• Proceedings of the KSR Conference
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• 1999.05a
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• pp.375-382
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• 1999

The use of compaction grouting system(C.G.S) evolved in the 1950's to correct structural settlement of buildings. Over the almost 50 years, the technology has developed and is currently used in wide range of applications. Compaction Grouting, the injection of a very stiff 'zero-slump' mortar grout under relatively high pressure, displaces and compacts soils. It can effectively repair natural or man-made soil strength deficiencies in variety of soil formations. Major uses of Compaction Grouting include densifying loose soils or fill voids caused by sinkholes, poorly compacted fills, broken utilities, improper dewatering, or soft ground tunneling excavation. Other application include preventing liquefaction, re-leveling settled structures, and using compaction grout bulbs as structural elements of minipiles or underpinning. So, on the basis of the case history constructed in recent year, a study has been performed to analyze the basic mechanism of the Compaction Grouting and verify the effectiveness of the ground improvement.

• Structural Engineering and Mechanics
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• v.55 no.1
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• pp.137-160
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• 2015

The one-way (two-way) flexural strength of RCC prisms (circular slabs) reinforced with glass fiber textiles is addressed. To this end, alkaline-resistant glass fiber textiles with three surface weights were used in the composite, the matrix concrete was designed with zero/nonzero slump, and the textiles were used with/without an intermediate layer provided by epoxy resin and sand mortar. Prisms were tested under a four-point loading apparatus and circular slabs were placed on simple supports under a central load. Effects of the amount and geometry of reinforcement, matrix workability, and the intermediate layer on the ultimate load and deflection were investigated. Results revealed that, with a specific reinforcement amount, there is an optimum textile tex for each case, depending on the matrix mix design and the presence of intermediate layer. Similar results were obtained in one-way and two-way bending tests.

• Journal of the Korea Institute of Building Construction
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• v.6 no.4 s.22
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• pp.93-98
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• 2006

Admixture materials are used in mixing concrete or mortar to improve quality and performance of the concrete. This study examines the potential use of talc as a substitute for cement, the benefits of recycling waste resources for economical efficiency and quality improvement of concrete. The test was carried out by replacing the plain mix with fine grains of talc at the rate of 10%, 20%, and 30%. Talc was divided into three groups depending on the degree of pulverizing. For wet concrete, porosity, slump, bleeding per unit, and setting time by penetration resistance were measured; similarly, for dry concrete, strength and watertight Property were tested. Test results showed that the amount of bleeding and setting time could be shortened, but the strength and watertight proofing severely deteriorated. However, at the replacement rate of 10%, talc showed equal performance with the plain at all degrees of pulverization, which suggests its potential use as admixture material.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.2
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• pp.152-158
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• 2015

In order to investigate the feasibility of stone dust sludge as fine aggregate, an experimental study was performed on cement mortar with stone dust sludge. fresh mortar properties and strength with various stone dust sludge replacement ratios were estimated. the replacement ratio adopted in this study was 0, 10, 20, 30%. Flow, air content, and rheological properties were considered as properties of fresh mortar. Compressive strength and flexural tensile strength were measured for strength. The results are as follows. Higher amount of stone dust sludge caused reduction in slump and air content. In the rheological properties, both yield stress and plastic viscosity increased as stone dust sludge content increased up to 20% replacement ratio, but there were no remarkable difference between 20 and 30%. Yield stress increased drastically between 10 and 20%. Compressive and flexural tensile strength results indicated that the strength variation was not significant according to stone dust sludge content, but the strength gain in the early age by adding stone dust sludge was evident. the strength at the age of 28 days however did not show noticeable effect of adding stone dust sludge.

• Journal of the Korea Concrete Institute
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• v.24 no.2
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• pp.121-127
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• 2012

Cement has been traditionally used as a main binding material of high ductile fiber reinforced cementitious composites. The purpose of this paper is to investigate the feasibility of using alkali-activated slag and polyvinyl alcohol (PVA) fibers for manufacturing high ductile fiber reinforced cementless composites. Two mixture proportions with proper flowability and mortar viscosity for easy fiber mixing and uniform fiber dispersion were selected based on alkali activators. Then, the slump flow, compression, uniaxial tension and bending tests were performed on the mixes to evaluate the basic properties of the composites. The cementless composites showed an average slump flow of 465 mm and tensile strain capacity of approximately 2% of due to formation of multiple micro-cracks. Test results demonstrated a feasibility of manufacturing high ductile fiber reinforced composites without using cement.

• Applied Chemistry for Engineering
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• v.16 no.6
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• pp.815-821
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• 2005

Three major commercially available organic chemical admixtures are modified lignosulfonates (LS), sulfonated naphthalene-formaldehyde resins (SNF) and sulfonated melamine-formaldehyde (SMF). In this study, various sulfonated melamine-formaldehyde (SMF) superplasticizers were synthesized via four synthetic steps including hydroxymethylation (Step 1), sulfonation (Step 2), polymerization (Step 3) and neutralization and stabilization (Step 4). In this synthesis, mole ratio of melamine to formaline and the amount of acid catalyst used were varied. The obtained SMF superplasticizers were applied to cement paste and mortar and their physical properties including workability, slump loss, compressive strength were investigated. Also their hydrate shapes were investigated by examining SEM images of the cured paste. It was found that the fluidity properties of cement were significantly influenced by the structure of SMF condensates.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.413-416
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• 2008

The concrete used most in construction materials. There is an overcrowded iron dimensions use of the concrete at time of the other concrete theory on the reinforcing rod back which did congestion and compares it with this, and there are more few dimensions of the aggregate than concrete, and quantity of aggregate passage is superior in mortar than concrete. If a volume rate of the aggregate writes mortar than concrete against this, therefore, unit amount increases, and quantity of paste increases and quantity of dry shrinkage than increase concrete. However, I let I regulate lay priest distribution of the aggregate, and the results rates increase and reduce unit amount and decrease quantity of dry shrinkage, and separation resistance and the gap passage characteristics are judged because it can be it in a substitute document of very superior concrete. I came to carry out the study that I watched to let I was useful a little more and do the improvement repair of a become building wall body, a basement pillar and repair reinforcement of the assistant in the reinforcing rod back, the old age when I made congestion here. I regulated lay priest distribution of the aggregate in the study and regulated substitution rate of the aggregate (40%, 50%, 60%) and divided W/C 30%, 40% standards and produced mortar and I compared quantity of air by this, slump, compression robbery and showed it this time.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.9
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• pp.143-150
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• 2019

The purpose of this study was to propose how to determine the setting time related to the determination of the surface finish working time of the concrete using a Durometer, which is used as a rubber hardness meter. Two different types of Durometer were used to measure the setting time of the concrete. High flowing concrete with 40% of water to binder ratio was fabricated maintaining $600{\pm}100mm$ of slump flow. The test results indicated that the application of the Durometer resulted in a high correlation with the penetration resistance tester in both mortar and concrete. When measuring the setting time of the concrete, with properly used with Durometer, evaluation of the setting time of the concrete can be available. Therefore, it is thought that the measurement of the final set of the durometer C type can be useful to decide the limit time of the finishing operation and the time of the rejuvenation of the curing process by measuring the finishing set at 40 HD in the case of the initial set and 10 HD in the case of D type.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3A
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• pp.547-553
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• 2006

To know the effect of pigments on the material properties of color concrete, mortar and concrete tests were carried out by the using 5 kinds of pigment. The major component of red, yellow and black pigments was iron oxide and coloring component of blue and green pigments was copper phthalocyanine. Properties of mortar and concrete were some of difference according to adding ratio and kind of pigments. In case of using red, yellow and black pigments, setting time of concrete speeded a little and compressive strength was tendency to increase and slump or air content of concrete was same or decreased. On the other hand, in case of using green and blue pigments, compressive strength of concrete decreased largely because of the excessive air entrainment of surfactant and sump or air content of concrete increased highly. When the antifoaming agent was added to the color concrete mixed with green and blue pigments, compressive strength of concrete was improved and similar to that of concrete without pigment.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.02a
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• pp.1-11
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• 2000

The use of Compaction Grouting evolved in 1950's to correct structural settlement of buildings. Over the almost 50 years, the technology has been developed and is currently used in wide range of applications. Compaction Grouting, the injection of a very stiff, 'zero-slump' mortar grout under relatively high pressure, displaces and compacts soils. It can effectively repair natural or man-made soil strength deficiencies in variety of soil formations. Major applications of Compaction Grouting include densifying loose soils or fill voids caused by sinkholes, poorly compacted fills, broken utilities, improper dewatering, or soft ground tunneling excavation. Other applications include preventing liquefation, re-leveling settled structures, and using compaction grout bulbs as structural elements of minipiles or underpinning. In this paper, on the basis of the case history constructed in this year, a study has been performed to analyze the basic mechanism of the Compaction Grouting. Also, the effectiveness of the ground improvement and the bearing capacity of the Compaction Pile has been verified by the Cone Penetration Test(CPT) and Load Test. Relatively uniform Compaction grouting column could be maintained by planning the Quality Control in the course of grouting. And, the Quality Control Plan has been conceived using grout pressure, volume of grout and drilling depth.