• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.731-736
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• 2003

Alkali silicate system has wide application to accelerating admixture for shotcrete, but it has several problems that decrease long-term strength and delay setting time. So alkali-free system was gradually focused on accelerating admixtures for shotcrete due to its environmental property. The aim of this study is to investigate effect of alkali-free accelerating admixtures on aluminum sulfate system containing diethanolamine or acrylic acid etc. The alkali-free accelerating admixture has better properties than silicate system accelerating admixtures on compressive strength and low pH as shotcrete. Especially, the compressive strength of alkali-free accelerating admixture containing diethanolamine was increased about 10% compared with the value of ordinary portland cement.

• 콘크리트학회논문집
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• 제17권6호
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• pp.879-884
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• 2005

응결시간은 터널 라이닝과 경사면의 보강 등의 품질에 영향을 미치는 매우 중요한 인자이다. 그러나 현재까지도 이를 개선하는데 이용될 급결제의 품질에 대한 기준은 잘 정립되어 있지 않은 상태이다. 본 연구에서는 급결제를 혼합한 시멘트의 응결시간 측정방법에 대한 평가가 Gillmore 및 Vicat needle 시험법들을 이용하여 수행되었다. 양 시험법에 있어서, 초결과 종결에 관계없이 동시첨가법이 후첨가법보다 우수하게 나타났다. Gillmore needle 시험법에서는 2종류의 측정법이 사용되었으며 동일한 급결제를 사용한 경우에도 시멘트의 종류에 따라 응결시간이 서로 달랐다. 따라서 급결제 제조사에서는 시멘트의 종류에 덜 민감한 급결제의 개발에 관심을 더 두어야 함을 알 수 있다. 한편, Vicat needle 시험법에서는 6종류의 측정법이 사용되었으며 급결제의 측정 방법에 대한 적절한 방법이 다음과 같이 제안되었다. (1) 사용되는 재료의 온도는 적절히 제어되어야 한다. (2) 급결제의 특성을 평가하기 위해서는 시멘트 무게 대비 $5\%$의 급결제를 사용해야 한다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.317-320
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• 2004

The setting time is very important factor affecting the quality of tunnel lining and reinforcement of sloped slope etc. Currently, however, the quality criteria of accelerating admixture to improve it is not established well. In this study, evaluation on setting time measuring methods of a cement accelerating admixture was performed. Six types of measuring methods were checked and a proper measuring method of the admixture were proposed as fellows: (1) the temperature of materials used shall be controlled exactly and (2) to evaluate the properties of it, an admixture usage of $5\%$ (ratio of cement weight) is recommended.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
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• pp.257-258
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• 2009

본 연구에서는 염해 저항성 평가방법인 KS F 2711과 NT Build 492와의 상관관계를 추정하기 위하여 결합재 종류별 염해 저항성을 평가하였다. 또한, 수화자극제 사용시의 효과도 평가하여 활용가능성을 검토하고자 하였다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2012년도 추계 학술논문 발표대회
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• pp.217-219
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• 2012

In this study, the experiment was conducted in the level of mortar as one of the basic studies on pre-cast concrete which acceleration curing is not done. This study has the purpose to develop the strength of mortar into 20MPa within 6 hours in the condition of room temperature using admixtures which can accelerate C3S hydration reaction. In this experiment, W/C was fixed into 20%, PCE which can stimulate C3S was used as an accelerating admixture. From the results of this experiment, maximum content of accelerating admixture was 1%. Also, as more than 20MPa was measured through 6-hour compressive strength, it can be known that strength can be developed without steam-curing.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2010년도 춘계 학술대회 제22권1호
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• pp.323-324
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• 2010

본 연구는 국내에서 사용하고 있는 숏크리트용 급결제의 알칼리-실리카 반응성을 검토하기 위하여 실시하였다. 따라서 국내산 1종 시멘트에 급결제(알루미네이트계, 알칼리프리계, 시멘트광물계)를 혼입하여 알칼리-실리카 반응에 대한 영향을 검토해 보았다. 시험 결과 비반응성 골재를 사용한 경우 급결제의 등가알칼리 함량이 달라져도 알칼리-실리카 반응으로 인한 유해한 팽창은 발생하지 않았다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2006년도 추계 학술논문 발표대회 논문집
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• pp.91-94
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• 2006

The way to shorten a construction period is considered to an very important technology development element as reducing the formwork removal periods with promoting strength revelation own concrete. This study executed experiment to review usability of early strength revelation chemical admixture which is judged in ways effective with premature removal of form about concrete. Use of early strength revelation AE water reducin admixture is apperaing so that strength revelation by early hydration promotions is excellent. The results of being applied proposed work process are that compressive strength are appeared more than 5MPa within 16 hours so that removal of vertical form was possible. the concrete compressive strength satisfied with a more than 2/3 of specified concrete strength for removal of horizontal form are appeared in 42 hours of 27 MPa proportioning strength, in 36 hours of 30, 35 MPa proportioning strength so that the 6 days cycle time of concrete structural frame work is cut by 2 days as shortening delayed period in works of removing slab forms. So construction cost reductions and a construction period shortening are judged so that it is possible.

• 한국세라믹학회지
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• 제53권1호
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• pp.116-121
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• 2016

The amount of carbon dioxide ($CO_2$) released while producing building materials is substantial and has been targeted as a leading contributor to global climate change. One of the most typical methods of reducing $CO_2$ in building materials is the addition of slag and fly ash, like pozzolan material another method is to reduce $CO_2$ production by developing carbon negative cement. MgO-based cement from the low-temperature calcination of magnesite required less energy and emitted less $CO_2$ than the manufacturing of Portland cements. It is also believed that adding reactive MgO to Portland-pozzolan cements can improve their performance and also increase their capacity to absorb atmospheric $CO_2$. In this study, basic research on magnesia cement using $MgCO_3$ and magnesium silicate ore (serpentine) as the main starting materials, as well as blast furnace slag for the mineral admixture, was carried out for industrial waste material recycling. In order to increase the overall hydration activity, $MgCl_2$ was also added. In the case of the addition of $MgCl_2$as accelerating admixture, there was a promoting effect on the compressive strength. This was found to be due to the production of needle-like dense Mg-Cl hydrates. Mgnesia cement has a high viscosity due to its high specific surface area therefore, when the PC-based dispersing agent was added at a level of more than 1.0%, it had the effect of improving fluidity. In particular, the addition of $MgCl_2$ in magnesia cement using $MgCO_3$and magnesium silicate ore (serpentine) as main starting materials led to a lower expansion ratio and an increase in the freeze-thaw resistance finally, the addition of $MgCl_2$ as accelerating admixture led to good overall durability.

• 한국구조물진단유지관리공학회 논문집
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• 제15권1호
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• pp.263-270
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• 2011

이 연구에서는 프리캐스트 콘크리트용으로 공장에서 생산되며 그 동안 국내에서 많이 사용되어온 음이온계 계면활성제의 일종인 나프탈렌 설폰산염계(Poly-Naphthalene Sulfonate Type) 혼화제와 국내 J사에서 개발된 조강형 폴리카본산계(Polycarboxilic Type) 혼화제인 WF2000의 성능을 평가하였다. 실험결과에 의하면, WF2000은 PNS계보다 20% 줄어든 사용량에도 제품이 가지고 있는 높은 감수율과 고온에서 콘크리트 응결의 촉진효과 및 우수한 분산작용으로 인하여 작업성의 개선되었으며 PHC 파일의 조기강도와 장기강도 발현에 유리하였다. 그리고 감수력과 유지력의 조절이 가능하여 원재료의 변동 및 환경조건의 변화에 적절한 대응이 가능한 혼화제로 하절기의 생산성과 작업성 저하 그리고 성형성 불량의 문제 및 동절기의 응결지연으로 인한 조기강도의 저하에 대한 문제 해결 등에 유리하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.201-206
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• 2002

The purpose of this study is to improve the anti-corrosive properties of coated reinforcing bar using polymer cement slurry. Poymer cement slurry are prepared with three types of polymer dispersions and corrosion inhibiting admixture. And tested for corrosion accelerating tests such as immersion in NaCl 10% solution NaCl 10% solution spray, high temperature and pressure steam in condition of 8cycles, carbonation before and after, penetration of NaCl solution. From the test results, it is concluded that the anti-corrosive properties are considerably improved by coating using polymer cement slurry at surface of reinforcing bar. And this trend is marked by adding of corrosion inhibiting admixture. The difference of the anti-corrosive properties is hardly recognized according to types of polymer dispersions. The anti-corrosive properties of coated reinforcing bar using polymer foment slurry are improved to a great extent compared to those of plain reinforcing bar accordiy to increasing content of chloride ion in cement concrete.