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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 17, Issue 6 - Dec 2005
Volume 17, Issue 5 - Oct 2005
Volume 17, Issue 4 - Aug 2005
Volume 17, Issue 3 - Jun 2005
Volume 17, Issue 2 - Apr 2005
Volume 17, Issue 1 - Feb 2005
Selecting the target year
An Experimental Study on the Rebound Degree Tendency of Linear Hitting Test Hammer
Ahn Hyo-Soo ; Seo Chee-Ho ;
Journal of the Korea Concrete Institute, volume 17, issue 3, 2005, Pages 313~322
DOI : 10.4334/JKCI.2005.17.3.313
Recently, as the remodeling market gradually substitute for new construction market and safety diagnosis for reconstruction apartment become a matter of principal Interest, it is demanded that scientific diagnosis and evaluation for existing concrete structure state. And it is increasing that the significance for reliability of data which is used for estimating the concrete compressive strength by nondestructive test. As a result, it is found that different proposal to material age and hitting angle is good to improving the reliability of presumption of concrete compressive strength in the linear hitting rebound test hammer. And for the reason that mutual relation between the compressive strength and rebound degree is highest in linear hitting rebound test hammer 25mm in all portion according to early md middle material age and hitting angle except the early material age
, analysis showed that linear hitting rebound test hammer is more reliable than existing schmidt hammer in presumption of concrete compressive strength.
A Study on the Priority Ranking Algorithm for Bridge Management at Network Level
Kim Kwang-Soo ; Kim Hyeong-Yeol ; Park Sun-Kyu ;
Journal of the Korea Concrete Institute, volume 17, issue 3, 2005, Pages 323~328
DOI : 10.4334/JKCI.2005.17.3.323
Bridge structures are properly designed in accordance with the design specifications with required safety margin. However, due to the heavy vehicle traffic and environmental attacks, bridge often requires repairs and the deteriorated one should be replaced or rehabilitated. In this paper, a prior ranking algorithm is proposed to assist a decision making process in bridge management at network level. Based on the literature survey for the existing studuies, two important factors which affect the decision making procedure for bridge management at network level are identified. These factors are implemented into the algorithm as a load carrying capacity function and traffic function, respectively.
Properties of Strength and Stress-Strain of Recycled-Plastic Polymer Concrete
Jo Byung-Wan ; Koo Jakap ; Park Seung-Kook ;
Journal of the Korea Concrete Institute, volume 17, issue 3, 2005, Pages 329~334
DOI : 10.4334/JKCI.2005.17.3.329
The use of Polymer Concrete (PC) is growing very rapidly in many structural and construction applications such as box culverts, hazardous waste containers, trench lines, floor drains and the repair and overlay of damaged cement concrete surfaces in pavements, bridges, etc. However, PC has a defect economically because resin which be used for binder is expensive. Therefore the latest research is being progressed to replace existing resin with new resin which can reduce the high cost. Here, Polymer concrete using the recycled PET(polyethylene terephthalate) has some merits such as decrease of environmental destruction, decrease of environmental pollution and development of new construction materials. The variables of this study are amount of resin, curing condition and maximum size of coarse aggregate to find out mechanic properties of this. Stress-strain curve was obtained using MTS equipment by strain control. The results indicated that modulus of elasticity was increased gradually in an ascending branch of curve, as an increase of resin content. Compressive strength was the highest for resin content of
. And Compressive strength was increased as maximum size of coarse aggregate increases. The strain at maximum stress increases with an increase of resin content and size of coarse aggregate. For the descending branch of stress-strain curve the brittle fracture was decreased when it was cured at the room temperature compared to high temperature.
Mechanical Characteristics of Recycled PET Polymer Concrete with Demolished Concrete Aggregates
Jo Byung-Wan ; Lee Du-Wha ; Park Seung-Kook ;
Journal of the Korea Concrete Institute, volume 17, issue 3, 2005, Pages 335~342
DOI : 10.4334/JKCI.2005.17.3.335
In this paper, fundamental properties of Polymer Concrete(PC), made from unsaturated polyester resin based on recycled PET and recycled aggregate were investigated. Mechanical properties include strength, modulus of elasticity, and chemical resistance. Resins based on recycled PET and recycled aggregate offer the possibility of low source cost for forming useful products, and would also help alleviate an environmental problem and save energy. The results of test for resin contents and recycled aggregate ratio we, first, the strength of Polymer Concrete made with resin based on recycled PET and recycled aggregate increases with resin contents relatively, however beyond a certain resin contents the strength does not change appreciably, Second, the relationship between the compressive strength and recycled aggregate ratio at resin
has a close correlation linearly whereas there is no correlation between the compressive strength and the flexural strength of RPC with recycled aggregate ratio. Third, the effect of acid resistance at resin
was found to be nearly unaffected by HCI, whereas the PC with
recycled aggregate showed poor acid resistance. Unlike acid, alkali nearly does not seem to attack the RPC as is evident from the weight change and compressive strength. And last, In case of stress-strain curve of polymer concrete with
of natural aggregate and
recycled aggregate it is observed the exceptional behavior resulting in different failure mechanisms of the material under compression.
Prediction of the Shear Strength of FRP Strengthened RC Beams (I) - Development and Evaluation of Shear strength model -
Sim Jong-Sung ; Oh Hong-Seob ; Moon Do-Young ; Park Kyung-Dong ;
Journal of the Korea Concrete Institute, volume 17, issue 3, 2005, Pages 343~351
DOI : 10.4334/JKCI.2005.17.3.343
This study developed a shear strength prediction model of FRP strengthened reinforced concrete beams in shear. The primary design parameters were shear crack angle and shear span to depth ratio of FRP reinforcement. Of primary concern In the suggested model was the FRP debonding failure, which Is a typical fracture mode of RC beams strengthened with FRP, The proposed model used a crack sliding model based on modified plasticity theory. To address the effect of the shear span to depth ratio, the arch action was considered in the proposed model. The proposed model was applied to RC beams strengthened with FRP. The results showed that the proposed model agree with test results.
Prediction of the Shear Strength of FRP Strengthened RC Beams (II) - Verification and parametric study -
Sim Jong-Sung ; Park Cheol-Woo ; Moon Do-Young ; Sim Jae-Won ;
Journal of the Korea Concrete Institute, volume 17, issue 3, 2005, Pages 353~359
DOI : 10.4334/JKCI.2005.17.3.353
To evaluate the proposed shear strength models developed in a companion paper, the shear strengths of test specimens strengthened with FRP were predicted by ACl specification, and elsewhere. The advantage and disadvantage of the models were investigated by the comparisons with the test results. The characteristics and limitations of the existing model were investigated with respect to FRP types, strengthening methods, shear span to depth ratio and effective strength of FRP. The results of this parametric study showed that the proposed shear strength model is more accurate than other models.
Development of Image Processing for Concrete Surface Cracks by Employing Enhanced Binarization and Shape Analysis Technique
Lee Bang-Yeon ; Kim Yun-Yong ; Kim Jin-Keun ;
Journal of the Korea Concrete Institute, volume 17, issue 3, 2005, Pages 361~368
DOI : 10.4334/JKCI.2005.17.3.361
This study proposes an algorithm for detection and analysis of cracks in digital image of concrete surface to automate the measurement process of crack characteristics such as width, length, and orientation based on image processing technique. The special features of algorithm are as follows: (1) application of morphology technique for shading correction, (2) improvement of detection performance based on enhanced binarization and shape analysis, (3) suggestion of calculation algorithms for width, length, and orientation. A MATLAB code was developed for the proposed algorithm, and then test was performed on crack images taken with digital camera to examine validity of the algorithm. Within the limited test in the present study, the proposed algorithm was revealed as accurately detecting and analyzing the cracks when compared to results obtained by a human and classical method.
A Technique for Pattern Recognition of Concrete Surface Cracks
Lee Bang-Yeon ; Park Yon-Dong ; Kim Jin-Keun ;
Journal of the Korea Concrete Institute, volume 17, issue 3, 2005, Pages 369~374
DOI : 10.4334/JKCI.2005.17.3.369
This study proposes a technique for the recognition of crack patterns, which includes horizontal, vertical, diagonal(
), and random cracks, based on image processing technique and artificial neural network. A MATLAB code was developed for the proposed image processing algorithm and artificial neural network. Features were determined using total projection technique, and the structure(no. of layers and hidden neurons) and weight of artificial neural network were determined by learning from artificial crack images. In this process, we adopted Bayesian regularization technique as a generalization method to eliminate overfitting Problem. Numerical tests were performed on thirty-eight crack images to examine validity of the algorithm. Within the limited tests in the present study, the proposed algorithm was revealed as accurately recognizing the crack patterns when compared to those classified by a human expert.
An Experimental Study on Bond Strength of High-Strength Reinforcing Bars with High Relative Rib Area
Hong Geon-Ho ; Choi Dong-Uk ; Choi Oan-Chul ; Hong Gi-Suop ;
Journal of the Korea Concrete Institute, volume 17, issue 3, 2005, Pages 375~384
DOI : 10.4334/JKCI.2005.17.3.375
The effects of bar deformation properties on bond of steel reinforcing bars to concrete are experimentally studied to predict the bond strength. Based on the previous research about high relative rib area, bond strength between reinforcing bars and concrete can be improved by the control of rib height and spacing. But, the equations in Korean code provisions to estimate development and splice length do not include these specifications of reinforcing bars. So the purpose of this paper is to determine the effect of relative rib area to the bond strength. This paper describes 2 kinds of experimental researches. Thirty beam-end specimens were tested to investigate the effects of bar size and relative rib areas ranging from 0.112 to 0.162. And, twelve lap-splice beam specimens were tested to the same variables. Each test results are normalized and compared with the proposed equations of ACI 408 committee. The results show that bond strength is increased as bar size and the relative rib area(Rr) increase. The distribution of flexural cracks and failure aspect do not appear to be affected by
An Experimental Study on the Durability of Recycled Aggregate Concrete
Seo Chi-Ho ; Kim Byung-Yun ;
Journal of the Korea Concrete Institute, volume 17, issue 3, 2005, Pages 385~392
DOI : 10.4334/JKCI.2005.17.3.385
The object of this study is to prove the quality and reliability of recycled aggregate concrete by finding a way to improve the durability of the material through the experiment on the accelerated carbonation, freezing and thaw, and drying shrinkage, analysing the influence on the durability to Promote more active use of recycled aggregate concrete. The result of study as follows. (1) Resistibility to the freeze and thaw of the recycled aggregate concrete showed relative dynamic modulus of elasticity over
which is very good, and all cycles show
dynamic modulus of elasticity which is improved compared with the
relative dynamic modulus of elasticity of ordinary concrete made of broken stone. (2) Carbonated thickness of the recycled aggregate concrete and the normal concrete was similar or it appeared with the tendency which it diminishes more or less. (3) Length change rate in drying contraction of the recycled aggregate concrete made of the recycled aggregate was lower than the ordinary concrete made of the broken stone by
in all blending.
Experiments on the Composite Action of Steel Encased Composite Column
Min Jin ; Jung In-Keun ; Shim Chang-Su ; Chung Young-Soo ;
Journal of the Korea Concrete Institute, volume 17, issue 3, 2005, Pages 393~400
DOI : 10.4334/JKCI.2005.17.3.393
Steel encased composite columns have been used for buildings and piers of bridges. Since the column section for the pier is relatively larger than that of building columns, economical steel ratio needs to be investigated for the required performance. Composite action between concrete and embedded steel sections can be obtained by bond and friction. However, the behavior of the column depends on the load introduction mechanism. Compression can be applied to concrete section, steel section and composite section. In this paper, experiments on shear strength of the steel encased composite column were performed to study the effect of confinement by transverse reinforcements, mechanical interlock by holes, and shear connectors. Bond strength obtained from the tests showed considerably higher value than the design value. Confinement, mechanical interlock and stud connectors Increased the shear strength and these values can be used effectively to obtain composite action of Steel Reinforced Concrete(SRC) columns.
Flexural and Shear Behavior of Reinforced Dual Concrete Beam
Park Tae-Hyo ; Park Jae-Min ; Kim Hee-Dae ;
Journal of the Korea Concrete Institute, volume 17, issue 3, 2005, Pages 401~409
DOI : 10.4334/JKCI.2005.17.3.401
In this study, reinforced dual concrete beam (RDC beam) composed of steel fiber reinforced concrete (SFRC) in the tension part and normal strength concrete (NSC) in the compression and remaining part is proposed. It is the epochal structural system that improves the overall structural performances of beam by partially superseding the steel fiber reinforced concrete in the lower tension part of conventional reinforced concrete beam (RC beam). Flexural and shear tests are performed to prove the structural excellence of RDC beam in comparison with RC beam. An analytical method is proposed to understand the flexrual behavior and is compared to experimental results. And for shear behavior, experimental results are compared to empirical equations predicting the ultimate shear strength of full-depth fiber reinforced concrete beam to examine the behavior of RDC beam under shear. From this studies, it is proved that RDC beam has more superior structural performance than RC beam, and the analytical method for flexural behavior agrees well with experimental results, and the partial-depth fiber reinforcements have no noticeable effect on ultimate shear strength but it is considerably effective to control and prevent evolutions of crack.
Durability of Polymer-Modified Mortars Using Acrylic Latexes with Methyl Methacrylate
Hyung Won-Gil ; Kim Wan-Ki ; Soh Yang-Seob ;
Journal of the Korea Concrete Institute, volume 17, issue 3, 2005, Pages 411~418
DOI : 10.4334/JKCI.2005.17.3.411
Polymer-modified mortar and concrete are prepared by mixing either a polymer or monomer in a dispersed, or liquid form with fresh cement mortar and concrete mixtures, and subsequently curing, and if necessary, the monomer contained in the mortar or concrete is polymerized in situ. Although polymers and monomers in any form such as latexes, water-soluble polymers, liquid resins, and monomers are used in cement composites such as mortar and concrete, it is very important that both cement hydration and polymer phase formation proceed well the yield a monolithic matrix phase with a network structure in which the hydrated cement phase and polymer phase interpenetrate. In the polymer-modified mortar and concrete structures, aggregates are bound by such a co-matrix phase, resulting in the superior properties of polymer-modified mortar and concrete compared to conventional mortar and concrete. The purpose of this study is to obtain the necessary basic data to develope appropriate latexes as cement modifiers, and to clarify the effects of the monomer ratios and amount of emulsifier on the properties of the polymer-modified mortars using methyl methacrylate-butyl acrylate(MMA/BA) and methyl methacrylate-ethyl acrylate(MMA/EA) latexes. The results of this study are as follows, the water absorption, chloride ion penetration depth and carbonation depth of MMA/BA-modified mortar are lowest. However, they are greatly affected by the polymer-cement ratio rather than the bound MMA content and type of polymer.
A Modified Equivalent Frame Model for Plat Plate Slabs Under Lateral Loads
Han Sang-Whan ; Park Young-Mi ;
Journal of the Korea Concrete Institute, volume 17, issue 3, 2005, Pages 419~426
DOI : 10.4334/JKCI.2005.17.3.419
This study is to propose a modified equivalent frame model for flat plate slabs under lateral loads. ACI 318 (2002) allows equivalent frame methods to conduct two-way slab system analysis subjected to gravity loads as well as lateral loads. Since the equivalent frame method in the ACI 318 (2002) has been developed base on the behavior of two-way system for gravity loads, and nay not predict the behavior of flat plate slabs under lateral loads with good precision. This study develops a modified equivalent frame model which can give more precise answer for flat plate slabs under lateral loads. This model reflects the actual force transfer mechanism among the components of flat plate slab system, which are slabs, columns and torsional members, more accurately under lateral loads than existing equivalent frame models. The accuracy of this model is verified by comparing the analysis results using the proposed model with the results of finite element analysis. The analysis results of other existing models are included in the comparison. For this purpose, 2 story building having 3 spans in both directions is considered. Analytical results show that the modified equivalent frame model produces comparable drift and slab internal moments with those obtained from finite element analysis.
Setting Time, Strength and Rebound Rate of Shotcrete according In Accelerators
Lee Seong-Haeng ; Kim Yong-Ha ; Hahm Hyung-Gil ; Kim Kwan-Jin ;
Journal of the Korea Concrete Institute, volume 17, issue 3, 2005, Pages 427~434
DOI : 10.4334/JKCI.2005.17.3.427
An experimental investigation was carried out in order to verify the compressive strength, flexural strength, equivalent bending strength, rebound rate of shotcrete according to silicate accelerator, aluminate accelerator, cement mineral accelerator respectively and to especially evaluate the performance of shotcrete using cement mineral accelerator for high quality. The test result of compressive strength was showed that all accelerators were satisfied the required test value for each age, for the requirement of having the
or higher compressive strength ratio to plain concretes at 28 days, cement mineral accelerator with
compressive strength ratio was only satisfied. In flexural strength test, cement mineral accelerator was satisfied the flexural strength requirement in steel fiber reinforced shotcrete for each age. Aluminate type was conformed to the requirement for 28 days, but not at 1 day, silicate type was failed to satisfy standard requirement. Rebound rate was measured between
and cement mineral accelerator was showed comparatively lower rebound rate. Based on the test results, cement mineral accelerator exhibited excellent strength improvement and lower rebound rate compared to the conventional accelerator, its result is showed the possibility of making high performance shotcrete.
Shear Behavior Prediction of Reinforced Concrete Columns Using Transformation Angle Truss Model
Kim Sang-Woo ; Chai Hyee-Dae ; Lee Jung-Yoon ; Lee Bum-Sik ;
Journal of the Korea Concrete Institute, volume 17, issue 3, 2005, Pages 435~444
DOI : 10.4334/JKCI.2005.17.3.435
This paper predicted the shear behavior of reinforced concrete columns using Transformation Angle Truss Model (TATM) considered the effects of bending moment and axial force. Nine columns with various shear span- to-depth ratios and axial force ratios were tested to verify the theoretical results obtained from TATM. Fine linear displacement transducers (LVDT) were attached to a side of the column near the shear critical region to measure the curvature, the longitudinal and transverse axial deformations, and the shear deformation of the column. The test was terminated when the value of the applied load dropped to about
of the maximum-recorded load in the post-peak descending branch. All the columns were failed in shear before yielding of the flexural steel. The shear strength and the stiffness of the columns increased, as the axial force increased and the shear span-to-depth ratio decreased. Shear stress-shear strain and shear stress-strain of shear reinforcement curves obtained from TATM were agreed well with the test results in comparison to other truss models (MCFT, RA-STM, and FA-STM).
Flexural Behavior of Prestressed Dual Concrete Beams
Park Tae-Hyo ; Yun Sung-Hwan ; Yun Hee-Dae ;
Journal of the Korea Concrete Institute, volume 17, issue 3, 2005, Pages 445~454
DOI : 10.4334/JKCI.2005.17.3.445
Cracks due to low tensile strength in prestressed concrete (PC) beams may decrease rigidity and structural performance, resulting in excessive deflection. In an effort to solve this problem, in this research, prestressed dual concrete (PDC) has been proposed, consisting of normal strength concrete in compression zone, and high performance steel fiber reinforced concrete(HPSFRC) with a partial depth in tensile zone. Three PDC beams with different depths of HPSFRC and two PC beams were cast for experiments. Analytical models at each stage, i.e., precracking, postcracking, and ultimate, were proposed for analysis of flexural behavior in PDC beams. The experimental results agree well to the analytical ones. Crack formation and its propagation are controlled by the HPSFRC in PDC beams. The initial cracking and service limit loads are increased along with the load carrying capacity and flexural stiffness.
Freezing and Thawing Resistance and fundamental Properties of Antiwashout Underwater Concrete Containing Mineral Admixtures
Moon HanYoung ; Shin Kook-Jae ; Song Yong-Kyu ;
Journal of the Korea Concrete Institute, volume 17, issue 3, 2005, Pages 455~464
DOI : 10.4334/JKCI.2005.17.3.455
Today the application of antiwashout underwater concrete to the construction sites is increasing steadily, while its reliability is in issue. Particularly, antiwashout underwater concrete is known to have very weak durability on frost attack, and hence Japan society of civil engineers(JSCE) regulated that not to use of antiwashout underwater concrete where the freezing and thawing is suspected. This study aims the improvement of the freezing and thawing resistance for antiwashout underwater concrete. From the results of fundamental test, FA20 and SG50 showed good performance in fluidity and long term compressive strength than control concrete. Meanwhile, MK10 marked the highest compressive strength through the whole curing age but a defect on fluidity was discovered. The results from the repeated freezing and thawing test show that the large volumes of air entrapped by cellulose based antiwashout underwater admixture gave bad effects to frost durability and hence not much benefits were confirmed from the use of mineral admixtures. However there were some increasing effects on frost durability of MK10 and SG50 by securing
of entraining air. In the meantime, there was a increasing tendency of frost durability by increasing blame's fineness of ground granulated blast furnace slag.
Mechanical Properties and Durability of Asphalt Emulsion-Modified Cement Mortars
Song Hun ; Do Jeong-Yun ; Soh Yang-Seob ;
Journal of the Korea Concrete Institute, volume 17, issue 3, 2005, Pages 467~472
DOI : 10.4334/JKCI.2005.17.3.467
Asphalt emulsion is manufactured by the emulsification of asphalt, and is considered as an energy-saving, ecologically safe material because it does not need any heating processes with gas emission and fire hazard in its use. This study is concerned with evaluating the feasibility of the use of an asphalt emulsion as a poly-meric admixture. Asphalt-modified mortars using an experimentally manufactured asphalt emulsion were prepared with various polymer-cement ratios, and tested far the mechanical properties such as strengths and adhesion and the properties related to durability such as water absorption, permeation, carbonation and chloride ion penetration. As a result, the waterproofness, carbonation resistance and chloride ion penetration resistance of the asphalt-modified mortars were markedly improved with an increase in the polymer-cement ratio, but their compressive strength and adhesion to mortar substrates were reduced with increasing polymer-cement ratio. Therefore, it is recommended to control their polymer-cement ratio to be
or lower in their practical applications. Further study to improve their compressive strength and adhesion is needed.
Optimal Mixture Proportion for High Performance Concrete Incorporating Ground Granulated Blast furnace Slag
Choi Jae-Jin ; Kim Eun-Kyum ; Yoo Jung-Hoon ;
Journal of the Korea Concrete Institute, volume 17, issue 3, 2005, Pages 473~480
DOI : 10.4334/JKCI.2005.17.3.473
In this study, a mix design for self compacting concrete was based on Okamura's method and concrete incorporated just a ground granulated blast furnace slag. Replacement ratio of slag is in the range of
of cement matrix by volume. For the optimal self compactability in mixture incorporating ground granulated blast furnace slag, the paste and mortar tests were first completed. Then the slump flow, elapsed time of 500mm slump flow, V funnel time and filling height by U type box were conducted in concrete. The volume of coarse aggregate in self compacting concrete was in the range of
to the solid volume percentage of coarse aggregate. Finally, the compressive and splitting tensile strengths were determined in the hardened self compacting concrete incorporating ground granulated blast furnace slag. From the test results, it is desirable for self compacting concrete that the replacement of ground granulated blast furnace slag is in the range of
of cement matrix by volume and the volume of coarse aggregate to the solid volume percentage of coarse aggregate with a limit of
Distribution of Calcium Hydroxide at the ITZ between Steel and Concrete
Ann Ki-Yong ; Kim Hong-Sam ; Kim Yang-Bae ; Moon Han-Young ;
Journal of the Korea Concrete Institute, volume 17, issue 3, 2005, Pages 481~485
DOI : 10.4334/JKCI.2005.17.3.481
The present study examines the distribution of calcium hydroxide, unhydrated cement grain and porosity at the steel-concrete interface. The formation of calcium hydroxide has been confirmed by microscopic analysis using BSE images containing the ITZ between the steel and concrete. It was found that calcium hydroxide does not form a layer on the steel surface, different from the hypothesis that has been available in investigating the corrosion of steel in concrete, ranging from 5 to
within the steel surface. Moreover, the high level of porosity at the ITZ was observed, accounting for
, which may reduce the buffering capacity of cement hydration products against a local fall in the pH. These findings may imply that the mole of (
) in pore solution as chloride threshold level lead to wrong judgement or to a wide range of values.