• Proceedings of the Korea Concrete Institute Conference
• /
• 1996.10a
• /
• pp.140-147
• /
• 1996

This study was performed to investigate the characteristics of workability and strength of the concrete containing admixtures such as silica fume, fly ash, blast furnace slag, and rice husk ash. For this purpose, the workability and the strength of the concrete containing each admixture were tested and analyzed according to the unit weight of binder and the replacement ratio of each admixture.

• Magazine of the Korea Concrete Institute
• /
• v.4 no.2
• /
• pp.119-126
• /
• 1992

고강도 시멘트 복합체의 유동성 손실을 감소시키기 위한 연구의 일환으로 시멘트계 입자에 대한 고성능감수제의 흡착특성, 현탄액 속에서의 응집특성을 관찰하여 시멘트풀과 모르터의 유동성과 관련시켜 고찰하였다. 본 연구결과 알루미네이트계 화합물이 많이 함유된 보통포틀랜드 시멘트의 흡착률이 가장 크며, 시멘트풀 및 모르처의 유동성 손실이 작았으며 나프탈린계 고성능 감수제가 유동성 손실면에서 얼마간 유리하였다.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.11a
• /
• pp.905-908
• /
• 2006

In this study examines physical and mechanical properties the use of domestic low grade meta-kaolin in light weight porous concrete. For this purpose light weight porous concrete incorporating low grade meta-kaolin admixture, was tested for tensile strength and acoustic characteristics. Checking tensile strength of cement and low grade meta-kaolin mixture was used to determine the optimum mix proportion of the low grade meta-kaolin admixture. In this paper sound absorbing material has been investigated by using the light weight porous concrete.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2020.11a
• /
• pp.83-84
• /
• 2020

The purpose of this study is to achieve a sufficient fluidity without segregation for normal compressive strength grade concrete mixture. The major obstacle of achieving fluidity of normal compressive strength grade concrete mixture is segregation. Therefore, in this research, the proper use of VMA was suggested to prevent segregation.

• Journal of the Korean Applied Science and Technology
• /
• v.34 no.1
• /
• pp.125-131
• /
• 2017

The influences of scatterer and absorber in turbid material by light scattering in concrete admixture were interpreted for the scattered intensity and wavelength. The molecular properties have been studied by Monte Carlo simulation in resin of New Austria Tunnel Method. It has been found that the effects of optical properties in scattering media could be investigated by the optical parameters(${\mu}_s$, ${\mu}_a$,${\mu}_t$). Monte Carlo Simulation method for modelling of light transport in the civil engineering and construction field was applied. The results using a phantom were discussed that the admixture for shrinkage compensating concrete in NATM-rasin from source to detector is measured, and scattering intensity is stronger with those obtained through Monte Carlo Simulation. It may also aid in designing the best model for coatings and corrosion for the durability of metal constructions.

• Magazine of the Korea Concrete Institute
• /
• v.7 no.2
• /
• pp.155-164
• /
• 1995

This study was performed to get high strength of the precase concrete adopting a steam curing by using a gypsum-admixture for the high strength concrete. The superplasticizer was used to compensate low slump of base concrete keeping its slump up about $6{\pm}1cm$. To examine the property for strength revelation of concrete using admixtures for a high strength concrete, steam and standard curing were compared each other. Test results were shown that admixtures for high strength concrete were more effective in steam curing than standard curing. On the condition that the unit cement content is about $530{\sim}600kg/m^3$, the compressive strength of concrete replacing by 10% of the admixture was obtained over $65Okgf/cm^2$, which was increased as 1.3 times as that for the nonreplacement. When the admixture was replaced to 15-30%, the compressive strengh was obtained over $700kgf/cm^2$ which was increased as 1.4 - 1.5 times. Therefore, the admixture for high strength concrete, being effective in steam curing, was more efficient to get a high strength concrete using only steam curing instead of an autoclave curing for the secondary products of cement.

• Korean Journal of Clinical Pharmacy
• /
• v.7 no.1
• /
• pp.45-49
• /
• 1997

The effect of the light on the stability of 5-fluorouracil admixture was investigated. Four sets of 5-fluorouracil admixture were prepared using 50 mg/ml injection in $5\%$ dextrose solution in PVC bags and glass bottles: (1) 5-fluorouracil 1 mg/ml concentration in glass bottles, (2) 5-fluorouracil 1 mg/ml in PVC bags, (3) 5-fluorouracil 10 mg/ml in glass bottles, and (4) 5-fluorouracil 10 mg/ml in PVC bags. In each set, one group was protected from the light (control group) and the other group was exposed to the fluorescent light (study group). All admixtures were stored at room temperature for 72 hours. Also, 5-fluorouracil injections (50 mg/ml) were prepared in plastic syringes. Half of the samples of 50 mg/ml concentration were protected from the light (control group) and the other half were exposed to the fluorescent light (study group). These were stored at room temperature for 48 hours. After visual inspection, the pHs of each admixture were determined. The 5-fluorouracil concentrations were measured by high-performance liquid chromatography with UV detection, with 5-bromouracil as an internal standard. Over the study period, no visual changes were observed. The pHs of 5-fluorouracil admixtures were in the range of $8.2\~8.5$. The peak area ratios (5-FU/5-BrU) of 5-fluorouracil admixtures protected from the light were compared with those of the admixtures exposed to the light. There was no statistically significant difference between two groups during the study period (p>0.05). In conclusion, 5-fluorouracil admixtures in $5\%$ dextrose solution exposed to the light were stable for 72 hours.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.11
• /
• pp.6890-6897
• /
• 2014

EAF reduction slag has unstable properties of expansion and destruction. Therefore, it cannot be used as a construction material. The purpose of this study was to use EAF reduction slag as a concrete admixture. EAF reduction slag contains $11CaO{\cdot}7Al_2O_3{\cdot}CaF_2$ and ${\beta}-C_2S$ (calcium aluminate compounds). To confirm the properties of EAF reduction slag as a concrete admixture, the condensation, compressive strength and activity factor due to substitution rate of EAF reduction slag were measured. Originally, EAF reduction slag was cured rapidly because of its chemical composition ($11CaO{\cdot}7Al_2O_3{\cdot}CaF_2$). On the other hand, when 8% gypsum was added, its properties of condensation and compressive strength were similar to the plain specimen. When 6% gypsum was added, the quality of the KS F 2536 standards (quality standard number 3) were met in terms of activity factor. Overall, 8% gypsum addition is the most appropriate by considering the activity factor in the long-term compressive strength.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.1 no.3
• /
• pp.173-180
• /
• 2013

This paper is to investigate an effect of waste cooking oil(WCO) on the engineering properties and durability of high volume admixture concrete. Fly ash with 30% and blast furnace slag with 60% were incorporated in OPC to fabricate high volume admixture concrete with 0.5 of W/B. Emulsified refining cooking oil(ERCO) was made by mixing WCO and emulsifying agent to improve fluidity. ERCO was replaced by cement from 0.25 to 1.0%. As results, the increase of ERCO resulted in decrease of slump and air contents. For compressive strength, the use of ERCO led to decrease the compressive strength at 28 days, while it had similar strength or much higher strength than plain concrete at 180 days. Resistance to carbonation and chloride penetration was improved with the increase of ERCO contents due to decreased pore distribution by saponification between ERCO and concrete, while freeze-thaw resistance was degraded due to air loss.

• KCI Concrete Journal
• /
• v.13 no.1
• /
• pp.3-9
• /
• 2001

This research concerns the effect of kaolin as material of cement admixture. which has the advantage of low price and high adaptability. Kaolin, a kind of soil, is well known as a raw material of pottery. which is widely scat-tered on the earth (especially in Korea). This research shows the method and process for activating kaolin to have the properties of a cement admixture through experiment. In the experiments, kaolin is baked in high temperature and then cooled suddenly to be activated. The temperature zone and time span, on which kaolin is activated are examined. The research looks over the effect of the activated kaolin based on several criteria regarding to chemical and physical characteristic of general admixtures. The results of this research are as follows; kaolin start activation at the temperature above 50$0^{\circ}C$ and make ends of activation at the temperature below 95$0^{\circ}C$ and there was little effect by the change of duration. It is concluded that compressive strength can be increased by putting activated kaolin in the concrete and the activated kaolin is good for water resistance and anti-chemical , and that it is effective for protecting the leakage of hazardous article like Cl- and for protecting damage by an organic salt like acid. The activated kaolin of proper temperature and time is effective in compressive strength, salt resistance and acid resistance. The adaptability of activated kaolin as a cement admixture was shown through this research.