• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.1
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• pp.25-35
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• 2018

This study presents microstructural characteristics and strength properties of alkali-activated kaolin(K)-fly ash(FA) blends binders. The compressive strength, X-ray diffraction(XRD), thermogravimetric(TG) analysis and SEM/EDS were measured for hardened samples. The results were shown that all the samples had developed the compressive strength over time, regardless of replacement levels of K. It was found that when the amount of K increased, the strengths of samples decreased. In XRD result, no new crystalline phases were observed in all the hardened samples other than the crystalline components of raw FA and K, whereas TG analysis showed that N-A-S-H gel was formed as a reaction product in all the samples. Samples did not have the typical microstructure of dense, and there is little significant difference between the microstructures of the samples despite the differences in the strength testing results with replacement ratios of K. This study showed that the strength of sample was larger for lower Si/Al ratio of reaction product formed in sample. According to the correlation between Si/Al ratio and strength in this study, it is expected that if a chemical additive is used for lowering the Si/Al ratio of reaction product(i.e., increasing the $Al_2O_3$ solubility) in alkali-activated K-FA blends binders, strength improvement in K-FA blends binders could be achieved.

• Resources Recycling
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• v.19 no.3
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• pp.33-44
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• 2010

In this study, the possibility of utilizing carbide lime waste, obtained from the generation of acetylene process, as a alkali activator of blast furnace slag cement was investigated. The physical and chemical analysis of the carbide lime waste was studied and three types lime waste in order to investigate behaviour as alkali activator were used. Lime wastes were added 0, 10, 20 and 30 wt.% in blast furnace slag and blast furnace slag containing lime waste were added 0, 10, 30 and 50 wt.% in OPC. As a result of analysis of hydration properties, in the case of calcium hydroxide rehydrated after heat treatment at $800^{\circ}C$, it was higher hydration rate than other specimens. For the results of compressive strength test, when lime waste passed 325 mesh sieve and rehydrated calcium hydroxide were used, it was higher compressive strength than OPC from hydration 7days. At OPC50 wt.%-BFS45 wt.%-AA5 wt.% system using lime waste of 325 mesh under, the highest compressive strength appeared.

• Journal of the Korean Ceramic Society
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• v.40 no.10
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• pp.1005-1014
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• 2003

This paper examines the hydration and physical properties of alkali-blast furnace slag cement activated by Na$_2$SiO$_3$, Na$_2$CO$_3$, NaOH, Na$_2$SO$_4$. Four levels of Na$_2$O content in mixtures, 1, 3, 5, and 7 wt%, were investigated, and a W/S ratio 0.5 was used to prepare paste and mortar specimens. Compressive strength measurement of mortars was carried out adding alkali activated slag 30 wt% to OPC. The main hydration products with alkali activator kinds were C-S-H,C$_4$AH$\_$13/, AFt and Al(OH)$_3$ etc. For using Na$_2$CO$_3$ activated slag, hydration ratio of slag was higher than that of different activators, and Na$_2$SO$_4$ activated slag mortar appeared the highest compressive strength values at 28 days with activator content of 5 and 7 wt%.

• Environmental Engineering Research
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• v.21 no.4
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• pp.341-349
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• 2016

To improve the utilization rate of construction waste as mine backfilling materials, this paper investigated the feasibility of using recycled powder as mine paste backfilling cementitious material, and studied the pozzolanic activity of recycled construction waste powder. In this study, alkali-calcium-sulfur served as the activation principle and an orthogonal test plan was performed to analyze the impact of the early strength agent, quick lime, and gypsum on the pozzolanic activity of the recycled powder. Our results indicated that in descending order, early strength agent > quick lime > gypsum affected the strength of the backfilling paste with recycled powder as a cementitious material during early phases. The strength during late phases was affected by, in descending order, quick lime > gypsum > early strength agent. Using setting time and early compressive strength as an analysis index as well as an extreme difference analysis, it was found that the optimal ratio of recycled powder cementitious material for mine paste backfilling was recycled powder:quick lime:gypsum:early strength agent at 78%:10%:8%:4%. X-ray diffraction analysis and scanning electron microscope were used to show that the hydration products of recycled powder cementitious material at the initial stages were mainly CH and ettringite. As hydration time increased, more and more recycled powder was activated. It mainly became calcium silicate hydrate, calcium aluminate hydrate, etc. In summary, recycled powder exhibited potential pozzolanic activities. When activated, it could replace cementitious materials to be used in mine backfill.

• Textile Coloration and Finishing
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• v.6 no.2
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• pp.40-46
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• 1994

In order to study the properties of cochineal color, variation of uv, visible spectra by pH, dyeing properties on the silk in several dyeing conditions and thermodynamic parameter were investigated. Cochineal colors had an unusual to pH, especially had instability in alkali condition. An increase in the dyeing temperature and in time resulted in an increase in the dye content of silk fibers. Concentration of cochineal color in the silk fiber was related to pH and the maximum exhaustion of cochineal colors showed at about pH 3. The value of apparent diffusion coefficients and standard affinities of dyeing increased with the increase of dyeing temperature. The standard heats of dyeing(ΔH°), variation of entropy(ΔS°) and activation energy(E/sub act/) were caculated to be -1.72kcal/mo1, -3.77cal/mo1ㆍdeg and 1.26kcal/mo1, respectively. Silk fabrics were dyed bright red by tin chloride, reddish purple by copper sulfate, and bluish gray by iron sulfate, respectively. Lightfastness of silk fabrics mordanted by metal ion was weak.

• Computers and Concrete
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• v.17 no.2
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• pp.255-269
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• 2016

The waste glass sludge is a waste produced in the glass industry. It is in a dust form and disposed with water. In the disposal process, various cohesive agents are incorporated in order to precipitate the glass particles efficiently. In this paper, we investigate the pozzolanic reaction of the waste glass sludge incorporating precipitation additives experimentally. The consumption of calcium hydroxide, the setting time and the compressive strength and the pore structure were tested for two different types of the waste glass sludge depending on whether precipitation additives were used. It was found that the waste glass sludge incorporating the precipitation additives had a higher pozzolanic potential than the reference waste glass sludge without precipitation additives.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.05a
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• pp.206-207
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• 2014

Blast furnace slag is one kind of industrial by-product and was utilized with recycled fine aggregates for the manufacture of zero cement mortar. As the blast furnace slag was from different areas, the strength of the specimen using blast furnace slag showed different performances. In this study, blast furnace slag generated in different areas in Korea has been chosen, fundamental performances of the blast furnace slag blended mortar has been tested to evaluate the quality of the blast furnace slag. Results showed that difference for flowability is limited. As the alkali activation of the blast furnace slag, the compressive strength showed different results. The flexural strength showed little difference when the aggregates and types of blast furnace slag changed.

• Journal of the Korean Ceramic Society
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• v.52 no.6
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• pp.483-488
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• 2015

Blast furnace slag(BFS) is well known for its hardening mechanism in ordinary Portland cement with alkali activation due to its latent hydraulic property. The possibility of using calcium compound as activator for BFS has been investigated in this study. The hydration properties of calcium compound activated BFS binders were explored using heat of hydration, powder X-ray diffraction and compressive strength testing. Heat of hydration results indicate that the hydration heat of BFS is lower than OPC paste by about 50%. And ettringite as hydration product was formed continuously as the calcium sulfate was decreased. The maximum compressive strength of hardened BFS mortar at 28 days is confirmed to be 83% as compared with hardened OPC mortar.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.273-274
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• 2010

This study investigated on the early hydration and physical characteristics of blast furnace slag through pH variation. The pH values applied to the experiments were, 12.0 and 13.0 which are the pH values of OPC, and type 3 of pH 14.0 which is a strong alkali condition. A paste and mortar method was used to test blast furnace slag and blast furnace slag containing 2wt% of gypsum. It was found that CAH and CSH phases were formed as key hydrates during the early hydration of blast furnace slag, and ettringites were produced extra during the early hydration of blast furnace slag containing 2wt% of gypsum.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.231-232
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• 2021

This study intended to verify the alkali activation effect of concrete by replacing FA and CBS-Dust with cement to find out how to utilize CBS-Dust generated during cement production. Experiments result shows that air flow and liquidity can be secured when CBS-Dust is replaced by 5% in FA 20%, and that relatively high compressive strength is expressed in the initial age of 3 days and 7 days and long-term age of 91 days.