• Economic and Environmental Geology
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• v.31 no.4
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• pp.349-360
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• 1998

The alkali granite occurred as small stock and dyke is distributed in the Kyeomyeongsan Formation in the vicinity of the Chungju city. Geochemical characteristics in major and trace element of alkali granite in the Kyeomyeongsan Formation indicate that the alkali granites are peralkaline and have similar geochemical features to the A-type alkali granite. The rock enriched in HFSE such as Zr, Nb, Y, REE etc. According to the discrimination diagram the alkali granites mostly belong to the within-plate granite field, and to the $A_1$ group of A-type granite. This suggests that they might be emplaced in a extentional rift environment. The alkali granites are characterized by remarkably high total REE content, and enriched, relatively flat to somewhat HREE-depleted patterns with large negative Eu anomaly. The Sm-Nd age of the alkali granite is $338{\pm}30Ma$ with ${\varepsilon}_{Nd(t)}$ beings -7.3 to -8.5. On the basis of the geochemical studies the source magma was derived from a enriched mantle-like source and had a few or clearly interaction with sialic continental crust. In conclusion, the alkali granitic rock of the Kyeomyeongsan Formation might be formed from the high F peralkaline magma that was emplaced in continental rift environment, and generated at the early Carboniferous.

• The Korean Journal of Ceramics
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• v.1 no.2
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• pp.86-90
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• 1995

Theoretical predictions for thermodynamically stable phases which formed when alkali(sodium and potassium) vapors reacted with alumina-chromia refractories under coal gasifying atmosphere were confirmed experimentally using a laboratory-scale coal gasifying reaction system and a commercial alumina-chromia refractory using SEM, XRD, and EDAX. Alkali concentration profiles in the refractory as a function of time were also determined. The results showed that the compounds that formed were $X_2O{\cdot}Al_2O_3, X_2O{\cdot}Cr_2O_3, X_2O{\cdot}5Al_2O_3, X_2O{\cdot}7Al_2O_3, X_2O{\cdot}11Al_2O_3(X=Na^+ \;or\; K^+)$, depending upon the alkali concentration and time of exposure at high temperatures. The presence of sulfur in gasifying atmospheres did not appear to affect the alkali reaction produces. Alkali pentration into the alumina-chromia refractory was deep and the formation of the $Na_2O{\cdot}Al_2O_3/K_2O{\cdot}Al_2O_3$ compunds resulted in the serious deformation of the refractory due to the large volume expansion at the reaction surface. The hot face of the alumina-chromia refractory in service under an alkali environment is prone to failure by alkali attack.

• Journal of the Korean Chemical Society
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• v.61 no.6
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• pp.311-319
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• 2017

By using Density Functional Theory (DFT), we have performed alkali metal and alkaline earth metal inside fullerene-like BeO cluster (FLBeOC) in terms of energetic, geometric, charge transfer, work function and electronic properties. It has been found that encapsulated processes of the alkali metal are exothermic and thermodynamically more favorable than alkaline earth metal encapsulation, so that interaction energy ($E_{int}$) of the alkali metal encapsulation FLBeOC is in the range of -0.02 to -1.15 eV at level of theory. It is found that, the electronic properties of the pristine fullerene-like BeO cluster are much more sensitive to the alkali metal encapsulation in comparison to alkaline earth metal encapsulation. The alkali and alkaline earth metal encapsulated fullerene-like BeO cluster systems exhibit good sensitivity, promising electronic properties which may be useful for a wide variety of next-generation nano-sensor device components. The encapsulation of alkali and alkali earth metal may increase the electron emission current from the FLBeOC surface by reducing of the work function.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.11a
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• pp.7-8
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• 2015

The purpose of this study is to investigate the expansion of alkali-activated geopolymer mortar containing reactive aggregate due to alkali-silica reaction. In addition, this study is particularly concerned with the behavior of these alkaline materials in the presence of reactive aggregates. The test method included expansion measurement of the mortar bar specimens and geopolymer compressive strength test. Major results that alkali-activated geopolymer mortars showed expansion due to the alkali-silica reaction. geopolymer mortars is safety for the expansion exhibited less than 0.2% at 14 day.

• The Korean Journal of Ceramics
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• v.1 no.1
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• pp.29-34
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• 1995

Theoretical predictions were made for thermodynamically stable phases which formed when alkali(sodium and Potassium) vapors reacted with the 90% $Al_2O_3$-10% $Cr_2O_3$ refractory under coal gasifying atmosphere using the computer program of SOLGASMIX-PV. The calculation results showed that the stable compounds that formed were $X_2O$.$Al_2O_3$ and $X_2O$.$llAl_2O_3$(X=$Na^+$ or $K^+$), depending upon the alkali concentration. The presence of sulfur in gasifying atmospheres did not appear to affect the species of alkali reaction products. Alkali attack at high temperatures is likely to cause serious degradation at the hot face of the refractory, indicating that the alkali concentration is an important factor to affect the degradation of the refroctory.

• Economic and Environmental Geology
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• v.19 no.2
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• pp.123-131
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• 1986

This study is focused on petrochemistry and petrogenesis of alkali granite which exposed at northern area of the Uljin mine in NE Korea. The rock is corresponded to the range of alkali feldspar granite and alkali feldspar quartz syenite on IUGS classification and contains characteristic Fe-rich biotite (annite) and sodic alkali amphibole (arfvedsonite). The alkali granite is the hypersolvus one-feldspar granite which is characterized by the absence of plagiclase except as a component of perthite and its normatve An contents are less than 5wt%. The bulk compositions of the alkali granite show reverse trends compared to Daly's. Tuttle and Bowen (1958) experimentally support that properties of the hypersolvus granite indicate that they have crystallized at high temperatures from a magma.

• Journal of Urban Science
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• v.7 no.1
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• pp.39-43
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• 2018

This study investigates microstructural characteristics of alkali-activated cements incorporating slag and fly ash. Samples were prepared with four fly ash:slag ratios, i.e., 100:0, 90:10, 70:30 and 50:50, and they were synthesized by using an alkali activator. Microstructural characteristics of the alkali-activated cements were determined by XRD, TGA, SEM, N2 gas adsorption/desorption methods, and compressive strength test. The results showed that properties of alkali-activated fly ash/slag were significantly affected by slag contents. Alkali-activated fly ash/slag with slag content of 30-50% showed higher compressive strength than ordinary Portland cement paste. An increase in slag content resulted in a denser microstructure, which composed of amorphous gel, therefore contributed to strength development of the material.

• Asian-Australasian Journal of Animal Sciences
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• v.8 no.6
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• pp.563-566
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• 1995

To improve the nutritive value of wheat straw it as treated with 0, 3, 4 and 5 percent levels of urea, 0 and 4 percent level of alkali at 40, 50 and 60 percent moisture levels and stored at room temperature. Total nitrogen contents of the straw increased significantly, from 0.77 percent with no urea treatment to 0.87, 1.16 and 1.19 percent with 3, 4 and 5 percent urea levels, respectively. Percent retention of nitrogen was 63.73 percent. Alkali treatment at 4 percent level, lowered significantly the crude fibre contents of the straw from 41.86 percent in control to 40.21 percent in the treated straw. Moisture level of 40 percent significantly lowered (p < 0.05) the crude fibre contents. Total ash content of straw increased significantly by urea and alkali treatment. Alkali treatment improved significantly the sodium contents also. The results of the study indicated that most beneficial results were obtained with 4 percent urea, 4 percent alkali at 50 percent moisture level.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.137-140
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• 1996

The deterioration of concrete due to alkali-aggregate reaction is dependent on the total alkali content per unit volume of concrete. It was reported that the expansion of high alkali concrete with the reactive aggregate increased easily due to high alkali of concrete with the reactive aggregate increased easily. And it has been confirmed that the addition of pozzolanic material prevents the concrete with reactive aggregate from deterioration caused by alkali-aggregate reaction. It is the aim of this study to provide the fundamental data on the possibility of alkali-aggregate reaction of high strength concrete and its preventing and repair technic.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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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.