• 한국산업융합학회 논문집
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• 제13권2호
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• pp.99-106
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• 2010

The effects of additive and shrinkage reducing agent on the drying and autogenous shrinkage of high strength concrete are investigated in this study. As results, when the ratio of W/B(low water to binder ratio) increase, the compressive strength is decreased. Comparing with PC(portland cement) concrete, the strength is 2.8%, 3.2% and 3.8% lower respectively than that of PC when concrete mixing ratio is 0.2%, 0.3% and 0.4% in 28 days curing. Drying shrinkage strain of PC concrete showed $-650{\times}10^{-6}$ in 91 days curing. When SR(shrinkage reducing agent) of 0.2%, 0.3% and 0.4% is mixed, the drying shrinkage strains are 21%, 34% and 41% lower than those of PC in 91 days curing. Autogenous shrinkage strain of PC concrete appeared $-480{\times}10^{-6}$ in 56 days curing. When SR of 0.2%, 0.3% and 0.4% is mixed, the autogenous drying shrinkage strain are 12.5%, 19.8% and 33.3% lower than those of PC in 56 days curing. In cases of using the mineral and shrinkage agent or only using a shrinkage reducing agent also appeared same reducing effects for drying shrinkage and autogenous shrinkage.

• 한국건축시공학회지
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• 제12권1호
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• pp.64-72
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• 2012

Recently, prepackaged-type surface preparation materials using redispersible polymer powders are widely used for interior and exterior finishing in the construction work. The purpose of this study is to evaluate the performance and the quality of prepackaged-type surface preparation materials using a VA/E/MMA terpolymer powder. Surface preparation materials using a VA/E/MMA terpolymer powder were prepared with shrinkage reducing agent contents of 0, 4 % and cellulose fiber contents of 0, 0.5, 1.0 %, and tested for drying shrinkage, strengths, adhesion in tension, crack and impact resistance, water absorption, permeability. As a result, prepackaged-type surface preparation materials show outstanding performance depending on the shrinkage reducing agent and cellulose fiber contents.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
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• pp.183-188
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• 1997

From a viewpoint of construction cost and preserving management of pavement, a policy of domestic pavement was gradually spreaded concrete pavement rather than asphalt. But the use of concrete with ordinary portland cement has shortages, such as dry-shrinkage, low flexural strength, etc. In order to overcome these problems, the concrete pavement using CSA expansive additive (Non-Shrinkage Cement) was studied and carried out the fie이 application. As the results, we find out Non-Shrinkage Cement that was distinguished in short-term construction by increasing flexural strength, shrinkage compensating and low-heat evaluation compared with OPC concrete.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 가을 학술발표회 논문집
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• pp.417-420
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• 2003

Concrete with low water to binder ratio (W/B) is prone to large autogenous shrinkage. Early age cracking of concrete would be caused by tensile stress induced by large autogenous shrinkage under restrained condition. Therefore, it is necessary to measure autogenous shrinkage to control the early age cracking of concrete. An objective of this study is to investigate the effects of W/B and blast furnace slag (BFS) on autogenous shrinkage of concrete. Autogenous shrinkage of concrete with various W/B ranging from 0.42 to 0.27 and BFS contents of 0, 30 and 50% were measured. Test results show that the autogenous shrinkage of concrete increases as the W/B decreases, and all BFS concretes showed larger autogenous shrinkage than OPC concretes with the same W/B. Moreover, the higher BFS content, the larger autogenous shrinkage.

• 한국산학기술학회논문지
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• 제17권7호
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• pp.342-347
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• 2016

본 연구에서는 일반 강도 콘크리트 초저수축 특성을 얻는데 필요한 현장 배합시 굵은 골재의 최대치수, 잔골재의 종류에 따른 굳지 않은 콘크리트 물성과 굳은 콘크리트의 물성 및 건조수축 길이변화 특성을 평가하였다. 또한 시공시 양생 온도에 따른 수축 특성을 평가하였다. 배합 인자로는 각각 굵은 골재 최대치수(13, 20, 25mm), 잔골재의 종류(세척사, 세척사+부순사, 부순사), 양생 온도(5, 20, $35^{\circ}C$) 총 9가지 배합 요인에 따른 콘크리트의 압축강도, 콘크리트의 건조수축 길이변화를 측정하였다. $350{\mu}{\varepsilon}$의 초저수축 특성을 일반 강도 콘크리트에서 얻는데 굵은 골재는 최대 25mm까지 적용 가능한 것으로 평가되었으며, 잔골재의 입도가 매우 큰 영향을 주는 것으로 나타났다. 또한 한중 및 서중 콘크리트를 제외한 양생 온도 범위에서 초저수축 특성을 얻을 수 있는 것으로 나타났다. 또한 분말형 수축저감제를 적용한 결과 굵은골재의 최대치수는 최대 25mm 내에서 $350{\mu}{\varepsilon}$ 내의 수축 특성을 나타내는 것으로 나타났다. 유동성과 압축강도는 굵은 골재의 최대치수가 커지면 각각 증가하고 감소하는 일반적 경향이 반영되었다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 봄 학술논문 발표대회
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• pp.209-210
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• 2021

This study aims to develop ultra-low-shrinkage high-quality concrete. Therefore, the concrete drying shrinkage characteristics according to the type and amount of the shrinkage reducing agent were reviewed. As a result, the performance of Hexylene Glycol(HG) and Polyol was superior to that of PolyEthylene Glycol(PEG), which is most widely used in Korea. In addition, the shrinkage reduction effect was improved as the amount of PEG was increased, but the disadvantage of the strength reduction when excessive use was confirmed.

• 한국세라믹학회지
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• 제33권7호
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• pp.725-734
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• 1996

점토질 소지에 있어서 수축 특성은 성형, 건조 및 소성 공정에 수반되어 치말화거등에 기여할 수 있는 구동력이 될 수 있다. 점토질 소지에서 저수축 치말화거동은 입자크기효과와 상전이 특성에 기인하는 열간 반응전이 거동을 포함하는 공정변수에 따라 크게 변화됨을 보였다. 90$0^{\circ}C$ 및 120$0^{\circ}C$에서 열처리된 Chamotte의 첨가를 통해서 점토질 소지의 열간 치밀화 과정에 기인하는 공정수축은 크게 억제될 수 있었다. 120$0^{\circ}C$에서 열처리된 조대한 Chamotte 입자는 점토 소지의 치밀화 거동을 억제하여 치밀한 소결미세구조를 얻을 수는 없었지만, 조대한 Chamotte 입자의 첨가는 neat-net-shape 제어를 촉진할 수 있었다. 점토질 소지에 있어서 미세구조/물성간의 연관관계는 저수축과 치밀화 거동사이의 상반된 특성을 제어함으로써 얻어진 최적조건에 따라 직접적인 영향을 받을 것으로 판단되었다.

• Transactions on Electrical and Electronic Materials
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• 제12권1호
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• pp.32-34
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• 2011

A zero-shrinkage sintering process in which the shrinkage of the x-y axis is controlled to be zero is in great demand due to the high integration trend in ceramic modules. Among the zero-shrinkage sintering processes available, the glass infiltration method proposed in the preliminary study with an $Al_2O_3/Glass/Al_2O_3$ structure is one promising method. However, problems exist in regard to the glass infiltration method, including partially incomplete joining between $Al_2O_3$ and glass layers due to the precipitate of Ti-Pb rich phase during the sintering process. Therefore, we wish to solve the de-lamination problems and suggest a mechanism for delamination and the solutions in the zero-shrinkage low temperature co-fired ceramic (LTCC) layers. The de-lamination problems diminished using the Pb-BSi-O glass without $TiO_2$ in Pb-B-Ti-Si-O glass and produced a very dense zero-shrinkage LTCC.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 춘계학술대회 논문집
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• pp.507-511
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• 2008

LTCC (Low Temperature Co-fired Ceramic) has been successfully applied to ceramic substrates for circuits and micro-fluidic systems and has proven its superior performance in a variety of applications. The prediction of shrinkage in LTCC process is an important for dimensional control of micro LTCC products which has influences on electronic characteristics. For avoiding the unpredictable shrinkage of LTCC during the sintering which makes accurate placement of the circuit devices difficult, pre-processes such as WIP (Warm Isostatic Pressing) and lamination must be modified. The objective of the present investigation is to establish a proper WIP conditions for near net shape fabrication of LTCC products. This paper discusses the influence of WIP conditions on the dimensional change of LTCC sheet. In the investigation, it is shown that the shrinkage values of sheets depend on WIP conditions and sheet directions. This work is a quantitative evaluation of the effect of WIP pressure on shrinkage of LTCC sheet. Additionally, the results show anisotropic shrinkage behaviour of sheet during LTCC process.

• 한국세라믹학회지
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• 제29권6호
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• pp.419-430
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• 1992

Fabrication possibility of low-shrinkage alumina without oxidation and wetting agent was presented on the basis of observation about oxidation behavior, microstructure and physical characteristics of such reaction agents free Al2O3-Al system. The composition less than Al 10w/o where Al can act as a sintering agent for Al2O3 was excluded. Under the condition of present experiments oxidation of Al2O3-Al system was dependent not on holding time but mainly on oxidation temperature. In thes case of Al powder not comminuted effectively during powder mixing of Al2O3-Al, columnar structure which would act as a hindrance to the densification during sintering developed more during oxidation with higher Al contents, and which made the fabrication of low-shrinkage Al2O3 ceramics impossible. If Al powder was comminuted effectively due to co-mixed Al2O3 characteristics, densification was improved because of no columnar structure and made the fabrication of sintered body with -2.7% dimensional change and 81% relative density possible. As a result, it is possible to fabricate dense low-shrinkage Al2O3 ceramics without oxidation and wetting agent under conditions such as smaller particle size of Al, Al contents below 50v/o, higher green density of Al2O3-Al compact and the use of Al2O3 powder used for high-density ceramics.