• Journal of the Korean Ceramic Society
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• v.27 no.7
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• pp.833-840
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• 1990

For the development of multi-functional materials which has water reducing power, air entraining power and waterproofing power as well as blending additive in cement mortar the coal ash was modified with asphalt-stearic acid or asphalt-boiled oil mixtures by mechanical treatment. And the physical properties of cement mortar blended with modified coal ashes were compared with those of the water-tightness-cement mortar and the ordinary-portland-cement mortar added with AE.water reducing agent. The mortar of coalash-blend-cement modified with asphalt-stearic mixture was increased acid about 20% in initial strengths and decreased about 20% in water absorption ratio than those of ordinary coalash-blend-cement. The mortar of coalash-blend-cement modified with asphalt-bolied oil mixture was similar to the cement mortar added with AE.water reducing agent in water reduction ratio, air entraining conents and the initial strengths, also was similar to the water-tightness-cement mortar in water absorption and water permeability ratios.

• Cement Symposium
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• s.48
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• pp.37-42
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• 2021

• Proceedings of the Korean Institute of Building Construction Conference
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• v.y2004m10
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• pp.21-26
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• 2004

This study deals with the Hydrated Ability of the Ready-Mixed Concrete's Sludge which is the recycling technology of that sludge. The experiment gathers sludge from Ready-mixed factory. shatters these into pieces in dry condition and understands the differences between current using Portland cement. And then. this examines the possibility of the recycle as a bonding agent through the Compressive Strength and considers the recovery of the hydration. This experiment concludes the same Chemical Composition with the normal Portland cement. while. under the appropriate procedure in hydration recovery. this sludge can be used as the bonding agent in cement. The chemical composition of solid Remicon sludge shows that it has 1.8 times $SiO_2$ than the normal Portland cement. meaning lots of aggregate in Remicon sludge. Also. the specific gravity of Remicon sluge increases with the rise of Baking Temperature and has no difference between 2.77 and 2.94. The mortar flow used for combining the baking material of Remicon sludge does was not changed and is the highest between $750^{\circ}C{\cdot}120min\;and\;800^{\circ}C{\cdot}180min$. Additionally. the Compressive Strength increases with the age, certifying the same Hydrated Ability like cement and the best condition for hydration is $750^{\circ}C{\cdot}120min.$

• Journal of the Korean Ceramic Society
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• v.44 no.9
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• pp.524-528
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• 2007

The results of evaluating steel corrosion in concrete containing chloride content of various levels indicated that the more chloride content in concrete leads to the lower potential and higher corrosion current density. However, the open circuit potential of steel varied with time and exposure condition, and the corelation between the open circuit potential and corrosion current density was not obvious. In order to determine the critical threshold content of chloride of steel corrosion in concrete, the concept of average corrosion current density was employed. The range of critical chloride content in portland cement concretes was about $1.56{\sim}1.77%$($Cl^-$, %, wt of cement content) along with water-cement ratio, and higher water-cement ratio resulted in reduction in critical threshold chloride content.

• Journal of the Korean Ceramic Society
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• v.24 no.3
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• pp.289-295
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• 1987

The changes of physical properties of portland cement pastes and mortars were investigated by addition of sodium gluconate. Flow table experiment and viscosity measurement were took in order to find dispersing effect, and time-dependent changesof viscosity and rates of hydration heat evolution were carried out for the sake of finding retardation effect of hydration. And changes of physical properties of cement pastes and mortars were discussed by setting time, compressive strength and porosity.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04a
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• pp.161-166
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• 1998

The main object of this study is to examine the basic properties of fresh concrete as well as hardened concrete using several types of cement such as ordinary portland cement, sulphate resisting portland cement, blast furnace slag cement, ternary blended cement. In addition, effects of each cement on the durability including drying shrinkage, freeze-thawing resistance, resistance of chloride ion penetration, carbonation of concrete were investigated. As the results of this study, it was proved that most of the properties of concrete using each cement were similar, but there were some differences in bleeding, setting time, resistance of chloride ion penetration and carbonation.

• International Journal of Concrete Structures and Materials
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• v.7 no.2
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• pp.119-125
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• 2013

Carbonation is a natural ageing process for cement. This study focuses on how the carbonation rate varies with selected hydration times and atmospheric conditions during the early stages of reacting dried cement paste. Diffuse reflection Fourier transform infrared spectroscopy is shown to be a suitable technique to monitor the formation of carbonates in cement. Combined with a previously developed freeze drying technique, carbonation can be studied at specific hydration stages. In ambient air both calcium hydroxide and calcium silicate hydrate (C-S-H) in cement are carbonated. Increased hydration time enhances the carbon dioxide uptake, which indicates that the calcium in the hydration products reacts more easily than the calcium in the clinker phase. In a humid $CO_2$ atmosphere, the carbonation process is so pronounced that it decomposes C-S-H into calcium carbonate and silica. In a moist $N_2$ atmosphere no carbonation occurs, but the sulfate chemistry of the cement seems to be affected due to the formation of ettringite.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.1041-1044
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• 2008

The addition of chemical inert filler in blended cement, such as limestone or chemical inert silica fume, will produce a physical effect on cement hydration. Due to the high surface area of inert filler in the mixtures, it provides sites for the nucleation and growth of hydration products, thus improving the hydration rate of cement compounds and consequently increasing the strength at early age. This paper proposes a model of hydration of Portland cement blended with chemical inert filler. This model considers the influence of water to cement ratio, cement particle size, cement composition and addition of chemical inert filler on hydration. The heat evolution, degree of hydration and porosity are obtained as accompanied results in hydration process. The prediction results agree well with experiment results.

• Structural Engineering and Mechanics
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• v.82 no.2
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• pp.133-149
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• 2022

This study investigates the resistance of sustainable ultra-high performance concrete (UHPC) on steel reinforcement corrosion. For enhancing the sustainability of UHPC, concrete mixes were prepared with ordinary Portland cement main binder, and mixes with moderate to high percentages of blast furnace cement (CEM III), fly ash (FA), and slag cement as partial replacements of the full quantity of the used cement. Linear polarization resistance technique was employed to estimate the electrochemical behavior of the concrete specimens. Results showed that the compressive strength and the resistance of steel to corrosion in marine environments can be enhanced by improving the sustainability of UHPC through incorporation of CEM III, FA, and slag cement. FA replacement of up to 50% with the addition of 15% SF content produced better compressive strength and steel corrosion resistance than slag cement whether with the use of ordinary Portland cement or blast furnace cement as the main binder.

• Cement Symposium
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• s.49
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• pp.75-83
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• 2022