• Advances in materials Research
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• v.7 no.1
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• pp.45-72
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• 2018

In the present study, a special attention has been paid to the effects regarding the use of different superplasticizers in different dosages. To do so, 36 mixes of normal and self-compacting concrete with two water/binder ratios of 0.35 and 0.45, four different types of superplasticizer including melamine-formaldehyde, naphthalene-formaldehyde, carboxylic-ether and poly-carboxylate, four different superplasticizer/cement ratios of 0.4%, 0.8%, 1.2% and 1.6% and two silica fume/cement ratios of 0% and 10% have been cast. Moreover, the initial and final setting time of the pastes have been tested. For self-compacting mixes, flow time, slump flow, V-funnel, J-ring and L-box tests have been carried out as well as testing the compressive strength and rupture modulus. For normal concrete mixes,slump test has been conducted to assess the workability of the mix and then for each mix, the compressive strength and rupture modulus have been determined. The results indicate that in addition to the important role of superplasticizer type and dosage on fresh state properties of concrete, these parameters as well as the use of silica fume could affect the hardened state properties of the mixes. For instance, the mixes whose superplasticizer were poly-carboxylic-ether based showed better compressive and tensile strength than other mixes. Besides, the air contents showed robust dependency to the type of the superplasticizer. However, the use of silica fume decreased the air contents of the mixes.

• Fire Science and Engineering
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• v.23 no.4
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• pp.1-6
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• 2009

High Strength Concrete has a disadvantage of the brittle failure under fire due to the spalling. It is reported that spalling is caused by the vapor pressure under fire and polypropylene (PP) fiber has an important role in protecting from spalling. The silica fume which is essentially mixed in high strength concrete decrease the permeability of concrete, and this will increase the degree of spalling. The fire resistance characteristics of high-strength reinforced concrete columns with various contents of PP fiber and silica fume were investigated in this study. In results, the ratio of unstressed residual strength of columns increases as the content of PP fiber increases from 0% to 0.2% and the ratio decreases as the content of silica fume increases from 7% to 21%.

• Proceedings of the Korea Concrete Institute Conference
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• 1991.10a
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• pp.21-25
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• 1991

For the purpose of improving the compressive strength of concrete, the high strength concrete which have the compressive strength about 800kg/$\textrm{cm}^2$ were made by using silica fume and high range water reducing admixture on reducing the water-cement ratio. But the facts that the slump loss of high strength concrete was high and the tensile strength and elastic modulus were not improved enough are indicated to problems which must be solved.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.3
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• pp.41-47
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• 2009

Post-tensioned concrete pavement(PTCP) was developed to built long-span concrete pavement(120 m span) and to maintain long-term service life(over 40 years) of concrete pavement. In the present study, research for high-durable concrete was conducted to utilize the advantage of PTCP construction method efficiently. First of all, 20% of fly ash(by binder weight) was replaced to control alkali silica reaction. Second, silica fume was applied to improve the water-permeability and early-age strength. Results of tests for mechanical properties, water-permeability resistance, and surface-scaling resistance of ternary blended cement concrete showed that the early-age strength was improved significantly with addition of silica fume. The water-permeability resistance was improved from "Low" to "Very Low"(ASTM C 1202). However, surface-scaling resistance was decreased with an increase of silica fume, therefore, content of silica fume should be kept in less than 5%(by binder weight) to assure field application considering durability. The results of air-void analysis showed that durability factors were improved since spacing factors were estimated as 250$\pm$15 micron in adjusted mixtures.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2007.04a
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• pp.51-54
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• 2007

This study investigates the properties of paste and mortar from different types and forms of silica fume on cement binder for ultra high strength. Although most Silica Fumes distributed in the market fulfill the KS quality standard, each type showed different levels of loss of ignition. When evaluating cement binder for ultra high strength in a form of paste. Flow, viscosity and moving freely time show great difference depending on the Silica Fume's form and type of primary particle's dispersibility. The evaluation of Silica Fume's dispersibility can be possible with the paste test since there is a high correlation of flow quality between paste and mortar. The compressive strength when using Silica Fume was correlated to the SiO2 content. Synthetically, selecting Silica Fume with the most the ideal primary particle is the key to optimizing the formation for cement binder for ultra high strength.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.05b
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• pp.239-242
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• 2009

As the high-rise building increase due to the gravitation of population to big cities recently, it requires high quality and high performance of Concrete. As a result, people are keenly interested in Meta-kaolin as new admixture favorable from an economic perspective, which has strength and endurance with admixture at the same level like Silica-fume. Accordingly, as to Meta-kaolin, this study was to set by three levels like domestic one, foreign one, and Silica-fume, the water-binding material ratio 25%, and four level substitute like 0, 10, 20, and 30(%) in order to compare and analyze the quality durability of high-concrete according to the substitute of Meta-kaolin applicable with replacement of Silica-fume. As a result of performing experiment it was found that when water-binding material ratio increases, resistance of neutralization, carbonation, salt damage and sulfate decrease, and when replacement ratio of mineral admixture increases, depth of accelerating carbonation gets greater. Also, the combination of SF and MK-B favored resistance to chloride ion penetration better than MK-A, and it was found that when replacement ratio of binding material increases, the resistance to sulphuric acid increases. Therefore, based on this study, it was understood that meta-kaolin is useable in replacement of silicafume.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.11a
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• pp.68-71
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• 2013

Reactive Powder Concrete (RPC) is an ultra high strength and high ductility cement-based composite material and has shown some promise as a new generation concrete in construction field. It is characterized by a silica fume-cement mixture with very low water-binder (w/b) ratio and very dense microstructure, which is formed using various powders such as cement, silica fume and very fine quartz sand (0.15~0.4mm) instead of ordinary coarse aggregate. However, the unit weight of cement in RPC is as high as 900~1,000 kg/㎥ due to the use of very fine sand instead of coarse aggregate, and a large volume of relatively expensive silica fume as a high reactivity pozzolan is also used, which is not produced in Korea and thus must be imported. Since the density of RPC has a heavy weight at 2.5~3.0 g/㎤. In this study, the modified RPC was made by the combination of ternary pozzolanic materials such as blast furnace slag and fly ash, silica fume in order to economically and practically feasible for Korea's situation. The fire resistance and structural behavior of the modified RPC exposed to high temperature were investigated.

• Proceedings of the Korea Concrete Institute Conference
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• 1993.10a
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• pp.11-17
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• 1993

In this study, the fundamental properties of High-Strength Concrete(HSC), such as the slump loss, the temperature increment, the strength development, are considered by experiment. In reducing the temperature and the slump loss, and developing the strength of HSC, the application of silica fume as an admixtures is very effective. And when gypsum is added, the slump loss is reduced and the strength of HSC is improved remarkably, but the temperature of concrete is increased, thus a more study to reduce the temperature increment is required

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.379-384
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• 2002

The deterioration of concrete due to sulfate ions in various sulfate environments such as groundwater, soil and seawater is one of important factors degrading the durability of concrete structure. The aim of this paper is to evaluate on the magnesium sulfate alttack resistance of mortars with silica fume. In this study, compressive strength loss and length change of prismatic mortars, containing silica fume, immersed in 5% magnesium sulfate solution for 270 days were investigated. Additionally, paste powders with same binder were used to observe reactants of cement matrices through the instrumental analysis such as XRD, SEM and MIP. Results obtained from this study indicate that the greater damaging effects of the magnesium soulution are due to the decomposition of the C-S-H gel to M-C-S-H.

• Computers and Concrete
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• v.17 no.4
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• pp.477-488
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• 2016

This paper aims to model the effects of five different variables which includes: cement content (C), the steel fiber amount (F), the silica fume amount (SF), the superplasticizer (SP), the silica fume amount (SF), and the water to cementitious ratio (w/c) on 28 days flexural toughness of Ultra High Performance Concrete (UHPC) as well as, a study on the variable interactions and correlations by using analyze of variance (ANOVA) and response surface methodology (RSM). The variables were compared by fine aggregate mass. The model will be valid for the mixes with 0.18 to 0.32 w/c ratio, 4 to 8 percent steel fiber, 7 to 13 percent cement, 15 to 30 percent silica fume, and 4 to 8 percent superplasticizer by fine aggregate mass.