• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.1
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• pp.25-35
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• 2018

This study presents microstructural characteristics and strength properties of alkali-activated kaolin(K)-fly ash(FA) blends binders. The compressive strength, X-ray diffraction(XRD), thermogravimetric(TG) analysis and SEM/EDS were measured for hardened samples. The results were shown that all the samples had developed the compressive strength over time, regardless of replacement levels of K. It was found that when the amount of K increased, the strengths of samples decreased. In XRD result, no new crystalline phases were observed in all the hardened samples other than the crystalline components of raw FA and K, whereas TG analysis showed that N-A-S-H gel was formed as a reaction product in all the samples. Samples did not have the typical microstructure of dense, and there is little significant difference between the microstructures of the samples despite the differences in the strength testing results with replacement ratios of K. This study showed that the strength of sample was larger for lower Si/Al ratio of reaction product formed in sample. According to the correlation between Si/Al ratio and strength in this study, it is expected that if a chemical additive is used for lowering the Si/Al ratio of reaction product(i.e., increasing the $Al_2O_3$ solubility) in alkali-activated K-FA blends binders, strength improvement in K-FA blends binders could be achieved.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.2
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• pp.94-101
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• 2016

This paper presents an investigation into the durability alkali-activated materials(AAM) mortar and paste samples manufactured using fly-ash(FA) and ground granulated blast furnace slag(GGBFS) exposed to a sulfate environment with different GGBFS replace ratios(0, 30, 50 and 100%), sodium silicate modules($Ms[SiO_2/Na_2O]$ 1.0, 1.5 and 2.0) and initial curing temperatures($23^{\circ}C$ and $70^{\circ}C$). The tests involved immersions for a period of 6 months into 10% solutions of sodium sulfate and magnesium sulfate. The evolution of compressive strength, weight, length expansion and microstructural observation such as x-ray diffraction were studied. As a results, as higher GGBFS replace ratio or Ms shown higher compressive strengths on 28 days. In case of immersed in 10% sodium sulfate solution, the samples shows increase in long-term strength. However, for samples immersed in magnesium sulfate solutions, the general observation was that the compressive strength decreased after immersion. The most drastic reduction of compressive strength and expansion of weight and length occurred when GGBFS or Ms ratios were higher. Also, the XRD analysis of samples immersed in magnesium sulfate indicated that expansion of AAM caused by gypsum($CaSO_4{\cdot}2H_2O$); the gypsum increased up to 6 months continuously.

• Journal of the Korea Concrete Institute
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• v.28 no.2
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• pp.205-212
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• 2016

This research investigates the influence of ground granulated blast furnace slag (GGBFS) composition on the alkali-activated slag cement (AASC). Aluminum oxide ($Al_2O_3$) was added to GGBFS binder between 2% and 16% by weight. The alkaline activators KOH (potassium hydroxide) was used and the water to binder ratio of 0.50. The strength development results indicate that increasing the amount of $Al_2O_3$ enhanced hydration. The 2M KOH + 16% $Al_2O_3$ and 4M KOH + 16% $Al_2O_3$ specimens had the highest strength, with an average of 30.8 MPa and 45.2 MPa, after curing for 28days. The strength at 28days of 2M KOH + 16% $Al_2O_3$ was 46% higher than that of 2M KOH (without $Al_2O_3$). Also, the strength at 28days of 4M KOH + 16% $Al_2O_3$ was 44% higher than that of 4M KOH (without $Al_2O_3$). Increase the $Al_2O_3$ contents of the binder results in the strength development at all curing ages. The incorporation of AASC tended to increases the ultrasonic pulse velocity (UPV) due to the similar effects of strength, but increasing the amount of $Al_2O_3$ adversely decreases the water absorption and porosity. Higher addition of $Al_2O_3$ in the specimens increases the Al/Ca and Al/Si in the hydrated products. SEM and EDX analyses show that the formation of much denser microstructures with $Al_2O_3$ addition.

• Journal of the Korea Institute of Building Construction
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• v.13 no.6
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• pp.602-608
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• 2013

The aim of this study is to investigate experimentally the effect of the combination of fine particle cement with high Blaine fineness (FC) and recycled aggregates on the engineering properties and micro structure of high volume blast furnace slag (BS) concrete with 75% BS and 21 MPa. FC manufactured by particle classification at the plant with Blaine fineness of more than $7000cm^2/g$ was used as additional alkali activator for high volume blast furnace slag concrete made with recycled fine and coarse aggregates. FC was replaced by 15, 20 and 25% OPC. Test results showed that the incorporation of FC resulted in an increase in the compressive strength compared to BS concrete without FC by as much as 30% due to accelerated hydration and associated latent hydraulic reaction. It was found that the use of FC and recycled aggregates played an important role in activating BS for high volume BS concrete by offering sufficient alkali.

• Applied Chemistry for Engineering
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• v.3 no.4
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• pp.710-716
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• 1992

Ethylphenyl carbarmate(EPC) was synthesized by oxidative CO carbonylation of aniline in the presence of transition metal catalysts and alkali metal halide cocatalysts at $120^{\circ}C$ under the pressure of 79atm. Oxygen gas was used for oxidizing agent. Kinetics of the reaction was studied and activation energies with different catalysts were estimated. About 100% conversion to EPC and 95% selectivity was obtained in 5 hour reaction. 5% Pd/C was more effective than 5% Rh/C. Effectiveness of cocatalysts was in the order of KI>KBr>KCl. As the temperature increased from $75^{\circ}C$ to $120^{\circ}C$, the conversion rate increased. The reaction was apparent first order and the activation energies with 5% Pd/C and 5% Rh/C were 5.647 and 5.780 kcal/mol, respectively.

• Journal of the Korea Concrete Institute
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• v.23 no.2
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• pp.203-209
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• 2011

The cement industry is expected to face a major set-back in the near future due to its large energy consumption and $CO_2$ production, causing global warming. In order to overcome these environmental problems, this research has bee carried out to find a cement substitute material. One possible cement substitute material is Zeolite cement. In this study, the materialistic characteristics of Zeolite cement mortar were evaluated. Natural Zeolite cement mortar was prepared using alkali activation (NaOH) instead of water ($H_2O$) to determine achievable strength and appropriate mixing ratio. Based on the mixing ratio, functional material was added to alkali active agent to harden Zeolite mortar to develop a highly functional construction material. The study result showed that pure Zeolite cement mortar achieved compressive strength of 42 MPa in 7 days depending on the mixing amount of alkaline catalyst and the hardening temperature, showing high efficiency and possibility as a new construction material.

• Clean Technology
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• v.15 no.1
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• pp.31-37
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• 2009

This study deals with the production process of activated carbons from the sewage sludge char by chemical activation reaction. KOH and NaOH were used as activating agents, which react well with carbon. From the experiments, it was found that activated carbons made with KOH treatment had better physicochemical properties in terms of iodine number and BET value than those made with NaOH treatment. It was also found that the optimal deposition ratio of an activating agent to the sewage sludge char was 75 wt% of KOH and 50 wt% of NaOH. Activated carbons were washed out by distilled water after neutralization with 5 M hydrochloric acid solution. The activated carbons that were produced from a sewage sludge char at this optimal conditions have BET surface areas of approximately $600m^2/g$.

• Applied Chemistry for Engineering
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• v.9 no.2
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• pp.286-293
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• 1998

Two methods were used to enhance the adsorption capacity of activated carbons. One is to impregnate activated carbons with chemical compounds which have a good affinity for $CO_2$. The other is to activate by heat-treating after impregnation with KOH on activated carbons(AC). The chemical compounds impregnated on AC were alkali metal, alkaline earth metal, and transition metal chlorides. The adsorption capacity of $CO_2$ on AC impregnated with these metals was less than that of pure AC. These compounds have not the chemical affinity for $CO_2$ and obstruct the micropore of AC. The experiment of breakthrough for $CO_2$ on AC impregnated with KOH showed the increase of the adsorbed amount of $CO_2$ in influent gases containing water vapor. This means that KOH adsorbes $CO_2$ gas. However, the adsorbents impregnated with KOH had not the reproducibility because of the production of $K_2CO_3$ by the reaction of KOH with $CO_2$. The amount of $CO_2$ adsorbed on the heat-treated AC at $800^{\circ}C$ increased with the amount of impregnation. The adsorption capacity of $CO_2$ was the largest when the ratio of weight of KOH to AC equal to 4. The isosteric heat of adsorption was calculated by the equation of Clausius-Clapeyron form adsorption capacity data of $CO_2$ for the temperature change. In addition, the characteristics of $CO_2$ breakthrough curve were surveyed for the change of flow rate and concentration.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.121-121
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• 2017

본 연구는 비전도성 폴리머 표면을 개질하여 감광성 금속을 유전체 표면에 흡착시키고, 감광성 금속의 광화학 반응을 이용하여 귀금속 촉매를 비전도성 폴리머 표면에 선택적으로 흡착시켜 무전해 Cu 도금을 수행하여 금속패턴을 형성하였다. 기능성 유연 필름은 일반적으로 투명한 플라스틱 고분자 기판을 기반으로 전기 전자, 에너지, 자동차, 포장, 의료 등 다양한 분야에서 폭넓게 활용 되고 있으며, 본 연구에서는 습식 도금 공정을 이용하여 폴리이미드 필름상에 $10{\mu}m$ 이하의 미세패턴을 형성하기 위한 공정을 개발하고자 하였다. 비전도성 폴리머 표면에 무전해 도금을 위해서 우선 폴리머 필름의 표면을 개질하는 공정이 필요하다. 이에 KOH 또는 NaOH 알카리 용액을 이용하여 표면을 개질하였으며 개질된 표면에 감광성 금속이온의 흡착시키기 위한 감광성 금속이온은 주석을 사용하였으며, 주석 용액의 안정성 및 퍼짐성 향상을 위해 감광성 금속 용액의 제조 및 특성을 관찰하였으며, 감광성 금속화합물이 흡착된 비전도성 유전체 표면을 포토마스크를 이용하여 특정 부위, 즉 표면에 금속패턴 층을 형성하고자 하는 곳은 포토마스크를 이용하여 광원을 차단하고 그 외 부분은 주 파장이 365nm와 405nm 광원을 조사하여 선택적으로 감광성 금속화합물의 산화반응을 유도하는 광조사 공정을 수행하였다. 광원이 조사되지 않은 부분에 귀금속 등의 촉매 입자를 치환 흡착시켜 금속 패턴이 형성될 수 있는 표면을 형성하였다. 위의 활성화 공정이후에 활성화 처리된 표면을 세척하는 수세 공정을 거친 후 무전해 도금공정에 바로 적용할 경우 미세한 귀금속 입자가 패턴이 아닌 부분 즉 자외선(UV) 조사된 부분에도 남아있어 도금시 번짐 현상이 발생한다. 이에 본 연구에서는 활성화 처리 후 약 알칼리 용액에 카르복실산을 혼합하여 잔존하는 귀금속 입자를 제거한 후 무전해 Cu 도금액을 이용하여 $10{\mu}m$ 이하의 Cu 금속 패턴을 형성하였다.

• Journal of the Korea Concrete Institute
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• v.27 no.2
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• pp.95-102
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• 2015

In this paper, the effects of sodium hydroxide (NaOH) and aluminum potassium sulfate ($AlK(SO_4)_2{\cdot}12H_2O$) dosage on strength properties were investigated. For evaluating the property related to the dosage of alkali activator, sodium hydroxide (NaOH) of 4% (N1 series) and 8% (N2 series) was added to 1~5% (K1~K5) dosage of aluminum potassium sulfate ($AlK(SO_4)_2{\cdot}12H_2O$) and 1% (C1) and 2% (C2) dosage of calcium oxide (CaO). W/B ratio was 0.5 and binder/ fine aggregate ratio was 0.5, respectively. Test result clearly showed that the compressive strength development of alkali-activated slag cement (AASC) mortars were significantly dependent on the dosage of NaOH and $AlK(SO_4)_2{\cdot}12H_2O$. The result of XRD analysis indicated that the main hydration product of $NaOH+AlK (SO_4)_2{\cdot}12H_2O$ activated slag was ettringite and CSH. But at early ages, ettringite and sulfate coated the surface of unhydrated slag grains and inhibited the hydration reaction of slag in high dosage of $NaOH+AlK(SO_4)_2{\cdot}12H_2O$. The $SO_4{^{-2}}$ ions from $AlK(SO_4)_2{\cdot}12H_2O$ reacts with CaO in blast furnace slag or added CaO to form gypsum ($CaSO_4{\cdot}2H_2O$), which reacts with CaO and $Al_2O_3$ to from ettringite in $NaOH+AlK(SO_4)_2{\cdot}12H_2O$ activated slag cement system. Therefore, blast furnace slag can be activated by $NaOH+AlK(SO_4)_2{\cdot}12H_2O$.