• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.997-1000
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• 2008

Strength development of concrete subjected to cold weather is generally delayed due to its low temperature. In case of soil nailing method, it is necessary to apply the shotcrete. However, the shotcrete placement under low temperature experiences retardation of strength development due to delayed hydration reaction. Therefore, in this paper, the use of fine particle cement which is produced through particle classification in cement manufacturing process, is discussed to enhance the strength development of the shotcrete under low temperature. According to the results, the concrete containing 100% of fine particle cement had excellent strength development even at $-9^{\circ}C$ of temperature and at 5days, it reached design strength with PE film curing. It is thought that more than 70% of fine particle cement can secure required strength of the shotcrete even at low temperature condition.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.6
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• pp.210-215
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• 2023

Raw mix burnability is an especially crucial factor in cement manufacturing technology, and it depends on the physical, chemical and mineralogical properties of each raw material. In this article, we compared the difference of burnability between the domestic and Japanese fly ash as cement raw materials by using Lafarge and Polysius evaluation method. Regardless of the type or amount of fly ash used, it was found to be more combustible when using fly ash. In both case, burnability improves as the amount of fly ash increases, especially the improvement in bunarbility is remarkable up to 3%. In conclusion, as the amount of fly ash increases within the range allowed by cement quality, burnability of raw materials improves, and thus the fuel cost required for the firing of clinker can also be expected to be reduced.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.11a
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• pp.65-66
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• 2012

The cement used in the construction industry of the manufacturing process, large amounts of the greenhouse gas, CO₂ and is currently being studied for cement substitutes that reduce greenhouse gas issue. Therefore, the this study as a replacement for cement industrial by-product of blast furnace slag, red mud, silica fume and alkali-activator, using only inorganic composites without high-temperature calcination process were manufactured. The waste gypsum board micro powder added to compensate for the shrinkage cracks, the compressive strength and flow, and length change characteristics were investigated. Consequently, The setting time was shortened as GB added And liquidity was reduced. GB 2%, 7 days curing the added strength of specimens was the highest. Came out, and change the length of the Plain least.

• KIEAE Journal
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• v.10 no.2
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• pp.3-8
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• 2010

Many countermeasures are presented to make excessive earth circumstance pollution better in the earth. A lot of researches are in progress to lessen $CO_2$ among the industries exhausting it. The industries manufacturing cement are making many countermeasures. Many concernments on ECO-friendly materials, rather than cement, are increased, and researches are in progress to develop them. Lime, material mostly used before Portland cement appeared, attracts the Occident as well as the Orient. In the Occident, lime mortar was used in common, for maintaining and repairing cultural properties, too. This study is aimed at offering basic materials for the modern use of lime, ECO-friendly material. This study measured the change of intensity and weight with lime, sand, and earth, basic materials of Samhoimool. As a result, at the beginning, hydrated lime displayed its density late, but as time was gone, density was promoted continuously. In addition, density was promoted, when it was given heat at the beginning. If heat-generation reaction of quicklime and water was used, density was promoted at the beginning, but liquidity showed a drop.

• Advances in concrete construction
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• v.9 no.2
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• pp.183-193
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• 2020

The present investigation is to identify an optimum mix combination amongst 28 different types of artificial lightweight aggregates by pelletization method with aggregate properties. Artificial aggregates with different combinations were manufactured from fly ash, cement, hydrated lime, ground granulated blast furnace slag (GGBFS), silica fume, metakaolin, sodium bentonite and calcium bentonite, at a standard 17 minutes pelletization time, with 28% of water content on a weight basis. Further, the artificial aggregates were air-dried for 24 hours, followed by hardening through the cold-bonding (water curing) process for 28 days and then testing with different physical and mechanical properties. The results found the lowest impact strength value of 16.5% with a cement-hydrated lime (FCH) mix combination. Moreover, the lowest water absorption of 16.5% and highest individual pellet crushing strength of 36.7 MPa for 12 mm aggregate with a hydrated lime-GGBFS (FHG) mix combination. The results, attained from different binder materials, could be helpful for manufacturing high strength artificial aggregates.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.11a
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• pp.83-84
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• 2018

As the concentration of greenhouse gases in the atmosphere increases, the reduction of CO2 is gaining worldwide attention. In the construction industry, cement replacement materials such as fly ash and blast furnace slag were investigated to reduce CO2 emissions in cement production process. Precast concrete is used in the field after manufacturing in the factory in the form of pipes and bricks because of shortening construction period and cutting construction cost. According to the results of previous research, it is known that early CO2 curing in concrete using OPC or fly ash has an initial strength enhancement effect and can be used for precast concrete production. Therefore, the purpose of this study is to evaluate the strength improvement effect by confirming the initial strength improvement effect when blast furnace slag is mixed.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.164-165
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• 2015

Recently, the reason of using foamed concrete is for core of panel, filler of construction material to give lightness. However, cement causes environmental problem. The cement generates CO₂ but we normally use cement during manufacturing foamed concrete. Accordingly, this study focuses on dynamic properties of matrix according to the addition ratio of paper ash to make lightweight matrix with blast furnace slag and paper ash which are industrial by-product. The experiment progessed in order to select th optimum mixing ratio of the blast furnace slag and paper ash. There are totally 7 levels such as B100:P0, B95:P5, B90:P10, B85:P15, B80:P20, B75:P25, B70:P30 in this study. As a result of the test, B95:P5 matrix has the best density and compressive strength.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.05b
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• pp.93-96
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• 2009

This study is to examine a change of quality and a material performance of fiber reinforced cement composite for mass production. It is necessary to make Strain-hardening cementitious composite(SHCC) by batcher plant for ready-mixed concrete and use the performance of SHCC which made based on laboratory level. This study makes a comparative performance of press and mechanics that is the property of Strain-hardening by direct tension. In case of making by batcher plant. This experiment has demonstrated that even if it takes long after being mixed small and compared with the one which made based on laboratory, it has a tendency to be dissatisfied with fiver's dispersion and lower its performance of Strain-hardening. The reason why the material performance of SHCC for mass production went down is through SHCC that mixed sometimes matrix's viscosity and fiber's dispersion.

• Journal of the Korea Institute of Building Construction
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• v.17 no.1
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• pp.47-54
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• 2017

Cement industry is typical carbon-emission industry. If the industrial by-products(granulated blast-furnace slag (GGBFS), fly ash, etc.) are used a large amount, it might be able to reduce cement consumption and mitigate carbon emissions. In this case, however, decrease of early strength is relatively large. Therefore, there is a limitation in increase of the amount of substitute. Considering these circumstances, it would be a good solution to reduce carbon emissions in cement industry to improve the performances of mixed cement through proper alkali-activation in Portland blended cement using GGBFS or fly ash. Therefore, this study prepared concrete in ready-mixed concrete manufacturing facilities with an addition of a binder which used 2.0% modified alkali sulfate activator after mixing Portland cement, GGBFS and fly ash in the ratio of 4:4:2 and assessed its basic properties. The results found the followings: The use of modified alkali-sulfate activator slightly reduced slump and shortened setting time. As a result, bleeding capacity decreased while early strength improved. In addition, there is no big difference in carbonation resistance. It appears that there should be continued experiments and analyses on the related long-term aged specimens.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.4
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• pp.553-560
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• 2021

In this study, cement clinker using a pure sample and clinker using 7% coal ash were sintered at a temperature of 1050~1500℃. Changes in the content of cement minerals and changes in microstructure by sintering temperature were reviewed. The application of coal ash as a raw material for cement clinker was applicable as a source of Al₂O₃ and SiO₂. At a sintering temperature of 1350℃ or higher, the cement clinker applied with coal ash showed the same level of mineral content as compared to the cement clinker applied with pure raw material. The microstructure also showed a similar state, confirming that coal ash can be used as a raw material for cement. In XRD-Reitveld analysis, a maximum amount of Belite was produced at 1250℃. The conversion from Belite to Alite was observed from 1350℃. From 1350℃, the interstitial phase and the mineral phase presumed to be alite were distinguished. It was clearly distinguished from 1400℃. As the sintering temperature increased, the shape and boundary of the crystal phase became clear, and the size of the crystal phase was also increased.