• 한국건축시공학회지
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• 제20권4호
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• pp.321-330
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• 2020

지오폴리머의 반응성은 원재료의 구성성분 및 Si/Al비, Na/Al비, 물-결합재비, 비정질 요소 등을 고려하여 명확한 메커니즘을 규명하는 것은 매우 중요하다. 따라서 원재료 및 알칼리 활성화제의 구성성분을 고려한 %Na₂O, M_s는 반응성을 결정하는 중요한 요소가 된다. 하지만 다수의 연구에서는 알칼리 활성화제의 농도와 양생 조건 등의 기본적인 요소만을 고려하는 한계점을 나타내고 있다. 따라서 본 연구에서는 %Na₂O, Ms 및 고로슬래그 미분말의 혼입량에 따른 지오폴리머 페이스트의 강도특성, 반응열, 길이변화, 미세구조 분석을 실시하였다.

• 한국재료학회지
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• 제18권9호
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• pp.463-469
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• 2008

Non-sintering cement was manufactured with briquette ash. Alkali activator for compression bodies used a NaOH solution. In order to apply alkali-activated briquette ash and the non-sintering cement to concrete, several experimental studies were performed. It was necessary to study the binder obtained by means of a substitute for the cement. This study concentrated on strength development according to the concentration of NaOH solution, the curing temperature, and the curing time. The highest compressive strength of compression bodies appeared as $353kgf/cm^2$ cured at $80^{\circ}C$ for 28 days. This result indicates that a higher curing temperature is needed to get a higher strength body. Also, geopolymerization was examined by SEM and XRD analysis after the curing of compression bodies. According to SEM and XRD, the main reaction product in the alkali activated briquette ash is aluminosilicate crystal.

• 한국세라믹학회지
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• 제47권5호
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• pp.381-386
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• 2010

Some basic properties of inorganic coatings hardened by the room temperature reaction with alkalies were examined. The coating paste was prepared from the powders in the system $Al_2O_3-SiO_2$-CaO using blast furnace slag, fly ash and amorphous ceramic fiber after mixing with a solution of sodium hydroxide and water glass. The mineralogical and morphological examinations were performed for the coatings prepared at room temperature and after heating to $1200^{\circ}C$ respectively. The binding force of the coating hardened at room temperature was caused by the formation of fairly dense matrix mainly composed of oyelite-containing amorphous phase formed by the reaction between blast furnace slag and alkali solution. At the temperature, fly ash and ceramic fiber was not reacted but imbedded in the binding phase, giving the fluidity to the paste and reinforcing the coating respectively. During heating up to $1200^{\circ}C$, instead of a break in the coating, anorthite and gehlenite was crystallized out by the reaction among the binding phase and unreacted components in ternary system. The crystallization of these minerals revealed to be a reason that the coating maintains dense morphology after heating. The maintenance of binding force after heat treatment is seemed to be also caused by the formation of welldispersed fiber-like mineral phase which is originated from the shape of the amorphous ceramic fiber used as a raw materials.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 가을 학술논문 발표대회
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• pp.77-78
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• 2020

An alkaline activator was synthesized by dissolving waste glass powder (WGP) in NaOH-4M solution to explore its effects on the Class-C fly ash (FA) and ground granulated blast furnace slag (GGBS) based alkali-activated material (AAM). The compressive strength and porosity were measured, and (SEM-EDX) were used to study the hydration mechanism and microstructure. Results indicated that the composition of alkali solutions was significant in enhancing the properties of the obtained AAM. As the amount of dissolved WGP increased in alkaline solution, the silicon concentration increased, causing the accelerated reactivity of FA/GGBS to develop Ca-based hydrate gel as the main reaction product in the system, thereby increasing the strength. Further increase in WGP dissolution led to strength loss, which were believed to be due to the excessive water demand of FA/GGBS composites to achieve optimum mixing consistency. Increasing the GGBS proportion in a composite also appeared to improve the strength which contributed to develop C-S-H-type hydration.

• 한국도로학회논문집
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• 제17권2호
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• pp.99-105
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• 2015

PURPOSES: In this study, alkali-activated blast-furnace slag (AABFS) was investigated to determine its capacity to absorb carbon dioxide and to demonstrate the feasibility of its use as an alternative to ordinary Portland cement (OPC). In addition, this study was performed to evaluate the influence of the alkali-activator concentration on the absorption capacity and physicochemical characteristics. METHODS: To determine the characteristics of the AABFS as a function of the activator concentration, blast-furnace slag was activated by using calcium hydroxide at mass ratios ranging from 6 to 24%. The AABFS pastes were used to evaluate the carbon dioxide absorption capacity and rate, while the OPC paste was tested under the same conditions for comparison. The changes in the surface morphology and chemical composition before and after the carbon dioxide absorption were analyzed by using SEM and XRF. RESULTS: At an activator concentration of 24%, the AABFS absorbed approximately 42g of carbon dioxide per mass of paste. Meanwhile, the amount of carbon dioxide absorbed onto the OPC was minimal at the same activator concentration, indicating that the AABFS actively absorbed carbon dioxide as a result of the carbonation reaction on its surface. However, the carbon dioxide absorption capacity and rate decreased as the activator concentration increased, because a high concentration of the activator promoted a hydration reaction and formed a dense internal structure, which was confirmed by SEM analysis. The results of the XRF analyses showed that the CaO ratio increased after the carbon dioxide absorption. CONCLUSIONS : The experimental results confirmed that the AABFS was capable of absorbing large amounts of carbon dioxide, suggesting that it can be used as a dry absorbent for carbon capture and sequestration and as a feasible alternative to OPC. In the formation of AABFS, the activator concentration affected the hydration reaction and changed the surface and internal structure, resulting in changes to the carbon dioxide absorption capacity and rate. Accordingly, the activator ratio should be carefully selected to enhance not only the carbon capture capacity but also the physicochemical characteristics of the geopolymer.

• 한국결정성장학회지
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• 제31권6호
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• pp.247-257
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• 2021

본 연구는 오토클레이브 양생시편이 예상과 달리 초기강도는 잘 발현되지 않는 반면, 수중에 장기 침지할 경우 압축강도가 향상되는 현상을 규명하기 위해 시작되었다. 증류수 및 알칼리 용액에 침지하였고, 세 가지 양생방법이 시도되었다. 알칼리용액에 침지할 경우 증류수 침지 시편이 추가적인 지오폴리머 반응에 의해 보다 더 높은 압축강도를 가질 것으로 예상하였으나, 실제로 추가적인 지오폴리머 반응에 의해 생성된 결정립들과 알칼리골재 반응에 의한 시편의 팽창 때문에 21일 침지 후 침지용액에 의한 압축강도의 변화는 크게 나타나지 않은 것으로 사료되었다. 지오폴리머의 수중 및 알칼리용액 내 장기공용성을 확보하기 위해서는 오토클레이브를 이용하여 양생 후 21일 이상 수중 침지를 시키면서 숙성(aging) 시키는 것이 바람직 한 것으로 결론지을 수 있었다.

• 한국결정성장학회지
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• 제32권2호
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• pp.68-76
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• 2022

본 연구는 오토클레이브에서 양생된 시편들을 침지했을 때 시편의 압축강도 변화 메커니즘(mechanism) 규명을 위해 수행되었다. 침지는 3일, 7일, 21일간 진행되었으며, 침지 용액은 증류수, 2M, 8M, 14M 알칼리용액에서 진행되었다. 단기간동안 침지한 시편들의 압축강도 변화는 크지 않았으나, 21일 동안 증류수 및 8M 알칼리 용액에 침지한 시편들의 압축강도는 추가적인 지오폴리머 반응에 의해 침지전 시편에 비해 2배 이상 증가하였다. 하지만, 일정농도 이상으로 알칼리를 공급해주면 알칼리 골재 반응에 의해 압축강도가 감소하였다. 따라서 오토클레이브에서 양생한 시편들의 압축강도 증진을 위해서는 증류수 및 8M 알칼리용액에서 21일 이상 장기간 침지하는 것이 바람직한 것으로 판단되었다.