• Title/Summary/Keyword: 정수위 투수시험

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Healing Performance of Concrete Containing Hybrid Self-healing Materials (하이브리드 자기치유 소재를 혼입한 콘크리트의 치유성능)

  • Mih-ho, Hwang;Hyuk, Kwon;Hyung-Suk, Kim;Sung, Choi;Kwang-Myong, Lee
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.10 no.4
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    • pp.569-576
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    • 2022
  • In this study, the healing performance of hybrid self-healing concrete was investigated by mixing bacterial pellets(BP) and solid phase capsules(SC), respectively, based on organic-inorganic self-healing material(MC). Constant water head permeability test was applied as a method of evaluating the healing performance, and the healing rate and the healed crack width calculated by the equivalent crack width were used as evaluation indicies. As a result of the water permeability test, when the initial crack width was 0.3 mm, the healing rates of MC-BP and MC-SC were 2.1~3.0 %pt higher than that of MC, and the healed crack width of hybrid concrete increased by 0.017~0.018 mm. In conclusion, it was found that the self-healing performance was not significantly improved even if the two types of healing materials are used together.

Correlation between Crack Width and Water Flow of Cracked Mortar Specimens Measured by Constant Water Head Permeability Test (정수위 투수시험에 의해 측정된 균열 모르타르 시편의 유출수량과 균열폭의 상관관계)

  • Choi, Seul-Woo;Bae, Won-Ho;Lee, Kwang-Myong;Shin, Kyung-Joon
    • Journal of the Korea Concrete Institute
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    • v.29 no.3
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    • pp.267-273
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    • 2017
  • Recently, the researches of self-healing concrete technology are being carried out actively due to the advent of importance for the maintenance of concrete structures. A water permeability test has been widely used for the evaluation of self-healing performance. However, it is difficult to compare tests results since there is no standard test method related to the self-healing. A standard method for measuring the crack width does not exist neither though the self-healing performance is significantly influenced by the initial crack width. In this study, the effect of water head and crack width on water flow was investigated using a constant water head permeability test equipment. The correlation equation between the initial crack width and water flow was suggested through the regression analysis of test data, and the predicted crack widths agree well with the real crack widths measured using microscopy.

Evaluation Method of Self-healing Performance of Cement Composites (시멘트 복합체의 자기치유 성능평가 방법)

  • Lee, Kwang-Myong;Kim, Hyung-Suk;Min, Kyung-Sung;Choi, Sung
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.8 no.1
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    • pp.134-142
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    • 2020
  • In this study, in order to evaluate the self-healing performance of cement composites the self-healing test method and the analysis method were suggested by applying constant water head permeability test, chloride migration test and repeated bending test. The method of making a cracked specimen and controlling crack width are also proposed. Constant head water permeability test can evaluate the healing performance by using the decreasing rate of water flow passing through the crack zone of a specimen. Furthermore, the equivalent crack width can be used to intuitively investigate the healing effect with healing period. The chloride migration test can evaluate the healing rate by the decreasing rate of the diffusion coefficient obtained by ASTM C 1202. Mechanical healing performance can be evaluated using ISR and IDR estimated from load vs. CMOD relationship graph obtained through the repeated bending test. Finally, the applicability of proposed self-healing evaluation methods was examined by testing mortar specimens with or without self-healing agents.

Evaluation Method of Healing Performance of Self-Healing Materials Based on Equivalent Crack Width (등가균열폭에 기반한 자기치유 재료의 치유성능 평가 방법)

  • Lee, Woong-Jong;Kim, Hyung-Suk;Choi, Sung;Park, Byung-Sun;Lee, Kwang-Myong
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.9 no.3
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    • pp.383-388
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    • 2021
  • In this study, constant head water permeability test was adopted to evaluate self-healing performance of mortars containing inorganic healing materials which consist of blast furnace slag, sodium sulfate and anhydrite. Clinker powder and sand replaced for a part of cement and fine aggregates. On constant head water permeability test for self-healing mortars, unit water flow rate of mortar specimens were measured according to crack width and healing period. As a result of evaluating the healing performance of self-healing mortar, it was confirmed that with the initial crack width of 0.3mm, the healing rate at healing period of 28 days increased by more than 30%p compared to plain mortar, greatly improving the healing performance. Furthermore, the coefficient(α) which was estimated from the relationship between crack width and unit water flow rate was used for calculating equivalent crack width. By analyzing the correlation of healing rate and equivalent crack width, the time and initial crack width attaining healing target crack width were predicted.

The Analysis of Permeability Coefficient and the Evaluation of Equations of Permeability Coefficient for an Unsaturated Soils (불포화토의 투수계수분석 및 투수계수 방정식의 적용성 평가)

  • Lim, Seong-Yoon;Lyu, Tae-Jin
    • Journal of the Korean Geotechnical Society
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    • v.24 no.1
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    • pp.5-13
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    • 2008
  • The coefficient of permeability for a soil can be determined by the direct or the indirect method. The direct method of permeability can be performed either in the laboratory or in the field. The indirect method can be predicted from the soil-water characteristic curve. In this study, the coefficient of permeability for an unsaturated soil was determined by the modified apparatus of steady-state method (Klute, 1972) and was predicted from the equations of Brooks & Corey (1964) and van Genuchten (1980). The experimental results were compared with predicted coefficient of permeability and the applicability of the two equations (from Brooks & Corey, van Genuchten) was reviewed.

An Experimental Study on the Self-Healing Performance of Solid Capsules According to the Composition Ratio of Crystal Growth Type Inorganic Materials (결정성장형 무기재료 조성비에 따른 고상 캡슐의 자기치유 성능에 관한 실험적 연구)

  • Nam, Eun-Joon;Oh, Sung-Rok;Kim, Cheol-Gyu;Choi, Yun-Wang
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.25 no.2
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    • pp.16-22
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    • 2021
  • In this paper, a solid capsule was prepared using a crystal growth type inorganic material capable of hydration reaction. The solid capsules were mixed at 3, 5, and 10% according to the composition ratio of 8:2, 7:3, 6:4 based on the cement mass, and the self-healing mortar was mixed, Durable healing properties were evaluated through the water permeability test. As a result of the water level permeability test, the effect of optimally improving the natural healing performance was shown by mixing the solid capsules prepared in a composition ratio of 7:3 of the solid capsules. In the case of a crack width of 0.3mm or less, it is estimated that more than 90% of the self-healing performance can be secured. As a result, it was judged that the self-healing performance of the solid capsule had an effect on the durable healing properties through the water permeability test, It is judged that there is a tendency to improve self-healing performance according to the mixing of solid capsules.

Engineering Characteristics of the Light Weight Soil Used Recycled Stylofoam Beads and Disposal Soils (폐스티로폴 입자와 현장 발생토를 활용한 경량혼합토의 공학적 특성)

  • Shin, Bang-Woong;Lee, Jong-Kyu
    • Journal of the Korean GEO-environmental Society
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    • v.1 no.1
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    • pp.43-50
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    • 2000
  • This paper presents the engineering property of light weight soil made of soil mixed with recycled stylofoam and stabilizer. Recycled stylofoam beads is able to use by lightweight fill materials because it is light, adiabatic, and effective for vibration interception. Especially, recycled stylofoam beads is easy to supply because stylofoam have been recycle item in 1996. In this study, physical and geotechnical properties of the light weight mixed soil(weathered granite soil mixed with Stylofoam Beads) were analyzed by laboratory experiments to examine its suitability for backfill materials. Laboratory tests were performed to evaluated strength, bearing capacity, weight, permeability, microphotograph analysis with variation of mixing ratio. Based on the results, it is concluded that the use of recycled stylofoam beads is acceptable lightweight fill.

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Self-healing Performance Evaluation of Cement Mortar with Inorganic Additives Based on Clinker Binder (클링커 바인더 기반 무기계 혼합재를 활용한 시멘트 모르타르의 치유성능 평가)

  • Jung-Il, Suh;Yoon-Suk, Choi;Byung-Sun, Park;Kwang-Myong, Lee
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.10 no.4
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    • pp.561-568
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    • 2022
  • In this study, the mechanical properties and self-healing performance of cement mortar containing clinker binder, calcium sulfoaluminate(CSA), and sodium sulfate(Na2SO4) were evaluated. The mechanical properties of cement mortar were investigated by measuring compressive strength and flexural strength, and the healing performance was evaluated through hydrostatic water permeability test and gas diffusion test. In addition, the healing products precipitated in the cracks were visually observed through an optical microscope and a scanning electron microscope(SEM). As a result, the incorporation of the clinker binder-based inorganic additives improved the initial and 28-day strength by about 20 %. Depending on the healing performance evaluation method, there was a difference in the healing rate, and the healing rate showed a tendency to be underestimated. Nevertheless, CaCO3 was precipitated as the main healing product inside the 0.3 mm crack when the inorganic additives were mixed with cement mortar, improving the self-healing performance.

Estimation of Hydraulic Conductivity of Soils Based on Biot's Theory of Wave Propagation (Biot 파동전파 이론을 이용한 지반의 투수계수 산정)

  • Song, Chung R.;Kim, Jinwon;Koocheki, Kianoosh
    • Journal of the Korean Geotechnical Society
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    • v.36 no.12
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    • pp.7-16
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    • 2020
  • This study presents an acoustic technique to estimate the hydraulic conductivity of soils. Acoustic attenuation and propagation velocity spectra were measured for dry and saturated sandy specimens to confirm that the relationship between Biot's characteristic frequency and its associated hydraulic conductivity exists only for saturated soils. From the experiments presented in this paper, both attenuation-based and propagation-velocity-based techniques resulted in almost identical characteristic frequencies for saturated soils. The propagation velocity based measurements, however, show a a a slightly clearer trend compared to the attenuation based measurements. The results also show that the acoustically estimated hydraulic conductivities of soils agree well with constant head laboratory test results, demonstrating that this acoustic technique can be a useful nondestructive tool to estimate the hydraulic conductivity of sandy or silty soils.

Relationship between Hydraulic Conductivity and Electrical Conductivity in Sands (사질토의 투수계수와 전기전도도 간의 상관관계)

  • Kim, Jinwook;Choo, Hyunwook;Lee, Changho;Lee, Woojin
    • Journal of the Korean Geotechnical Society
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    • v.31 no.6
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    • pp.45-58
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    • 2015
  • The aim of this study is to suggest a semi-empirical equation for estimating the hydraulic conductivity of sands using geoelectrical measurements technique. The suggested formula is based on the original Kozeny-Carman equation; therefore varying factors affecting the Kozeny-Carman equation were selected as the testing variables, and six different sands with varying particle sizes and particle shapes were used as the testing materials in this study. To measure both hydraulic and electrical conductivities, a series of constant head permeameter tests equipped with the four electrodes conductivity probe was conducted. Test results reveal that the effects of both pore water conductivity and flow rate in relation between hydraulic conductivity and formation factor (=pore water conductivity / measused conductivity of soil) of tested materials are negligible. However, because the variations of hydraulic conductivity of the tested sands according to particle sizes are significant, the estimated hydraulic conductivity using the formation factor varies with particle sizes. The overall comparison between the measured hydraulic conductivity and the estimated hydraulic conductivity using the suggested formula shows a good agreement, and the variation of hydraulic conductivity with varying Archie's m exponents is smaller compared with varying porosities.