• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.183-188
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• 1997

From a viewpoint of construction cost and preserving management of pavement, a policy of domestic pavement was gradually spreaded concrete pavement rather than asphalt. But the use of concrete with ordinary portland cement has shortages, such as dry-shrinkage, low flexural strength, etc. In order to overcome these problems, the concrete pavement using CSA expansive additive (Non-Shrinkage Cement) was studied and carried out the fie이 application. As the results, we find out Non-Shrinkage Cement that was distinguished in short-term construction by increasing flexural strength, shrinkage compensating and low-heat evaluation compared with OPC concrete.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.05a
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• pp.283-286
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• 2012

According to increase of the waste concrete occurrence, recycling has being important more and more. This study is to recycle the waste concrete powder, which is occurred in dry-process during recycling of construction waste. We have tried the waste concrete powder to apply as the replacement of the silica powder in cement extruding product. As a result, it is satisfied that the autoclave cured pannel of 50% replacement ratio of waste concrete powder staisty the level of the flexural strength of 14MPa stipulated by "KS F 4735 Extruding concrete panel" was the same thermal properties as base specimen.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.17-20
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• 2005

In this study, the properties of autogenous shrinkage stress and dry shrinkage stress for high strength concrete using Type I and Type IV cement were discussed. According to experimental results, autogenous shrinkage stress of SN30(the high strength concrete using type I cement) shows values higher than SL30(the high strength concrete using type IVcement). It is observed that the total shrinkage stress of SN30 is higher than that of SL30, because the ratio of autogenous shrinkage stress of the total shrinkage stress is relatively large. Therefore, SL30 is more effective to control or minimize the cracking of the high strength concrete, compared with SN30.

• Magazine of the Korean Society of Agricultural Engineers
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• v.42 no.2
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• pp.93-98
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• 2000

This study is performed to evalute experimentally the nondestructive properties on the concrete that is treated with crushed oyster shell powder of 0.15m or smaller in diameter. The ultrsonic pulse velocity of crushed oyster shell concrete(COSC) is in the range of 4.110-4.267m/s, and the dynamic modulus of elasticity of COSC range from 288$\times$10$^3$ to 318 $\times$10$^3$kgf/$\textrm{cm}^2$. The ultrasonic pulse velocity and dynamic modulus of elasticity are similar to those of normal portland cement concrete. The highest ultrasonic pulse velocity and dynamic modulus of COSC are measured at the 2.5% addition rate by weight of crushed oyster shell powder. The acid-resistance in increased of the content of crushed oyster shell powder. The acid-resistance of COSC with 15% addition rate by weight of crushed oyster shell power is 1.6 times greater than that of normal portland cement concrete. It is concluded that the addition of crushed oyster shell powder to normal portland cement concrete contributed to improve the nondestructive properties of concrete.

• Computers and Concrete
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• v.26 no.6
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• pp.577-585
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• 2020

By the increasing amount of waste materials, it eventually dumped into the environment and covering a larger area of the landfill which cause several environmental pollution problems. The utilization of Palm Kernal Shell Ash (PKSA) in concrete might bring a great benefit in addressing both environmental and economic issues. This article investigates the effect of PKSA as a partial cement replacement of High Strength Concrete (HSC). Several concrete mixtures were prepared with different PKSA of 0%, 10%, 20%, and 30% replaced by the cement mass. This procedure was replicated twice for the two different target mean strengths of 40 MPa and 50 MPa. The mixtures were prepared to test different fresh and hardened properties of HSC including slump test, the compressive strength of 3, 7, 14, 28, and 90 days, flexural strength of 28-days, drying shrinkage, density measurement, and sorptivity. It was observed 10% PKSA replacement as optimum percentage which reduced the drying shrinkage, sorptivity, and density and improved the late-age compressive strength of concrete.

• Journal of Industrial Technology
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• v.22 no.A
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• pp.193-200
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• 2002

Drying shrinkage cracking which may be caused by the relatively large specific surface IS a matter of grave concern for latex modified concrete(LMC) overlay and rapid-setting cement latex modified concrete(RSLMC) overlay. LMC and RSLMC were studied for field applications very actively in terms of strength and durability in Korea. However, there were no considerations in drying shrinkage. Therefore, the purpose of this dissertation was to study the drying shrinkage properties of LMC and RSLMC with the main experimental variables such as cement types(ordinary portland cement, rapid setting cement), water-cement ratios and curing days at a same controlled environment of 60% of relative humidity and $20^{\circ}C$ of temperature The drying shrinkage for specimens was measured with a digital dial gauge of Demec. The test results showed that the drying shrinkage of LMC and RSLMC were considerably lower with low water-cement ratio, respectively This might be attributed to the interlocking of hydrated cement and aggregates by a film of latex particles, water retention due to hydrophobic, and colloidal properties of the latexes resulting in reduced water evaporation.

• Journal of the Korea Concrete Institute
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• v.15 no.5
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• pp.739-746
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• 2003

Various researches on the application of polymer dispersions to the cement mortar and concrete have been carried out in many countries like America, Japan and Germany and so on due to their high performance and good modification effect. PAE of polymer dispersion widely used in situ was employed that the high flowability may be induced in the cement mortar. In order to investigate the modification of cement mortar with high flowability by PAE and fracture mode of adhesive strength properties in tension of that, experimental parameters were set as PAE solid-cement ratio(P/C) and cement: fine aggregate(C:F) and the experiments such as unit weight, flow, consistency change, crack resistance and segregation that inform on the general properties have been done. Adhesion in tension is measured with a view to comprehending the properties and fracture mode in tensile load. Consistency change of cement mortar modified by PAE did grow better as the ratio of PAE solid-cement increased and was much superior to that of resin based flooring such as polyurethane and epoxy which recorded the loss of consistency in 90 min. after mixing. Adhesive strength in tension increased with continuity during curing period and showed the maximum in case of C:F=1:1 and P/C=20%.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.905-908
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• 2008

The existing concrete using ordinary portland cement has difficult in earth strength. so our study proceeded in using the micro cement. the result of experiment is follow that strength of micro cement was hard better than ordinary portland cement in early strength but flow of ordinary portland cement was better than micro cement. when OPC and MC mixed by fly-ash, flow degree is increased because of ball baring. fly-ash type wicked in early strength but flyash type hard than 28days strength of OPC. flow of GBFS is decreased, early strength is increased. when fly-ash mixed in MC, it was wicked strength.

• Computers and Concrete
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• v.14 no.5
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• pp.527-546
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• 2014

Portland cement concrete, which has higher strength and stiffness than asphalt concrete, has been widely applied on pavements. However, the brittle fracture characteristic of cement concrete restricts its application in highway pavement construction. Since the polypropylene fiber can improve the fracture toughness of cement concrete, Polypropylene Fiber-Reinforced Concrete (PFRC) is attracting more and more attention in civil engineering. In order to study the effect of polypropylene fiber on the generation and evolution process of the local deformation band in concrete, a series of three-point bending tests were performed using the new technology of the digital speckle correlation method for FRC notched beams with different volumetric contents of polypropylene fiber. The modified Double-K model was utilized for the first time to calculate the stress intensity factors of instability and crack initiation of fiber-reinforced concrete beams. The results indicate that the polypropylene fiber can enhance the fracture toughness. Based on the modified Double-K fracture theory, the maximum fracture energy of concrete with 3.2% fiber (in volume) is 47 times higher than the plain concrete. No effort of fiber content on the strength of the concrete was found. Meanwhile to balance the strength and resistant fracture toughness, concrete with 1.6% fiber is recommended to be applied in pavement construction.

• Advances in concrete construction
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• v.5 no.1
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• pp.31-48
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• 2017

Supplementary cementitious materials (SCM) have turned out to be a vital portion of extraordinary strength and performance concrete. Metakaolin (MK) is one of SCM material is acquired by calcinations of kaolinite. Universally utilised as pozzolanic material in concrete to enhance mechanical and durability properties. This study investigates the fresh and hardened properties of conventional concrete (CC) and self compacting concrete (SCC) by partially replacing cement with MK in diverse percentages. In CC and SCC, partial replacement of cement with MK varies from 5-20%. Fresh concrete properties of CC are conducted by slump test and compaction factor tests and for SCC, slump flow, T500, J-Ring, L-Box, V-Funnel and U-Box tests. Hardened concrete characteristics are investigated by compressive, split tensile and flexural strengths at age of 7, 28 and 90 days of curing under water. Carbonation depth, water absorption and density of MK based CC and SCC was also computed. Fresh concrete test results indicated that increase in MK replacement increases workability of concrete in a constant w/b ratio. Also, outcomes reveal that concrete integrating MK had greater compressive, flexural and split tensile strengths. Optimum replacement level of MK for cement was 10%, which increased mechanical properties and robustness properties of concrete.