• Resources Recycling
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• v.12 no.5
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• pp.23-28
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• 2003

Converter slag was reduced and modified with the addition of 5~10 weight percent of $SiO_2$, $Al_2O_3$ and $SiO_2+Al_2O_3$. which was water quenched and used as a cement additives. Additive was mixed from 10 to 30 weight percent with ordinary portland cement and made 9 kinds of mixed cement. Compressive strength of mixed cement mortar was tested md compared with com pressive strength of ordinary portland cement mortar. Effect of hydration reaction on the compressive strength of cement mortar was investigated by means of x-ray diffraction and scanning electron microscopy.

• Journal of the Korean Ceramic Society
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• v.36 no.1
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• pp.77-81
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• 1999

In order to investigate the effect of fineness on the properties of Portland cement, we prepared five kinds of portland cements with different Blaine values(2300, 2500, 3000, 3500, 45oo $\textrm{cm}^2$/g) and measured Ca(OH)2 analysis, hydration heat, the fluidity and the physical properties of them. According to the results, as the Blain value of cement is lower, the rate of hydration is delayed, and the hydration heat and the compressive strength are decreased. But the fluidity of cement paste is improved. Especially, the hydration heat of the cement with 2500$\textrm{cm}^2$/g of Blaine value is decreased about 15% compared with 3500 $\textrm{cm}^2$/g cement.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.667-670
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• 2003

The purpose of this study is to present data for the reusing, reinforcement and estimation of safety of the RC structure damaged by fire, and for the prevention of explosive spalling by checking the character of explosive spalling according to kinds of fine aggregate, admixture and water-cement ratios. The materials used fine aggregates were sea sand, crushed sand and recycled sand, and the admixtures were fly ash and blast-furnace slag. Also the water-cement ratios was 55% and 30.5%. After those were heated respectively for 30 and 60 minutes in accordance with Standard Time-Temperature Curve. And then conditions of explosive spalling were divided into five grades, and characters of explosive spalling were investigated.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10b
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• pp.921-924
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• 2000

The purpose of this paper is to investigate the effects of admixture such as AE water reducing agent and Flyash on properties of cement mortar for floor. As for the effects of AE water reducing agent kinds, fluidity and air content increase in order for melamine type, lignine type and naphtalene type. As Flyash contents increase, fluidity shows high, but air content shows decline tendency. compressive strength according to AE water reducing agent kinds increase in order for melamine type, lignine type and naphtalene type. As AE water reducing agent content increases, it shows to be decreased. As for the effects of Flyash, it retards at early age but at later age it gains high with increase of Flyash contents due to pozzanic reaction. Drying shrinkage shows to be docreased slightly with increase of AE water reducing agent.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.469-472
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• 2006

The use of admixture(PNS type & PC type) played a important role in the development of rapid hardening concrete. This paper presents an experimental study on the effect of a kinds of admixture on hydration characteristics, mini slump, apparent viscosity of fresh cement pastes and workability, compressive strength properties of hardened concrete for rapid hardening. Measurements have showed that their characteristics depends on the type of the admixture. As a result, the excellent quality was obtained, also being widely used for the construction field is expected.

• Proceedings of the Korea Concrete Institute Conference
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• 1993.04a
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• pp.93-98
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• 1993

In order to discuss the mechanical properties of fiber reinforced composites with fly ash, lime, gypsum and polymer emulsion-Stylene Butadiene Rubber Latex (SBR) , experimental studies on FRC were carried out. The kinds of fiber used in FRC are PAN-dervied and Pitch-derived carbon fiver, alkali-resistance glass fiber. As a test results, the flexural strength and tougthness of fiber reinforced fly ash. lime.gypsum cement composites are remarkably increased by fiber contents ,but compressive strength of the composites are influenced by kinds of fiber more than by fiber contents. Also, addition of a polymer emulsion (SBR) to the composites decreased the bulk specific gravity, but compressive and flexural strengths, toughness of the composites are not influenced by it, are considerably improved by increasing fiber contents.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.199-204
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• 2000

When fresh concrete is exposed to low temperature, the concrete may suffer from the frost damage at early ages and the strength development may be delayed. To solve such problems of cold weather concreting, admixtures called agent for enduring cold climate are developed to prevent the fresh concrete from being frozen at early ages In this study, the experiments are carried out on several kinds of agent for enduring cold climate to present their performance. According to experimental results, most kinds of agent for enduring cold climate show the satisfactory properties of decreasing the freezing point and acceleating the cement hydration in low temperature environment, which is available for placing concrete in spite of cold weather.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.777-780
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• 2006

Recently, owing to the development of industry and the improvement of building techniques, the concrete structure is becoming larger and higher. In hardening these large concrete, the heat of hydration gives rise to considerable thermal stress depending on the size and environmental condition of concrete, which might cause thermal cracking. Especially, the crack may cause severe damage to the safety and the durability of concrete structure. This study is investigated the thermal properties of concrete according to several binder conditions, such as OPC, Belite Rich Cement(BRC), Low-Heat-Mixed Cement(LHC), Fly ash added cement. As a result of this study, the Flowability of concrete was beetter with BRC and LHC than FA(25) and OPC. On the other hand, LHC gets superior effect in the control of heat hydration, it's caused by the volume of OPC.

• Journal of the Korean Ceramic Society
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• v.37 no.5
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• pp.438-443
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• 2000

This dissertation is focused on the study over the improvement for the early strength of belite-rich cement(BRC). For this purpose, the initial hydration behaviors according to addition of different calcium sulfate types were evaluated. From the observations by XRD, DSC and SEM, the BRC II and III with the addition of natural anhydrate and flue gas desulphurization(FGD) gypsum, respectively, formed much ettringite after 7 days more than the BRC I with the addition of chemical gypsum. The compressive strength of the BRC II and III developed outstandingly due to the formation of calcium aluminate hydrate within pores of hardened BRC paste. Especially, in the case of BRC III adding FGD with low impurities, the early as well as long term compressive strengths were shown very high, compared with other specimens.

• Proceedings of the Korea Concrete Institute Conference
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• 1994.10a
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• pp.387-392
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• 1994

Recently, as the problems according to lack of skilled labour and superior construction materials were gathering strength, there were required the advent of a special materials in building construction division. As a view of the point, the cement-based Self leveling mortar was developed for improvements of the former problems. The Self leveling mortar has the all kinds of the properties as followed the premixed products in plant, self-smoofhing, non shrinkgae etc, accordingly the finishing of concrete floor don't need skilled labour. The purpose of this study is to establish the introduction of a finishing construction method for concrete floor and slab using the cement-based self leveling mortar. Presented is a study on the basic properties of fresh and hardened self leveling mortar. To this end, an actual floor's finishing construction using the cement-based self leveling mortar was conducted in approximately 1,800㎡ floor as to compare the flatness and levelness after finighing.