• Cement Symposium
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• s.41
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• pp.82-87
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• 2014

• Journal of Korean Society of Environmental Engineers
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• v.29 no.7
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• pp.810-819
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• 2007

Investigation of alkali activation of fly ash and blast furnace slag was carried out using waterglass and sodium hydroxide. XRD, FTIR, $^{29}Si$ and $^{27}Al$ NMR, TGA and SEM were used to observed the reaction products and microstructure of the fly ash/slag cement (FSC) pastes. The reaction products were amorphous or low-ordered calcium silicate hydrate and aluminosilicate gel produced from alkali activation of blast furnace slag and fly ash, respectively. On the basis of this investigation, waterglass solution with a modulus(Ms) of 1.0 and 1.2 is recommended for alkali activation of fly ash and blast furnace slag. Morphology of FSC pastes alkali-activated with Ms of 1.0 and 1.2 shows a more solid and continuous matrix due to restructuring of gel-like reaction products from alkali-activated fly ash and blast furnace slag together with another hydrolysis product(i.e., silica gel) from water glass.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.4
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• pp.114-121
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• 2010

Portland cement production is under critical review due to high amount of CO2 gas released to the atmosphere. Attempts to increase the utilization of a by-products such as fly ash and ground granulated blast-furnace slag to partially replace the cement in concrete are gathering momentum. But most of by-products is currently dumped in landfills, thus creating a threat to the environment. Many researches on alkali-activated concrete that does not need the presence of cement as a binder have been carried out recently. However, most study deal only with alkali-activated ground granulated blast furnace slag or fly ash, as for the combined use of the both, little information is reported. In this study, we investigated the influence of mixture ratio of fly ash/ blast furnace slag tand curing condition on the flowability and compressive strength of mortar in oder to develop cementless alkali-activated concrete. In view of the results, we found out that the mixture ratio of fly ash/blast furnace slag always results to be significant factors. But the influence of curing temperature in the strength development of mortar is lower than the contribution due to other factors. At the age of 28days, the mixture 50% fly ash and 50% ground granulated blast furnace slag activated with 1:1 the mass ratio of 9M NaOH and sodium silicate, develop compressive strength of about 65 MPa under $20^{\circ}C$ curing.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.1
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• pp.200-207
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• 2019

Cement is one of the most commonly used materials in the construction and civil engineering industry. However, emissions of carbon dioxide generated during the production of cement have been linked to climate change and environment pollutants. In order to replace cement, many studies have been actively performed research to utilizing Blast Furnace Slag(BFS), which is a byproduct of the steel industry. This study aims to investigate the physiochemical properties of the BFS powder based grout to determine whether it can be used as an environment-friendly grout material. As a fine powder, BSF can be used instead of cement grout due to its potential hydraulic property. BSF has also been known for its ability to strengthen materials long-term and to densify the internal structure of concrete. In order to investigate the physicochemical properties of the BFS powder based grout as a grout material, in this study assessment tests were performed through a gel-time measurement, uniaxial compressive strength, and chemical resistance tests, and heavy-metal leaching test. Characteristics and advantages of the slag were studied by comparing slag and cement in various methods.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.3
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• pp.204-210
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• 2022

Cement is pointed out as the main cause of carbon dioxide emission in the construction industry. Many researchs are underway to use blast furnace slag, an industrial by-product, as a substitute for cement to reduce carbon dioxide emitted during the manufacturing the cement. When blast furnace slag is used as a substitute for cement, it has advantages such as long-term strength and chemical resistance improvement. However, blast furnace slag has a problem that makes initial strength low. This is due to the impermeable film on the surface created during the production of blast furnace slag. The created film is known to be destroyed in an alkaline environment, and based on this, previous studies have suggested a solution using various alkali activators. But, alkali activator is dangerous product since it is a strong alkaline material. And it has the disadvantage in price competitiveness. In this study, an experiment was conducted to improve the initial hydration reactivity of the blast furnace slag to secure the initial strength of the mortar substituted with the blast furnace slag and to check whether the carbonation resistance was increased. As a result of the experiment, it was confirmed that the mortar using alkaline water showed higher strength than the mortar using tap water, and there were more hydration products generated inside. In addition, it was confirmed that the mortar using alkaline water as a compounding water had high carbonation resistance.

• Magazine of the Korea Concrete Institute
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• v.3 no.1
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• pp.18-23
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• 1991

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.525-528
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• 2008

This study is performed to know influence on the hydration according to alkali activator and method of pulverization and fineness in slag-cement. The compressive strength of mortar were examined when the SG powder of which the specific surface area are 4,000, 6,000, and 8000cm$^2$/g were substituted for 50wt.% of ordinary portland cement. Na$_2$SO$_4$, Ca(OH)$_2$, NaOH were used as alkali activator. respectively, As the results, the compressive strength of mortar increased as following the order, Na$_2$SO$_4$>Ca(OH)$_2$>None>NaOH until 7days. But at 28days, mortar used Ca(OH)$_2$ as alkali activator were the highest strength.

• Journal of the Korea Concrete Institute
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• v.18 no.2 s.92
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• pp.267-274
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• 2006

Greenhouse gas reduction will be highlighted as the most pending question in the cement industry in future because the production of Portland cement not only consumes limestone, clay, coal, and electricity, but also release waste gases such as $CO_2,\;SO_3$, and NOX, which can contribute to the greenhouse effect and acid rain. To meet the increase of cement demand and simultaneously comply with the Kyoto Protocol, cement that gives less $CO_2$ discharge should be urgently developed. This study aims to manufacture non-sintering cement(NSC) by adding phosphogypsum(PG) and waste lime(WL) to granulated blast furnace slag(GBFS) as sulfate and alkali activators. This study also Investigates the hydration reaction of NSC through analysis of scanning electron microscopy(SEM), X-ray diffraction(XRD), differential thermal analysis(DTA), and pH. Results obtained from analysis of the hydrate have shown that the glassy films of GBFS are destroyed by the activation of alkali and sulfate, ions eluted from the inside of GBFS react with PG and produce ettringite, and consequently the remaining component in GBFS slowly produced C-5-H(I) gel. Here, PG is considered not only to play the role of simple activator, but also to work as a binder reacting with GBFS.

• Resources Recycling
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• v.20 no.3
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• pp.40-47
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• 2011

In this study, we investigated the strength, shrinkage and durability of alkali-activated mortar using blast furnace slag only, and admixed with blast-furnace slag and fly ash as cementious materials in oder to develop cementless alkali-activated concrete. In order to compare with the alkali-activated mortar, the normal mortar using ordinary portland cement was also test. In view of the results, we found out that strength development, the resistance to shrinkage and freezing-thawing of the cementless alkali-activated mortar have better than the mortar using ordinary portland cement. Especially, using the combined with blast furnace slag and fly ash develop high strength of above 60 MPa, reduce shrinkage of about 40% and improve freezing-thawing durability of approximately 20%, but promote the velocity of carbonation of 2~3 times.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.197-198
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• 2018

As part of the effort to shorten the construction period, this study examined the strength expression characteristics at the early age of concrete using high fineness cement and blast furnace slag. accordingly to provide a basic data on how to solve the problem that the initial strength is lowered.