• Title/Summary/Keyword: 압축강도 회복율

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Self-Healing Characteristics of Mortar Blocks according to the Mixing Ratio of Self-Healing Capsules (자기치유용 캡슐 혼입율에 따른 모르타르 블록의 자기치유 특성)

  • Yoon, Joo-Ho;Kim, Chae-Young;Na, Bum-Su;Lee, Jae-In;Choi, Se-Jin
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2023.05a
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    • pp.321-322
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    • 2023
  • This study compared the compressive strength and healing strength to confirm the self-healing performance of mortar incorporating Bioinspired Self-healing Capsule (BSC) into cement composites as part of a study to mitigate the problem of durability deterioration due to cracks in concrete structures. As a result of the evaluation, it was found that the healing performance decreased as the mixing ratio of the BSC capsule increased.

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Evaluation of the Resilient and Permanent Behaviors of Cohesive Soils (점성토의 회복 및 영구변형 특성 평가)

  • SaGong, Myung;Kim, Dae-Hyeon;Choi, Chan-Yong
    • Journal of the Korean Society for Railway
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    • v.11 no.1
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    • pp.61-68
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    • 2008
  • Resilient modulus has been used for characterizing the stress-strain behavior of subgrade soils subjected to traffic loadings. With the recent release of the M-E Design Guide, highway agencies are further encouraged to implement the resilient modulus test to improve subgrade design. The subgrade design for the trackbed, however, is primarily relying on the static test results such as $K_{30}$ and deformation modulus, Ev. Therefore applicability of the resilient modulus for the design of trackbed needs to be evaluated. In this study, physical property tests, unconfined compressive tests and resilient modulus tests were conducted to assess the resilient and permanent strain behavior of 14 cohesive subgrade soils. A predictive model for estimating the resilient modulus is proposed based on the results of unconfined compressive tests and tangent elastic modulus, unconfined compressive strength, failure strain, secant modulus at peak, and yield strain. The predicted resilient moduli using the predictive models compared satisfactorily with measured ones. Although the permanent strain occurs during the resilient modulus test, the permanent behavior of subgrade soils is currently not taken into consideration.

The Effects of Steel-Fiber Reinforcement on High Strength Concrete Replaced with Recycled Coarse Aggregates More Than 60% (순환굵은골재 60% 이상 사용한 고강도 콘크리트에 대한 강섬유 보강 효과)

  • Kim, Yoon-Il
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.4 no.4
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    • pp.404-417
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    • 2016
  • The purpose of this study is to examine the extent to which the deterioration in strength of high strength concrete of 60MPa replaced by a large amount of recycled coarse aggregates (more than 60% to 100% of replacement ratio) could be recovered with steel fiber reinforcement through material compressive strength test and shear failure test on short and middle beams and then to offer useful data for aggregate supply system of a sustainable resource circulation type. This study first examined the results of previous related tests. The results of the material compressive strength tests confirmed that when using a combination of steel fiber reinforcements of volumn ratio 0.75% and high quality recycled coarse aggregates with an water absorption rate within 2.0%, the strength characteristics of high strength concrete of 60MPa level were not only restored to the strength level of concrete made with natural aggregates, but also showed superior ductility. And the shear failure tests on short and middle beams using recycled coarse aggregates more than 60% with shear span to depth ratio (a/d) of 2 and 4 controlled by shear forces mainly confirmed that effects of superior shear strength increase and ductile behavior characteristics were showed by steel fiber reinforcements.

고온 환경조건의 육용종계에서 비타민 섭취에 의한 난각질 저하 방지 효과

  • 지규만;정만기
    • Proceedings of the Korea Society of Poultry Science Conference
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    • 2003.05a
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    • pp.49-59
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    • 2003
  • Heat stress환경의 육용종계에서 사료에 첨가한 비타민 C(200 mg/kg)와 비타민 E(250 mg/kg)가 난각 품질 및 경골 강도에 미치는 영향을 확인하고자 실험을 실시하였다. 강제 환우에서 회복된 83주령의 Ross품종 육용종계 160수를 4처리 4반복 10수씩 개별 케이지에 수용 한 뒤, 10일간의 적응 기간을 둔 뒤, 3주간에 걸쳐 32$^{\circ}C$에서 지속적으로 온도를 유지하면서 사료 섭취량, 산란율, 폐사율, 난중, Haugh unit, 난각의 품질, 경골 파괴강도 그리고 혈액 중의 혈구 세포 등을 조사하였다. Heat stress는 폐사율, 산란율, 난중, 그리고 Haugh unit를 감소시키는 경향이 있었으나 통계적으로 유의하지는 않았다. 난각의 SWUSA와 압축 파괴강도는 비타민 C/E 첨가구에서 2, 3주차에 무첨가구보다 유의하게 높았으나 (P<0.05), 비타 C 또는 E 첨가구 사이에서는 유의차가 없었다. Heterophil과 lymphocyte의 숫자는 heat stress 동안에 각각 증가 또는 감소하였다. 처리구간에는 비타민 C/E 첨가구가 H/L/ratio 수준이 가장 낮았으며, 무첨가구가 가장 높은 경향을 나타내었다. 경골의 파괴강도는 비타민 C 첨가구에서 가장 높았다(P<0.05). 혈액 중의 비타민 C 농도는 비타민 C첨가구와 비타민 C/E 첨가구에서 각각 12.73 g/ml과 8.23 g/ml으로 높았다(P<0.05). 비타민 E 첨가구와 비타민 C/E 첨가구에서 혈액 중 비타민 E 농도가 유의하게 높았다 (P<0.05). Corticosterone 농도는 무첨가구에서 5.97g/ml으로 통계적으로 유의하게 높았다.(P<0.05).

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An Experimental Study on Crack Self-Healing and Mechanical Recovery Performance of Cement Composites Materials Using Encapsulated Expandable Inorganic Materials based Solid Healing Materials (캡슐화된 팽창성 무기재료 기반 고상 치유재 활용 시멘트 복합재료의 균열 자기치유 및 역학적 회복성능에 관한 실험적 연구)

  • Choi, Yun-Wang;Nam, Eun-Joon;Kim, Cheol-Gyu;Oh, Sung-Rok
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.10 no.1
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    • pp.92-100
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    • 2022
  • In this paper, to evaluate the effect of SC on the crack self-healing performance and mechanical recovery performance of cement composites, encapsulated intumescent inorganic material-based solid healing materials were prepared. SC was mixed with cement composite materials to evaluate the basic properties, permeability test, and load reload test. SC slightly improved the flow of cement composites, and the compressive strength decreased by about 10 %. Also, the flexural strength decreased by about 30 %. It was found that when SC was mixed with the cement composite material by 5 %, the crack self-healing rate of Plain was improved by about 𝜟10 %. As a result of the load reload test, it was found that the mechanical recovery rate of Plain was improved by about 𝜟20 %. In addition, as a result of analyzing the correlation between the crack self-healing rate and the mechanical recovery rate by the load reload test, it is judged that the healing area of the Plain can be increased due to SC.

Investigation of Oswatitsch Scheme for Maximum Total Pressure Recovery of Hypersonic Wedge-type Intakes (극초음속 쐐기형 흡입구의 최대 전압력 회복률을 위한 오스와치 기법 분석)

  • Heo, Yub;Moon, Kyoo-Hwan;Sun, Hong-Gye
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.45 no.12
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    • pp.1031-1038
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    • 2017
  • In order to improve the performance of the air breathing engines, it is important to maximize the total pressure recovery through air intake. In this study, we investigated whether the Oswatitsch method, which guarantees the maximum pressure recovery for supersonic intake, is effective at hypersonic speed by compressing the intake air with the same intensity at each ramp. The non-linearity of the shock wave normal Mach number at each ramp stage was analyzed by comparing the compression ramp angle and the number of ramp to the inflow Mach number in terms of compressible thermodynamics and the operation limits of the inlet. Based on this analysis, the Oswaitisch technique yields valid conditions not only in supersonic but also hypersonic flight regime.

Physical Properties of Self-healing Concrete Mixed with Hydrogel Carrier of Microorganism (미생물 혼입 하이드로젤 지지체 첨가에 따른 자기치유 콘크리트의 물성 변화)

  • Chu, Inyeop;Woo, Jinho;Woo, Sang-Kyun;Lee, Byungjae
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.22 no.6
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    • pp.24-29
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    • 2018
  • The properties of concrete with addition of microgel - containing hydrogel support were investigated. As a result of measuring the slump of the self - healing concrete, the target slump was satisfied in all the mixing conditions, but the slump was decreased as the mixing amount of the hydrogel support increased. The change of porosity due to incorporation of hydrogel support was minimal. As a result of the evaluation of the compressive strength of the self - healing concrete, the incorporation of the hydrogel support did not affect the strength. However, under the same mixing condition, the dispersion value of the specimens tended to increase with increasing hydrogel support contents. As a result of the permeability test of self-healing concrete according to the incorporation of hydrogel support, it was confirmed that the mixing ratio of hydrogel support was effective to decrease the permeability coefficient.

An Experimental Study on Strength Properties of Concrete Using Blast-Furnace Slag Subjected to Freezing at Early Age (초기재령에서 동결을 받은 고로슬래그 콘크리트의 강도발현특성에 관한 실험적 연구)

  • Choi, Sung-Woo;Ban, Seong-Soo;Ryu, Deuk-Hyun;Choi, Bong-Joo
    • Journal of the Korea Concrete Institute
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    • v.15 no.1
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    • pp.43-51
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    • 2003
  • Recently, to consider financial and constructive aspect usage of Admixture such as Blast-Furnace Slag and Fly-Ash, are increased. Also the use of cold-weather-concrete is increased. Blast-Furnace Slag, a by-product of steel industry, have many advantage to reduce the heat of hydration, increase in ultimate strength and etc. But it also reduces early-age strength, so it is prevented from using of Blast-Furnace Slag at cold-weather-concrete. In this study, for the purpose of increasing usage of Blast-Furnace Slag at cold-weather-concrete, it is investigated the strength properties of concrete subjected to frost damage for the cause of early age curing. The factors of this experience to give early frost damaged were Freezing temperature(-1, -10, $-15^{\circ}C$), Early curing age(0, 12, 24, 48hour), Freezing times(0, 12, 24, 48hour). According to this study, if early curing is carried out before haying frost damage, the strength of concrete used admixture, subjected to frost damage, is recovered. And that properties are considered, the effect of using admixture like blast-furnace-slag, is very high

INFLUENCE OF SODIUM ALGINATE CONTENTS ON THE STRAIN IN COMPRESSION, ELASTIC RECOVERY, AND COMPRESSIVE STRENGTH OF EXPERIMENTAL ALGINATE IMPRESSION MATERIALS (알긴산소오다 함량이 실험적 알지네이트 인상재의 압축변형율, 탄성회복율 및 압축강도에 미치는 영향)

  • Lee Yong-Sik;Choi Boo-Byung;Lee Sung-Bok
    • The Journal of Korean Academy of Prosthodontics
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    • v.41 no.2
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    • pp.243-257
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    • 2003
  • The purpose of this study was to search the influences of the increase of the contents of sodium alginate in the experimental alginates on the some mechanical properties. 3 commercial alginates were selected for the purpose of comparison of the results of experiments. 7 experimental alginates were manufactured with the rise of contents of sodium alginate from 8.8% to 18.3% with the decrease of contents of diatomaceous earth and with the constant contents of calcium sulfate 12.5%. sodium phosphate 2.2%, zinc fluoride 2.0%. Splitable metal mold with 12.5mm diameter and 20.0mm height was filled with mixed alginate to prepare the cylinder shaped specimens. Strain in compression, elastic recovery, compressive strength were tested using the ISO specification number 1563, alginate impression material. Experimental groups were 7, and 10 specimens were used for each test items and each groups. Following results were obtained ; 1. Strain in compression was decreased with the increase of sodium alginate contents (p=0.0077, r2 = 0.6302). 2. Elastic recovery was decreased with the increase of sodium alginate contents but was not significant(p=0.0639, r2=0.7449). 3. Compressive strength was increased with the increase of sodium alginate contents (p<0.0001, r2 = 0.9617). These results mean that the increase of sodium alginate contents make alginate harder but may result the increased permanent deformation.