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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korea Concrete Institute
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Journal DOI :
Korea Concrete Institute
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Volume & Issues
Volume 16, Issue 6 - Dec 2004
Volume 16, Issue 5 - Oct 2004
Volume 16, Issue 4 - Aug 2004
Volume 16, Issue 3 - Jun 2004
Volume 16, Issue 2 - Apr 2004
Volume 16, Issue 1 - Feb 2004
Selecting the target year
A Study on Corrosion Resistance of the Reinforement in Concrete Using Blast-Furnace Slag Powder
Kim Eun-Kyun ; Kim Jin-Keun ; Lee Dong-Hyuk ; Kim Young-Ung ; Kim Yong-Chul ;
Journal of the Korea Concrete Institute, volume 16, issue 1, 2004, Pages 1~9
DOI : 10.4334/JKCI.2004.16.1.001
This paper represents the permeability of chloride ions and the corrosion performance in the concrete blended with granulate blast furnace slag exposed to chloride environment. An ordinary cement (type I ) and sulfate resisting cement(type V) were used for the experiment. The two cements were combined with
of the granulated blast furnace slag. The accelerated permeability tests of chloride ions were performed in accordance with ASTM C1202, and the accelerated corrosion tests of steel were carried out by using the method of immersion/drying cycles. After water curing 28 days, 56 days and 91 days, these tests were conducted until 30 cycles. In every cycle, test specimens were wetted in
NaCl solution for three days and dried again in
air for four days. As an experimental results, the diffusion coefficient of chloride ions of the ordinary cement Concrete Combined granulated blast furnace slag was much lower than that of non granulated blast furnace slag concrete. Moreover, the diffusion coefficient of chloride ions of sulfate resisting cement concrete was higher than that of ordinary cement concrete. On the basis of the results of accelerated corrosion tests, corrosion resistance of the concrete mixed with granulated blast furnace slag shows good to corrosion resistance, however, the concrete with sulfate resisting cement shows bad to corrosion resistance.
Evaluation on the Shear Performance of U-type Precast Prestressed Beams
Yu Sung-Yong ;
Journal of the Korea Concrete Institute, volume 16, issue 1, 2004, Pages 10~17
DOI : 10.4334/JKCI.2004.16.1.010
Shear tests were performed on four ends of full scale U-type beams which were designed by optimum process for the depth with a live load of 4903Pa. The ratio of width to depth of full scale 10.5 m-span, composite U-type beams with topping concrete was greater than 2. Following conclusions were obtained from the evaluation on the shear performance of these precast prestressed beams. 1) Those composite U-type beams performed homogeneously up to the failure load, and conformed to ACI Strength design methods in shear and flexural behaviors. 2) The anchorage requirements on development length of strand In the ACI Provisions preyed to be a standard to determine a failure pattern within the limited test results of the shallow U-type beams. 3) Those all shear crackings developed from the end of the beams did not lead to anchorage failure. However, initiated strand slip may leads the bond failure by increasing the size of diagonal shear crackings. 4) The flexural mild reinforcement around the vertical center of beam section was effective for developments of a ductile failure.
Optimization for Precast Prestressed Wide-U Beams with the Least Depth
Yul Sung-Yong ;
Journal of the Korea Concrete Institute, volume 16, issue 1, 2004, Pages 18~26
DOI : 10.4334/JKCI.2004.16.1.018
The cost of underground work is a dominant factor to determine the total construction fee. It is generally 2
2.5 times higher than that of above ground for building with the same height. 'A new precast prestressed framing plan for underground parking building' was suggested with the beam of the least depth - U-type beams. The depth of regular rectangular reinforced concrete beam which is currently used in the underground parking of apartments could be reduced up to 12
34cm/story due to the development of a U-beams from the optimum process. Two full scale prototype U-beams were tested in this study. It was found that the Wide U-beams in the test showed higher strength than calculated nominal and design, however need to provide temporary supports to meet the flexural moment of construction load at the simply supported state before the lopping concrete hardens.
Evaluation of Split Tension Fatigue Test Method for Application in Concrete
Kim Dong-Ho ; Lee Joo-Hyung ; Jeong Won-Kyong ; Yun Kyong-Ku ;
Journal of the Korea Concrete Institute, volume 16, issue 1, 2004, Pages 27~35
DOI : 10.4334/JKCI.2004.16.1.027
Most of concrete fatigue tests currently used are flexural tension or compression methods to investigate the tensile or compressive properties, respectively. However, the concrete pavement or concrete slab is actually subjected to a combined stress condition such as biaxial or triaxial. The split tension test may result in similar stress condition to biaxial stress condition. The purposes of this study were to evaluate the split tension fatigue test method for application in concrete. These were done by a finite element analysis and experimental series. The results were as follows: The optimum configuration of split tension fatigue test was a cylinder of 15cm in diameter and 7.5cm in thickness, which had a little different thickness compared to the KS standard cylinder of
. The concrete stress ratio of compressive against horizontal from FEA was 3.1, while that from theory was 3.0. The stress distributions of mortar and steel were almost similar at different thicknesses. The measured static split tensile strengths of concrete and mortar were quite similar at 30cm and 7.5cm thickness cylinders. The measured stress-strain relationship showed their consistency at all specimens regardless of thickness, and confirmed the results from FEA. As a results, the concrete split tension specimen, cylinder of 15cm in diameter and 7.5cm in thickness, could be used at fatigue test because of its accuracy, simplicity and convenience.
A Study on the Prediction of Shortening for Steel-Reinforced Concrete(SRC) Column in the High-Rise Buildings
Jeong Eun-Ho ; Kim Jeom-Han ;
Journal of the Korea Concrete Institute, volume 16, issue 1, 2004, Pages 36~42
DOI : 10.4334/JKCI.2004.16.1.036
Although steel-reinforced concrete(SRC) is widely used in a high-rise building, a methods used to predict the column shortening of SRC structural members has many problems in applying a theoretical equation which considers only the material characteristics of reinforced concrete. In this study, the degree of accuracy of the existing method calculating the column shortening of a high-rise building is examined. For this, first, the actual measurement data are chosen about the column shortening of a high-rise building established with SRC structural members. Then the column shortening of a SRC structural member is calculated through computer program. Finally, the comparison between the measurement data and the analytical ones is executed. According to this study, it can be concluded that there is little difference between the former and the latter. Therefore, the existing method can be used to evaluate the column shortening of a high-rise building using a SRC structural members.
Evaluation of the Minimum Shear Reinforcement Ratio of Reinforced Concrete Members
Lee Jung-Yoon ; Yoon Sung-Hyun ;
Journal of the Korea Concrete Institute, volume 16, issue 1, 2004, Pages 43~53
DOI : 10.4334/JKCI.2004.16.1.043
The current Korean Concrete Design Code(KCI Code) requires the minimum and maximum content of shear s in order to prevent brittle and noneconomic design. However, the required content of the steel reinforcement In KCI Code is quite different to those of the other design codes such as fib-code, Canadian Code, and Japanese Code. Furthermore, since the evaluation equations of the minimum and maximum shear reinforcement for the current KCI Code were based on the experimental results, the equations can not be used for the RC members beyond the experimental application limits. The concrete tensile strength, shear stress, crack inclination, strain perpendicular to the crack, and shear span ratio are strongly related to the lower and upper limits of shear reinforcement. In this research, an evaluation equation for the minimum content of shear reinforcement is theoretical proposed from the Wavier's three principals of the mechanics of materials.
Setting Behavior of Polystyrene Mortars with Elapsed Curing Time
Choi Nak-Woon ; Kim Han-Sang ;
Journal of the Korea Concrete Institute, volume 16, issue 1, 2004, Pages 54~60
DOI : 10.4334/JKCI.2004.16.1.054
This study deals with the setting behavior of polystyrene mortars using waste expanded polystyrene(EPS) solution-based binders. The binders for polystyrene mortars are made by mixing crosslinking agent with EPS solutions prepared by dissolving EPS in styrene. Polystyrene mortars are prepared with various EPS concentrations of EPS solutions and crosslinking agent contents, subjected to a dry curing, and tested for working life, peak exotherm temperature and 10h-length change. From the test results, He working lives of polystyrene mortars are shortened with raising EPS concentration of EPS solution and crosslinking agent content. Low-shrinkage or non-shrinkage polystyrene mortars could be obtained by adjusting EPS concentration of EPS solution and crosslinking agent content.
A Theoretical Study on the FRP Retrofit of Existing Circular Bridge Piers for Seismic Performance Enhancement
Kwon Tae-Gyu ; Choi Young-Min ; Hwang Yoon-Knok ; Yoon Soon-Jong ;
Journal of the Korea Concrete Institute, volume 16, issue 1, 2004, Pages 61~69
DOI : 10.4334/JKCI.2004.16.1.061
The bridge piers under service suffered a brittle failure due to the deterioration of lap-spliced longitudinal reinforcement without developing its flexural capacity or ductility. The earthquake induced lateral force results in tension which causes bond-slip failure at the lap-spliced region in circular bridge piers. In this case, such a brittle failure can be controlled by the seismic retrofit using FRP laminated circular tube. The retrofitted piers using FRP laminated circular tube showed significant improvement in seismic performance due to FRP's confinement effect. This paper presents the analytical results on the seismic strengthening effect of circular bridge piers with poor lap-splice details and strengthened with FRP laminated circular tube. FRP's confinement effect is predicted by the classical elasticity solution for the laminated circular tube manufactured with several layers. The FRP laminated circular tube induces the flexural failure instead of a bond-slip failure of the circular reinforced concrete piers under seismic induced lateral forces. To investigate the correctness and effectiveness of analytical solution derived in this study, the analytical results were compared with the experimental data and it was confirmed that the results were correlated well each other, The effects on the confinement of FRP laminated circular tube, such as the number of layers, the fiber orientations, and the mechanical properties, were investigated. From the parametric study, it was found that the number of layers, the fiber orientations, and the major Young's modulus (E11) of the FRP laminated circular tube were the dominant parameters affecting the confinement of reinforced concrete circular bridge piers.
Setting Time and Strength Characteristics of Cement Mixtures with Set Accelerating Agent for Shotcrete
Kim Jin-Cheol ; Ryu Jong-Hyun ;
Journal of the Korea Concrete Institute, volume 16, issue 1, 2004, Pages 70~78
DOI : 10.4334/JKCI.2004.16.1.070
Although set accelerating agents are used generally in New Austrian Tunneling Method, the standards for test methods and quality of set accelerating agents are not prescribed domestically. In this study, the proprieties of the various standards and the characteristics of set accelerating agents for shotcrete were evaluated. The alkali contents of set accelerating agents based on silicate, aluminate and cement were higher than those of alkali-free ones. From the result, it is thought that the quality control of aggregate should be enhanced and that the number of test cycle of alkali-aggregate reaction should be increased. The setting times of cement paste with set accelerating agents based on silicate and alkali-free ones were different largely with mixing methods. Compressive strength of mortar with set accelerating agents based on silicate, aluminate and cement at one day satisfied the specifications of Korea Concrete Institute. However, the strength ratio compared to control mix at 28 days showed as
except for the alkali-free set accelerating agents. As a results of setting time and strength test, the establishment of domestic standards that can reflect the characteristics of materials and construction methods of tunnels and that can increase quality of set accelerating agents is required immediately.
An Experimental Study for Recycling of the Waste PET Bottle as a Fine Aggregate for Lightweight Concrete
Choi Yun-Wang ; Moon Dae-Joong ; Jung Moon-Young ; Cho Sun-Kyu ;
Journal of the Korea Concrete Institute, volume 16, issue 1, 2004, Pages 79~87
DOI : 10.4334/JKCI.2004.16.1.079
The qualify of lightweight aggregate made from waste PET bottle(WPLA) and the workability, the unit weight and strength property of concrete with WPLA were investigated for the purpose of recycling the waste PET bottles as lightweight concrete fine aggregate. This study indicated a good result that WPLA should be replaced with less than
of natural fine aggregate. When WPLA was replaced with
of natural fine aggregate, the specific gravity and water absorption of mixed fine aggregate were greatly reduced about 23 and
respectively in comparison with those of river sand. The quality of WPLA affected on the properties of lightweight aggregate concrete. The workability of fresh concrete with WPLA(WPLAC) was improved with increasing the replacement ratio of WPLA and water cement ratio. Slump increasing ratio of the former showed about
because that a specific gravity of fine aggregate was decreased from 2.6 to 1.7. The unit weight of concrete with
WPLA was decreased about
in comparison with that of control concrete. Furthermore, the compressive strength of concrete with 25 and
WPLA at the age of 28 days increased higher than 30 MPa regardless with water cement ratio (W/C=45, 49 and
) of this study. Specific strength of concrete with
, was higher than that of contro concrete in water cement ratio of
. The compressive strength-splitting tensile strength ratio and compressive strength-modulus of elasticity ratio of WPLAC were similar to that of nomal lightweight aggregate concrete. This results showed a good estimation that WPLA will be able to recycled as a fine aggregate for lightweight concrete.
Applicability of Epoxy Injection Method In Cracked RC Beams Considering Pre-Loading Conditions
Hong Geon-Ho ; Shin Yeong-Soo ;
Journal of the Korea Concrete Institute, volume 16, issue 1, 2004, Pages 88~93
DOI : 10.4334/JKCI.2004.16.1.088
The objective of this study was to investigate applicability of epoxy injection method to cracked RC beams and structural behavior of repaired RC beams considering pre-loading conditions. For this purpose, five test beams were fabricated under two experimental variables. The main variables of this experimental study were pre-loading conditions and repair methods. The two pre-loading conditions were selected as
of nominal strength and the repair methods were to repair the cracked RC beams under free loading after crack and sustained loading. The comparative study was executed to evaluate effects of pre-loading conditions on the structural behavior of the cracked RC beams after crack-repair. The strains of reinforcement and concrete and deflections of beams at each loading step were measured and evaluated. As the results of this study, repair methods have much influence on structural behavior of epoxy injected RC beams and epoxy injection method for cracks of RC structures is appeared to be efficient.
Flexural Behavior of Reinforced Concrete Beams Retrofitted with Modified Polymer Mortar System
Hong Geon-Ho ; Choi Eun-Gyu ; Lee Su-Jin ; Shin Yeong-Soo ;
Journal of the Korea Concrete Institute, volume 16, issue 1, 2004, Pages 94~101
DOI : 10.4334/JKCI.2004.16.1.094
This study shows the test results of seven RC beams retrofitted with modified polymer system and parametric study about the effects of tensile strength of retrofitting materials by analytical method on the flexural behavior. The main parameters are the retrofitted depth and length. The beams are loaded to the failure by four-point loading. Test results show that the effect of the retrofitted length on the structural behavior is more significant than that of depth. As the retrofitted depth is increased, the beams represents the brittle failure mode The non-linear analysis is carried out to grasp the effect of the tensile strength of retrofitting material on the structural behavior. As the retrofitted depth and length are increased, the tensile strength becomes more effective so these parameters should be considered to determine the retrofitted area. The analytical results show that failure strength is less than that of experimental results, but the stiffness is vice versa.
Early Prediction of Concrete Strength Using Ground Granulated Blast Furnace Slag by Hot-Water Curing Method
Moon Han-Young ; Choi Yun-Wang ; Kim Yong-Gic ;
Journal of the Korea Concrete Institute, volume 16, issue 1, 2004, Pages 102~110
DOI : 10.4334/JKCI.2004.16.1.102
Recently, production cost of ready mixed concrete(remicon) has been increased due to the rising cost of raw materials such as cement and aggregate etc. cause by the upturn of oil price and increase of shipping charge. The delivery cost of remicon companies, however, has been decreased owing to their excessive competition in sale. Consequently, remicon companies began to manufacture the concrete by mixing ground granulated blast furnace slag(GGBF) in order to lower the production cost. Therefore, the objective of this study was to predict 28-day strength of GGBF slag concrete by early strength(1 day-strength, 7 day-strength) for the sake of managing with ease the quality of remicon. In experimental results, the prediction equation for 28 day-strength of GGBF slag concrete could be produced through the linear regression analysis of early strength and 28 day-strength. In order to acquire the reliability, all mixture were repeated as 3 times and each mixture order was carried out by random sampling. The prediction equation for 28 day-strength of GGBF slag concrete by 1-day strength(hot-water method) won the good reliability.
Strength Degradation and Failure of Circular RC Bridge Columns with Longitudinal Steel Connection under Cyclic Lateral Load
Lee Jae-Hoon ; Jung Chul-Ho ; Ko Seong-Hyun ; Son Hyeok-Soo ;
Journal of the Korea Concrete Institute, volume 16, issue 1, 2004, Pages 111~124
DOI : 10.4334/JKCI.2004.16.1.111
This research is a part of a research program to verify the seismic performance of circular reinforced concrete bridge columns with respect to longitudinal steel connection details under cyclic lateral load. A total of 21 column specimens were constructed and tested. Main variables in this test program were longitudinal steel connection details(continuous, lap-spliced, and mechanically connected), confinement steel ratio, and axial force ratio, etc. The test results of the columns with different longitudinal steel connection details showed different failure mode, strength degradation, and seismic performance. From the quasi-static test, it was found that the columns with all longitudinal reinforcement lap-spliced showed significantly reduced ductility. However, seismic performance of the columns with half of longitudinal reinforcement lap-spliced showed limited ductility but much more ductile behaviour than the columns with all longitudinal reinforcement lap-spliced. It was also found that the seismic performance, failure mode and strength degradation of columns with mechanical connected longitudinal reinforcement were similar to those of columns with continuous longitudinal reinforcement.
A Thermal Conductivity Model for Hydrating Concrete Pavements
Jeong Jin-Hoon ; Kim Nakseok ;
Journal of the Korea Concrete Institute, volume 16, issue 1, 2004, Pages 125~129
DOI : 10.4334/JKCI.2004.16.1.125
Hydrating concrete pavement is typically subjected to temperature-induced stresses that drive cracking mechanisms at early concrete ages. Undesired cracking plays a key role in the long-term performance of concrete pavement systems. The loss of support beneath the concrete pavement due to curling caused by temperature changes in the pavement may induce several significant distresses such as punch out pumping, and erosion. The effect of temperature on these distress mechanisms is both significant and intricate. Because thermal conductivity dominates temperature flow in hydrating concrete over time, this material property is back-calculated by transforming governing equation of heat transfer and test data measured in laboratory. Theoretically, the back- calculated thermal conductivity simulates the heat movements in concrete very accurately. Therefore, the back- calculated thermal conductivity can be used to calibrate concrete temperature predicted by models.
Effects of Cement Type and Fly Ash on the Sulfate Attack Using ASTM C 1012
Ahn Nam-Shik ;
Journal of the Korea Concrete Institute, volume 16, issue 1, 2004, Pages 130~138
DOI : 10.4334/JKCI.2004.16.1.130
The primary factors that affecting concrete sulfate resistance are the chemistry of the Portland cement and the chemistryandreplacementlevelofmineraladmixtures. In order to investigate the effect of those on the sulfate attack the testing program involved the testing of several different mortar mixes using the standardized test, ASTM C 1012. four different cements were evaluated including one Type I cement, two Type I-II cements, and one Type V cement. Mortar mixes were also made with mineral admixtures as each cement was combined with three different types of mineral admixtures. One Class F fly ash and one Class C fly ash was added in various percent volumetric replacement levels. The expansion measurements of mortar bars were taken and compared with expansion criteria recommended from past experience to investigate the effect of each factor.