• Cement Symposium
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• no.30
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• pp.49-62
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• 2003

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.2
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• pp.219-226
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• 2020

Over the last decades, great efforts have been devoted to reuse industrial wastes and by-products from various industries as supplementary cementitious materials in order to reduce carbon dioxide(CO₂) emission by reducing the use of Portland cement in construction. Oyster shell waste, originating from the fishery industry, is available in huge quantities in certain areas, and is generally discarded or landfilled. In this study, we aimed to reuse oyster shell as an alternative to limestone in limestone calcined clay cement(LC³). The oyster shell calcined clay cement(OC³) paste were produced and were characterized via X-ray diffraction, isothermal calorimetry, compressive strength tests, and thermogravimetry. The results revealed that OC³ pastes exhibited similar strength development and reactivities by pozzolanic reaction with LC³, which implies that oyster shell could be used as a substitute for limestone in LC³.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.3
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• pp.252-260
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• 2022

In Korea, low-quality kaolin has significantly greater reserves and superior economic efficiency than high-purity kaolin. However, the utilization is low because it does not match the demand conditions of the market, and it is difficult to find a suitable source of demand. The purpose of this study is to derive the possibility and optimal calcination temperature of domestic low-quality kaolin that can be used as a raw material for limestone plastic clay cement (LC³). Isothermal calorimetry, X-ray diffraction analysis, Thermogravimetric Analysis, and compressive strength tests were conducted to evaluate hydrate generation and mechanical properties of LC³ paste according to calcination temperatures (600 ℃, 700 ℃, 800 ℃, 900 ℃). As a result, although 50 % of the clinker was replaced, the domestic low-quality kaolin clay produced calboaluminate hydrate and C(A)SH from the 3rd day of hydration, showing almost equal or higher strength to OPC, and there was a big difference in strength depending on the firing temperature.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.133-134
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• 2021

Limestone-calcined clay-Cement (LC3) concrete provides a solution for sustainability, durability, and profitability of concrete industry. This study shows experimental studies of the macro properties (residual compressive strength), the meso properties (mesoscopic images), and micro properties (thermogravimetric (TG) analysis, X-ray powder diffraction (XRD), FTIR spectra, Raman spectra, Mercury intrusion porosimetry, and SEM) of LC3 paste with various mixtures and at high elevated temperatures (20 ℃, 300 ℃, 550 ℃ and 900 ℃). We find (1) Regarding to macro properties, LC3 cementitious materials are at a disadvantage in compressive strength when the temperature is higher than 300 ℃. (2) Regarding to meso properties, when the temperature reached 550 ℃, all samples generated more meso cracks. (3) Regarding to micro properties, first, as the substitution amount increases, its CH content decreases significantly; second, at 900 ℃, for samples with calcined clay, a large amount of gehlenite crystalline phase was found; third, at elevated temperatures (20 ℃, 300 ℃, 550 ℃ and 900 ℃), there is a linear relationship between the residual compressive strength and the cumulative pore volume; fourth, at 900 ℃, a large amount of dicalcium silicate was generated, and damage cracks were more pronounced. The experimental results of this study are valuable of material design of fire resistance of LC3 concrete.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.151-152
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• 2023

This study investigates the effect of nano-silica and nano-calcite on the hydration properties and mechanical performance of limestone calcined clay cement (LC³) paste. The pastes were synthesized by replacing limestone with nano-silica and nano-calcite in order to enhance the mechanical properties in both early and late stages of hydration. The nano-calcite enhanced the strength of LC³ pastes at 1 day of hydration, however, the strength decreased compared to the ordinary LC³ pastes afterwards due to excessive amount of carboaluminate produced in the pastes. On the other hand, nano-silica improved the mechanical properties of LC³ pastes at all ages of hydration. This is mainly due to the nucleation effect and pozzolanic reaction of nano-silica, affecting the early age and late ages of hydration, respectively. The nucleation effect of both nanomaterials were confirmed by the analysis of hydration heat, supporting the enhanced early age strength of nanomaterial incorporated LC³ pastes. Furthermore, the dense matrix was shown in the pore size distribution, and the increased C-S-H due to the pozzolanic reaction evidence the improved compressive and splitting tensile strength of nano-silica incorporated LC³ pastes.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.549-552
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• 2008

The cement is accomplished with CaO, SiO2, Al2O3 and Fe2O3, etc. After pulverizing materials of the limestone, the sand and the clay(shale), iron ore, the cement becomes clinker materials sintering from the rotary kiln of oxidizing atmosphere. The part in the materials of the clinker is substituted with slag, sludge etc. and it is used. because The chromium which is to be included in the clinker materials, in sintering process hexavalent chromium is converted with the chrome. Consequently it changed the type and a content of clinker materials and test hexavalent chromium of the clinkers which is manufactured.