• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.1071-1076
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• 2001

As a rule, in case of CFT for high-rise building, high strength concrete is required since it should have high fluidity, segregation resistance and large proportion of cement per unit considering the filling beneath the diaphragm. However, regarding the low-rise building under 20 stories, it is somewhat difficult to use high strength concrete. This is a fundamental study to develop a concrete with normal strength and high fluidity for CFT of low-rise building, whose Purposes are in speculating several kinds of changes in concrete's characteristics through various experiments and offering basic documents for practicalization in site and production through mock-up test.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.385-390
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• 1997

In the mixing proportion of high flowing concrete we have to use quantity of power such as cement and superplasticizer, and increase the proportion of fine aggregate more than that of plain concrete to increase flowability and segregation resistance. Therefore, the fresh state of high flowing concrete is largely affected by superplasticizer and change of grade the percentage of surface water. This study aims at development of self-filling up high flowing concrete without compaction, in case of using the fine aggregate of standard grade range, by examination on the influence of fresh state of high flowing concrete, and by understanding influence on various fluidity such as flowability, reinforcement passibility, fillingability, segregation resistance.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.461-464
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• 2006

Recently, as structures become bigger and higher, it is needed that high strength, high flow and high durability concrete. Demanding of High performance concrete that equality is maintained without material separation while flow, strength is increased by using low W/C rate and admixture, carbonation does not occur because of dense filling and has high durability is increasing rapidly. Because this high performance concrete is superior to general concrete in workability and durability, it is widely used in many construction and engineering works fields. However, it is reported that when it was exposed in fire, violent explosive spalling would be happened. Therefore, the purpose of this study evaluates explosive spalling properties of fire damaged high performance concrete according to the heating time.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.2A
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• pp.177-184
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• 2010

This study was performed to determine the effects of filling materials on the physical properties of permeable polymer concrete. The filling materials were ground calcium carbonate, ground granulated blast furnace slag and fly ash. In this experiment, permeable polymer concrete mixtures with unsaturated polyester resin contents from 5 to 7 weight %, filler/resin ratio of 0~2.0 and crushed coarse aggregate passing 15 mm sieve were prepared and coefficient of permeability, void ratio, compressive strength and flexural strength were tested. As the test results, increase in the strength and decrease in the coefficient of permeability of the permeable polymer concrete were generally observed with increasing the resin contents and filler/resin ratio. The compressive and flexural strength of the permeable polymer concrete were in the range of 8.0 to 35.0 MPa and 2.0 to 9.0 MPa respectively and the highest strength was shown at the mixtures with 7 weight % unsaturated polyester resin contents, 2.0 ratio of filler/resin and filler of ground calcium carbonate. On the other hand, in the level of 20 MPa compressive strength, the mixtures with filler of fly ash was shown as the most economic permeable polymer concrete.

• 기술발표회
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• s.2006
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• pp.162-171
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• 2006

Segmental Grid Retaining Wall is one of the segmental grid retaining walls using headers and stretchers to establish the framework of the wall In this method, grids formed by the intersection of headers and stretchers are generally filled with the gravel to maintain the weight of the wall Therefore, the construction can be carried out with higher speed and much economically when compared with the concrete retaining wall Furthermore, it has high drain capacity, and environmentally friendly aspects also have been pointed out because the possibility of the planting at the front of the wall However, in the segmental grid retaining wall method, the relative movement between the individual headers and stretchers was generally recognized, and stress redistribution in the gravel filling was also observed when subjected to the external loading and self-weight of filling Therefore, it has been thought that the distribution of the earth pressure in the segmental grid retaining wall system differ from that of the concrete retaining wall In this study, the surcharge tests using the scaled model segmental grid retaining wall was carried out to observe the distribution of the earth pressure in the segmental grid retaining wall The earth pressure was measured in the six specified height of wall, and the distribution of the pressure was analyzed. Furthermore, the earth pressure by computation or by the test using the concrete retaining wall was also considered to make comparison

• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.1
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• pp.71-77
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• 2005

Recycling of reclaimed concrete (RC) is very important in the management of construction and demolition wastes. Most of RC is utilized for land-filling after crushing in this country. In this study, a series of elution experiments were conducted to investigate the type and amount of pollutants released from the crushed RC. Most water quality parameters including heavy metals and some organic compounds were below standards for drinking water. Some of heavy metals such as As, Cd, Pb, Hg were detected in 0.5 N H2S04 solution after 24-hour immersing RC, which was conducted for evaluating a long term release effect. The concentration of the heavy metals were higher than the drinking water standards. The results also showed significant adsorption of heavy metals by crushed Re. Potential risks, based on the result of this study were not high in using crushed RC for land-filling. Appropriate management of RC would reduce the risk, for example the separation of hazardous materials from construction wastes. Long term evaluations for the sites of land filled with RC would be required to assess the environmental impacts.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.413-416
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• 2003

Experimental tests on the high strength self-compacting concrete with light-weight fine aggregate and light-weight coarse aggregate(LHSSC) were performed with slump-flow, reaching time to the slump-flow of 500mm, V-funnel dropping time and U-box difference level and compressive strength. LHSCC with light-weight fine aggregate of 75% and light-weight coarse aggregate of 100% was only satisfied with the property conditions of second self-compacting concrete(SCC), like as flowability, resistance to segregation and filling ability. The 28-day compressive strength of LHSCC indicated above 300kgf/$\textrm{cm}^2$ in all concrete mixtures, and it was increased to increase the replacement ratio of light-weight fine aggregate or to decrease the replacement ratio of light-weight coarse aggregate. Therefore, for satisfying the properties of fresh SCC and hardened concrete with above 350kgf/$\textrm{cm}^2$, it would expected that the replacement ratio of light-weight fine aggregate and light-weight coarse aggregate will be determined with 50~75% and 25~50%, respectively.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.112-116
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• 1996

This experimental study was performed to produce high flowing nomal strength concrete using viscosity agent. Test variables were selected to the viscosity agent contents with 4 levels, the cement contents with 5 levels and the coarse aggregate contents with 3 levels, etc. As a result, the high flowing and filling properties of concrete were obtatined by proper amount of viscosity agent and superplasticizer in the normal strength concrete. For the concrete mix proportions, it was found that unit weight of cement was more than 364kg/㎥ and volume of coarse aggregate was less than $280\ell/\textrm{m}^3$ in this study.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.333-338
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• 2003

Although porous concrete is resently used as a pavement at a parking lot, a public squre and a bicycle road, we use without enough examining. most the maintenance of quality for porous concrete is only dealt with strength and color tone. also, there is not yet enough fundamental data about dynamical properties for strength, rate of void and water permeability. even when it is applied to at the scene, it is been a matter. Accodingly in this study analyzed influences through the dynamical properties, combination, and time to vibration. After the analyzation, they investigated peculiar dynamics which are strength of porous concrete, rate of void, and water permeability follow the rate of increase on an admixture making pozzolan reaction. This is purpose to improve capacity of the sidewalk permeable concrete and development of the economical technique for pavement.

• Magazine of the Korea Concrete Institute
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• v.10 no.6
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• pp.281-289
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• 1998

This study has been performed to test the flowability and filling ability of high flowing concrete as well as distribution of aggregate and pore of core specimen, heat of hydration, compressive strength and core strength of concrete. In addition, the resistance to chloride ion penetration and chemical solutionof concrete was tested in order to evaluate the resistance to sea water of concrete and its application of high flowing concrete using blended low heat cement in the field of Seohae Grand Bridge. The properties of high flowing concrete with blended low heat cement were compared with ordinary 25-240-15 concrete using Type V cement. As the results of this study, the flowability and filling ability of high flowing concrete with blended low heat cement is satisfied without vibration. Though the cement content of high flowing concrete with blended low heat cement was 400kg/m$^2$, the rising temperature of it was relatively lower than that of the ordinary 25-240-15 concrete with Type V cement. Also, the compressive of high flowing concrete with blended low heat cement is similar to that of the ordinary 25-240-15 concrete with Type V cement.