• Journal of the Korea Institute of Building Construction
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• v.18 no.6
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• pp.507-515
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• 2018

The purpose of this research is to develop a slurry-type accelerator that contains various beneficial properties such as reduction of dust generation, lower alkalinity, early age strength development, etc., and uses such slurry type accelerator to produce high performance shotcrete that present excellent resistant against chloride ion penetration. In this work, shotcrete mixtures of 0.44 and 0.338 water-to-binder ratio (w/b) were produced at construction site using slurry-type accelerator. The mechanical properties and chloride ion penetration resistance of such shotcrete (including base concrete) were evaluated. According to the experimental results, the slurry-type accelerator was successfully used to produce both w/b 0.44 and 0.338 shotcretes. The 1 day and 28 day compressive strength of shotcrete were found to be closer to or higher than 10MPa and 40MPa, respectively. The w/b 0.338 shotcrete that used 40% replacement of blast furnace slag showed lower compressive strength than w/b 0.44 shotcrete without any mineral admixture at 1 day. However, the compressive strength with 40% blast furnace slag increased significantly at 28 day. Moreover, there was more than 50% increase in chloride ion penetration resistance with blast furnace slag, showing its strong potential for higher performance shotcrete application.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10a
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• pp.307-312
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• 1998

Recently the study on high flowing concrete which has high workability and Self-compacting is being proceeded actively in the university and corporative laboratory. There are some cases that has been applied to the field. This high flowing concrete has higher fluidity and segregation resistance than Plain of flowing concrete. And it is being focused as a remarkable know-how which can make high-quality concrete and reduction effect of labor force. This properties of high flowing concrete are influenced by the relationship of several factors; binder content, water binder ratio and unit water content. It is the aim of this study to propose reference data at mix design of high flowing concrete, after comparing and analyzing the fluidity and strength properties of high flowing concrete according to water binder content ratio and unit water content.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2002.05a
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• pp.57-60
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• 2002

Recently, the coal ash production has been increased by increase of consumption of electric power. So it is important to find a reclaimed place and treatment utility for treating coal ash. Accordingly, in this study we performed an experimental study to compare and analyze the Properties of concrete according to W/C and bottom ash replacement ratio. As a result of this study, it was found that the bleeding content was decreased according to decrease of W/C and increase of bottom ash replacement ratio, and the compressive strength of concrete using bottom ash was similar to plain concrete(replacement ratio 0%).

• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.3
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• pp.43-52
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• 1988

In this paper, three kinds of proportioning method on concrete mixes containing fly ash as an admixture were compared and investigated. As the test results for relationships between substitution ratio of fly ash, water-binder ratio, ages and strength besides the proportioning methods and workability of fresh concrete beneficial reference data to estimate quality of domestic fly ash were atained.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.10a
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• pp.79-80
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• 2016

In this study, we measured the relative density and the compressive strength in order to select the appropriate W/ B for the ultra-high strength concrete development. If W/B is lowered than the W/B of highest relative density, it was confirmed that the strength is lowered. However, if water is increased than the W/B of highest relative density, the relative density is decreased compressive strength was similar. The selection of the W/B of the lower than the highest relative density is not appropriate. Appropriate W/B is selected to be more than the maximum relative density of W/B.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.52-53
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• 2018

In this study, viscosity analysis of the lightweight foamed mortar was conducted to evaluate the foam stability. According to a series of experiment, void volume related with density of the mixture and viscosity of the mixture were infleunced by water-to-binder ratio and addition of viscosity modifying admixture (VMA). Especially, the stability of the foam inside the mortar was confirmed with adding VMA.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.05a
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• pp.79-80
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• 2011

In this study, W/B that affect the strength and shrinkage were 4 level(14.5~11.5%), so that the and the physical and shrinkage properties were verified. And the shrinkage formula is suggested at the age of 91. The results showed that the strength of W/B 12.5% was the highest strength. And as W/B decreased, the shrinkage ratio increased. The autogenous shrinkage was rapidly decreased after 28 days.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2002.11a
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• pp.29-36
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• 2002

High fluid concrete unlike OPC concrete is made with various material, and the phase of fresh concrete is considerably different. In order to understand fluidity phase and mix properties of high fluid concrete, concrete is required to access as suspension structure which consists of aggregate and paste. The focus of this paper is to analyze the test results and quantify the effect of mix proportions of molar and fineness modulus of ,and on the properties of fresh mortar. The effect of water-binder ratio, sand-binder ration, content; of ggbs (by mass of total cementitious materials), and various contents of water reducing agent on the yield stress and plastic viscosity of the mix is studied. Based on the experimental results, the following conclusion; can be drawn: (1) The mixing time needed (or high fluid mortar was approximately two times more than that of ordinary portland mortar. (2) The fluidity phase of mortar could be explained by yield stress of mix and the fluidity of mortar. (3) As the content of ggbs increased, yield stress of mortar was decreased and plastic viscosity of it was increased. (4) For the high fluid mortar, it was appeared that sand-binder ratio should be below 1.5.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.7 no.3
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• pp.213-221
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• 1987

To use fly ash as an additive for concrete, authors collected 15 kinds of domestic fly ashes and tested the chemical compositions and physical properties of the fly ashes. Fluidity of the fly ash paste was also investigated. The result shows that the chemical compositions of the fly ashes were in the range of regulation of Korean Industrial Standards except ignition loss and the following relationships in fly ash were studied; specific surface and residue in standard sieve, specific surface and unit weight, residue in standard sieve and ignition loss. For the given flow properties, fly ash paste required higher water-binder ratio than cement paste.

• Journal of the Korea Concrete Institute
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• v.23 no.4
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• pp.431-440
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• 2011

Concrete structures exposed to fire produce changes in their internal structure, resulting in their service life reduction due to the deterioration of its strength and performance capacity. The deterioration level are dependent on the temperature, exposure time, concrete mix proportions, aggregate property, and material properties. This study was performed to evaluate the thermal behavior of ultra-high strength concrete for the parameters of water to cement ratio (compressive strength), fine to total aggregate ratio, and maximum coarse aggregate size. At room temperature and $500^{\circ}C$, tests of ultrasonic pulse velocity, resonance frequency, static modulus of elasticity, and compressive strength are performed using ${\varnothing}100{\times}200\;mm$ cylindrical concrete specimens. The results showed that the residual mechanical properties of ultra-high strength concrete heated to $500^{\circ}C$ is influenced by variation of a water to binder ratio, fine to total aggregate ratio, and maximum coarse aggregate size.