• Title/Summary/Keyword: low shrinkage

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Performance review of ultra-low shrinkage concrete by field application (현장적용을 통한 초 저수축 콘크리트의 성능 검토)

  • Kim, Kang-Min;Lee, Hyun-Seung;Seo, Tae-Seok
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2022.11a
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    • pp.211-212
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    • 2022
  • In this study, the cracking control performance of ultra-low shrinkage concrete was investigated by the field application. As a result, drying shrinkage crack occurred in normal concrete wall, but no crack occurred in ultra-low shrinkage concrete wall. It is determined that the drying shrinkage crack control effect of the ultra-low shrinkage concrete is excellent.

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An Experimental Study on the Shrinkage Properties of Ultra-Low Shrinkage Concrete (초 저수축 콘크리트의 수축특성에 관한 실험적 연구)

  • Seo, Tae-Seok;Kim, Kang-Min;Lee, Hyun-Seunh
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2021.11a
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    • pp.148-149
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    • 2021
  • In Japan, ultra-low shrinkage concrete has been developed and commercialized to control drying shrinkage cracks to the limit. However, in the case of South Korea, the study on this technology has not yet been conducted in earnest. Therefore, the study was conducted for the development of ultra-low shrinkage concrete to control the drying shrinkage crack of concrete to the limit, and in this study, after determining the mixture of ultra-low shrinkage concrete, a wall type mock-up specimen was produced to observe the shrinkage behavior of ultra-low shrinkage concrete.

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Analysis of Crack Control Effect of Ultra-low Shrinkage Concrete through Wall Mock-up Test (벽체 실물대부재실험을 통한 초 저수축 콘크리트의 균열제어 효과 분석)

  • Seo, Tae-Seok;Lee, Hyun-Seung;Kim, Kang-Min
    • Journal of the Korea Institute of Building Construction
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    • v.22 no.1
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    • pp.45-55
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    • 2022
  • Ultra-low shrinkage concrete is very effective for securing the quality and appearance of a concrete structure because it can control the drying shrinkage cracks of the concrete structure to within a certain limit. In this study, with the purpose of commercializing ultra-low shrinkage concrete, the optimal amount of expansive agent and shrinkage reducing agent was determined through a lab test, and a concrete wall mock-up test was conducted to examine the shrinkage properties and crack control effects of ultra-low shrinkage concrete. As a result, it was confirmed that there was little drying shrinkage deformation in the wall specimen, and furthermore that no cracks were generated.

A Preliminary Study on the Development of a High Elastic Modulus and Low-Shrinkage Roller-Compacted Concrete Base for Composite Pavement (복합포장용 고탄성 저수축 롤러전압콘크리트 기층 개발을 위한 기초연구)

  • Chung, Gun Woo;Lee, Seung Woo
    • International Journal of Highway Engineering
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    • v.19 no.1
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    • pp.45-52
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    • 2017
  • PURPOSES : The main purpose of this study is to develop a high elastic modulus and low-shrinkage roller-compacted concrete base (RCCB) in order to prevent fatigue cracking and reflective cracking in the asphalt surface layer of composite pavement. Using a rigid base material with low shrinkage can be a solution to this problem. Moreover, a strong rigid base with high elastic modulus is able to shift the location of critical tensile strain from the bottom of the asphalt layer to the bottom of the rigid base layer, which can prevent fatigue cracking in the asphalt layer. METHODS : Sensitivity analysis of composite pavement via numerical methods is implemented to determine an appropriate range of elastic modulus of the rigid base that would eliminate fatigue cracking. Various asphalt thicknesses and elastic moduli of the rigid base are used in the analysis to study their respective influences on fatigue cracking. Low-shrinkage RCC mixture, as determined via laboratory testing with various amounts of a CSA expansion agent (0%, 7%, and 10%), is found to achieve an appropriate low-shrinkage level. Shrinkage of RCC is measured according to KS F 2424. RESULTS : This study shows that composite pavements comprising asphalt thicknesses of (h1) 2 in. with E2 > 19 GPa, 4 in. with E2 > 15 GPa, and 6 in. with E2 > 11 GPa are able to eliminate tensile strain in the asphalt layer, which is the cause of fatigue cracking in this layer. Shrinkage test results demonstrate that a 10% CSA RCC mixture can reduce shrinkage by 84% and 93% as compared to conventional RCC and PCC, respectively. CONCLUSIONS : According to the results of numerical analyses using various design inputs, composite pavements are shown to be able to eliminate fatigue cracking in composite pavement. Additionally, an RCC mixture with 10% CSA admixture is able to reduce or eliminate reflective cracking in asphalt surfaces as a result of the significant shrinkage reduction in the RCC base. Thus, this low-shrinkage base material can be used as an alternative solution to distresses in composite pavement.

Factors Influencing the Camber of Cofired Resistor/Low Temperature Cofired Ceramics (LTCC) Bi-Layers (동시 소성된 저항/저온 동시 소성 세라믹(LTCC) 이중층의 캠버에 영향을 미치는 인자)

  • Ok Yeon Hong;Seok-Hong Min
    • Korean Journal of Materials Research
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    • v.33 no.12
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    • pp.537-549
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    • 2023
  • The sintering shrinkage behaviors of low temperature cofired ceramics (LTCC) and resistors were compared using commercial LTCC and thick-film resistor pastes, and factors influencing the camber of cofired resistor/LTCC bi-layers were also investigated. The onset of sintering shrinkage of the resistor occurred earlier than that of LTCC in all resistors, but the end of sintering shrinkage of the resistor occurred earlier or later than that of LTCC depending on the composition of the resistor. The sintering shrinkage end temperature and the sintering shrinkage temperature interval of the resistor increased as the RuO2/glass volume ratio of the resistor increased. The camber of cofired resistor/LTCC bi-layers was obtained using three different methods, all of which showed nearly identical trends. The camber of cofired resistor/LTCC bi-layers was not affected by either the difference in linear shrinkage strain after sintering between LTCC and resistors or the similarity of sintering shrinkage temperature ranges of LTCC and resistors. However, it was strongly affected by the RuO2/glass volume ratio of the resistor. The content of Ag and Pd had no effect on the sintering shrinkage end temperature or sintering shrinkage temperature interval of the resistor, or on the camber of cofired resistor/LTCC bi-layers.

Differential Drying Shrinkage and Autogenous Shrinkage of Concrete at Early Ages (초기재령 콘크리트의 부등건조수축과 자기수축에 관한 연구)

  • 김진근;이칠성
    • Proceedings of the Korea Concrete Institute Conference
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    • 1998.04a
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    • pp.309-314
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    • 1998
  • The moisture diffusion and self-desiccation cause the differential drying shrinkage and autogenous shrinkage at early ages, respecitvely. Thus total shrinkage strain includes the differential drying shrinkage and self-desiccation shrinkage. Thus in this study the shrinkage strain was measured at various positions in the exposed concrete and in the sealed concrete the self-desiccation shrinkage was measured. In low-strength concrete, the differential drying shrinkage increases very rapidly, but self-desiccation shrinkage is very small. But high-strength concrete shows the reverse result. And the analytical results for differential drying shrinkage were in good agreement with the test results.

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Changes of Camber on Lamination Conditions in alumina/Tungsten Cofiring Multilayer Package (알루미나/텅스텐 동시소성에 의한 다층 팩키지 제조시 적층조건에 따른 camber의 변화)

  • 성재석;구기덕;윤종광;이상진;박정현
    • Journal of the Korean Ceramic Society
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    • v.34 no.6
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    • pp.601-610
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    • 1997
  • In cofiring of multilayered alumina with tungsten, the change of camber with lamination condition was experimented and the effect of sintering shrinkage of alumina and tungsten was investigated. From the exact measurement of sintering shrinkage of tungsten thick film, as lamination pressure increased, the sintering shrinkage of alumina decreased but that of tungsten thick film was not changed. So it was though that the main factor which induced the sintering shrinkage difference between ceramics and metal with lamination condition was the change of sintering shrinkage of ceramics. In case of high lamination pressure, high green sheet density, the cofired specimen showed low camber due to low shrinkage difference between alumina and tungsten and there was a linear relation between camber and shrinkage difference. It was found that this shrinkage difference could change the thickness of tungsten film and the microstructure within via hole during cofiring.

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Effect of Autogenous Shrinkage on Shrinkage behavior in High Stength Concrete (자기건조수축을 고려한 고강도 콘크리트의 수축변형 특징에 관한 연구)

  • Paek, Nak-Seung;Cha, Soo-Won;Lee, Seong-Cheol
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.05b
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    • pp.429-432
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    • 2006
  • The shrinkage mechanism of high strength concrete is different from that of normal concrete. The shrinkage of normal concrete is subjected to evaporate moisture in concrete, but most shrinkage in high strength concrete is caused by chemical reaction. To analyze shrinkage of concrete exactly, it is necessary to divide drying shrinkage with autogenous shrinkage in terms of degree of hydration, especially in concrete with low W/C ratio. The proposed method can provide a rational basis for prediction of shrinkage in high strength concrete structure.

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Evaluation of Properties of Ultra-Low Shrinkage Concrete for Omission of Paking Lot Floor Joint (주차장 바닥 줄눈 생략을 위한 초저수축 콘크리트 물성 평가)

  • Kim, Kang-Min;Lee, Hyun-Seung;Yoon, Seob;Seo, Tae-Seok
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2022.04a
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    • pp.194-195
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    • 2022
  • The jointing of unsupported concrete on the parking lot floor is a process for cracking and stress relief due to concrete drying shrinkage and restraint, but curling occurs due to long-term drying shrinkage after the initial age. will be lowered Therefore, by using an expansion material and a shrinkage reducing agent, the dry shrinkage of concrete is realized to 200 με or less.

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Analysis of Characteristics in Low-shrinkage Cement Treated Base (저수축 시멘트 안정처리 기층의 특성분석)

  • Lee, Seung-Woo;Jeon, Beom-Jun;Kim, Jong-Won
    • International Journal of Highway Engineering
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    • v.6 no.2 s.20
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    • pp.61-70
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    • 2004
  • Cement treated Soil has superior characteristics as pavement-base including strength, curability, hardness, freezing resistance. However drying shrinkage of Cement treated base has been indicated as disadvantage, since reflection crack of surface layer is induced from drying shrinkage of cement treated base. This study propriety about low-shrinkage cement treated base that can control shrinkage of cement and control reflection crack at asphalt overlay & concrete slab.

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