• Title/Summary/Keyword: 결합재 비

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Cyclic Responses of Steel Reinforced ECC Column under Reversed Cyclic Loading Conditions (철근 보강된 ECC 기둥의 반복하중에 대한 이력거동)

  • Hyun, Jung-Hwan;Shim, Young-Heung;Bang, Jin-Wook;Kim, Yun-Yong
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.19 no.4
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    • pp.75-82
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    • 2015
  • In this study, experimental research was carried out to evaluate steel reinforced ECC (Engineered Cementitious Composites) column, which exhibits excellent crack control property and highly ductile behavior. Ordinary portland cement and high volume fly ash were used as binding materials in the mixture proportions for the purpose of achieving a high level of multiple cracking property with the tightly controlled crack width. To compare with the cyclic behavior of steel reinforced ECC column specimen, a conventional reinforced concrete column was prepared and tested under reversed cyclic loading condition. Based on the cyclic load test, ECC column exhibited higher cyclic behavior, compared to the conventional RC column, in terms of load carrying capacity and energy dissipation capacity.

Effect of Hydration Heat and Drying Shrinkage of Mass Concrete Using Hwangtoh Binder (황토결합재를 이용한 매스콘크리트의 수화열과 건조수축 효과)

  • Kang, Sung-Soo;Lee, Seong-Lo
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.04a
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    • pp.649-652
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    • 2008
  • In this paper, the applicability of hwangtoh, as an alternative of cement paste, is investigated for the solution of internal heat and shrinkage caused by the hydration of cement paste. Several small-sized specimens of hwangtoh and ordinary portland concrete(OPC) were compared as to compressive strength, heat of hydration, and shrinkage strain. Moreover, the applicability of mass structure was reviewed through the test of large-size specimens. The 28-day compressive strength of hwangtoh concrete(HBC), ranged 18 to 33 Mpa, can reach that of ordinary portland concrete. Not only the maximin internal temperature of HBC was read about 1/4 of OPC as it is cured, but also its drying shrinkage decreased as lower as 50% of OPC starting from 60 days. Therefore, hwangtoh binder is more favorable than cement one in the view of hydration heat and shrinkage under the construction of mass structures.

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A Study of 240MPa Ultra High Strength Concrete Properties Using High Flow Cement (하이플로 시멘트를 이용한 240MPa 초고강도 콘크리트 물성에 관한 연구)

  • Kim, Kang-Min;Yoo, Seung-Yeup;Song, Yong-Soon;Koo, Ja-Sul;Kang, Suck-Hwa;Jeon, Hyun-Kyu
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.04a
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    • pp.365-368
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    • 2008
  • This research is related to 240MPa ultra-high strength concrete(UHSC) with extremely loss W/B ratio. For this development, High flow cement is mainly used which has a short reaction rate due to the high blaine and high early strength, which can make greater fluidity in case of very low W/C ratio. It made the best mixture using the mineral admixtures silica fume, slag powder and special admixture. For dispersibility and homogeneity of cement binder, cement of premix type is produced using omni-mixer. Moreover, it ensures the fluidity of ultra-high strength concrete(UHSC). For having a good fire performance, we made an experiment special coarse aggregate. As a result, we got 180MPa in case of water curing, 200MPa in case of steam curing and uniform UHSC of 240MPa in case of a special curing method.

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Micro-shear bond strength of resin-modified glass ionomer and resin-based adhesives to dentin (상아질 위치에 따른 접착성 수복재의 미세전단결합강도에 관한 연구)

  • Hong, Hyun-Kyung;Choi, Kyoung-Kyu;Park, Sang-Hyuk;Park, Sang-Jin
    • Restorative Dentistry and Endodontics
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    • v.28 no.4
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    • pp.314-325
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    • 2003
  • 이 연구의 목적은 수종 상아질 접착 시스템과 복합 레진 및 resin-modified glass ionomer를 상아질 표면에 접착하여 재료 및 상아질내 위치에 따른 미세전단결합강도를 측정, 비교하는 것이다. 상아질 접착 시스템으로는, 3-step인 Scotchbond Multi-Purpose Plus, 2-step인 Single Bond와 자가 부식형 시스템인 Clearfil SE Bond를, 1-step인 Prompt L-Pop을 사용하였다. 이와 함께 hybrid type의 복합 레진인 Clearfil AP-X와 2250을 사용하였으며 resin-modified glass ionomer로는 Fuji II LC를 사용하였다. 상악 소구치를 치아의 근원심 중앙부를 절단하여 상아질면을 노출시켰다. 5개 실험군으로 분류하고 상아질면을 위치에 따라 치관부의 occlusal $\frac{1}{3}$, middle $\frac{1}{3}$, cervical $\frac{1}{3}$과 치근부로 구분지어 시편을 부착하였다. 미세전단결합강도측정는 Universal testing machine(EZ-test; Shimadzu, Japan)에서 측정하였다. Occlusal 1/3부위에서는 SE가 가장 높은 값을, SM과 SB간에는 유의차가 없었으며, PL, GI순으로, Middle 1/3부위에서는 $SM{\;}{\geq}{\;}SE{\;}{\geq}{\;}SB{\;}{\geq}{\;}PL{\;}{\geq}{\;}GI$순으로, cervical 1/3부위에서는 SM, SE, SB간에 유의차가 없었다. Root dentin에서는 SM이 가장 높은 값을 보였으며 SE, PL, GI간에 유의차가 없었다. SE만이 치관부 상아질에 비해 치근부에서 유의할만한 결합강도의 감소를 나타냈다(p<0.05). GI는 치관부 상아질에서는 다른 군에 비해 유의성 있게 낮은 결합강도를 보였으나 치근부에서는 SE, PL과 유의차가 없었다.

Shear bond strength of rebonded orthodontic bracket with flowable resin (Flowable resin을 이용한 브라켓의 재접착 시 전단결합강도에 대한 연구)

  • Kim, Dong-Woo;Son, Woo-Sung
    • The korean journal of orthodontics
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    • v.35 no.3 s.110
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    • pp.207-215
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    • 2005
  • This study was performed to evaluate clinical practicality of the rebonding method with flowable resin without the removal of the residual resin on the debonded theeth and debonded bracket base after debonding. The samples of the control group (group I) were rebonded with Transbond XT using the usual rebonding method after the residual resin was removed. At experimental group, the brackets were rebonded with Transbond XT(group II) and CharmFil Flow (group III) without removal of residual resin which is the possibility becoming the index (or rebonding to similar position With initial bonding. The Shear bond Strength of the each group was measured. Patterns of bonding failure were evaluated with modified ARI score. and the shear bond strength according to patterns of bonding failure at experimental group was compared. Between the control group $(6.51\pm1.21MPa)$ and the group II rebonded with Transbond XT $(6.30\pm1.01MPa)$ did not have significantly difference in the shear bond strength (p=0.534), and the shear bond strength of group II was Significantly lower 4han the group III rebonded With CharmFil Flow $(7.29\pm1.54 MPa)$ (P=0.009). At control group, there was not large difference if distribution of bending failure pattern. But at experimental group, bond failure did not occur in interface between the resin-enamel. and bond failure between the resin-bracket, within the resin was distributed similarly. There was not significantly difference in the shear bond strength according to patterns of bonding failure at experimental group (P>0.05) The result of this study showed that the method suggested in this study aid flowable resin as rebonding adhesive could be useful in clinically.

Physical Properties of the Hardened Loess Using Natural Binding Materials (천연 결합재를 사용한 황토경화체의 물성에 대한 연구)

  • Kim, Jin Seok;Oh, Young Hun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.16 no.4
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    • pp.44-51
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    • 2012
  • In this study, hardened loess bodies, which did not compose of cement or any chemical binder, were made and tested to evaluate the physical properties such as slump, air content, and compressive strength. Addition of a natural binding material to mixture of loess and lime showed better performance in physical properties. However a lime among natural binding materials is considered as a superior binder to improve the properties of the hardened bodies. According to the experimental results, mixing proportion with 45% of W/B ratio, $285kg/m^3$ of water content, and 60% lime substitution ratio was recommended to acquire the good performance of physical properties for the hardened loess bodies.

Mechanical Properties of Alkali Treated Kenaf Fiber Filled PP Bio-Composites (알칼리 처리된 Kenaf 섬유가 충전된 Polypropylene/Kenaf 바이오복합재의 기계적 특성)

  • Kim, Samsung;Lee, Byoung-Ho;Kim, Hyun-Joong;Oh, Sei Chang;Ahn, Sye-Hee
    • Journal of the Korean Wood Science and Technology
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    • v.37 no.3
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    • pp.222-230
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    • 2009
  • This study was to investigate the effect of alkali treatment for long kenaf fiber to improve fiber surface characterics by removal of wax, lignin and hemicellulose which affect adversely for matrix union. SEM observation was also studied to check out the interface adhesion improvement by the alkali pre-treatment. From the result, interface coherence increased by 3% alkali pre-treatment and reached a maximum by 5% alkali pre-treatment. However, the 3% the bio-composites treated with 3% alkali was highest tensile and flexural strength than other.

Suggesting Optimum Mix Proportion of Hardener for Soil-pavement Concrete Incorporating Natural Organic Lime and Magnesia-lime (천연유기석회 및 고토석회를 조합한 흙 포장 콘크리트용 경화재의 최적배합안 도출)

  • Han, Min-Cheol;Han, Jun-Hui
    • Journal of the Korea Institute of Building Construction
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    • v.20 no.2
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    • pp.113-121
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    • 2020
  • Lots of soil-pavement concrete placed showed a number of problems such as decreasing strength, and durability. In this research, to provide a solution of the problem reported the wasting materials of natural organic lime and magnesia lime were used as a hardener to achieve sufficient performance of soil-pavement concrete. Namely, as a stimulus of blast furnace slag, the natural organic lime and magnesia lime were tested within the mix proportion of 0 to 10 % for each lime to make a new hardener. As a result, in the case of mortar with 1 to 3 % of cement to fine aggregate, 30 % replaced blast furnace slag showed the more favorable results with 5 to 5 % of mix proportion for natural organic lime and magnesia lime.

Effect of Surface Treatments of Titanium on Bond Strength and Interfacial Characterization in Titanium-Ceramic Prosthesis (티타늄의 표면처리방법에 따른 티타늄-세라믹 보철시편의 결합강도와 계면특성)

  • Chung, In-Sung;Kim, Chi-Young
    • The Journal of the Korea Contents Association
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    • v.10 no.10
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    • pp.219-225
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    • 2010
  • The bonding strength between titanium and ceramic were analyzed according to the bonding agent and the coating methods of Au and TiN respectively. The bonding strength was measured through the 3 point bending test. Consequently, the bonding strength of the special bonding agent after the TiN coated (SPTB) group was $72.20({\pm}5.25)MPa$ which was the strongest one among groups. The bonding strength of the special bonding agent treated only (SPB) group was $67.66({\pm}12.10)MPa$, the special bonding agent after the Au coating SPGB group was $46.95({\pm}12.48)MPa$ and the SP group was $43.80({\pm}5.12)MPa$. Taking these results into account, the bonding strength of the SPB group shows the same as it of the SPTB group, however, it is stronger than SP group. And the TiN coated SPTB group shows the stronger bonding strength than the Au coated SPGB group.

Durability of High Strength Concrete according to the amount of Admixture (혼화재의 사용량에 따른 고강도 콘크리트 내구성)

  • Kim, Dong-Baek;Lee, In-Duk;Lee, Jae-Won;Kim, Jong-Hoon
    • Proceedings of the Korean Society of Disaster Information Conference
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    • 2022.10a
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    • pp.301-302
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    • 2022
  • 최근 들어 염해, 콘크리트의 탄산화, 동결융해 등의 열화요인 의하여 발생할 수 있는 콘크리트의 내구성에 대한 다양한 연구가 진행되고 있는데, 이러한 열화요인은 독립적이 아닌 복합열화의 형태로 작용하게 되는데, 열화현상을 저감하는 한 방편으로 플라이애쉬와 같은 혼화재를 사용하디도 한다. 플라이애쉬는 유동성 증진을 통한 내구성의 향상과, 수화열 저감을 통한 균열감소 및 장기강도 증진 등의 효과가 있으며, 시멘트를 대체함으로써 경제적인 효과를 유발하는 장점도 가지고 있다. 그러나 플라이애쉬는 품질편차가 크고, 경우에 따라서 미연탄소분에 의한 AE제 흡착 등으로 인한 콘크리트의 내구성 및 강도를 저하시킬 수 있는 요소를 내포하고 있으므로 사용 시 주의가 필요하다. 본 연구에서는 열화를 저감하고, 내구성을 갖는 고강도 콘크리트를 제조하기 위하여 다양한 배합비의 플라이애쉬 혼입 콘크리트를 실험한 후 그 결과를 분석·고찰함으로써 내구성 콘크리트의 제작 시 혼화재로서의 적용성 및 타당성을 검증하고자 하며, 플라이애쉬를 내구성 재료로 그 활용을 극대화하고, 다양한 플라이애쉬의 사용량과 물/결합재비(W/B)에 대하여 내구성이 높은 고강도 콘크리트 제조방법을 범용화하며, 그 품질을 평가하는 것을 목적으로 한다.

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