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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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Korea Concrete Institute
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Volume & Issues
Volume 25, Issue 6 - Dec 2013
Volume 25, Issue 5 - Oct 2013
Volume 25, Issue 4 - Aug 2013
Volume 25, Issue 3 - Jun 2013
Volume 25, Issue 2 - Apr 2013
Volume 25, Issue 1 - Feb 2013
Selecting the target year
Emission in the Process of Cement Manufacture Depending on CaO Content
Kim, Sang-Hyo ; Hwang, Jun-Pil ;
Journal of the Korea Concrete Institute, volume 25, issue 4, 2013, Pages 365~370
DOI : 10.4334/JKCI.2013.25.4.365
In this study, contents of limestone in cement manufactured by six domestic plants for Portland cement were investigated in terms of the strength and its relation to the
emission due to limestone material and its physical properties in cement manufacturing process. the relationship among CaO content, compressive strength, and
emission was surveyed for the limestone quantity in decomposition reaction and the loss of limestone quantity contained in each cement. As a result of
emission calculation for unit cement, it was found that the
emission due to decomposition of limestone was occupied 67% of total emission quantity. Furthermore, there was a difference in
emission quantity depending on the cement manufacturing process management. Also, it was shown that fossil fuel usage and material loss had a major influence as main factors of
emission. An increase in the CaO content in cement resulted in an increase in the compressive strength. On the contrary, CaO content and compressive strength were reduced with the growth of loss quantity of limestone. It was verified that the material and process management were more effective than CaO yield in cement manufacturing for
emission with the growth of
emission quantity. Pozzolanic materials such as PFA and GGBS in concrete mix affected the price,
emission and development of strength of concrete.
Tension-Stiffening and Cracking Behavior of 100 MPa Shrinkage-Compensated Ultra High-Strength Strain-Hardening Cement Composite (UHS-SHCC) Ties
Song, Young-Jae ; Yun, Hyun-Do ;
Journal of the Korea Concrete Institute, volume 25, issue 4, 2013, Pages 371~379
DOI : 10.4334/JKCI.2013.25.4.371
This paper investigates the cracking and tension-stiffening behavior of 100 MPa shrinkage-compensated strain-hardening cement composite (SHCC) and conventional concrete tie elements in monotonic and cyclic tension. Strain and surface crack formation of tension ties were monitored with two strain displacement transducers and a photo microscope with a lens of magnification 50 times. Three different cement composites such as conventional concrete, shrinkage-compensated SHCC, and normal SHCC were used in the tie specimens to investigate the influence of the cement composite type on the tension stiffening and cracking behavior. Test results indicated that initial shrinkage of the ultra high-strength cement composites is greatly reduced as the 10% replacement of cement by the shrinkage-compensating admixture based on calcium sulfo-aluminate (CSA). The test results on the SHCC tension ties showed that the first cracking load decreases proportionally to the initial shrinkage strain. Reinforced ultra high-strength SHCC ties with the initial shrinkage compensation exhibited improved tension stiffening and smaller crack spacings, i.e. the reduction in crack width. Cyclic loading did not have a significant effect on tension stiffening and cracking behavior of tension ties with normal concrete and SHCC materials.
A Study on Effect of Anchor Plate on Concrete Breakout Capacity and Elasticity-Based Analysis Model of Anchor Plate
Shin, Ji-Uk ; You, Young-Chan ; Choi, Ki-Seon ; Kim, Ho-Ryong ; Kim, Jun-Hee ;
Journal of the Korea Concrete Institute, volume 25, issue 4, 2013, Pages 381~388
DOI : 10.4334/JKCI.2013.25.4.381
This study presents that effect of anchor plate on concrete breakout strength was evaluated. The addition of the anchor plate is to improve the concrete breakout capacity for a single anchor system in a thin-walled concrete panel (Insulated concrete sandwich wall panel). In this study, an elasticity-based simplified model was developed and used to predict effect on the anchor plate. Flexural stresses of the plate with respect to the concrete breakout strength obtained from CCD (Capacity Concrete Design) approach were compared with the test results. Through the test results, while the concrete breakout strength was improved due to increment of the width and thickness of the anchor plate, improvement of the strength was steadily declined. In addition, the It was observed that the analytical and experimental flexure of the anchor plate was comparatively in good agreement using the simplified elastic analysis model.
A Study on the Shear Behavior of Recycled Aggregate Reinforced Concrete Beams without Stirrups
Lee, Jung-Hoon ; Kim, Woo-Suk ; Baek, Seung-Min ; Kang, Thomas H.K. ; Kwak, Yoon-Keun ;
Journal of the Korea Concrete Institute, volume 25, issue 4, 2013, Pages 389~400
DOI : 10.4334/JKCI.2013.25.4.389
Little investigations have been carried out to study the shear behaviors of RC beams with recycled aggregates. So, this experiment investigates the shear performance and suggests the possible application of Recycled Concrete Aggregate (RCA) for building structures. In general, shear strength of reinforced concrete beam without stirrups is dependent on the compressive strength of concrete, the longitudinal steel ratio, and the shear span-to-depth ratio. In this study, total 28 recycled aggregate concrete beams without shear reinforcement were tested by two-point load and all beams were singly reinforced. The variables studied in this investigation are shear span-to-depth ratios (a/d=2, 3 and 4), RCA replacement ratios (0, 15, 30 and 50%) and longitudinal steel ratios (0.80, 1.27 and 1.84%). The designed concrete compressive strength with a 30 MPa is used. This research will play an important role toward the establishment of the structural design standard for RCA concrete.
Hydrodynamic Motion and Structural Performance of Concrete Floating Structure by Length Using Numerical Analysis
Lee, Du-Ho ; You, Young-Jun ;
Journal of the Korea Concrete Institute, volume 25, issue 4, 2013, Pages 401~409
DOI : 10.4334/JKCI.2013.25.4.401
In the present study, numerical analysis was performed for hydrodynamic motion and structural performance on four different concrete floating structures, which have same cross-section but different length. The hydrodynamic analysis of floating structures is carried out using ANSYS AQWA with the different 34 wave load on regular wave period from three seconds to ten seconds in 35 m water depth. In order to evaluate structural performance of floating structures under the critical wave load which obtained from hydrodynamic analysis. The integrated analysis is also carried out through the mapping method, which can directly connect the wave-induced hydraulic pressure obtained form ANSYS AQWA to Finite Element Model in ANSYS Mechanical. As a results of this study, the hydrodynamic motion of floating structures is decreased as the length of structure increased. It means that the effect of wave-structure interaction is strongly dependent on the relationship between a wave period and a length of structure. Moreover, it is found that tension stress on bottom slab of floating structure is occurred by the critical wave load, the sectional force is not influenced by length of a structure.
A Comparative Study on Strength Development, Chloride Diffusivity and Adiabatic Temperature Rise of Marine Concrete Depending on Binder Type
Bae, Jun-Young ; Cho, Sung-Hyun ; Shin, Kyung-Joon ; Kim, Yun-Yong ;
Journal of the Korea Concrete Institute, volume 25, issue 4, 2013, Pages 411~418
DOI : 10.4334/JKCI.2013.25.4.411
Recently, in order to reduce a damage of chloride attack and hydration heat in marine concrete structures, blended cement in mixing the marine concrete is widely used. Long term strength development is distinct in concrete with blended cement and it also has excellent resistance to chloride attack and reduction of hydration heat. However, blended cement has a characteristic of relatively low compressive strength in early age of 28 days. On the other hand, a high level of compressive strength is required in the Standard Specification for marine concrete mix design. Such concrete mix design satisfying Standard Specification is effective to chloride attack but disadvantageous for hydration heat reduction due to large quantity of binder. In this study, the material properties of marine concrete considering water-binder ratio and binder type are experimentally investigated. Through the research results, compressive strength in blended cement at the age of 56 days is similar although it has smaller compressive strength at the age of 28 days compared with result of OPC (ordinary portland cement). Even though blended cement has a large water-binder ratio and small unit of binder content, chloride ion diffusion coefficient is still small and hydration heat is also found to be reduced. For meeting the required compressive strength in Standard Specification for marine concrete at 28 days, the increased unit content of binder is needed but the increased hydration heat is also expected.
Evaluation of Seismic Performance of High Strength Reinforced Concrete Exterior Beam-Column Joints Using High Ductile Fiber-Reinforced Mortar
Ha, Gee-Joo ; Shin, Jong-Hak ;
Journal of the Korea Concrete Institute, volume 25, issue 4, 2013, Pages 419~428
DOI : 10.4334/JKCI.2013.25.4.419
In this study, experimental research was carried out to evaluate the constructability and seismic performance of high strength R/C exterior beam-column joints regions, with or without the shear reinforcement, using high ductile fiber-reinforced mortar. Five specimens of retrofitted the exterior beam-column joint regions using high ductile fiber-reinforced mortar are constructed and tested for their retrofit performances. Specimens designed by retrofitting the exterior beam-column joint regions (BCJNSP series) of existing reinforced concrete building showed a stable mode of failure and an increased its maximum load-carrying capacity by 1.09~2.03 times in comparison with specimen of BCJNS due to the effect of enhancing dispersion of crack control at the time of initial loading and bridging of fiber from retrofitting new high ductile materials during testing. Specimens of BCJNSP series attained its maximum load carrying capacity by 0.92~0.96 times and increased its energy dissipation capacity by 1.62 times when compared to standard specimen of BCJC with a displacement ductility of 4.
Numerical Evaluation of Stress Loss Rates and Adjusting Coefficients due to Internal and External Constraints of Concrete Long-Term Deformation
Yon, Jung-Heum ; Kim, Hyun-Jin ;
Journal of the Korea Concrete Institute, volume 25, issue 4, 2013, Pages 429~438
DOI : 10.4334/JKCI.2013.25.4.429
An object oriented numerical analysis program of axial-flexural elements and the step-by-step method (SSM) has been developed to analyze concrete long-term behaviors of structures constrained internally and externally. The results of the numerical analysis for simple and continuous prestressed (PS) concrete box and composite girders, pre-cast slab of continuous steel composite girder, and simple preflex composite girder show that the adjusting coefficient decreases by increasing constraint. The loss rates of pre-tension force were not sensitive but those of pre-compression force were increased rapidly by decreasing adjusting coefficient. This indicates that the design based on the loss rate of pre-tension can over-estimate the pre-compression force in a concrete section constrained internally and externally. The adjusting coefficients which satisfy results of the numerical analysis are 0.35~0.95, and it can be used as an index of constraint of concrete long-term deformation. The adjusting coefficient 0.5 of Bridge Design Specifications can under-estimate residual stress of PS concrete slab, and the coefficient 0.7 or 0.8 of LRFD Bridge Designing Specifications can under-estimate the loss rates of continuous PS concrete girders. The adjusting coefficient of hybrid structures should be less then 0.4.
Effect of Substituting Normal-Weight Coarse Aggregate on the Workability and Mechanical Properties of Heavyweight Magnetite Concrete
Mun, Jae-Sung ; Mun, Ju-Hyun ; Yang, Keun-Hyeok ; Lee, Ho ;
Journal of the Korea Concrete Institute, volume 25, issue 4, 2013, Pages 439~446
DOI : 10.4334/JKCI.2013.25.4.439
The objective of this study is to evaluate the workability and various mechanical properties of heavyweight magnetite concrete and examine the reliability of the design equations specified in code provisions. The main parameters investigated were the water-to-cement ratio and substitution level of normal-weight coarse aggregate (granite) for magnetite. The oven-dried unit weight of concrete tested ranged between 2446 and
. The measured mechanical properties included compressive strength development, stress-strain curve, splitting tensile strength, moduli of elasticity and rupture, and bond stress-slip relationship of concrete. Test results revealed that the initial slump of heavyweight magnetite concrete increased as the substitution level of normal-weight coarse aggregate increases. The substitution level of normal-weight coarse aggregate had little influence on the compressive strength and tensile resistance capacity of heavyweight concrete, while it significantly affected the modulus of elasticity and stress-strain curves of such concrete. The design equations of ACI 349-06 and CEB-FIP provisions mostly conservatively predicted the mechanical properties of heavyweight magnetite concrete, but the empirical equations for modulus of elasticity and splitting tensile strength need to be modified considering the unit weight of concrete.
Experimental Studies and Detailing Suggestion for Reinforced Concrete Slabs with Steps
Kim, Sang-Hee ; Hong, Geon-Ho ; Park, Hong-Gun ; Han, Kyoo-Beom ; Kang, Thomas H.K. ;
Journal of the Korea Concrete Institute, volume 25, issue 4, 2013, Pages 447~455
DOI : 10.4334/JKCI.2013.25.4.447
In this study, reinforced concrete slabs with steps were experimentally studied to analyze their structural performance and to suggest reinforcing details in the step. Because the stepped slabs may behave very poorly in terms of bending strength, stiffness, deflection, cracking, etc., the study is aimed to suggest proper reinforcing details such that the same bending strength is obtained as that without steps. The bending strengths of 12 test specimens with a variety of different reinforcing detail types or other parameters were compared with each other. The specimen without any additional reinforcement in the step had a very low bending strength and significant damage, and the specimens with diagonal reinforcements in the step showed substantial early cracks, experienced hinging of the step, and had a substantial loss of the bending strength. In contrast, the specimens with a combination of U-bars, reversed U-bars, L-bars, and reversed L-bars performed very well and almost reached to 100% of the slab bending strength. The U-bars and reversed U-bars were effective in controling the diagonal cracks, while the L-bars and reversed L-bars were effective in preventing from yielding of slab reinforcement near the step.
Influence of Mixtures and Curing Conditions on Strength and Microstructure of Reactive Powder Concrete Using Ternary Pozzolanic Materials
Janchivdorj, Khulgadai ; Choi, Seung-Hoon ; So, Hyoung-Seok ; Seo, Ki-Seog ; So, Seung-Young ;
Journal of the Korea Concrete Institute, volume 25, issue 4, 2013, Pages 457~465
DOI : 10.4334/JKCI.2013.25.4.457
This study discussed the influence of mixtures and curing conditions on the development of strength and microstructure of RPC using ternary pozzolanic materials. Through pilot experiment, various RPC was manufactured by adding single or mixed ternary pozzolanic materials such as silica fume, blast furnace slag and fly ash by mass of cement, up to 0~65%, and cured by using 4 types of method which are water and air-dried curing at
, steam and hot-water curing at
. The results show that the use of ternary pozzolanic materials and a suitable curing method are an effective method for improving development of strength and microstructure of RPC. The unit volume of cement was greatly reduced in RPC with ternary pozzolanic materials and unlike hydration reaction in cement, the pozzolanic reaction noticeably contributes to a reduction in hydration heat and dry shrinkage. A considerable improvement was found in the flexural strength of RPC using ternary pozzolanic materials, and then the utilization of a structural member subjected to bending was expected. The X-ray diffractometer (XRD) analysis and Scanning Electronic Microscope (SEM) revealed that the microstructure of RPC was denser by using the ternary pozzolanic materials than the original RPC containing silica fume only.