• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.2
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• pp.157-166
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• 2012

Most of the roads are paved with impermeable materials such as asphalt concrete and cement concrete, and in the event of heavy rainfall, rainwater directly flows into river through a drainage hole on the pavement surface. This large quantity of rainwater directly spilled into the river frequently leads to the flooding of urban streams, damaging lowlands and the lower reaches of a river. In recent years there has been a great deal of ongoing research concerning water permeability and drainage in pavements. Accordingly, in this research, a porous polymer concrete was developed for permeable pavement by using unsaturated polyester resin as a binder, recycled aggregate as coarse aggregate, fly ash and blast furnace slag as filler, and its physical and mechanical properties were investigated. Also, 3 types of permeable polymer block by optimum mix design were developed and rainfall runoff reduction effects by permeability pavement using permeable polymer block were analyzed based on hydraulic experimental model. The infiltration volume, infiltration ratio, runoff initial time and runoff volume in permeability pavement with permeable polymer block of $300{\times}300{\times}80$ mm were evaluated for 50, 100 and 200mm/hr rainfall intensity.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.325-328
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• 2008

Recently increasing interest in high-rise building around the world for more than 100 floor, the trend is the increasing use of high-strength and high-flowable concrete so as of productivity improvements and cost savings to improve the performance of the early strength development. This study is to reach the optimal combination by reviewing the performance of high-rise building which is required. The results, lower the ratio of W/B was an increase in compressive strength and early strength in the use of admixture decreased in the combination of higher replacement ratio of admixture.

• Journal of the Korean institute of surface engineering
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• v.32 no.2
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• pp.165-171
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• 1999

The etching reaction of $UO_2$ in $CF_4/O_2$ gas plasma is examined as functions of $CF_4/O_2$ ratio, plasma power, and substrate temperature at up to $370^{\circ}C$ under the total pressure of 0.30 Torr. It is found that the highest etching rate is obtained at 20% $O_2$ mole fraction, regardless of r. f. power and substrate temperature. The existence of the optimum $CF_4/O_2$ ratio is confirmed by SEM, XPS and XRD analysis. The highest etching reaction rate at $370^{\circ}C$ under 150W exceeds 1000 monolayers/min., which is equivalent to 0.4$\mu\textrm{m}$/min. The mass spectrometry analysis results reveal that the major reaction product is uranium hexa-fluoride $UF_6$. Based on the experimental findings, dominant overall reaction of uranium dioxide in $CF_4/O_2$ plasma is determined : $8UO_2+12CF_4+3O_2=8UF_6+12CO_{2-x}$ where $CO_{2-x}$ represents the undetermined mix of $CO_2$ and CO.

• Journal of the Korea Concrete Institute
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• v.13 no.2
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• pp.114-122
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• 2001

The purpose of this study was to manufacture sintered lightweight aggregate using paper sludge ash and to evaluate the qualities of the aggregate according to various mix proportions, conditions of pelletization and sintering. The paper sludge ash alone, due to its mineral and chemical compositions could not gain suitable expansion and strength. Hence, it was essential to add mineral additives such as clay, fly ash etc. The optimum muting ratio range determined in this study is as follows , paper sludge ash 30∼50 %, clay 30∼50 %, fay ash 0∼40 %, Paper sludge 0∼10% and hematite 2∼3 %(for manufacturing lightweight aggregate both for non-structural and structural concrete). It was possible to manufacture various lightweight aggregate whose dry specific gravity ranged about from 0.6 to 1.4 by using this optimum mixing ratio. From the test results of the qualities of aggregate, it showed that the 10% granules crushing value test and water absorption percentage ranged about 5∼10 ton and 10∼20%. Thus, it was favorably comparable to those of the imported aggregate. The manufactured lightweight aggregate could be used for structural concrete and non-structural concrete.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.1C
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• pp.17-25
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• 2012

CLSM (Controlled Low Strength Material) using coal ash, which has the advantages of self-leveling, self-compacting, flowability, easy re-excavation, has been developed. In this study, CLSM additionally mixed with foaming agent for structural backfill material, aimed at lightness of materials, was developed called light-weight foamed CLSM. As the basic study of this material, to determine the optimum final mixing time and dilution ratio of existing light-weight foamed CLSM, flow, slurry unit weight and unconfined compressive strength test according to each impact factor were performed at the standard mix proportion. As the results of tests, CASE N (Final mixing time 4 min, dilution ratio 2%), CASE O (Final mixing time 3 min, foam agents ratio 3%, dilution ratio 2%) were satisfied with the standard of flow test (above 20cm), slurry unit weight test (12~15 $kN/m^3$) and unconfined compressive strength test (800 kPa~1200 kPa). These results will indicate the standard optimum final mixing time and dilution ratio of light-weight foamed CLSM for structural backfill.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.1
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• pp.120-127
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• 2011

Recently, there are problems due to the exhaustion of natural aggregate resources, and strict restrictions. In this study, the possibility of using Water Granulated Ferro-Nickel slag as a substitutive material of fine aggregate is determined from the properties of mechanical and durability for the concrete that is made with Water Granulated Ferro-Nickel slag. According to the test results, when the mixing rate of Water Granulated Ferro-Nickel Slag aggregates concrete is adjusted, up to 50% of its aggregates by mixing rate can be mixed with general aggregates. The optimum mix ratio is considered to be 40%. The freezing and thawing resistance of Water Granulated Ferro-Nickel Slag aggregates concrete is identical to that of general aggregates concrete, while the carbonation resistance is found to be same as or lower than that of general aggregates concretes.

• Advances in concrete construction
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• v.8 no.3
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• pp.239-246
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• 2019

Substitution of natural fine aggregates with industrial by-products like precious slag balls (PS Balls) offers various advantages like technical, economic and environmental which are very important in the present era of sustainability in construction industry. PS balls are manufactured by subjecting steel slag to slag atomizing Technology (SAT) which imparts them the desirable characteristics of fine aggregates. The main objective of this research paper is to assess the feasibility of producing good quality concrete by using PS balls, to identify the potential benefits by their incorporation and to provide solution for increasing their utilization in concrete applications. The study investigates the effect of PS balls as partial replacement of fine aggregates in various percentages (20%, 40%, 60%, 80% and 100%) on mechanical properties of concrete such as compressive strength, splitting tensile strength, and flexural strength. The optimum mix was found to be at 40% replacement of PS balls with maximum strength of 62.89 MPa at 28 days curing. Permeability of concrete was performed and it resulted in a more durable concrete with replacement of PS balls at 40% and 100% as fine aggregates. These two specific values were considered as optimum replacement is 40% and also the maximum possible replacement is 100%. Scanning electron microscope (SEM) analysis was done and it was found that the PS balls in concrete were unaffected and with optimum percentage of PS balls as fine aggregates in concrete resulted in good strength and less cracks. Hence, it is possible to produce good workable concrete with low water to cement ratio and higher strength concrete by incorporating PS balls.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.452-459
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• 2017

In recent years, to reduce self-weight of structural elements, the use of SCP (Steel Concrete Plate) instead of prestressed concrete is increasing. Because SCP has a complicated sectional shape and includes a large number of studs, the use of high-fluidity concrete is required. Therefore, in this study, to prevent the restrained shrinkage behavior by the stud, the effects of using an expansive agent (EA) and shrinkage reducing agent (SRA) were investigated, and the optimal mixture proportions to maximize the filling capacity were determined based on the fine aggregate ratio. The test results indicated that the combined use of EA and SRA exhibited the smallest shrinkage. The ratio of the crushed sand and washed sea sand was determined to be 5:5, and the proper fine aggregate ratio was found to be 55.6%, because when the ratio was too high, a decrease in strength and an increase in shrinkage strain were expected. The high-fluidity concrete effectively filled the large-sized SCP module.

• Journal of the Korea Institute of Building Construction
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• v.13 no.3
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• pp.282-290
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• 2013

In this study, the adjustment range of mixture factor with replacement mineral admixture was reviewed to secure the mixture change data of high volume concrete compared to general concrete. When changing the concrete mix to high volume concrete within the universal concrete mixing, the adjustment range of mixture to ensure optimum quality is as follows. Unit-water content is $20{\sim}30kg/m^3$ downward. Fine aggregate ratio dropped by approximately 1% when W/B was reduced by 5%, and it is reduced by approximately 0.12% when there is a 5% increase in the total replacement rate. When the FA replacement rate was increased by 5%, the AE agent was approximately 20% to 30% higher compared with the conventional one. When the FA and BS replacement rate rose by 5%, W/B was reduced by about 1 to 4%.

• Geomechanics and Engineering
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• v.28 no.6
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• pp.547-557
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• 2022

Dune sands are poorly graded collapsible soils lacking fines. This experimental study explored the technical feasibility of sustainable invigoration of fine waste materials to improve the geotechnical properties of dune sand. The fine waste considered in this study is fine marble waste. The fine waste powder was mixed with dune sand at different contents (5, 10,15, 20, 25, 50%), where the gradation, void ratio, compaction, and shear strength characteristics were assessed for each fine marble waste -dune sand blend. The geotechnical properties of the dune sand-fine marble waste mix delineated in this study reveal the enhancement in compaction and gradation characteristics of dune sand. According to the results, the binary mixture of dune sand with 20% of fine marble waste gives the highest maximum dry density and results in shear strength improvement. In addition, a numerical study is conducted for the practical application of the binary mix in the field and tested for an isolated shallow foundation. The elemental analysis of the fine marble waste confirms that the material is non-contaminated and can be employed for engineering applications. Furthermore, the numerical study elucidated that the shallow surface replacement of the site with the dune sand mixed with 20% fine marble waste gives optimal performance in terms of stress generation and settlement behavior of an isolated footing. For a sustainable mechanical performance of the fine marble waste mixed sand, an optimum dose of 20% fine marble waste is recommended, and some correlations are proposed. Thus, for improving dune sand's geotechnical characteristics, the addition of fine marble waste to the dune sand is an environment-friendly solution.