• Journal of the Korean Ceramic Society
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• v.33 no.5
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• pp.519-523
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• 1996

Calcium hydroxide produced by cement hydration decreases the durability and the compressive strength of cement mortars. Pozzolanic property of meta kaolin and silica fume allows to avoid this drawback. Calcium hydroxide consumption according to pozzolanic raction is evaluated by Fourier differential thermal analysis. Particulary the properties of high performance and high strength of cement mortar containing above 10% meta kaolin and silica fume were resulted in the pozzolanic activity.

• Journal of the Korea Institute of Building Construction
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• v.15 no.1
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• pp.17-23
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• 2015

In this research, the $CO_2$ absorption performance of mortar was investigated. The level of $CO_2$ absorption in mortar with various binders including cement and nonsintered cement was examined. As a result for the mortar with photosynthetic bacteria, the compressive strength was similar to the one without the bacteria at early age but decreased at the age of 28 days. However, for the $CO_2$ absorption, with photosynthetic, the performance of the mortar with OPC, and nonsintered cement deceased to 21%(234 ppm) and 19.7%(243 ppm) respectively after 12 hours age.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.05a
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• pp.242-243
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• 2014

In this study, industrial by-products including blast furnace slag, incineration ash and waste gypsum were used with recycled fine aggregates to manufacture the zero-cement mortar. The replacement ratio of anhydrite gypsum was fixed as 0, 10%, 20% the replacement ratio fo WA1 was fixed as 0.5% and 1.0%, respectively. It could be identified that when the replacement of gypsum was 20% and WA1 of 1.0%, the strength could be in the range of normal strength.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.1
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• pp.85-92
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• 2021

The purpose of this study is to investigate the properties of hardener-free epoxy-modified mortars(EMMs) using ground granulated blast furnace slag(GGBFS) and alkali activators. The hardener-free EMMs with a GGBFS content of 20% using 4 types of alkali activators were prepared with various polymer-binder ratios, and tested for strengths, water absorption, carbonation depth, chloride ion and H2SO4 penetration depth. The conclusions obtained from the test results are summarized as follows: The compressive strength of the EMMs with a GGBFS content of 20% attains a maximum at a polymer-binder ratio of 10%. The flexural strength of the hardener-free EMMs using Ca(OH)2 as a alkali activator is improved with increasing polymer-binder ratios. However, the flexural strength of the EMMs using NaCO3, Na2SO4 and Li2CO3 is gradually decreased with increasing polymer-binder ratios. Regardless of the type of alkali activator, the water absorption, chloride ion penetration and carbonation depth are remarkably decreased with increasing polymer-binder ratios due to the epoxy film formed in the EMMs. The H2SO4 penetration depth of the hardener-free EMMs with a GGBFS content of 20% is gradually increased with increasing polymer-binder ratio. In this study, the properties of hardener-free EMMs using Ca(OH)2 as a alkali activator are more excellent than those of other alkali activators.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.11a
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• pp.217-219
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• 2012

In this study, the experiment was conducted in the level of mortar as one of the basic studies on pre-cast concrete which acceleration curing is not done. This study has the purpose to develop the strength of mortar into 20MPa within 6 hours in the condition of room temperature using admixtures which can accelerate C3S hydration reaction. In this experiment, W/C was fixed into 20%, PCE which can stimulate C3S was used as an accelerating admixture. From the results of this experiment, maximum content of accelerating admixture was 1%. Also, as more than 20MPa was measured through 6-hour compressive strength, it can be known that strength can be developed without steam-curing.

• Journal of the Korea Institute of Building Construction
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• v.15 no.2
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• pp.161-167
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• 2015

Nowadays, all the world face to the global warming problems due to the emission of $CO_2$. From the previous studies, recycled aggregates were used as an alkali activator in blast furnace slag to achieve zero-cement concrete, and favorable results of obtaining strength were achieved. In this study, gypsum and incineration waste ash were used as the additional alkali activation and effects of the gypsum and incineration waste ash to enhance the performance of the mortar were tested. Results showed that although the replacement ratio of 0.5% of incineration waste ash and 20% of anhydrous gypsum resulted in the low of mortar at the early age, while it improved the later strength and achieved the similar strength to that of conventional mortar (at 91 days).

• Journal of Korean Society of Environmental Engineers
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• v.37 no.3
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• pp.159-164
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• 2015

This study investigated the environmental risk for up-cycling of air-cooled ladle furnace slag (LFS) and evaluated the mortar compressive strength of binary and ternary blended cements using LFS of 3, 5, 10 wt%. Based on the Soil Environment Conservation Act standard, there was no environmental risk of the up-cycling of LFS. Results of mortar compressive strength assesment showed that the compressive strength of two blended cements using LFS of lower than 5 wt% was about 1.1 times superior to that of un-substituted cement (ordinary portland cement, OPC); however the compressive strength of those with LFS of 10 wt% decreased with 10% compared with that of OPC.

• Polymer(Korea)
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• v.36 no.2
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• pp.216-222
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• 2012

We synthesized microcapsule absorbent with crosslinked poly(styrene-$alt$-maleic anhydride) (PSMA) as a core and PSMA as a shell by a precipitation polymerization method for the delayed absorption of excess water in cement mortar. cPSMA-PSMAs with core-shell structure were synthesized with ratios of 1/1, 1/2 and 1/3 as core monomer mass to shell monomer mass to control shell thickness. We observed the hydrolysis of PSMA in cement-saturated aqueous solution by a FTIR spectrometer. We observed good core-shell structure microcapsules for 1/2(cPSMA #3), but observed incomplete core-shell structure for 1/1(cPSMA #2) and 1/3(cPSMA #4) of core/shell monomer ratios. The swelling ratio of cPSMA #3 in cement-saturated aqueous solution was increased until 20 min. After that it was decreased until 2 hrs swelling time, and they started to increase again. The viscosities of cement paste with cPSMA #3 microcapsules were very slowly increased until 1 hr and increased fast after 1.5 hrs. Cement mortar with 0.5 wt% cPSMA #1 having only core part showed about 5% increase in compressive strength compared to that of plain cement mortar. cPSMA #3 added cement mortar showed the highest compressive strength with 7% increase.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.1
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• pp.80-87
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• 2020

The purpose of this study is to investigate the physical properties and self-healing effects of hardener-free epoxy-modified mortars(EMMs) using ground granulated blast furnace slag(GGBFS). The EMMs with GGBFS were prepared with various polymer-binder ratios and GGBFS contents, and tested for strengths, adhesion in tension, water permeation and self-healing effects. The conclusions obtained from the test results are summarized as follows. The compressive strength of the EMMs with GGBFS is reduced with increasing polymer-binder ratios because of reduction of the degree of hardening in the EMMs, and is somewhat inferior to that of unmodified mortars. In the flexural and tensile strengths, the flexural strength of the EMMs is almost constant with increasing polymer-binder ratios. However, the tensile strength of the EMMs is gradually increased with increasing polymer-binder ratios. Regardless of the GGBFS contents, the adhesion in tension of the EMMs increases sharply with increasing polymer-binder ratios. The water permeation of the EMMs is remarkably reduced with increasing polymer-binder ratios and GGBFS contents. The self-healing effect of the hardener-free EMMs with GGBFS is improved with increasing water immersion period at a GGBFS content of 20%.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.4
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• pp.438-444
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• 2019

In this study, the effect of polypropylene fiber on the freeze-thaw damage of mortar was evaluated experimentally. The effects of the reinforcing of polypropylene fiber on the compressive and bending performance of mortar after 300 cycles of freeze-thaw test were evaluated by comparing the normal mortar and the mortar with polyvinyl alcohol fiber. In addition, the mass loss, relative dynamic elastic modulus, and cumulated pore volume of mortar were measured by each cycle of freeze-thaw test. As a result, it was confirmed that the fiber reinforced mortar, regardless of the fiber type, was effective not only in maintaining the performance of the compressive strength and the bending strength but also suppressing the mass loss after the freeze-thaw test of 300 cycles. Meanwhile, it was confirmed that not only polyvinyl alcohol fibers but also polypropylene fibers can effectively act to suppress the damage of the mortar by freeze-thaw. However, in order to improve the freeze-thaw resistance of mortar mixed with polypropylene fiber, it is necessary to increase the bonding performance with the cement matrix which can be expected from polyvinyl alcohol fiber.