• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.1
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• pp.163-170
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• 2007

To evaluate on the applicability of Chemical Compaction Pile (CCP) method to weak soil improvement, two kinds of testing chambers were fabricated and the changes of water content and shear stress associated with soil types, ages and distances from the center of pile were measured with different mixing proportions of CCP such as bottom ash, lime powder and added admixture. As results of test, it was noted that water content and shear stress of ground are mainly affected by the amount of lime powder and increase of the amount corresponds to rapid improvement of soil. And the improvement depended greatly on the types of soil also. It was finally found that CCP developed can be applicable to bearing pile as well as soil improvement since CCP has a bearing capacity enough to carry loads.

• Journal of the Korea Concrete Institute
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• v.14 no.3
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• pp.409-419
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• 2002

Nowadays, antiwashout underwater concrete is widely used for constructing underwater concrete structures but they, especially placed in marine environment, can be easily attacked by chemical ions such as SO$\^$2-/$\_$4/ Cl$\^$-/ and Mg$\^$2＋/, so the quality and capability of concrete structures go down. In this paper, to solve and improve those matters, flyash and GGBFS(ground granulated blast furnace slag) were used as partial replacements for ordinary portland cement. As results of experiments for fundamental properties of antiwashout underwater concrete containing 10, 20, 30％ of flyash and 40, 50, 60 ％ of GGBFS respectively, setting time, air contents, suspended solids and pH value were satisfied with the "Standard Specification of Antiwashout Admixtures for Concrete" prescribed by KSCE, and also slump flow, efflux time and elevation of head were more improved than that of control concrete. From the compressive strength test, it was revealed that the antiwashout underwater concrete containing mineral admixtures(flyash and GGBFS) is more effective for long term compressive strength than control concrete. An attempt to know how durable when they are under chemical attack has also been done by immersing in chemical solutions that were x2 artificial seawater, 5 ％ sulphuric acid solution, 10％, sodium sulfate solution and 10％ calcium chloride solution. After immersion test for 91days, XRD analysis was carried out to investigate the reactants between cement hydrates and chemical ions and some crystalline such as gypsum ettringite and Fridel′s salt were confirmed.

• Analytical Science and Technology
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• v.7 no.3
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• pp.315-320
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• 1994

Li-GICs as a high performance energy storager were synthesized as a function of the Li content by the admixture and add-pressure method. The characteristics of these prepared compounds have been determined from the studies by X-ray diffraction, UV-VIS spectrometry and CHN analysis. It follows from the results of X-ray diffraction that the lower-stage intercalation compounds are formed as the Li contents increase, however the mixed stages in these compounds are also observed. In the case of the $Li_{40wt%}$, the compound with the structure of stage 1 has been predominently, but the structure of only stage 1 is not obtained. The $d_{001}$ value of stage 1 was determined to be ca. $3.70{\AA}$. An analysis of spectrometric data shows that each of the compounds gives distingushible energy state spectra. It is seen from the spectra that the positions of $R_{min}$ values, with increase in the Li contents, are shifted in the region of higher energy state. Such a result can be attributed to the formation of stable stages. The results of CHN analysis allow us to find the mixing state related to chemical compositions of the intercalated compounds and the superiority to admixture and add-pressure method. From the results determined, it reveals that $Li_{10wt%}$-GIC and $Li_{20wt%}$-GIC can be utilized for an anode of rechargable battery.

• Magazine of the Korea Concrete Institute
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• v.11 no.1
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• pp.183-190
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• 1999

This paper investigated the possibility of appling to concrete through fundamental experiment for garnet, which was industrial wastes generated in kyung pook region, in aspects of development of new materials and recycling of industrial wastes due to shortage of natural resources. Consequently, garnet powder showed the possibility of admixture as showed in the chemical composition because the content of silica and alumina in relation to pozzolanic activity was about 50%. The time of setting was more or less diminished as the increasing of replacement ratio of garnet. In flow test, flow values tended to increase to some degree as the increasing of replacement ratio of garnet. Therefore, application of garnet was expected to improve the workability of concrete. The compressive strength of mortar replaced by garnet was respectively increased as compared with plain mortar and the maximum strength was showed in replaced by 10%, however a little different to the change of W/B ratio. Also, the possibility of admixture to reduce the amount of cement and to improve the property of concrete was showed as the strength of mortar replaced by garnet was comparable to that by existing admixture(silica fume, fly-ash).

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.34 no.3
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• pp.86-91
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• 2024

In this study, the characteristics of mortar using carbondioxide conversion capture materials (CCMs), fabricated by reacting CO₂ with desulfurization gypsum (DG) by-produced from a oil refinery, as a cement mixture. Based on the chemical component and particle size analysis results, it estimated that desulfurized gypsum reacted with carbon dioxide to produce carbonate crystals such as CaCO₃. Using CCMs as a cement mixture, physical property and durability analysis were conducted by measuring such as workability, compressive strength, compressive strength ratio after freezing-thawing and accelerated carbonation depth. The experimental results showed that as the content of the admixture increased, workability and compressive strength characteristics decreased. Compressive strength after freezing-thawing and accelerated carbonation depth also showed similar characteristics to the physical property measurement results. In addition, compared to desulfurized gypsum, using CCMs showed better physical properties and durability. This was assumed to be due to differences in the crystal phases of the mixed materials such as free-CaO and CaCO₃.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.63-67
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• 2002

The induced chemical and salt solution in water or admixture are originated to the corrosion process of the steeo rebar. These liquids penetrate into concrete as the accompanied by the chemical reaction and cause to attack the steel rebar in concrete. Concrete surfaces which it exposed to deicing, water and sea water is allowed to enter the chlorides in the structures. To prevent from the source of corrosion and deterioration Is subjected to put an end to corrode or reduce to contaminate on the steel rebar. As this reason the MCI 2022 products are applied to the surface of concrete and steel rebar. The concrete samples were made of to the kind of four, i.e. RF, MR, MS, and MM. Corrosion inhibitor is applied to coat on the surface of concrete after it had been cured for 28days. Specimen were immersed in a 3.5％ sodium chloride solution. Concrete specimen were tested to determine the changes of the resistance polarization, Rp, over a 22 weeks period. MCI 2022 is significantly shown the corrosion inhibition of steel rebar in 3.5% NaCl solution. In the each different concrete sample, MS and MM is seemed to be better than others. The results are proofed that MCI 2022 is promised to maintain the inhibition of corrosion with high resistance polarization of the steel rebar in concrete.

• Magazine of the Korea Concrete Institute
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• v.11 no.2
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• pp.85-94
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• 1999

It was investigated to evaluate the characteristics of cement-flyash paste which was affected the replacement level, curing method and chemical admixtures. The strength of cement-flyash paste was lower than that of cement paste only and the differences increased with increasing the replacement level. However, in steam curing, the strength of cement-flyash pastes was improved and specially, the early strength was effectively increased. The inclusion of $Na_2SO_4$ increased the early strength of cement-flyash paste. In addition, the strength of concrete including 30% of fly ash and $Na_2SO_4$ has improved and obtained the highest strength compared to other concrete mixes.

• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3547-3552
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• 2013

Single crystal EPR and optical studies of a mixed ligand zinc(II) complex doped with VO(II) ion is carried out to establish the structural properties. The angular variation of vanadyl hyperfine lines indicates a single site, with spin Hamiltonian parameters as: $g_{xx}=1.985$, $g_{yy}=1.979$, $g_{zz}=1.943$; $A_{xx}=8.71$, $A_{yy}=6.41$ and $A_{zz}=17.80$ mT. By comparing the direction cosines of principal g and A values with the direction cosines of metalligand bonds, it has been confirmed that the vanadyl ion has entered the lattice interstitially. The exact interstitial position of VO(II) in host lattice has been calculated using the fractional coordinates of atoms in the host lattice out of many assumptions. The EPR and optical data have been confirmed to obtain various bonding parameters, from which the nature of the bonding in the complex is discussed. FT-IR confirms the formation of structure of host lattice.

• Journal of the Korean Ceramic Society
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• v.54 no.5
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• pp.380-387
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• 2017

In this study, unstable CaO was converted into a stable Ca compound by using carbonation in a circulating fluidized bed boiler of fly ash to confirm material usability as cement admixture; also undertaken was carbonation test and mortar to examine chemical and physical change by measuring absorption rate and compressive strength. To investigate the chemical properties of circulating fluidized bed boiler fly ash, XRD and TG-DTA were used to determine how the properties of the reaction product change quantitatively during carbonation. In order to stabilize CaO, carbonation of CaO is considered to be the most desirable process. This is because $CaCO_3$, which is a Ca compound, was produced by carbonate reaction of unstable CaO, and decrease of the absorption rate and improvement of the compressive strength were observed when the carbonated fly ash was replaced with cement.

• Journal of the Korean Geotechnical Society
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• v.15 no.3
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• pp.17-25
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• 1999

The feasibility of using waste lime, which is produced as a byproduct during the manufacture of sodium carbonate in Inchon, Korea. as a stabilization admixture with weathered granite soil was investigated. Laboratory tests were conducted to determine the chemical composition, pH, compaction characteristics, unconfined compression strength. X-ray diffraction analysis of waste lime and weathered granite soil admixtures. Based on the present tests, it appears that the admixtures are environmentally safe and can be used as landfill material.