• Journal of the Korea Concrete Institute
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• v.20 no.5
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• pp.543-548
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• 2008

Solid hydrated by hydro-thermal synthesis reaction is cured two times, the first curing is the steam curing at atmospheric pressure and the second one is a high-pressure steam curing, that is autoclaving. Steam curing is to acquire the proper strength for the resistance of treatment in the first curing process, it was not evaluated properly so far. Because of ignorance about curing, some engineers even think that the dry curing is better than the steam curing. The relation between compressive strength of solid hydrated by hydrothermal synthesis reaction and curing condition are presented in this paper. In order to investigate the effect of curing on the strength properties of specimen, the hydration behavior of solid hydrated by hydro-thermal synthesis reaction has been studied over curing condition using XRD, DT-TGA and porosimeter, SEM analysis technique. The results show that the specimens which are cured with blended method of dry and steam curing appear to have better strength properties than that of dry curing and steam curing. Also, there are significant difference of hydration behavior among curing condition in the solid hydrated by hydro-thermal synthesis reaction.

• Composites Research
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• v.21 no.1
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• pp.16-21
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• 2008

The cure behavior of epoxy resin with a conventional amide-type hardener(HD) was investigated in the presence of castor oil(CO), cashew nut shell liquid(CNSL) and CNSL-formaldehyde resin(CFR) by using a dynamic differential scanning calorimetry(DSC). The activation energy of curing reaction was also calculated based on the non-isothermal DSC thermograms at various heating rates. An one-stage curing was noted in the case of epoxy resin filled with CO, while the epoxy resin with CNSL and CFR showed a two-stage curing process. A competitive cure reaction was noted for the epoxy resin/CNSL(or CFR)/HD blends. In the absence of HD, the CFR showed lower values of curing enthalpy than that of CNSL. The activation energy of epoxy resin curing increased with increasing the CNSL and CFR loading.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.665-668
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• 2008

Portland cement production-1.5billion tonnes yearly worldwide-contributes substantially to global atmospheric pollution($\sim$7% of total of CO$_2$ emissions). Attempts to increase the utilization of fly ash, a 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. Therefore, In this study, influence of curing temperature(30, 60, 90$^{\circ}$C) on the strength of properties fly ash based cement ZERO mortar was investigate, measured a weight change and pH change according to each care of curing temperature. The test results that a curing at 90$^{\circ}$C is appropriate in case of the high strength concrete is required in the early-age of the curing and 60$^{\circ}$C is efficient for the case of requiring high strength at age 28 days. Furthermore pH variation and value of compressive strength are judged to correlate but change of weight is not the case.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.05a
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• pp.33-34
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• 2013

Recently, as the policy of state that it is the low carbon green growth is promoted, the effort for reducing the CO₂ gas generation ejected from the construction industry in the cement production is continued. That is, the method using the mineral admixtures including the silica fume and red mud, silica fume and etc. it is the industrial byproduct with the method solving the exhaustion problem of the environmental contamination settlement and natural resources, the great quantity as the cement substitute material is examined. Accordingly, in this research, the strength characteristic of the curing body differentiating the curing method of the ternary system inorganic binder using the blast furnace slag and red mud, silica fume and etc. as the cement substitute material tried to be examined.

• Journal of Urban Science
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• v.11 no.1
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• pp.21-28
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• 2022

Raman spectroscopy is effective to investigate functional groups via molecular vibration. The technique offers the structural information of compounds including subtle changes in the chemical composition of local atomic coordination without critical damage. Thus, the effect of carbonation on the hydration characteristics of Portland cement under pre-curing conditions for carbonation was investigated via Raman spectroscopy in the present study. Gaseous CO₂ was injected within 60 seconds, and the reaction time was varied from 0 minute to 90 minutes. The test results indicated that the Ca/Si ratio of C-S-H reduced immediately after mixing and then the C-S-H with a relatively high Ca/Si ratio coexisted as the reaction time increased. The calcium carbonates formed in the present study included calcite and amorphous calcium carbonates. The test results via Raman spectroscopy provide valuable information about the carbonation characteristics of OPC under pre-curing conditions for carbonation.

• Journal of Powder Materials
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• v.26 no.6
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• pp.493-501
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• 2019

In this work, ultra-fine calcium oxide (CaO) powder derived from eggshells is used as the starting material to synthesize mineral trioxide aggregate (MTA). The prepared CaO powder is confirmed to have an average particle size of 500 nm. MTAs are synthesized with three types of fine CaO-based powders, namely, tricalcium silicate (C3S), dicalcium silicate (C2S), and tricalcium aluminate (C3A). The synthesis behavior of C3S, C2S and C3A with ultra-fine CaO powder and the effects of C₃A content and curing time on the properties of MTA are investigated. The characteristics of the synthesized MTA powders are examined by X-ray diffraction (XRD), field emission-scanning electron microscope (FE-SEM), and a universal testing machine (UTM). The microstructure and compressive strength characteristics of the synthesized MTA powders are strongly dependent on the C3A wt.% and curing time. Furthermore, MTA with 5 wt.% C3A is found to increase the compressive strength and shorten the curing time.

• The Journal of the Korea Contents Association
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• v.14 no.4
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• pp.389-396
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• 2014

This study was conducted as the basic research for the replacement of Blast Furnace Slag, Red Mud, Silica Fume, etc., with cement as a solution to the problems arising from the global warming caused by the generation of $CO_2$, and conducted the experimental review to examine the feasibility of matrix having properties identical to those of cement by using the Blast Furnace slag, Red mud, Silica fume, and alkali-activator. For this, by using the the inorganic binder, such as Blast Furnace Slag, Red Mud, Silica Fume, etc., and NaOH, $Na_2SiO_3$ and others as the cement substitute material, the strength characteristic according to the mixture time variation was performed in the tentative experiment. Based on the preceding experiment, this study performed the experiment to analyze the strength properties of hardener through the curing by air-dry temperature, curing by temperature in water, coating curing, and Korean paper curing. For the water curing at $80^{\circ}C$, the compressive strength and flexural strength were found to be the most excellent at the age of the 28th day, and furthermore, it was found that the non-cement hardener could be made, which is considered to affect the production of eco-friendly concrete.

• Textile Coloration and Finishing
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• v.4 no.3
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• pp.122-130
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• 1992

To improve the physical properties and the dyeing properties of silk, the silk fabric was treated with urea resin and reactive dyeing. The effects of urea resin concentration, pH of padding bath and curing condition were investigated in order to find optimum condition and the following results are obtained The optimum condition for the crease recovery of silk fabric was urea resin concentration of 80 g/ι, pH of 7, the curings temperature of about 135$^{\circ}C$, and the curing time of 3 minutes. The crease recovery and the thermal insulation ratio of silk fabric were increased by the above treatment. K/S increased as the adding amount of Na$_2$SO$_4$ increased, K/S, however was not affected by the adding amount of Na$_2$CO$_3$. Co1or fastness of the dyed fabrics treated with urea resin were improved slightly compared with untreated ones.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.05a
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• pp.100-101
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• 2014

The global warming because of the CO₂ emission and solution about this emerge as the international enviroment problem. Particularly, it is the absolutely it is needed for reducing the CO₂ in the cement industry and harmful material actual condition. And the construction of home and abroad and material manufacturers tries for the technology development for the carbon dioxide and harmful material reduction which the portland cement in manufacture is usually emitted along with the increase of concerns about the environment-friendly concrete and panel. Therefore, in this research, the compressive strength of the inorganic binder and flexural strength tries to be measured in order to draw the inappropriate high temperature cure time of the ternary system inorganic binder using the blast furnace slag, red mud, silica fumewhich is the industrial byproduct with the cement substitute material, and etc.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.141-142
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• 2023

In this study, the strength development characteristics of calcium silicate cement mixed mortar according to carbonation hardening conditions were evaluated. As a result of measuring the compressive strength, the strength increased according to the carbonation hardening time, and the strength increase rate was higher for the specimen with a CO₂ concentration of 20%.