• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.11a
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• pp.81-82
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• 2020

Cement paste is the basic material constituting concrete and the most basic data of workability. This study quantitatively evaluated the measured data using a ring flow and a rotary viscometer to estimate the flow of cement paste, and also evaluated the flow and rheology over time. For this, the current work has studied admixtures that affect the fluidity of cement paste. As a result of the experiment, since fluidity and plastic viscosity are inversely proportional to each other, more experimental studies are needed to obtain high fluidity and high viscosity at the same time.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.107-108
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• 2021

In the global trend of countries around the world announcing the declaration of carbon neutrality, the development of low-carbon cement in the cement industry can be seen as a very important issue that can determine the future development of the cement industry in the future. Therefore, this study evaluated the strength characteristics of limestone cement paste with limestone powder of CaCO3 and refinery desulfurization waste catalyst of high Al₂O₃ content, and using a Minitab mixture design to optimize a limestone cement content. As a resuls it was confirmed that limestone cement paste with 5-10% of limestone powder and 1.25-2.5% of the waste catalyst exhibits similar compressive strength to that of OPC.

• Journal of the Korea Institute of Building Construction
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• v.4 no.4
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• pp.95-101
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• 2004

The purpose of this paper is to compare free-chloride content with water-soluble chloride in blast furnace cement(BSC) paste. The content of free-chloride in cement paste measured by pore solution analysis and water-soluble chloride measured by ASTM. The result of this study are as follows: 1. The concentration of chloride ion in pore solution of BSC-solidified matrix is almost as low as 43-71% compared to that of OPC-solidified matrix containing the same chloride content in cement paste. 2. The binding capacity of specimens, OPC Pl-P5, are 93.5-77%, but the binding capacity of specimens, BSC Pl-P5 are 97.1-86.1%, which is to be as high as 2-9.1% compared to OPC containing the same chloride content. 3. In terms of water-soluble chloride content in BSC paste are 15-31.7 percent of chloride addition but free-chloride content in pore solution are 2.9-13.9 percent of chloride addition. The free-chloride content in pore solution is 19.3-43.8 percent lower for the water-soluble chloride content in cement paste.

• Journal of Microbiology and Biotechnology
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• v.25 no.8
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• pp.1328-1338
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• 2015

Years of research have shown that the application of microorganisms increases the compressive strength of cement-based material when it is cured in a culture medium. Because the compressive strength is strongly affected by the hydration of cement paste, this research aimed to investigate the role of the microorganism Sporosarcina pasteurii in hydration of cement paste. The microorganism's role was investigated with and without the presence of a urea-CaCl₂ culture medium (i.e., without curing the specimens in the culture medium). The results showed that S. pasteurii accelerated the early hydration of cement paste. The addition of the urea-CaCl₂ culture medium also increased the speed of hydration. However, no clear evidence of microbially induced calcite precipitation appeared when the microorganisms were directly mixed with cement paste.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.10a
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• pp.25-29
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• 1995

To perform high-strength of concrete, fine powers of pozzolan such as fly ash, silica fume mixed with cement. But mobility of cement and concrete decreased due to using of these powers. To control decrease of this mobility, it is required that mobility is improved by using of chemical admixture such as superplasticizer. We used admixtures -NSF, NM-2, NT-2 etc- in order to improve mobility of cement paste being substituted by 10, 20% of pozzolans respectively. It proved that optimum dosage of NSF, NT-2 was 2.0% for being substituted 10%, 3.0% for 20% so as to increase mobility of cement paste mixed paste mixed with fine powers of pozzolan at W/C=0.40.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.06a
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• pp.27-28
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• 2020

In this study, as a measure to recycle red mud, which is a byproduct of the Bayer Process, red mud was manufactured as liquid and recycled without drying and grinding. Previous studies have shown that mechanical performance decreases when liquid red mud is applied to cement concrete. Therefore, in this study, liquid red mud was neutralized with nitric acid and applied to cement paste to examine the properties of cement paste according to the addition of red mud. As a result, the compressive strength of 10% liquid red mud decreased by 37.7% compared to Plain, and 10% liquid red mud indicates similar strength to Plain and restores the strength.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.189-190
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• 2023

In this study, the compressive strength and hydration heat of cement paste mixed with cellulose nanocrystal(CNC) and graphene oxide (GO) were evaluated. The difference was compared by mixing 0.1 vol.% ~0.4 vol.% of CNC and 0.05 wt.% ~ 0.1 wt.% of GO in a cement paste with a water cement ratio of 0.3. As a result, it was confirmed that the compressive strength increased as CNC and GO were mixed respectively, and then the compressive strength decreased when the appropriate mixing rate was exceeded. In the hydration heat measurement, there was no significant difference when only CNC was mixed, but it was confirmed that the hydration heat decreased as the amount of CNC mixing increased when used in combination with GO.

• Journal of the Korean Ceramic Society
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• v.50 no.2
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• pp.149-156
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• 2013

This study examines the effects of limestone's factors on the fluidity of cement paste when of up to 15%. As the substitution ratio of limestone powder increases, the fluidity of the paste is also improved; however, it has no correlation to the $CaCO_3$ content of the limestone, fineness of the limestone, and fluidity of the pastes. Regardless of clay content of the limestone, it showed a similar mini-slump, so there was no correlation between the clay content and the fluidity of the paste. Also, the total organic carbon content of the limestone and the fluidity of the paste showed no correlation. Regardless of the limestone's grade or fineness, n value of powder gained by using the Rosin-Rammler distribution function showed that the fluidity of the paste increased as the n value reduced. It was also shown that particle size distribution of ordinary Portland cement with limestone powder had a major effect on the fluidity of the paste.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.174-175
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• 2022

The blast furnace slag, which is widely used as a cement admixture, has latent hydraulics under the influence of cement hydrate, and fly ash and silica fume mainly cause a pozolane reaction. As a result, the cement structure becomes dense, and it is possible to compensate for defects when concrete is usually made with portland cement alone. When fixing carbon dioxide through reaction with carbon dioxide, the amount of calcium hydroxide in the cement paste is important. The larger the amount of calcium hydroxide, the more active the reaction may occur. It is also an important variable in calculating the depth of neutralization through carbonization. In this study, calcium hydroxide in cement paste using mixed materials was quantified through thermal analysis.

• Journal of the Korean GEO-environmental Society
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• v.5 no.3
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• pp.31-39
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• 2004

The bored pile is widely used as a low noise and vibration piling method in Korea. However, there is design tendency to minimize the friction capacity of the bored pile because of uncertainty and the quality control specification is not set up. This research analysed the strength characteristics of cement paste after the uniaxial compression test with various condition. Test results show that the compressive strength of cement paste with w/c=0.83 was up to $156.0kgf/cm^2$, and the lower w/c ratio and the longer age, the strength of cement paste increased. Also the higher soil mixing ratio, the strength of soil cement decreased, and too high soil mixing ratio caused the malfuction of soil cement. Also this research analysed the 188 dynamic pile test results which were performed before and after hardening of cement paste. Analysis result showed that the average ultimate unit friction capacity was $9.1tf/m^2$ and this result surpassed the common design criteria of the bored pile.