• Magazine of RCR
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• v.12 no.1
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• pp.16-22
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• 2017

• Magazine of RCR
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• v.6 no.3
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• pp.18-21
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• 2011

• Journal of the Korean Recycled Construction Resources Institute
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• v.1 no.1
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• pp.35-41
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• 2013

In this study, we investigated the strength development and durability of geopolymer mortar using blast furnace slag only, and admixed with blast-furnace slag and fly ash as cementious materials in oder to develop cementless geopolymer concrete. In order to compare with the geopolymer 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 freezing-thawing of the geopolymer 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, and improve the resistance of freezing-thawing of approximately 20%, but promote the velocity of carbonation of 2.2~3.5 times.

• Journal of the Korea Institute of Building Construction
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• v.14 no.5
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• pp.397-405
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• 2014

There are many literatures reporting that the service life of re-bars in concrete structures is reduced in the oceanic environment due to chloride attack. To solve this problem, this study used geo-polymer as a mix material for concrete to increase its resistance to salt damage, and the external voltage method, one of the electric methods, is was applied to evaluate the likelihood of re-bars in the oceanic structure being exposed to the extreme salt environment. The items evaluated include the natural potential of re-bars and the corrosion rate. The results of the tests showed that in all of the salt environmental conditions (submerged zone, tidal zone, and crack), the tested materials were remarkably effective compared with ordinary concrete. The corrosion protective property was found not only in the evaluation of the natural potential but also in the evaluation of the corrosion rate, suggesting that the external voltage method can be used stably for geo-polymer RC structures in an extreme salt environment.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.319-320
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• 2009

The alkali activation products of slag, fly ash C and fly ash F were investigated using compressive strength test and synchrotron x-ray diffraction. We propose that the predominantly amorphous geopolymer formed under ambient conditions is a disordered form of one of the ABC-6 group of zeolites, which includes poly-types such as hydroxycancrinite, hydroxysodalite, chabazite, levyne or fransinite.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.4
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• pp.119-126
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• 2012

Portland cement production-1.5billion tonnes yearly worldwide-contributes substantially to global atmospheric pollution(7% of total of $CO_2$ emissions). Attempts to increase the utilization of fly ash, by-products from thermal power plant to partially replace the cement in concrete are gathering momentum. But most of fly ash 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. Instead, the sources of material such as fly ash, that are rich in Silicon(Si) and Aluminium(Al), are activated by alkaline liquids to produce the binder. Hence concrete with no cement is effect reduction of $CO_2$ gas. In this study, we investigated the influence of the compressive strength of mortar on alkaline activator and curing condition in oder to develop cementless fly ash based alkali-activated concrete. In view of the results, we found out that it was possible for us to make alkali-activated mortar with 70MPa at the age of 28days by using alkaline activator manufactured as 1:1 the mass ratio of 9M NaOH and sodium silicate and applying the atmospheric curing after high temperature at $60^{\circ}C$ for 48hours.

• Magazine of RCR
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• v.12 no.1
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• pp.8-15
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• 2017

• Computational Structural Engineering
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• v.24 no.1
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• pp.26-30
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• 2011

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.4
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• pp.418-424
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• 2016

This study is an experimental study on the recycling of bottom ash in coal ash discharged from a thermal power plant. Bottom ash has limited research on recycling because it has more porous and higher water absorption ratio than fly ash. In this paper, the bottom ash was pulverized to a specific surface area of $4,000cm^2/g$ in order to use as a binder, and the flow, compressive strength test and microstructure analysis of the bottom ash based geopolymer mortar were performed. The flow measurement results of the geopolymer mortar showed that the flow rate was improved by increasing mixing water as the molar concentration of activator was increased. Compressive strength increased with increasing curing temperature and molar concentration. Through the microstructure analysis, we could confirm the geopolymer gel produced by the reaction of the condensation polymerization. It is considered that it is possible to make the bottom ash based geopolymer concrete through proper molar concentration of activator and high temperature curing.

• Resources Recycling
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• v.27 no.6
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• pp.59-67
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• 2018

Efflorescence is a white deposit of powders in the surface of cement concrete which can also occur in geopolymers. Efflorescence occurs when sodium ions in alkali activator react with atmospheric carbon dioxide to form sodium carbonate components. In this study, we investigated whether the secondary efflorescence can be reduced by controlling the Na/Al mole ratio or by changing the curing temperature and heat curing time in fly ash-based geopolymers. The 28 days compressive strength in geopolymers having Na/Al ratio of 1.0 was higher than geopolymers having Na/Al ratio of 0.8. The strength increased with the increasing curing temperature and longer heat curing time. On the other hand, efflorescence was lower when the curing temperature was high and the heat curing time was longer in the geopolymers having Na/Al ratio of 1.0. The geopolymers having Na/Al ratio of 0.8 showed accelerated efflorescence occurrence than the geopolymers having Na/Al ratio of 1.0. In order to reduce the occurrence of the secondary efflorescence of fly ash-based geopolymers, it will be advantageous to maintain the Na/Al ratio at 1.0, increase the curing temperature, and lengthen the heating curing time.