• 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.

• Journal of the Korean Ceramic Society
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• v.18 no.3
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• pp.157-162
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• 1981

A converter slag has been heat-treated above melting point at reduced condition by cokes. As the result, most iron was separated. To make hydraulic compounds, calcium oxide was added to the reduced converter slag and the mixtures were sintered. This modified converter slag clinker mainly contained tricalcium silicate and calcium aluminates, and have a great potential to be a good hydraulic cement. The hydrates of the hydraulic compounds and gypsum with and without granulated slags, were mainly C-S-H, ettringite, calcium monosulfoaluminate hydrate, calcium aluminate hydrate, and $Ca(OH)_2$

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.505-512
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• 1999

Soft marine clay deposits pose several foundation problems. Generally, lime stabilization is used worldwide for solidifying of soft marine clay deposits. In this paper, a series of laboratory tests were conducted to verify clay-lime reaction. A clay was collected from Pusan, which was mixed with various quantities of quick lime and slaked lime. Various compounds produced by clay-lime reaction were identified by X-ray diffraction analysis. The physico-chemical properties of the clay were also investigated. Compounds such as calcium silicate hydrate (CSH), calcium aluminate hydrate (CAH), calcium aluminate (CA), hillebrandite, and gehlenite were identified. It is likely that such compounds were mainly produced by pozzolanic reaction. Based on the change of physico-chemical properties obtained by the reaction, the water content was considerably decreased when lime was added to the clay. In addition, unconfined strength was increased. In the other hand, quick lime was more effective than slaked lime in decreasing and increasing of the water content and unconfined strength, respectively. Fewer cracks were produced when the clay was mixed with quick lime. It is suggested that these beneficial changes produced by the mixing of the clay and lime depend on the properties of compounds obtained by chemical reaction.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.11
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• pp.6890-6897
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• 2014

EAF reduction slag has unstable properties of expansion and destruction. Therefore, it cannot be used as a construction material. The purpose of this study was to use EAF reduction slag as a concrete admixture. EAF reduction slag contains $11CaO{\cdot}7Al_2O_3{\cdot}CaF_2$ and ${\beta}-C_2S$ (calcium aluminate compounds). To confirm the properties of EAF reduction slag as a concrete admixture, the condensation, compressive strength and activity factor due to substitution rate of EAF reduction slag were measured. Originally, EAF reduction slag was cured rapidly because of its chemical composition ($11CaO{\cdot}7Al_2O_3{\cdot}CaF_2$). On the other hand, when 8% gypsum was added, its properties of condensation and compressive strength were similar to the plain specimen. When 6% gypsum was added, the quality of the KS F 2536 standards (quality standard number 3) were met in terms of activity factor. Overall, 8% gypsum addition is the most appropriate by considering the activity factor in the long-term compressive strength.

• Journal of the Korea Concrete Institute
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• v.19 no.5
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• pp.639-646
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• 2007

This study performed several tests for the durability of the concrete coated with nano synthesis ceramics which do not contain volatile organic compounds harmful to environment. The tests were adhesion test on dry and humid concrete, SEM test, MIP analysis, carbonation, chloride diffusion by electronic facilitation, freezing-thawing resistance, alkaline resistance, and brine resistance test. In the adhesion test on dry and humid concrete, nano synthesis ceramics coating produced the highest results among all the coatings tested. Nano synthesis ceramics adhered solidly on the concrete surface. The adhesive strength seemed to result from the hydrogen bond between nano synthesis ceramics which are inorganic and generated by hydrolysis and re-condensation reaction and the concrete's hydrates such as calcium silicate aluminate or calcium silicate hydrate. SEM test and MIP analysis results show surface structure with finest crevices pore in the nano synthesis ceramics coating applied concretes. In the carbonation, chloride diffusion, and freezing-thawing resistance tests, the concretes with nano synthesis ceramics coating indicated the best results. Based on these test results, further progress in application of nano synthesis ceramics coatings to various concrete structures including costal structures and sewerage arrangements can be expected.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.4
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• pp.443-450
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• 2021

The effects of blast furnace slag(BFS) and desulfurized gypsum(FDG) on the compressive strength of CFBA, and self-hydration of CFBA were studied. CFBA has self-hydrating and hardening properties, and it can be seen that the compressive strength of CFBA can be improved by using appropriate amounts of BFS and FDG. In addition, the self-hardening properties of CFBA are similar to the hydration reaction of 4CaO·Al₂O₃·Fe₂O₃ (C₄AF), a cement clinker mineral, and when free-CaO, CaSO₄ and CaCO₃ coexist, Compressive strength of CFBA is expressed by the formation of calcium carbo compounds and hydrates of ettringite, calcium silicate, and calcium aluminate.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.238-239
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• 2018

This paper presents the synthesis results of CaO-Al₂O₃ system clinker using the CaCO₃ and the Al₂O₃ according to the synthesis methods dependent on the temperature. The purpose of this study is the formation of the CaO-Al₂O₃ system clinker containing high ratio of CaO·2Al₂O₃ (CA₂). The maximum sintering temperature for the synthesis of CaO-Al₂O₃ compounds was 1250℃, 1300℃ and 1400℃. The CaO-Al₂O₃ compounds was sintered at the maximum sintering temperature for three hours. After sintering, the compounds was analyzed using X-ray diffraction method. The 12CaO·7Al₂O₃ (C1₂A₇) and CaO·Al₂O₃ (CA) increased as elevating the maximum sintering temperature whereas the CA₂ decreased. Especially, at the 1250℃ of maximum sintering temperature, the un-reacted CaO and Al₂O₃ was identified.

• Journal of the Korean Ceramic Society
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• v.53 no.2
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• pp.206-214
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• 2016

This study aims to produce dolomitic hydraulic lime (D-NHL) using domestic low grade dolomitic limestone and to determine the effect of adding blast furnace slag (BFS) and gypsum as part of an investigation of the hydration properties of D-NHL to increase the mechanical properties. The main mineral phases of D-NHL as a hydraulic lime binder were $Ca(OH)_2$, $Mg(OH)_2$, $C_2S$, $C_3S$, and MgO residues. $Ca(OH)_2$ transformed into $CaCO_3$ in D-NHL paste over the period of 28 days, but the carbonation of $Mg(OH)_2$ and the hydration of $C_2S$ did not occur until hydration, after 28 days. Through an investigation of the hydration properties of D-NHL pastes mixed with BFS and gypsum, Al-based compounds such as calcium aluminate hydrates ($C_4AH_{13}$) and ettringite were observed at early hydration time. The compressive strength was improved due to the increased quantities of these hydration products. These results show that good performance results from the application of dolomitic hydraulic lime and that a high value product can be made from domestic waste materials.