• 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.

• Magazine of the Korean Society of Agricultural Engineers
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• v.42 no.1
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• pp.83-91
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• 2000

The purpose of this study is to estimate quantitatively lateral pressure of super-workable fresh concrete applied to form-work of prototype structures, such as tall wall, retaining wall and beam. As a result of this experiment, a function applicable to design a form work system and to predict lateral pressure curve is formulated . Super-workable concrete may be used for the structures reinforced with dense re-bar like box culvert to place concrete at a time, and this study for lateral pressure of super-workable concrete may be useful for form design.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.05a
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• pp.34-35
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• 2014

When various construction types of architectural construction are proceeded in order, the reinforced concrete construction is the frame construction which takes up the most important proportion among the construction process. Thus, the analysis of the effectiveness and productivity of the reinforced concrete construction is necessarily needed for smooth performance of construction projects. However, the conventional studies are performing the analysis of the productivity of only part(mould and steel) of the reinforced concrete construction and they have limitation in that they do not propose quantitatively the overall productivity of reinforced concrete construction.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.395-398
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• 2000

Recently, increasement of usage contents of sea sand in constructing concrete structures due to insufficiency of high quality river sand, led to many studies for steel corrosion and control methods on it in concrete. But, domestic studies for threshold chloride contents of steel corrosion are not so many as those of foreign states. In this study, the electrochemical test as half cell potential measurement and linear polarization method to estimate the corrosion of steel in contents mixed with several levels chloride contents was performed, thereby, pre-mixed chloride were compared with results measured quantitatively for steel corrosion. And, based on these data, a trial to determine threshold chloride contents of steel corrosion was made.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.233-236
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• 2006

This study presents a technique to quantitatively measure the corrosion level of a reinforcing bar using the infrared thermography system. The temperature-distribution of the concrete surface is monitored and the temperature change of the reinforcing bar is analysed in terms of corrosion level and concrete cover depth. The experimental results indicate that temperature increase of the reinforcing bar is significant when the corrosion level is high, which implies that the quantity of heat is strongly dependent on corrosion level. Also, as the concrete cover depth of the specimen and the atmosphere temperature increase, the temperature variation becomes small.

• Corrosion Science and Technology
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• v.4 no.3
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• pp.81-88
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• 2005

The effects of rebar corrosion on the structural behaviour of reinforced concrete structures were discussed based on recent experimental investigation. The load carrying capacity of the deteriorated beams was quantitatively estimated by evaluating the degree of rebar corrosion in terms of the average cross-sectional loss of longitudinal reinforcing bars and bond deterioration between corroded reinforcing bars and concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.503-508
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• 2001

With difference to strengthening which could be evaluated structural efficiency, it is hard to do quantitative repair efficiency evaluation achieved compressive strength test or appearance investigation. In this paper, chloride ion penetration test is exacted to core specimens picked from repaired structure for quantitative repair evaluation. The result of experimentation shows repair efficiency quantitatively by means of difference between penetration amount of chloride ion for repaired and unrepaired core specimens.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.531-532
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• 2009

This paper presents crack spacing which quantitatively considers the fiber distribution and prediction of uniaxial tensile behavior of ECC on the basis of crack spacing and fiber distribution. The predictions exhibit similar tensile stess-strain curves to the test results within 10% error.

• Computers and Concrete
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• v.17 no.2
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• pp.189-199
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• 2016

Chloride penetration is considered as a most crucial factor for the determination of the service life of concrete. A lot of experimental tools for the chloride penetration into concrete have been developed, however, the mechanism was based on only diffusion, although permeability is also main driving forces for the chloride penetration. Permeation reacts on submerged concrete impacting for short to long term durability while capillary suction occurs on only dried concrete for very early time. Furthermore, hydrostatic pressure increases in proportional to measured depth from the surface of water because of the increasing weight of water exerting downward force from above. It is thought, therefore, that the water pressure has a great influence on the chloride penetration and thereby on the service life of marine concrete. In this study, new experiment is designed to examine the effect of water pressure on chloride penetration in concrete quantitatively. As an experiment result, pressure leaded a quick chlorides penetration by a certain depth, while diffusion induced chlorides to penetrate inward slowly. Therefore, it was concluded that chloride should penetrates significantly by water pressure and the phenomena should be accelerated for concrete exposed to deep sea. The research is expected as a framework to define the service life of submerged concrete with water pressure and compute water permeability coefficient of cementitious materials.

• Structural Engineering and Mechanics
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• v.18 no.2
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• pp.167-194
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• 2004

In this paper axial loading tests on low strength concrete members, which were confined with various thickness of carbon fiber reinforced polymer (CFRP) composite sheets are described. Totally 46 specimens with circular, square and rectangular cross-sections with unconfined concrete compressive strengths between 6 and 10 MPa were included in the test program. During the tests, a photogrammetrical deformation measurement technique was also used, as well as conventional measurement techniques. The contribution of external confinement with CFRP composite sheets to the compressive behavior of the specimens with low strength concrete is evaluated quantitatively, in terms of strength, longitudinal and lateral deformability and energy dissipation. The effects of width/depth ratios and the corner radius of the specimens with rectangular cross-section on the axial behavior were also examined. It was seen that the effectiveness of the external confinement with CFRP composite sheets is much more pronounced, when the unconfined concrete compressive strength is relatively lower. It was also found that the available analytical expressions proposed for normal or high strength concrete confined by CFRP sheets could not predict the strength and deformability of CFRP confined low strength concrete accurately. New expressions are proposed for the compressive strength and the ultimate axial strain of CFRP confined low strength concrete.