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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 27, Issue 6 - Dec 2015
Volume 27, Issue 5 - Oct 2015
Volume 27, Issue 4 - Aug 2015
Volume 27, Issue 3 - Jun 2015
Volume 27, Issue 2 - Apr 2015
Volume 27, Issue 1 - Feb 2015
Selecting the target year
Correlation between Mix Proportion and Mechanical Characteristics of Steel Fiber Reinforced Concrete
Choi, Hyun-Ki ; Bae, Baek-Il ; Koo, Hae-Shik ;
Journal of the Korea Concrete Institute, volume 27, issue 4, 2015, Pages 331~341
DOI : 10.4334/JKCI.2015.27.4.331
The main purpose of this study is reducing the cost and effort for characterization of tensile strength of fiber reinforced concrete, in order to use in structural design. For this purpose, in this study, test for fiber reinforced concrete was carried out. Because fiber reinforced concrete is consisted of diverse material, it is hard to define the correlation between mix proportions and strength. Therefore, compressive strength test and tensile strength test were carried out for the range of smaller than 100 MPa of compressive strength and 0.25~1% of steel fiber volume fraction. as a results of test, two types of tensile strength were highly affected by compressive strength of concrete. However, increase rate of tensile strength was decreased with increase of compressive strength. Increase rate of tensile strength was decreased with increase of fiber volume fraction. Database was constructed using previous research data. Because estimation equations for tensile strength of fiber reinforced concrete should be multiple variable function, linear regression is hard to apply. Therefore, in this study, we decided to use the ANN(Artificial Neural Network). ANN was constructed using multiple layer perceptron architecture. Sigmoid function was used as transfer function and back propagation training method was used. As a results of prediction using artificial neural network, predicted values of test data and previous research which was randomly selected were well agreed with each other. And the main effective parameters are water-cement ratio and fiber volume fraction.
Durability Performance Evaluation On Early-Aged Concrete with Rice Husk Ash and Silica Fume
Saraswathy, Velu ; Kwon, Seung-Jun ;
Journal of the Korea Concrete Institute, volume 27, issue 4, 2015, Pages 343~351
DOI : 10.4334/JKCI.2015.27.4.343
Currently, lots of researches have been performed for reducing cement usages due to increasing social/engineering problems caused by
emission. Supplementary cement materials like fly ash, slag, and silca fume are usually employed for cement replacement, and nowadays rice husk ash (RHA) is widely studied for enhancement of concrete performance as mineral admixture. In this paper, concrete samples with RHA and SF which is known for its engineering advantages are prepared and a resistance to chloride attack is evaluated in early-aged concrete. For the work, replacement ratios of 10~30% for RHA concrete and 2~8% for SF concrete are considered, and various durability tests such as density, void, sorptivity, current measurement, and chloride diffusion coefficient are performed including mechanical test like compressive and tensile strength. Replacement of RHA 10~15% shows better improvement of corrosion resistance and strength than that of SF 2~4% and normal concrete, which shows a strong applicability for utilization as construction materials.
Seismic Performance of PC Moment Frame with Plastic Shear Hinge
Lim, Woo-Young ; Hong, Sung-Gul ;
Journal of the Korea Concrete Institute, volume 27, issue 4, 2015, Pages 353~362
DOI : 10.4334/JKCI.2015.27.4.353
Cyclic loading tests for the PC moment frame with plastic shear hinges were performed to evaluate the seismic performance. The plastic shear hinges consisted of two steel plates were installed at the mid-length of the beam to connect the PC frames. Three shear links are existed in each steel plate. The three shear links were designed using shear force corresponding to the shear capacity of 50%, 75%, and 100% of the beam shear capacity. The proposed connections showed an efficient energy dissipation capacity and good structural performance. As a result, it is reasonable to design the plastic shear hinges using design shear capacity less than 100% of the beam shear capacity.
Effect of Different Energy Frames on the Impact Velocity of Strain Energy Frame Impact Machine
PARK, Seung Hun ; PARK, Jun Kil ; TRAN, Tuan Kiet ; KIM, Dong Joo ;
Journal of the Korea Concrete Institute, volume 27, issue 4, 2015, Pages 363~375
DOI : 10.4334/JKCI.2015.27.4.363
This research investigated the effects of diameter and material of energy frame on the impact velocity or strain rate of Strain Energy Frame Impact Machine (SEFIM). The impact speed of SEFIM have been clearly affected by changing the diameter and material of the energy frame. The reduced diameter of the energy frame clearly increased the impact velocity owing to the higher strain at the moment of coupler breakage. And, titanium alloy energy frame produced the fastest speed of impact among three materials including steel, aluminum and titanium alloys because titanium alloy has faster wave velocity than steel. But, aluminium energy frame was broken during impact tests. In addition, the tensile stress versus strain response of high performance fiber reinforced cementitious composites at higher and wider strain rates between 10 and 72 /sec was successfully obtained by using four different energy frames.
Analysis of Lateral Behavior of PSC Bridge Girders under Wind Load During Construction
Lee, Jong-Han ; Kim, Kyung Hwan ; Cho, Baiksoon ;
Journal of the Korea Concrete Institute, volume 27, issue 4, 2015, Pages 377~385
DOI : 10.4334/JKCI.2015.27.4.377
The span-lengthening of PSC I girder has increased the risk of lateral instability of the girder with the increases in the aspect ratio and self-weight of the girder. Recently, collapses of PSC I girder during construction raise the necessity of evaluating the lateral instability of the girder. Thus, the present study evaluated the lateral behavior and instability of PSC I girders under wind load, regarded as one of the main causes of the roll-over collapse during construction. Lateral instability of the girder is mainly dependent on the length of the girder and the stiffness of the support. The analysis results of this study showed the decrease in the critical wind load and the increase in the critical deformation and angle of the girder, leading to the lateral instability of the girder. Finally, this study proposed analytical equations that can predict the critical amount of wind load and lateral deformation of the girder, which would provide quantitative management values to maintain lateral stability of PSC I girder during construction.
Flexural Performance and Cracking Resistance of Continuous Composite Slab using Micro Steel Fibers
Hwang, Hyeon-Jong ; Park, Hong-Gun ; Hong, Geon-Ho ; Kim, Gap-Deug ; Choi, Se-Jin ;
Journal of the Korea Concrete Institute, volume 27, issue 4, 2015, Pages 387~397
DOI : 10.4334/JKCI.2015.27.4.387
In the present study, to enhance the constructability, a composite slab system using deck plate and micro steel fiber concrete was studied. In the proposed slab system, on-situ re-bar placement is not required. Steel fibers replace the temperature reinforcement. The present study focused on the crack control at the slab top in the continuous composite slab without spliced bars. Eight continuous slabs with various parameters were tested under vertical loading. The test parameters were the amount and types of micro steel fibers, types of deck plate, and the use of top bars in the continuous slab. To evaluate the crack resistance of the slabs, crack widths were measured in the continuous slabs. The test results showed that although the top spliced bars were not used, cracking were restrained by large flexural stiffness of the composite sections.
Shear Strength of Prestressed PC-CIP Composite Beams with Vertical Shear Reinforcement
Suh, Jung-Il ; Park, Hong-Gun ; Hong, Geon-Ho ; Kang, Su-Min ; Kim, Chul-Goo ;
Journal of the Korea Concrete Institute, volume 27, issue 4, 2015, Pages 399~409
DOI : 10.4334/JKCI.2015.27.4.399
Recently, the use of composite construction method using precast (PC) and cast-in-place (CIP) concrete is increased in modular construction. For PC members, pre-tensioning is used to improve efficiency of the structural performance. However, current design codes do not clearly define shear strength of prestressed PC-CIP composite members. In this study, 22 specimens were tested to evaluate shear strength of prestressed composite members with vertical shear reinforcement. The test variables were the area ratio of high-strength (60 MPa) to low-strength concrete (24 MPa), prestressing force of strands, shear span-to-depth ratio(a/d), and vertical shear reinforcement ratio. The test results showed the prestressing force did not completely restrain diagonal cracking of non-prestressed concrete in the web. Thus, the effect of prestress force was not insignificant in the effect for monolithic beams. The vertical shear strength and horizontal shear strength of the composite beams were compared with the strength predictions of KCI design method.
Face Damage Characteristic of Steel Fiber-Reinforced Concrete Panels under High-Velocity Globular Projectile Impact
Jang, Seok-Joon ; Son, Seok-Kwon ; Kim, Yong-Hwan ; Kim, Gyu-Yong ; Yun, Hyun-Do ;
Journal of the Korea Concrete Institute, volume 27, issue 4, 2015, Pages 411~418
DOI : 10.4334/JKCI.2015.27.4.411
This paper investigates the effects of fiber volume fraction and panel thickness on face damage characteristics of steel fiber-reinforced concrete (SFRC) under high-velocity globular projectile impact. The target specimens were prepared with
prismatic panels with thickness of 30 or 50 mm. All panels were subjected to the impact of a steel projectile with a diameter of 20 mm and velocity of 350 m/s. Specifically, this paper explores the correlation between mechanical properties and face damage characteristics of SFRC panels with different fiber volume fraction and panel thickness. The mechanical properties of SFRC considered in this study included compressive strength, modulus of rupture, and toughness. Test results indicated that the addition of steel fiber significantly improve the impact resistance of conventional concrete panel. The front face damage of SFRC panels decreased with increasing the compressive toughness and rear face damage decreased as the modulus of rupture and flexural toughness increased. To evaluate the damage response of SFRC panels under high-velocity impact, finite element analysis conducted using ABAQUS/Explicit commercial program. The predicted face damage of SFRC panels based on simulation shows well agreement with the experimental result in similar failure mode.
An Experimental Study on the Optimum Mix Design and Site Application Case of Soil Mixing Wall for Trench Stability
Kwon, Yeong-Ho ;
Journal of the Korea Concrete Institute, volume 27, issue 4, 2015, Pages 419~426
DOI : 10.4334/JKCI.2015.27.4.419
The purpose of this study is to investigate experimentally the optimum mix design and site application case of soil mixing wall (SMW) method which is cost-effective technique for construction of walls for cutoff wall and excavation support as well as for ground improvement before constructing LNG storage tank typed under-ground. Considering native soil condition in site, main materials are selected ordinary portland cement, bentonite as a binder slurry and also it is applied
as an unit volume weight of native soil, Variations for soil mixing wall are as followings ; (1) water-cement ratio 4cases (2) mixing velocity (rpm) 3levels (3) bleeding capacity and ratio, compressive strength in laboratory and site application test. As test results, bleeding capacity and ratio are decreased in case of decreasing water-cement ratio and increasing mixing velocity. Required compressive strength (1.5 MPa) considering safety factors in site is satisfied with the range of water-cement ratio 150% below, and test results of core strength are higher than those of specimen strength in the range of 8~23% by actual application of element members including outside and inside in site construction work. Therefore, optimum mix design of soil mixing wall is proposed in the range of unit cement
, unit bentonite
, water-cement ratio 150% and mixing velocity 90rpm and test results of site application case are satisfied with the required properties.
Mixture-Proportioning Model for Low-CO
Concrete Considering the Type and Addition Level of Supplementary Cementitious Materials
Jung, Yeon-Back ; Yang, Keun-Hyeok ;
Journal of the Korea Concrete Institute, volume 27, issue 4, 2015, Pages 427~434
DOI : 10.4334/JKCI.2015.27.4.427
The objective of this study is to establish an rational mixture-proportioning procedure for low-
concrete using supplementary cementitious materials (SCMs) achieving the targeted
reduction ratio as well as the conventional requirements such as initial slump, air content, and 28-day compressive strength of concrete. To evaluate the effect of SCM level on the
emission and compressive strength of concrete, a total of 12537 data sets were compiled from the available literature and ready-mixed concrete plants. The amount of
emission of concrete was assessed under the system boundary from cradle to concrete production stage at a ready-mixed concrete plant. Based on regression analysis using the established database, simple equations were proposed to determine the mixture proportions of concrete such as the type and level of SCMs, water-to-binder ratio, and fine aggregate-to-total aggregate ratio. Furthermore, the
emissions for a given concrete mixture can be straightforwardly calculated using the proposed equations. Overall, the developed mixture-proportioning procedure is practically useful for determining the initial mixture proportions of low-
concrete in the ready-mixed concrete field.
Permeability Evaluation of OPC and GGBFS Concrete with Cold Joint
Choi, Se-Jin ; Kim, Seong-Jun ; Moon, Jin-Man ; Kwon, Seung-Jun ;
Journal of the Korea Concrete Institute, volume 27, issue 4, 2015, Pages 435~441
DOI : 10.4334/JKCI.2015.27.4.435
Concrete, as a porous media, has permeability and it is considered as a major parameter for durability evaluation. Cold joint caused by delayed placing of concrete accelerates water permeation and intrusion of harmful ions. In the paper, concrete specimens containing GGBFS (Ground Granulated Blast Furnace Slag) and OPC (Ordinary Portland Cement) are prepared with cold joint section, and water permeability and water flow at the age of 91 days are measured for 2 weeks. Sound concrete with GGBFS shows decreased permeability to 89% for sound concrete with OPC and 0.86 of decreasing ratio is evaluated in GGBFS concrete with cold joint. Through WPT (Water Penetration Test), the effects of mineral admixture and cold joint on water permeability are evaluated, and variation in water behavior via cold joint is analyzed through probabilistic method as well.
Microstructure and Strength of Class F Fly Ash based Geopolymer Containing Sodium Sulfate as an Additive
Jun, Yubin ; Oh, Jae-Eun ;
Journal of the Korea Concrete Institute, volume 27, issue 4, 2015, Pages 443~450
DOI : 10.4334/JKCI.2015.27.4.443
This paper presents an investigation of the mechanical and microstructural properties of Class F fly ash based geopolymer containing sodium sulfate as an additive. Sodium sulfate was used as an chemical additive at the dosage levels of 0, 2, 4, and 6wt% of fly ash. Sodium hydroxide and sodium silicate solutions were used to activate fly ash. The compressive strengths of geopolymer pastes were measured at the age of 28 days. The microstructures of the geopolymer pastes were examined using XRD, MIP and SEM tests. The additions of 2wt% and 4wt% sodium sulfate produced geopolymers with high strength, while increasing the dosage of levels to 6% resulted in almost no changes in strength, comparing with the control geopolymer. The optimum increase in strength was obtained with the addition of 4wt% sodium sulfate. As the amount of sodium sulfate is increased, no additional crystalline phase was detected and no change of amorphous phase indicated despite the change in the strength development. The increase in the strength was due to the change of pore size distribution in samples. As addition of sodium sulfate altered the morphologies of reactive productions and Si/Al ratios of the reaction products, the strengths were thus affected. It was found that the strengths of geopolymer were larger for lower Si/Al ratios of reaction products formed in samples. The optimal amount of sodium sulfate in the fly ash based geopolymer helps to improve mechanical properties of the geopolymer, on the other hand, the high percentage of sodium sulfate could exist as an impurity in the geopolymer and hinder the geopolymer reaction.
Experimental Study on RC Frame Structures with Non-Seismic Details Strengthened by Externally-Anchored Precast Wall-Panel Method (EPWM)
Choi, Seung-Ho ; Hwang, Jin-Ha ; Lee, Deuck Hang ; Kim, Kang Su ; Kwon, Yong-Keun ; Kim, Kil-Hee ;
Journal of the Korea Concrete Institute, volume 27, issue 4, 2015, Pages 451~458
DOI : 10.4334/JKCI.2015.27.4.451
The infill-wall strengthening method has been widely used for the seismic performance enhancement of the conventional reinforced concrete (RC) frame structures with non-seismic detail, which is one of the promising techniques to secure the high resisting capacity against lateral forces induced by earthquake. During the application of the infill-wall strengthening method, however, it often restricts the use of the structure. In addition, it is difficult to cast the connection part between the wall and the frame, and also difficult to ensure the shear resistance performances along the connection. In this study, an advanced strengthening method using the externally-anchored precast wall-panel (EPCW) was proposed to overcome the disadvantages of the conventional infill-wall strengthening method. The one-third scaled four RC frame specimens were fabricated, and the cyclic loading tests were conducted to verify the EPCW strengthening method. The test results showed that the strength, lateral stiffness, energy dissipation capacity of the RC frame structures strengthened by the proposed EPCW method were significantly improved compared to the control test specimen.