• Journal of the Korea institute for structural maintenance and inspection
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• v.3 no.4
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• pp.179-189
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• 1999

This study attempts to propose an evaluation considering the property of concrete pore which affects the deterioration of neutralization and the rebar resistance of concrete. Understanding pore property of concrete in using extent, for practical using of concrete manufacturing condition. basic quality property and durability estimation etc, the results of the experiment are as follows. 1) The result of analysis pore property of every specimen with the method of area ratio, in limitation of $10^{-6}{\sim}10^{-5}m$, the pore distribution ratio was maximum. It was high value as W/C was increased and the unit cement content was decreased. 2) In case of using admixture. the volume of pores was some increased as variation of mixing content. In high W/C range, it was very increased compared with plain concrete. 3) Concerned with compressive strength and volume of pores in hardened concrete, it is possible compressive strength estimation using the property of concrete pores. 4) Direct measurement of concrete pore property is difficult. the valuation of the dynamic modulus of elasticity using ultrasonic wave velocity was available. 5) Quantitatively evaluation of concrete structure durability by past result of pore distribution estimation, and it can be estimative scale of property study on the concrete materials.

• International Journal of Concrete Structures and Materials
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• v.18 no.3E
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• pp.165-171
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• 2006

Environment-friendly materials are increasingly used as building construction materials nowadays, and the market share of those is growing. Accordingly, the research and developments in terms of environmental value are progressing steadily now. The main characteristics of environmental products are far-infrared radiation, negative-ion emission, electromagnetic wave shielding, and antimicrobial property. These products are often used in mortar and as spray on the finishing material. Nevertheless, there are hardly any research on the functional properties of concrete, the main material in construction field. Thus, we evaluated such basic properties of concrete as slump, compressive strength and air content while using such functional materials as sericite, wood-pattern sandstone, carbon black and nano-metric silver solution to focus on their functional properties like far-infrared radiation, negative ion emission, electro magnetic wave shielding, and antimicrobial activity in this research. The results indicated that the most useful material in the functional materials was carbon black. Sericite and nano-metric silver solution had a little effect on the functional property. Moreover, although wood-pattern sandstone had very high functional property, it exhibited too low compressive strength to be applied, to concrete as a factory product. Antimicrobial property of nano-metric silver solution in the concrete was not clear demonstrated, but if these specimens were to be aged in $CO_2$ gas for a long time, it might be apparent.

• Proceedings of the Korea Concrete Institute Conference
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• 1994.10a
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• pp.93-98
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• 1994

The property of concrete at different places in mass concrete is affected by the age under the same curing temperature. For more accurate analysis of thermal stress in mass cocnrete, it is necessary to obtain the property of concrete with age and curing temperature. In this study, the effects of curing temperature and age (Maturity) on the development of the property of concrete were investigated by using concrete specimens made with type I cement. The curing temperatures are 23$^{\circ}C$, 5$0^{\circ}C$, and 8$0^{\circ}C$, respectively. As the maturity increases, the strength of concrete was increased. The results obtained experimentlly was compapred with the previous models, and good agreements was obtained.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.991-996
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• 2002

In this study, there are kind of property experiments like fluidity, compressive strength, bleeding measurement, concrete sink for CFT use high fluidity concrete. The property difference between before transmit and after transmit concrete in the mock up test with ready mixed concrete equipment is examined. The variable factors in mock up are diaphragm existence and nonexistence, diaphragm placing hole sizes. To investigate the concrete property under diaphragm, concrete packing ability tests is peformed. High fluidity and strength concrete which satisfied with mix criteria could apply to building construction field. It it is quality managed with use of packing ability analysis.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.223-228
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• 2003

Recently, owing to the deterioration of reconstruction and the construction, much of the construction waste is discharged in our construction field, and the amount of construction waste is rapidly increased. These waste are raised to financial and environmental problems, so the method of reusing waste concretes has been studied and carried out many direction. Especially being want of resources, if waste concrete could be recycled as aggregates for concrete, it will contribute to solve the exhaustion of natural aggregate, in terms of saving resources and protecting environment. This study is that the mechanical properties of concrete with recycled coarse aggregate were investigated for types of mineral admixture and the substitution of recycled coarse aggregate. The result of this study, in case of using mineral admixture, the property of fresh concrete was rised. And the property of harden concrete for the substitution ratio of recycled coarse aggregate was decreased. But the property of concrete with mineral admixture was better than that of concrete used only cement.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.405-406
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• 2009

This study aims at evaluating and analyzing hydration property and intensity property of structural concrete and joint separation test body in order to test and control the intensity of structural concrete. It also aims at examining validity and the plan to make similar environment with structural concrete

• Journal of the Korea Institute of Building Construction
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• v.2 no.1
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• pp.163-169
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• 2002

In this study, there are kind of property experiments like fluidity, compressive strength, bleeding measurement, concrete sink for CFT use high fluidity concrete. The property difference between before transmit and after transmit concrete in the mock up test with ready mixed concrete equipment is examined. The variable factors in mock up are diaphragm existence and nonexistence, diaphragm placing hole sizes. To investing the concrete Property under diaphragm, concrete packing ability, hydration heat, core specimen strength tests are performed.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.209-212
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• 2004

Recent economic development caused a vast use of mineral resources in Korea. Consequently, a supply of poor quality course aggregate (poor particle shape as well as poor gradation) in construction material become a social problem. In this study, an effect of aggregate particle shape on property of concrete was evaluated. The flat and elongation ratio of crushed aggregate was controled to 8, 15, 25, 35, and $47\%$ in order to evaluate fresh concrete behavior as well as physical properties in hardened concrete. Test result shows a poor aggregate particle shape cause a significant increase in entrapped air in fresh concrete, while no significant effect on hardened concrete property, such as strength as well as stiffness. This increase in entrapped air, however, believed to cause a significant decrease in concrete durability.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2007.11a
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• pp.27-30
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• 2007

Recently, use of light-weight panel is increasing in building. Styrofoam sandwich panel is inexpensive and it is excellent in insulation ability and constructability. But styrofoam of panel inside is low ignition point. Consequently, when panel is fired, it is occur in poisonous gas. On the other hand, light-weight foamed concrete is excellent in insulation ability, fire resistance due to inner pore. Properties of light-weight concrete is influenced by foaming agent type. Accordingly, this study investigate in insulation property of according to foaming agent type in order to using light-weight foamed concrete instead of styrofoam. As a results, Non-heating zone temperature of light-weight foamed concrete of using AP, FP are lower than light-weight foamed concrete of using AES. Light-weight foamed concrete of using AES, FP are satisfied with fire performance of two hours at foam ratio 50, 100. Light-weight foamed concrete of using AP is satisfied with fire performance of two hours at AP ratio 0.1, 0.15. Insulation property is better closed pore by made AP, FP than open pore by made AES.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.367-372
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• 2003

Fiber Reinforced Cementitious Composite, DFRCC has strain hardening property with multiple crack in failed of compressive, tensile, bending force, concrete is not so that. But DFRCC could not use to the building element for which has not structural stiffness only has ductile property. DFRCC is used for repair only in recently. In that reason, we considered the concrete of light weight concrete, porous concrete, mortar complex with DFRCC. and DFRCC reinforced by fiber net, steel bar. In this study, results of experiment on complex method of concrete and DFRC were shown as follows; The complex methods of concrete lay on DFRCC, sandwich layer composition were effective for bending force depending on section size each layer, and reinforce DFRCC by fiber net, steel bar was effective method also.