• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.4
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• pp.104-112
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• 2012

This study involves investigating the correlation between variation of internal structure and heating temperature of alkali-activated fire protection materials using fly ash. Dehydration and micro crack thermal expansion occur in cement hydrates of cementitious materials heated by fire. Internal structure difference due to both the dehydration of cement hydrates and pore solution causes and influences changes in the properties of materials. Also, this study is concerned with change in microstructure and dehydration of the alkali-activated fire protection materials at high temperatures. The testing methods of alkali-activated fire protection materials in high temperature properties are make use of TG-DSC and mercury intrusion porosimetry measurements. The study results show that the alkali-activated fire resistant finishing material composed of potassium hydroxide, sodium silicate and fly ash has the high temperature thermal stability. These thermal stability is caused by the ceramic binding capacity induced by alkali activation reaction.

• Resources Recycling
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• v.20 no.3
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• pp.40-47
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• 2011

In this study, we investigated the strength, shrinkage and durability of alkali-activated mortar using blast furnace slag only, and admixed with blast-furnace slag and fly ash as cementious materials in oder to develop cementless alkali-activated concrete. In order to compare with the alkali-activated mortar, the normal mortar using ordinary portland cement was also test. In view of the results, we found out that strength development, the resistance to shrinkage and freezing-thawing of the cementless alkali-activated mortar have better than the mortar using ordinary portland cement. Especially, using the combined with blast furnace slag and fly ash develop high strength of above 60 MPa, reduce shrinkage of about 40% and improve freezing-thawing durability of approximately 20%, but promote the velocity of carbonation of 2~3 times.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.2
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• pp.59-64
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• 2013

The present study is to evaluate physical and mechanical properties of porous concrete having non cement that mainly causes carbon emission. This study aims to explore eco-friendly concrete technology capable of reducing the amount of carbon emission due to the use of normal cement by substituting it with non cement porous concrete to which alkali-activator and blast-furnace slag powder are impregnated. As experimental variables, 5 %, 6 %, 7 %, 8 %, 9 % and 10 % of alkali-activator were substituted as binders and applied. Testing evaluated in this study were pH value, void ratio, compressive strength and residual compressive strength shown after being immersed in $H_2SO_4$ solution and $Na_2SO_4$ solution. The test results were compared with those tested with the use of porous concrete to which 400 $kg/m^3$ of unit cement amount was applied as binder. In consequence, it was concluded that; as for pH value, it was decreased than was the case in which cement was used, but increased with the more the use of alkali activator; as for void ratio and compressive strength, the mix proportion in which 9 % and 10 % of alkali activator were applied in terms of substitution ratio showed the result similar to the mixture in which 400 $kg/m^3$ of unit cement ratio was applied; and, as for residual compressive strength in the case of being immersed in $H_2SO_4$ solution and $Na_2SO_4$ solution, the compressive strength was increased, thus leading to improved chemical resistance.

• Korean Chemical Engineering Research
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• v.50 no.3
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• pp.427-434
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• 2012

Waterborne polyurethane dispersions (PUD) were synthesized from poly (carbonate diol), isophrone diisocyanate and dimethylol propionic acid at different NCO/OH molar ratios. Subsequently, the PUD was mixed with different types of alkali metal salts ($LiClO_4$, $NaClO_4$, and $KClO_4$) to prepare antistatic waterborne polyurethane coating solutions. Effects of the types and amounts of alkali metal salts were investigated on the surface resistances of the resulting coating films. The surface resistances of coating films were decreased with increasing the amounts of alkali metal salts added in the PUD. The coating films prepared with the same amount of alkali metal salts showed increased ionic conductivity with the order of $LiClO_4$ > $NaClO_4$ > $KClO_4$. Also, the surface resistances of coating films were increased with increasing the molar ratios of NCO/OH in the PUD.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.1
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• pp.31-37
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• 1993

To analyze and classify the varietal variation of alkali digestibility in detail, which is closely connected with the gelatinization temperature and physical characteristics of cooked rice, the patterns of alkali decomposition changed along the alkali concentration were investigated for thirty three Korean leading rice cultivars and new breeding lines(japonica : 25, Tongil-type:8) including five glutinous rice. Principal component analysis was used to condense the information and to classify rice materials according to decomposed reaction pattern at several levels of potassium hydroxide(KOH) concentration. Thirty three rice varieties were classified largely into four groups by the distribution on the plane of upper two principal component scores which contained above 92% of total informations. Group I was consisted of one variety, Dobongbyeo, which owned almost same strong resistance to alkali digestion at the range of 0.8% to 1.6% KOH solutions. Group II included three japonica and Tongil-type glutinous rice varieties, which revealed medium alkali digestion value(ADV) at 1.4% KOH solution and intermediate change in ADV from 0.8% to 1.6% KOH solutions. Most of Tongil-type and early-maturity japonica rice, which exhibited medium-high ADV at 1.4% of KOH concentration and large ADV difference between low and high alkali solutions, were contained in Group III. Group N included most of medium or medium-late-maturity japonica, which showed high ADV at 1.4% KOH and medium or intermediate-high ADV change between low and high alkali solutions. The 1st principal component indicated the average index of ADV through 0.8-1.6% KOH solutions and the 2nd principal component pointed out the factor related with ADV difference between low and high alkali solutions or regression coefficients of ADV change along with the KOH concentrations.

• International Journal of Concrete Structures and Materials
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• v.3 no.2
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• pp.97-101
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• 2009

It has been known that acid-resistant concretes on the liquid glass basis have high porosity (up to 18${\sim}$20%), low strength and insufficient water resistance. Therefore they can not be used as materials for load-bearing structural elements. Significant increasing of silicate matrix strength and density was carried out by incorporation of special liquid organic alkali-soluble silicate additives, which block of superficial pores and reduces concrete shrinkage deformation. It was demonstrated that introduction of tetrafurfuryloxisilane additive sharply increases strength, durability and shock resistance of silicate polymer concrete in aggressive media. This effect is attributable to hardening of contacts between silicate binder gel globes and modification of alkaline component owing to "inoculation" of the furan radical. The optimal concrete composition with the increased strength, chemical resistance in the aggressive environments, density and crack resistance was obtained.

• Membrane Journal
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• v.26 no.6
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• pp.458-462
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• 2016

Saline water electrolysis, known as chlor-alkali (CA) membrane process, is an electrochemical process to generate valued chemicals such as chlorine, hydrogen and sodium hydroxide with high purities higher than 99%, using an electrolytic cell composed of cation exchange membrane, anode and cathode. It is necessary to reduce energy consumption per a unit chemical production. This issue can be solved by decreasing intrinsic resistance of the membrane and the electrodes and/or by reducing their interfacial resistance. In this study, the electron radiation grafting of a $Na^+$ ion-selective polymer was conducted onto a hydrocarbon sulfonated ionomer membrane with high chemical resistance. This approach was effective in improving electrochemical efficiency via the synergistic effect of relatively fast $Na^+$ ion conduction and reduced interfacial resistance.

• Applied Chemistry for Engineering
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• v.20 no.6
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• pp.622-627
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• 2009

Using an alkali-solution developable photosensitive resin and a carbon black as a conductive filler, photo-patternable pastes for polymer thick film resistor were fabricated and evaluated. A photo solder resist (PSR), which is usually used as protecting layer of printed circuit board (PCB), was used as a photosensitive resin so that ultraviolet exposure and alkali-aqueous solution development of paste were possible. After fabricating the photosensitive polymer resistor paste, the electrical properties of thick film resistors were measured using PCB test boards. Sheet resistance was decreased with increasing amount of carbon black, but the developability was limited in excess loading of carbon black. The sheet resistance was also reduced by re-curing and the change rate was smaller in higher carbon black loading. Moreover, finely patterned meander-type thick film resistors were fabricated using photo-process and large resistance up to several tens of sheet resistance could be obtained in small area by this technique.

• International Journal of Highway Engineering
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• v.17 no.2
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• pp.1-11
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• 2015

PURPOSES : This study set out to investigate the fundamental properties of alkali-activated concrete (AAC) using modified slag as the pavement maintenance material. METHODS: The material properties of modified slag based alkali-activated concrete (MSAAC) were analyzed and evaluated against those of alkali-activated slag concrete (AASC). Several mix formulations were considered, including one MSACC and four AASCs. The main variables considered in the study were slump, air content, compressive strength, rapid chloride permeability test, scaling resistance, freeze-thaw test, XRD, SEM, and EDS. RESULTS: MSAAC exhibits a compressive strength in excess of 21 MPa six hours after curing. Also, the charge passed of the MSACC was found to be less than 2000 coulombs after seven days and about 1000 coulombs after 28 days. The weight loss determined from a scaling test did not exceed $1kg/cm^2$ in the case of the MSACC, but that of the AASCs had already exceeded $1kg/cm^2$ at the 10th cycle. Based on the results of the freeze-thaw test, the relative dynamic modulus of every mix was found to be in excess of 90%. An energy dispersive spectroscopy(EDS) analysis found that the weight rate percentage of the calcium and aluminum in the MSAAC mix is twice that of the AASC mixes. CONCLUSIONS : It was found that the MSAAC mix exhibits significantly better performance than AASC mixes, based on various fundamental properties.

• Journal of the Korean Chemical Society
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• v.42 no.6
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• pp.696-702
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• 1998

The effect of alkali metal salt on the activity of Co-Mo catalyst which has high resistance to sulfur poisoning for water gas shift reaction(WGSR) was studied. Two groups of catalysts were prepared to investigate the effects of anion and cation in alkali metal salts. For K-doped catalysts made with various potassium salts having different anion, the catalytic activity was explained to depend mainly on the BET surface area. Among the catalysts prepared by various nitrates of alkali metal as precursor, the Li-doped catalyst showed the best activity, and the others did not make significant differences giving relatively low activities. And the change of BET surface area by varying the loading of alkali metal showed a similar trend to that of activity. In this case, the activity was dependent on both BET surface area and the ratio of $Mo^{6+}$ with a tetrahedral coordination symmetry to $Mo^{6+}$ with an octahedral one, $Mo^6+[T]/Mo^{6+}[O]$ value.