Yu Gun
    • 보존과학연구
    • /
    • s.33
    • /
    • pp.57-67
    • /
    • 2012
  • The Uiseong Tapriri Five-Storied stone pagoda has occurred exfoliation, granular disintegration and discoloration by physical and chemical weathering factors with the major deterioration occurring due to efflorescence by salt. According to the results of SEM-EDS and X-ray diffraction analysis, salts consists of gypsum, taranakite. Artificial salt weathering tests were carried out using the same type of rocks as those in the stone pagoda. The test results showed that efflorescence occurred on the surface of the rock, and that exfoliation and granular disintegration occurred inside the rock due to salt crystallization.

  • PDF

Variations of Mechanical Properties of Hallasan Trachyte with respect to the Degree of Weathering (풍화진행에 따른 한라산조면암의 역학적 특성변화)

  • Cho, Tae-Chin;Lee, Sang-Bae;Hwang, Taik-Jean;Won, Kyung-Sik
    • Tunnel and Underground Space
    • /
    • v.19 no.4
    • /
    • pp.287-303
    • /
    • 2009
  • Rock mass in Baekrokdam at the summit of Hallasan in Jeju island is composed of two volcanic rock types: Baekrokdam trachybasalt at the eastern region and Hallasan trachyte at the western region. On-going rockfall and subsequent collapse of Baekrokdam wall rock are closely linked to the weathering of trachyte distributed in the western region of Baekrokdam. Samples of Hallasan trachyte showing different weathering grades had been collected and the polarizing microscopic observation, X-ray diffraction analysis and analysis for chemical weathering had been conducted. Formation of secondary minerals, especially clay minerals, by chemical weathering has not been identified, but the change of chemical weathering indices indicated that chemical weathering process had been proceeded to the degree for increasing and decreasing the contents of some chemical components. Changes in physical and mechanical rock properties due to weathering has also been examined. Artificial weathering test of freezing-thawing reveals that the process of crack initiation and propagation deteriorated the mechanical characteristics of Hallasan trachyte and $D_B$ = 1.5 or porosity = $20{\sim}21%$ would be the ultimate limiting value induced by the mechanical weathering processes.

Application for Prediction of Crown Settlements Using RMR in Weathering Rock Tunnels (RMR을 이용한 풍화암 터널의 천단침하량 예측 평가)

  • Kim, Young-Su;Kim, Dae-Man
    • Journal of the Korean Geotechnical Society
    • /
    • v.25 no.10
    • /
    • pp.67-76
    • /
    • 2009
  • Statistical analysis was performed using a series of data on RMR, RMR* and crown settlements collected from sites of weathering rock tunnels in Korea. The crown settlements were predicted by recurrence analysis, exponential function, and artificial neural network (ANN) using collected in-situ data. The result of the prediction fitted well compared to the measured settlement in the order of ANN, exponential function, and recurrence analysis. The range of crown settlement predicted by recurrence analysis widely scattered and promised larger settlement than the measured. Also in all method, the predicted value by RMR well matched compared to the measured settlement predicted by RMR*.

Characterization of the Behavior of Naturally Occurring Radioactive Elements in the Groundwater within the Chiaksan Gneiss Complex : Focusing on the Mineralogical Interpretation of Artificial Weathering Experiments (치악산 편마암 지질의 지하수 내 자연 방사성 원소의 거동 특성 연구: 인공풍화 실험을 통한 광물학적 해석)

  • Woo-Chun Lee;Sang-Woo Lee;Hyeong-Gyu Kim;Do-Hwan Jeong;Moon-Su Kim;Hyun-Koo Kim;Soon-Oh Kim
    • Korean Journal of Mineralogy and Petrology
    • /
    • v.36 no.4
    • /
    • pp.289-302
    • /
    • 2023
  • The study area was Gangnim-myeon, Hoengseong-gun, Gangwon-do, composed of the Chiaksan gneiss complex, and it was revealed that the concentrations of uranium (U) and thorium (Th) within the groundwater of the study area exceeded their water quality standards. Hence, artificial weathering experiments were conducted to elucidate mineralogically the mechanisms of their leaching using drilling cores obtained from the corresponding groundwater aquifers. First of all, the mineralogical compositions of core samples were observed, and the results indicated that the content of clinochlore, a member of the chlorite group of minerals that can form through low- and intermediate-temperature metamorphisms, was relatively higher. In addition, the Th concentration was measured ten times higher than that of U. The results of artificial weathering experiments suggested that the Th concentrations gradually increased through the dissolution of radioactive-element-bearing minerals up to the first day, and then they tended to decrease. It could be attributed to the fact that Th was leached with the dissolution of thorite, which might be a secondary mineral, and then dissolved Th was re-precipitated as the various forms of salt, such as sulfate. Even though the U content was lower than that of Th in the core samples, the U concentration was one hundred times higher than that of Th after the weathering experiments. It is likely caused by the gradual dissolution and desorption of U included in intensively weathered thorite or adsorbed as a form of UO22+ on the mineral surface. In addition, the leaching tendency of U and Th was positively correlated with the bicarbonate concentration. However, the concentrations between U and Th in groundwater exhibited a relatively lower correlation, which might result from the fact that they occurred from different sources, as aforementioned. Among various kinetic models, the parabolic diffusion and pseudo-second-order kinetic models were confirmed to best fit the dissolution kinetics of both elements. The period that would be taken for the U concentration to exceed its drinking-water standard was inferred using the regressed parameters of the best-fitted models, and the duration of 29.4 years was predicted in the neutral-pH aquifers with relatively higher concentrations of HCO3, indicating that U could be relatively quickly leached out into groundwater.

Quality Property of the Artificial Stone Using the Waste Porcelain (폐자기를 사용한 인조석재의 품질평가)

  • Yoo, Yong-Jin;Lee, Sang-Soo;Song, Ha-Young
    • Proceedings of the Korean Institute of Building Construction Conference
    • /
    • 2015.05a
    • /
    • pp.171-172
    • /
    • 2015
  • Recently, it is the global warming phenomenon because of the greenhouse gas exhaustion caused by and the environment problem is serious. And it is the situation where the problem of the exhaustion of resource because of the indiscriminate picking of the that is the raw material of the cement, limestone and natural aggregate are emphasized. In addition, thus the cement reduction amount of use and substitute material research is the urgent actual condition with the gas emission, which here it is generated in conducting compression molding in the building stone manufacturing process performance degradation phenomenon and fire resistance, and problem of the durability. Therefore, in this research, the waste porcelain is applied to the artificial stone and the durability property of the artificial stone according to it tries to be investigated.

  • PDF

The biodeterioration and conservation of stone historical monuments (석조문화재의 생물학적 손상과 보존방안)

  • Chung, Yong-Jae;Seo, Min-Seok;Lee, Kyu-Shik;Han, Sung-Hee
    • 보존과학연구
    • /
    • s.24
    • /
    • pp.5-28
    • /
    • 2003
  • Stone has been one of the most intensely studied materials in conservation. Understanding the deterioration of stone needs various knowledge in different mineralogical and physical characteristics and its weathering response under different climate and environment. The alteration and weathering of stone is affected by natural or artificial elements whether they are physical, chemical or biological damaging factors. It can be said that the bio deterioration of stone is coupled with every environmental factors, which induce decomposition of stone structure, either directly or indirectly as a form of catalysis. Many elements contribute to the deterioration of stone monuments and other objects of cultural value such as pagoda, stature of Buddha, etc. This report concentrates on the action of biodeteriorative factorsincluding bacteria, algae and higher plants. Preventive and remedial methods and a selection of chemical treatments are also described.

  • PDF

Soil buffer capacities from the differrent host rocks by the treatment of artificial acid precipitation

  • Min, Ell-Sik;Kim, Myung-Hee;Song, Suck-Hwan
    • Proceedings of the Zoological Society Korea Conference
    • /
    • 1999.10b
    • /
    • pp.150.2-150
    • /
    • 1999
  • To investigate the weathering soil buffering capacities of the artificial acidic precipitation, the weathering soils and their leachate solutions were sampled from the host rocks(granite;GR, rhyolite;RH, gabbro;GA, basalt;BA, two serpentinite;SE1, SE2 and limestone;LI) and analyzed for pH and chemical properties. 1n the soil pH of the GR and RH ,the acidic rocks, were 5.02 and 5.95, respectively. And the GA and BA, basic rocks, were 6.52 and 7.57. The SE1 and SE2 were 8.90 and 8.89. While the LI was 7.84. These results means the typical soil pH properties by host rocks. After the artificial acidic precipitation input 5OOml, the average changes of soil leachate solutions treated by pH levels(pH 5.0, 4.0 and 3.0), were pH 5.73, 5.00 and 4.40. in GR soil, and pH 6.19, 5.99 and 5.57 in RH. GA were pH 6.31, 6.04 and 5.86, BA were pH 7.05, 6.85 and 6.56 and SE1 were pH 8.31, 8.26 and 7.71. SE2 were pH 8.29, 8.24 and 7.96. LI were pH 7.55, 7.46 and 6.79. The soil leachate pHs from volcanic rocks were higher than those from the plutonic rocks and GR soils showed greater response than other soils. With increasing 100ml input-solution, the soil leachate pHs were mainly decreased. Cation concentrations, CEC, EC and total nitrogen concentrations of RH and BA soils, the volcanic rocks, were higher than those of GR and GA soil, the plutonic rocks. On the contrary, Al concentrations of the GR and GA soils were higher than those of RH and BA soils, partly because of high quartz content in GR and Al content in the biotite and plagioclase in GA.

  • PDF

A Study on Discoloration of Traditional Paintings by an Inorganic Pigment (무기 안료에 의한 전통회화의 변색 연구)

  • Kim, Dong Won;Kwak, Sam Tak;Seo, Yong Soo;Kim, Il Kyu;Moon, Myung Jun
    • Applied Chemistry for Engineering
    • /
    • v.23 no.6
    • /
    • pp.567-571
    • /
    • 2012
  • The discoloration of traditional paintings could be induced by various chemical reactions of inorganic pigments due to temperature, humidity, light and air pollution. In this study, we made artificial samples including azurite and malachite as inorganic pigments using the traditional method on hanji called 'Korean paper'and investigated the artificial aging process occurred by the interaction between pigments and environmental factors. It was found that the azurite was influenced by the humidity of weathering tests and the salt fog of salt spray tests according to XRD and TGA results. However, it was shown that the malachite was chemically changed by the ultraviolet radiation of weathering tests and UV radiation tests according to color difference and TGA results.

Conservation Scheme and Deterioration States of the Wanggung-ri Five-storied Stone Pagoda in the Iksan, Korea (익산 왕궁리 5층 석탑의 훼손현황과 보존방안 연구)

  • Yang, Hee-Jae;Lee, Chan-Hee;Kim, Sa-Dug;Choi, Seok-Won
    • 보존과학연구
    • /
    • s.25
    • /
    • pp.171-195
    • /
    • 2004
  • This research presents an evaluation of the weathering and deterioration state of the Wanggung-ri five-storied stone pagoda in the Iksan (National Treasure No. 289) and suggests conservational schemes. A deterioration map of the pagoda was drawn from the aspects of petrological, physical, chemical, biological, structural and artificial weathering.The rock properties consisting of the pagoda were medium-grained biotite granite that had leucocratic phenocryst developed in parts. The body of each story suffered severely from the secondary contamination that turned the colors into light grey, pitch dark, yellowish brown, and reddish brown as well as granular decomposition, exfoliation and peel-off. The roof stones were heavy exfoliated or peeled off in most of the cases. In addition to the fine cracks, there were layered cracks on the corners. The roof stones of the3rd and 4th story in the north and west side had some stones fall-off, while those of the 2ndstory in the north side had steel reinforcement filled for a fixing purpose. Those of the 5th story showed big gaps that must have originated from cracks and were easily subject to granular decomposition and rainfall. The inside clay filler was missing in the lower part of the roof stones of the 4th and 5th story and the supporting stones, which were thus covered by light grey or pitch dark sediments. The contact area of the materials was about 70 % in the parts where there was a space due to the filler missing and washigher than 90 % in the lower parts of the pagoda. About 90 % or more of the roof stones surface of each story were covered by aerial plants that formed a thick biological mat. Thus it seemed necessary to come up with the conservational measures to remove the plans living on the surface of the stone materials, with the plans to prevent rain from falling inside, and with the water repellent and hardening treatments to postpone the surface weathering of the rock properties. All those measures and plans must be based on the results of long-term monitoring and thorough detail investigations.

  • PDF

Effect of Short-Term Weathering on Flame Retardant Performance of Korean Red Pine Wood Coated with Dancheong (단기간 풍화가 단청도채된 소나무재의 방염성능에 미치는 영향)

  • Son, Dong Won;Hong, Jong Ouk;Park, Jin Ho;Lee, Hwa Soo;Chung, Yong Jae;Han, Gyu-Seong
    • Journal of the Korean Wood Science and Technology
    • /
    • v.44 no.5
    • /
    • pp.785-808
    • /
    • 2016
  • The objective of this study was to investigate the effect of the short-term weathering on the flame retardant performance of wood coated with Dancheong. Flame retardants were applied on the Dancheong coated Korean red pine. Flame retardants applied panels were layed at the two conditions of outdoor exposure and artificial aging to assess the reliability of artificial aging. Flame retardants used were commercial products developed for historical wooden buildings. Scanning electron micrographs revealed the forming of carbonized membrane by melting of flame retardant on wood surface. These carbonized membranes may help delay the further combustion of wood. Flame retardant performance was assessed by measuring heat release rate (HRR) and total heat release (THR) by cone calorimetry. There was no difference in flame retardant performance between before and after 6-month outdoor exposure tests. And also no difference in flame retardant performance between before and after 2-week artificial aging which corresponds to 6-month outdoor exposure. Both tests showed the similar results of combustion characteristics.