• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.121-124
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• 2005

As a countermeasure about that, in this situation that suggest utilizing mixed drush sand and particle washed sand, this study is reviewing and comparing, as a experimental and positive test, mixed both workability and engineering properties of mortar, The purpose of this study make a suggestion that is fundamental data for utilizing mixed crush sand and particle washed sand.

• Journal of the Korea Institute of Building Construction
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• v.8 no.3
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• pp.75-83
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• 2008

In this paper, concrete material tests were carried out to investigate influence of steel fiber volumn ratios on variations of workability and strength characteristics of steel fiber reinforced high-strength concrete, $50MPa{\sim}90MPa$ of compressive strength, according to increase of fiber volume. Test specimens were arranged with six levels of concrete compressive strength and fiber volumn ratios, 0.0%, 0.5%, 1.0%, 1.5%, 2.0%. The test results showed that steel fiber reinforced high-strength concrete($70MPa{\sim}90MPa$, 1.5% fiber volumn ratio) with good workability of slump 20cm could be used practically and effects of steel fiber reinforcement in improvement of concrete strength and toughness characteristics such as splitting tensile strength, flexural strength, and diagonal tensioned shear strength, were more distinguished in high-strength concrete than general strength concrete. And the test results indicated that splitting tensile strength of fiber reinforced concrete was proportioned to the product of steel fiber volumn ratios, $V_f(%)$ and sqare root of compressive strength, $\sqrt{f_{ck}}$, and the increasing rate was in contrast with that of flexural strength, and increase of diagonal tensioned shear strength was remarkable at steel fiber volumn ratio, 0.5%.

• Journal of the Korea Institute of Building Construction
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• v.23 no.4
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• pp.381-392
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• 2023

This research scrutinizes the mechanical characteristics of ultra-high strength concrete using oxide graphene nanoplatelet(GO) and hollow glass powder(HGP). The investigation covered various mechanical attributes, including workability, compression strength, tensile strength, water resistance, and the internal microstructure of standard concrete. Our findings reveal that workability experiences a significant improvement with the incorporation of a minimal amount of HGP, and an increase was also observed in tensile strength and water resistance. It was confirmed that cGO(C company GO) and HGP demonstrated commendable dispersion and the pore volume exhibited a reduction of more than 20%. The potential of cGO and HGP to substitute silica fume(SF) was also explored. Consequently, it was found that both workability and mechanical properties were enhanced in the absence of SF when cGO and HGP were used. This finding implies that the utilization of these novel materials could potentially modify conventional methods of concrete manufacturing.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.6D
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• pp.961-968
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• 2006

Curbs and L-type gutters installed at the edge of a road are very important structures to protect pedestrians from traffic accidents and to restraint slip of cars due to rain. However, existing construction method where great parts of the construction progress are done by human power has many problems in workability, quality and cost etc. In this paper, a new construction method for improvement in workability and quality for curbs and L-type gutters is developed. In order to investigate the structural safety and quality of curbs and gutters installed by the new method, tensile and lateral load tests are performed on curbs installed by existing and new methods and uniaxial compression tests are also performed on concrete samples of gutters constructed by existing and new methods. The test results show that the alignment of curbs and the strength of gutter concrete are very much improved by applying the new method. The tensile and lateral load capacities of the curbs installed by the new method are 10.7 and 2.5 times higher than those of curbs by existing method, respectively.

• Korean Journal of Construction Engineering and Management
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• v.22 no.6
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• pp.138-146
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• 2021

135 Degree standard hook workability crossed in the Reinforced Concrete (RC) Structure is improved and it reinforces in one side 90° hook binding. As a result, we proposed a One-touch Rebar Reinforcing Clip(RCC Device) that demonstrates the same performance as the 135° standard hook. It was developed through the evaluation of construction and economic analysis. As a result of analyzing 13 sites applied from June 2020, As expected, most of the cases were applied to the structural supervision or the point of the construction supervisor as an irresistible measure. therefore, Through field performance analysis, Various methods such as the method that the original contractor first purchases and then provides after contract with the partner company were proposed for the use of efficient and voluntary reinforcing clip. As a result, It is expected that the contribution in the field will be very high in terms of quality and process management through active utilization.

• Journal of the Korea Institute of Building Construction
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• v.6 no.3 s.21
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• pp.91-97
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• 2006

Sewage facilities are positively necessary for environment improvement such as rainwater removal, sewage disposal, preservation of the qualify of water and health of the citizens in present-day. Meanwhile, a deterioration of the concrete sewer pipe is increasing rapidly due to the chemical and physical attack and especially biochemical attack that is to say biodeterioration. In this study, researches for the development of antibiotics and antimicrobial concrete were conducted to reduce biochemical corrosion of sewage concrete. First of all, desired performance, such as watertightness, antibiosis, homogeneity, workability and harmlessness, was proposed and performance of antibiotics and antimicrobial concrete were evaluated by them. And developed antimicrobial concrete was applied to actual construction field. As results of this study, dispersibility and antibiosis of liquid antibiotics superior to powdery antibiotics. Antibiosis of antimicrobial concrete was verified, and amount of elution of harmful and effective ingredients was little. In workability, setting time of antimicrobial concrete was delayed. Compressive strength and resistance to carbonation of antimicrobial concrete were more increased than ordinary concrete. Finally, as there were no problems in quality and construction progress of antimicrobial concrete produced in plant, applicability of antimicrobial concrete to actual construction field was verified.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2006.05a
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• pp.23-26
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• 2006

The study about the concrete to use recently a light weight aggregate, processed actively. And concrete pumping with a high pressure pump has been popularized, the mechanical development, such as high pressure pumps or pipes, is progressing rapidly. Concrete placing by pumping has the advantage of the reduction of the construction period with workability, easiness of work and the increase of placing, but the quality variation of concrete is caused by pumping is seldom considered, including the increase of the pipe length by high-rising and large-sizing, there by the loss of the unit quantity of water, with pumpability or workability deteriorated. In this research, we will compare and analyze before pumping and after pumping samples of ready-mixed light weight concrete. The result of study as follow. The case of a light weight concrete which the low slump is more decrement compared with high slump light weight concrete in after pumping samples. After pumping the water by pressure of a pump was absorbed to the aggregate inside, and it showed an increase of compression strength about $5{\sim}20%$.

• Advances in concrete construction
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• v.5 no.6
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• pp.575-586
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• 2017

The disposal of polythene waste and fly ash is causing serious threat to the environment. Aim of this study is to decrease environmental pollution by using polythene waste and fly ash in concrete. In this study, cement was partially replaced with 0%, 5%, 10%, 15% and 20% fly ash (by weight) and plastic waste was added in shredded form at 0.6% by weight of concrete. The specimens were prepared for the concrete mix of M25 grade and water to cementitious material ratio (w/c) was maintained as 0.45. Fresh concrete property like workability was examined during casting the specimens. Hardened properties were found out by carrying out the experimental work on cubes, cylinders and beams which were cast in laboratory and their behavior under test were observed at 7 & 28 days for compressive strength and at 28 days for density, flexural strength, dynamic modulus of elasticity, abrasion resistance, water permeability and impact resistance. Overall results of this study show that addition of 0.6% (by weight of the concrete) plastic waste with 10% (by weight of cement) replacement of cement by fly ash result an improvement in properties of the concrete than conventional mix.

• KIEAE Journal
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• v.5 no.3
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• pp.49-56
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• 2005

Recently the Volatile Organic Compound, HCHO, a harmful object spout from the construction materials is made an issue of social problem. Also the appearance of the building where the confidentiality is high was interior air pollution and it was brought about a huge problem. The government research facility and a relation industry sector conducts a many effort to improves like this actual condition. The Diverse ability building material which contains the natural material of the jade, the charcoal and the hwangto instead of the finish material which contains the harmful chemical material, is becoming development and utility. Hereupon the study have carried out research on hwangto plaster that was composed of hwangto and rice straw. The result of test that is deduced by basic proportion is properly appeared with suitable ratio of the hwangto and the sand to 4:6~5:5 by the compressive strength and crack control, workability. The result of test, that adds the rice straw to basic blending for a crack control, appeared with the fact that it is most suitable 3%to add the rice straw that has a length of 0.5cm~2cm. The result of test that plaster over the large size to compare a cement plaster with a hwangto plaster show a similar efficiency by workability. Also it controlled the crack and peeling off actual condition which is discovered from the hwangto plaster of existing perfectly.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10b
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• pp.1215-1220
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• 2000

Blast-Furnace Slag, a by-product of the iron or steel industry, has potential sa a cementitious material. The addition of a Blast-Furnace Slag generally reduces the heat of hydration and can confer significant improvements in resistance to sulfate attack and alkali-aggregate reaction, as well as increases in ultimate strength. But it also reduces early-age strength. In this study, for the purpose of improvement of early-age quality of Blast-Furnace Slag concrete, we choose blaine fineness of $6, 000~8, 000cm^2/g$ of Blast-Furnace Slag, and investigate the various properties of concrete. As a result, workability and early-age strength of Blast-Furnace Slag concrete were improved according to the increase of blaine fineness of Blast-Furnace Slag.