• 한국세라믹학회지
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• 제22권1호
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• pp.25-34
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• 1985

The states of alkali occuring in Portland cement clinker were studied. Potassium was added to raw mixture by there kinds ; $K_2SO_4$, $K_2CO_3$ and KOH. In case of $K_2CO_3$ and KOH addition the new state of unstable alkali was found when alkakli content is high and $SO_3$ content is low in the clinker. Unstable state of highly basic free 4K_2O$ causes lowering burnability much more than alkali sulfate especially at the early stage of burning. Lowered burnability by 4K_2O$ became more serious with higher LSF. Unstable free-4K_2O$ which is readily soluble with water reacts with gypsum to form $Ca(OH)_2$ and syngenite as soon as water is added. As a results the liberation rate of heat of hydration at the early hydration process(1st peak) was increased.

• 한국세라믹학회지
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• 제34권9호
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• pp.949-956
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• 1997

With the increase of ZnO content, burnability of raw materials was improved and the formation of clinker minerals was accellerated. When ZnO was added 1wt%, the clinkering temperature was decreased about 30~5$0^{\circ}C$. As an increase of ZnO added, aluminate phase was decreased and ferrite phase was increased. When ZnO was added more than 3.0wt.%, the new phases, such as ZnO.Al2O3 and ZnO.Fe2O3 were formed. In the excess of amount of ZnO added, the decomposition of alite phase was intensed and the lamella structure in belite could not be observed due to the decomposition.

• 한국세라믹학회지
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• 제28권10호
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• pp.751-756
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• 1991

Continuous microstructural changes on heating of hardened paste prepared from primary clinker of CA2 composition was studied. On heating period, several characteristic shrinkages and microstructural changes took place in the specimen due to the dehydration and recrystallization of calcium aluminates without regard to the accelerative shrinkage resulted from sintering. Though micropores formed by dehydration decreased with recrystallization of calcium aluminates, micropores formed by plate-type gibbsite in the hydrates were maintained up to the temperature at which CA2 becomes main phase and had influence to the microstructure of the final clinker.

• 한국건축시공학회지
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• 제11권1호
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• pp.83-90
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• 2011

The purpose of this research is to investigate the effect of AFm formation on the stiffening process of cement paste. High and low alkali sulfate clinkers were used for the experiments. The flow and stiffening behavior of cement paste was investigated using modified ASTM C403 penetration resistance test and oscillatory shear rheology. X-ray powder diffraction (XRD) was used for phase identification associated with stiffening of the paste. It was found from the results that low alkali clinker mixture produced very strong premature stiffening whereas high alkali clinker mixture did not cause premature stiffening. This is because of the large amount of alkali sulfate present in the clinker. Addition of calcium and sodium chloride to the high alkali clinker mixture caused faster stiffening and set.

• 한국연소학회지
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• 제8권2호
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• pp.34-40
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• 2003

Analyses for concentration, surface phenomena, and crystal structure were performed to identify the causes of clinker formation in three type of pulverized coal fired boilers. Some clinkers had partially molten surface and more CaO and $Fe_2O_3$ as compared with fly ash, and the major crystalline phases identified in the clinker were mullite and quartz. Clinkers were formed in high temperature zone of the boiler according to the identification of mullite by XRD. Free $SiO_2$ in sand combined with K, Na and Ca in limestone served as a fluxing agent to form clinkers in a circulating bed boiler.

• 한국세라믹학회지
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• 제23권2호
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• pp.64-70
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• 1986

In this investigation x-ray diffraction method was mainly studied for quantitative analysis of clinker mineral composition. And also optical microscopic observation and Bogue calculation method were applied to compare with the x-ray diffraction method. In the procedure of x-ray diffraction analysis graphite monochromator automatic divergence slit and spinner for sample holder were used for minimizing the error due to the operation of the equipment. Especially the separation of overlapped peaks were proceeded by micro-processor automatically. The results of x-ray diffraction method for synthesized clinker were consistent with the Bogue value and the results of optical microscopic observation. However the results of quantitative analysis of mineral composition or commercial clinker containing solid solution of minor component were different from the Bogue value. On the other hand they agreed reasonably well with results of the optical mic-roscopic observation.

• 한국세라믹학회지
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• 제19권1호
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• pp.35-43
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• 1982

It was found that the burnability of raw mix and characteristics of clinker was affected by the difference in grades of limestones. The thermal decomposition temperature of raw mix which used low grade limestone was lower than that of high grade, and the fast formation of $C_2S$ was due to the rich content of calcite and quartz over critical grain size, which caused the bad effects in the burnability, but $C_3S$ was formed slowly. The structure of clinker had many pores, and the growth of clinker minerals was inferior.

• 한국세라믹학회지
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• 제44권4호
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• pp.224-229
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• 2007

To evaluate the cooling rate of clinker quantitatively, several clinkers with different cooling rate were made in the laboratory. The X-ray diffraction pattern of Ferrite 002 reflection were measured and the parameters were calculated by using split type pseudo-Voigt function. The X-ray diffraction patterns of the Ferrite phase in the clinkers from cement manufacturing plant were analyzed by using the parameters and the analysis program was developed to calculate the cooling rate quantitatively. The cooling rate coefficients of the clinkers were calculated by using the profile fitting method of the program and the influence of cooling rate on strength was evaluated. The results show that there is a close relation between the cooling rate of clinker and the strength of cement.

• 한국세라믹학회지
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• 제36권8호
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• pp.876-885
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• 1999

In order to develop high performance basic dam block for tundish vessel in steel-making binders and additives on hydration and thermal characteristics of magnesiz castable refractories were studied. Crack initiation and propagation in cement bonded magnesia castables due to slaking of magnesia clinker at drying process were suppressed by using spinel clinker instead of magnesia powder. In case of Na2O$.$2CaO$.$P2O5(NC2P) bonded castable crack initiation due to slaking of magnesia clinker did not occur but bending strength at high temperature was low. Mechanical properties of NC2P bonded castable refractories at high temperature were improved by using magnesia clinker that contains low SiO2 contents.

• 시멘트
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• 통권36호
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• pp.43-48
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• 1970