• Proceedings of the Korean Geotechical Society Conference
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• 2002.10a
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• pp.673-680
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• 2002

The mechanical characteristics and compressibility of Light-Weighted Foam Soil (LWFS) are investigated. LWFS is composed of the dredged soil from offshore, cement and foam to reduce the unit-weight and increase compressive strength. For this purpose, the unconfined compression tests and triaxial compression tests are carried out on the prepared specimens of LWFS with various conditions such as initial water contents, cement contents, and confining stresses. The test results of LWFS indicated that the stress-strain relationship and the compressive strength are strongly influenced by the cement contents rather than the intial water contents of the dredged soils. In this study, the normalized factor considering the ratio of initial water contents, cement contents, and foam contents is suggested to evaluate the relationship between compressive strength and normalized factor.

• Advances in concrete construction
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• v.6 no.6
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• pp.611-629
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• 2018

The objective of present study is to investigate the effect of granulated blast furnace slag (GBS) as partial substitution of natural sand on behaviour of cement mortar. For this, the methods of factorial design with water cement (w/c) ratio and incorporation percentages of GBS as replacement of natural fine aggregate i.e., GBS(%) as factors are followed. The levels of factor w/c ratio are fixed at 0.4, 0.45, and 0.5 and the levels of factor GBS(%) are kept fixed as 0%, 20%, 40%, 60%, 80% and 100%. The compressive strength (CS) of mortar after 3, 7, 14, 28, 56 and 90 days, and water absorption (WA) are chosen as responses of the study. Analysis of variance (ANOVA) of experimental results has been carried out and those are illustrated by ANOVA tables, main effect and interaction plots. The results of study depict that the selected factors have substantial influence on the strength and WA of mortar. However, the interaction of factors has no substantial impact on CS and WA of mixes.

• Journal of the Korean Ceramic Society
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• v.27 no.8
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• pp.1034-1042
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• 1990

Investigation for the preparation of high strength hardened cement paste using ordinary portland cement, hydroxypropyl methyl cellulose(HPMC) with various admixtures was carried out. The cement paste was mixed with 0.1 of water cement ratio by twin roll mill and cured 60 days in humidity chamber. When the quartz powder or white cement was added to the paste, the flexural strength was 900∼1000kg/㎠ and the Young's modulus was 8∼9×105kg/㎠. When the silicafume was added, the flexural strength was 800kg/㎠ and the Young's modulus was 6×105kg/㎠.

• Journal of the Korean Geosynthetics Society
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• v.6 no.2
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• pp.17-20
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• 2007

In this study, a series of uniaxial unconfined compression test and constant-head test were performed to investigate the mechanical characteristics of porous concrete using recycled-aggregate for the varying unit weight and water-cement ratio. To enhance the permeability of the porous concrete, the recycled-aggregate with similar grain size in the range of $40{\pm}5mm$ was used and water-cement ratio that leads to the lean-mix was adapted. The mechanical characteristics of the porous concrete cured for 3 days were examined; the compressive strength and $E_{50}$ showed their maximum values with 40% water-cement ratio and $1.8t/m^3$ unit weight and the permeability coefficient was averagely measured in the range of $0.9{\times}10^0cm/sec$ regardless of water-cement ratio and unit weight.

• Journal of the Korea Institute of Building Construction
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• v.6 no.3 s.21
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• pp.107-114
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• 2006

In this study, the experiment was carried out to investigate and analyze the engineering properties of concrete using fine aggregate of PS bal slagl. The main experimental variables were water/cement ratio 30, 40, 50(%), water content $170kg/m^3$, replacement ratio of slag fine aggregate 0, 25, 50, 75(%) in experiment I and water/cement ratio 30, 40, 50(%), water content 165, 170, 175($kg/m^3$), replacement ratio of fine aggregate of PS ball 0, 50 in experiment II. According to the test results, the principle conclusions are summarized as follows (1) The workability of slag fine aggregate-mixed concrete tends to improve, as the replacement rate increases. (2) The air content of slag fine aggregate-mixed concrete tends to decrease, as the replacement rate increases. (3) The unit volume weight of slag fine aggregate-mixed concrete tends to significantly increase, as the replacement rate increases. (4) The compressive strength of slag fine aggregate-mixed concrete tends to show more increasing propensity, in case the curing period is relatively long, as the replacement rate increases.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.61-64
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• 1997

As construction technology advances, most of concrete structures are becoming larger and taller. Therefore, high strength and quality concrete is necessary for them. So, the proposal of using belite cement is investigated to satisfy high flowing, low heat, and high strength. In this study, the compressive strength, tensile strength, and modulous of elasticity of concrete using belite cement was considered according to the mix proposition condition as a water-cement ratio, unit cement content, and sand percentage.

• Journal of the Korean Ceramic Society
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• v.44 no.9
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• pp.524-528
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• 2007

The results of evaluating steel corrosion in concrete containing chloride content of various levels indicated that the more chloride content in concrete leads to the lower potential and higher corrosion current density. However, the open circuit potential of steel varied with time and exposure condition, and the corelation between the open circuit potential and corrosion current density was not obvious. In order to determine the critical threshold content of chloride of steel corrosion in concrete, the concept of average corrosion current density was employed. The range of critical chloride content in portland cement concretes was about $1.56{\sim}1.77%$($Cl^-$, %, wt of cement content) along with water-cement ratio, and higher water-cement ratio resulted in reduction in critical threshold chloride content.

• Journal of Ocean Engineering and Technology
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• v.20 no.1 s.68
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• pp.7-15
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• 2006

In this research, the behavior characteristics of cement mixing lightweight soil (CMLS) for recycling of dredged soil in the Nakdong River estuary are experimentally investigated. CMLS is composed of the dredged soil from Nakdong River estuary, cement, and air foam. For this purpose, uniaxial compression tests are carried out for artificially prepared specimens of CMLS, with various initial water contents, cement contents, and mixing ratio of dredged soils. The experimental results of CMLS indicated that the compressive strength is strongly influenced by the cement contents, rather than water contents and air foam. Compressive strength of CMLS increased with an increase in cement content, while it decreased with an increase in water content and air foam content. It was also found that the modulus of deformation E50 was in a range of 44 to 128 times greater than the value of uniaxial compressive strength, cured in 28 days.

• Journal of the Korean Ceramic Society
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• v.44 no.1 s.296
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• pp.23-31
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• 2007

To examine the effects of chemical admixture on the fluidity and strength development of high chloride cement, experiments were conducted in which lignosulfonate (LS), naphthalenesulfonate (NS), and polycorboxylate (PC) were each added in standard and excessive amounts, and the results were as follows. 1. Because adding KCl to NS causes a decrease in flow, adding PC is better in maintaining high cement fluidity. 2. When cement contained much chloride comes in contact with water, hydration begins 4 h after contact and securing workability becomes difficult, but by adding PC, workability can be secured to 10 h. 3. The bound water ratio and compressive strength in aging 3 days occupy $70\sim80%$ of those in aging 28 days, and the early compressive strength increases not only by adding KCl, but also by chemical admixture. 4. Although compressive strength development is excellent in NS, PC, if NS is added excessively, hydration becomes slow and while the pore structures become slightly minute, the strength development decreases due to severe setting retardation.

• Computers and Concrete
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• v.11 no.4
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• pp.305-316
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• 2013

This paper aims to study the effect of measurement methods and cracking on chloride transport of concrete materials. Three kinds of measurement methods were carried out, including immersion test, rapid migration test and steady-state migration test. All of these measurements of chloride transport show that chloride ion diffusion coefficient decreased with the reduction of water to cement ratio. Results of the immersion test were less than that of rapid migration test and steady-state migration test. For the specimen of lower water to cement ratio, the external electrical field has little effect on chloride binding relatively. Compared with the results obtained by these different measurement methods, the lower water to cement ratio may cause smaller differences among these different methods. The external voltage can reduce chloride binding of concrete, and the higher electrical field made a strong impact on the chloride binding. Considering the effect of high voltage on the specimen, results indicate that results based on the steady-state migration test should be more reasonable. For cracked concrete, cracking can accelerate the chloride ion diffusion.