• Title/Summary/Keyword: Artificial weathering

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The change of rock properties by artificial weathering tests and its implications for durability of building stones

  • Min Kyoung-Won;Park Jin-Dong
    • 한국지구물리탐사학회:학술대회논문집
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    • 2003.11a
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    • pp.557-560
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    • 2003
  • Some well-known artificial weathering tests such as freezing-thawing, acid immersion, and salt crystallization are adopted to examine the change of rock properties during the processes of artificial weathering. Granites and other rock types of limestone, marble and basalt collected from different quarries in south Korea were sampled for this study. All tests were performed up to 30 cycles and physical properties were measured after experiencing every ten cycles of artificial weathering tests. During the tests, the variation trends of rock properties were too variable to draw generalized variation patterns but it can be concluded that weathering agents have different effect on rock properties depending on weathering circumstance and time. Even in short terms of salt crystallization tests, some rocks were severely deformed and then burst, and in the early stages of salt weathering, recrystallized salts filling pores and cracks in rocks could be a important factor affecting rock properties.

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A Study of Weathering Characteristics of Cretaceous Granite in Kimhae Area due to Artificial Weathering Processes (인공풍화과정에 의한 김해지역 백악기 화강암의 풍화특성에 관한 연구)

  • Um, Jeong-Gi
    • Tunnel and Underground Space
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    • v.22 no.1
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    • pp.32-42
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    • 2012
  • It is very difficult to capture the weathering characteristics of rock because of limitation caused by time and space. A new scheme of experiment that includes physical and chemical weathering processes was implemented on Cretaceous granitic rock samples from Kimhae area to investigate the variations of geomechanical properties of deteriorated rocks due to artificial weathering processes. The seismic velocity was found to decrease with increasing artificial weathering cycle. Effective porosity and absorption tend to increase with artificial weathering processes. The amount of deterioration of rock samples depend on pre-test degree of weathering. Effective porosity, absorption and seismic velocity can be used as the measure of weathering characteristics of granite in the study area. Weathering is accelerated by combined effect of physical and chemical weathering processes. The new experimental methodology conducted in this study has strong capability to analyze the weathering characteristics of rocks.

Effects of salt crystallization on stone durability (염분의 결정화 현상이 석재 내구성에 끼치는 영향)

  • 김성수
    • Economic and Environmental Geology
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    • v.32 no.2
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    • pp.203-208
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    • 1999
  • The main objective of this study is to suggest a new assessment method of the influence of weathering due to salt crystallization on the engineering property of rock. For this purpose, various sources of salt and salt crystallization were investigated, and artificially accelerated weathering tests were carried out. In natural envionment, weathering rate is very slow and weathering process involves complex mechanisms. Therefore artificial weathering test is essential for systematic analysis. Arificial weathering test is defined as test which controls weathering rate and agents by controlling arificial environmental condition. In this study, salt crystallization test was selected among various artificial weathering test methods, for its important role in weathering. Change of various stone properties were detexted. The change of physical properties by salt crystallization were observed as follows : 72% in Brazilian tensile strength and 72% in Slake durability. These results explain the importance of salt crystallization in the mechanical behaviour and properties of stone.

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Evaluation on Weathering Characterization on Rock Types Using Artificial Weathering Test (인공풍화시험을 이용한 암종별 풍화특성 평가)

  • Heo, Yeul;Kang, Changwoo;Kwon, Youngcheul;Bae, Wooseok
    • 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.

Quantitative Evaluation for Effectiveness of Consolidation Treatment by Using the Chemical of Ethyl Silicate Series for the Sandstone in Yeongyang (영양 사암을 대상으로 한 에틸실리케이트 계열 처리제의 강화효과 평가)

  • Lee, Jang-Jon;Han, Min-Su;Song, Chi-Young;Jun, Byung-Kyu;Do, Min-Hwan
    • 보존과학연구
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    • s.30
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    • pp.125-136
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    • 2009
  • Stone cultural heritages in Korea have a severe damages from chemical and biological weathering because most of them have been situated in outdoors without any suitable protection systems, and this in turn causes deformation and structural damage. To counteract these problems and increase durability, various kinds of conservation materials are used in the conservation and restoration treatments. However until now there are not many practical and technological experiments on this subject. This paper attempts quantitative evaluation of effectiveness about chemical of ethylsilicate based resin for sandstone in Yeongyang-gun. It takes a long time to evaluate durability and side effect after conservation materials treatment. So we use artificial weathering through freezing§ thawing experimental method. As a result of this experiment, porosity and absorptance increased, and elastic wave speed, elastic modules, unconfined compression strength and tensile strength decreased more than before. This study plans to make a scientific method study about weathering factor and mechanism, and to deduce correlation between artificial weathering and natural weathering.

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A Study on the Change of Conservation Materials Properties Using Artificial Weathering Test (인공풍화 실험을 이용한 보존처리제의 물성 변화 연구)

  • Do, Min-Hwan;Han, Min-Su;Lee, Jang-Jon;Jun, Byung-Kyu;Song, Chi-Young
    • 보존과학연구
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    • s.29
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    • pp.149-162
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    • 2008
  • Because stone cultural heritages in Korea are mostly situated outdoors without any notable protection, there are severe damages from physical, chemical and biological weathering. And this in turn causes deformation and structural damage. To counteract this problem and increase durability, various kinds of conservation materials are used in the conservation and restoration treatment. However, there are not many practical and technological experiments on this subject. Accordingly this research is for analysis of effect for treatment to make use a resin of the ethyl silicate for the granite in Mt. Nam of Gyeongju. It takes a long time to confirm the test result regarding durability and side effects of the conservatives after treatment. So we built up an artificial environment through freezing and melting test, and evaluated the conservation materials. As a result of this experiment, porosity and absorptivity was increased in accordance with processing of freezing and melting test. But other things such as elastic wave speed, elastic modulus, uniaxial compressive strength and tensile strength was decreased. It will make a plan to form a method of research systematically for mechanism and element of weathering and to elicit a correlation among experiment of artificial weathering and practical natural weathering from next research.

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Variation of Geomechanical Characteristics of Granite and Orthogneiss in Wonju Area due to Accelerated Artificial Chemical Weathering Tests (강원도 원주일대에 분포하는 화강암 및 화강편마암의 화학풍화실험에 의한 물성 변화 연구)

  • Woo, Ik;Um, Jeong-Gi;Park, Hyuck-Jin
    • 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.

A Study of Engineering Properties of Rock Mass Weathered by Sea water (해수에 의한 암반 풍화의 공학적 특성 연구)

  • Choi Kang-Il;Kang Coo-Won;Go Chin-Surk
    • 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.

Artificial Accelerated Weathering of Volcanic Rocks from Ulleungdo Island (인공풍화가속실험을 통한 울릉도에 분포하는 화산암의 풍화특성 고찰)

  • Woo, Ik
    • The Journal of Engineering Geology
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    • v.25 no.4
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    • pp.499-510
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    • 2015
  • Artificial accelerated weathering test evaluated rocks from near the circuit road of Ulleungdo island, approximately 120 km from east of the Korean Peninsula. The tests subjected rock specimens to conditions based on the climate of the island. The specimens (such as basaltic breccia, trachyte, volcanic breccia) were preliminarily classified using a TAS diagram (XRF data) and based on the constituent minerals (XRD data); they were further classified by weathering degree according to their absorption ratios. During the artificial accelerated weathering, the absorption ratio of most of the specimens increased, but the point-load strength did not decrease in most cases, except for the volcanic breccia. The greater initial absorption ratio of trachyte rock specimen in comparison with the other specimens led to a greater increase of its absorption ratio during the artificial accelerated weathering test. The volcanic breccia specimens showed the greatest increase of absorption ratio and the biggest reduction ratio of the point- load strength during the tests. These results could aid prediction of the weathering rate of rocks in Ulleungdo island subjected to weathering processes; trachyte which appears to accelerate with time, and volcanic breccia whose mechanical strength can largely decrease in a relative short period of time. Proper measures therefore appear necessary for the prevention of natural disaster such as rock fall and landslide around the circuit road.

Influence of natural and accelerated weathering of polycarbonate (폴리카보네이트 소재의 자연폭로와 실내촉진 내후성 영향)

  • Moon, Jung-mi;Jang, Ho-Jin;Kim, Chang-Hwan
    • Journal of the Korean institute of surface engineering
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    • v.55 no.6
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    • pp.383-389
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    • 2022
  • Natural(outdoor) and accelerated(artificial) weathering tests were performed to investigate their influence on polycarbonate. The polycarbonate materials were prepared of various formulations divided into three batches, with existing, development materials1, development materials2, containing mixture of UV additives. Weathering tests were carried out as outdoor weathering(Seosan, South Korea) and accelerated weathering(xenon-arc), and the results analysis were evaluated based on yellow-index(YI), scanning electron microscope(SEM/EDS), energy dispersive x-ray spectroscopy(XRD), and gel permeation chromatography(GPC). Among the three materials, processing method development materials1 with UV stabilizer was excellent in weathering. This study can provide basic data for standardization of development and performance evaluation on livestock barn roof.