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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 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
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Ductility Evaluation of Heavyweight Concrete Shear Walls with Wire Ropes as a Lateral Reinforcement
Mun, Ju-Hyun ; Yang, Keun-Hyeok ;
Journal of the Korea Concrete Institute, volume 27, issue 3, 2015, Pages 207~214
DOI : 10.4334/JKCI.2015.27.3.207
This study examined the feasibility of wire ropes as lateral reinforcement at the boundary element of heavyweight concrete shear walls. The spacing of the wire ropes varied from 60 mm to 120 mm at an interval of 30 mm, which produces the volumetric index of the lateral reinforcement of 0.126~0.234. The wire ropes were applied as a external hoop and/or internal cross-tie. Five shear wall specimens were tested to failure under constant axial load and cyclic lateral loads. Test results showed that with the increase of the volumetric index of the lateral reinforcement, the ductility of shear walls tended to increase, whereas the variation of flexural capacity of walls was minimal. The flexural capacity of shear walls tested was slightly higher than predictions determined from ACI 318-11 procedure. The displacement ductility ratio of shear walls with wire ropes was higher than that of shear wall with the conventional mild bar at the same the volumetric index of the lateral reinforcement. In particular, the shear walls with wire rope index of 0.233 achieved the curvature ductility ratio of more than 16 required for high-ductility design.
Structural Performance Evaluation of Steel Fiber-Reinforced Concrete Beams with Recycled Coarse Aggregates
Shin, Jae-Lin ; Kim, Woo-Suk ; Baek, Seung-Min ; Kang, Thomas H.-K. ; Kwak, Yoon-Keun ;
Journal of the Korea Concrete Institute, volume 27, issue 3, 2015, Pages 215~227
DOI : 10.4334/JKCI.2015.27.3.215
In this study, twenty four steel-fiber reinforced concrete (SFRC) beams using recycled coarse aggregates (RCA) were manufactured to examine the shear behavior of SFRC and to determine the beams' ultimate shear strengths. The RCA replacement ratio was fixed at 30%. The variables studied in this investigation are: (1) shear span-to-depth ratios (a/d) of 2, 3 and 4; (2) longitudinal reinforcement ratio (
) of 0.008 and 0.0127; and (3) steel fiber volume fractions (
) of 0, 0.5, 0.75 and 1%. Test results were analyzed and then compared with the findings and proposals of various other researchers. Based on the test results, the more steel fiber volume fraction is increased, the large crack resistance and shear strength are exhibited. Most of the experimental data is higher than the theoretical value. Therefore, steel-fiber reinforced concrete beams using recycled coarse aggregates are suggested to be applied for building structures.
Effects of Aggregate Size and Steel Fiber Volume Fraction on Compressive Behaviors of High-Strength Concrete
Ahn, Kyung-Lim ; Jang, Seok-Joon ; Jang, Sang-Hyeok ; Yun, Hyun-Do ;
Journal of the Korea Concrete Institute, volume 27, issue 3, 2015, Pages 229~236
DOI : 10.4334/JKCI.2015.27.3.229
This paper describes the effect of aggregate size on compressive behavior of high-strength steel fiber reinforced concrete. The Specified compression strength is 60 MPa and the range of fiber volume fraction is 0~2%. The main variable is the aggregate size, which was used for the aggregate size of 8 and 20 mm. So, ten concrete mixtures were prepared and tested to evaluate the fresh and hardened properties of SFRC at curing ages (7, 14, 28, 56 and 91 days), respectively. Items estimated in this study are the fresh properties (air contents, slump), hardened properties (compressive strength, modulus of elasticity, post-peak response and compressive toughness). As a result, the aggregate size has little effect on the compressive strength and modulus of elasticity. On the other hand, the ductile behavior was shown after post peak and the compressive toughness was increasing as decreasing the aggregate size. These effects are clearly represented in the fiber volume fraction 2%, which are the point appeared fiber ball. It is considered that the decreasing the aggregate size has effect on the fiber dispersibility.
Properties of Non-Sintered Cement Mortar using Alkali and Sulfate Mixed Stimulants Accroding to Curing Method
Park, Sung-Joon ; Kim, Ji-Hoon ; Hyung, Won-Gil ;
Journal of the Korea Concrete Institute, volume 27, issue 3, 2015, Pages 237~244
DOI : 10.4334/JKCI.2015.27.3.237
Entering the 20th century since the industrial revolution, the cement has been widely used in the field of construction and civil engineering due to the remarkable development of construction industry. However, result from that development, each kind of industrial by-products and waste and the carbon dioxide generated in the process of cement production cause air pollution and environmental damage so earth is getting sick now slowly. Therefore, we have to recognize importance about this. It means that the time taking specific and long-term measures have come. In this research paper, as substitution of the cement generating environmental pollution, we investigate the hydration reaction of non-Sintered Cement mortar mixed with GBFS, active stimulant of alkaline and sulphate series by using SEM and XRD, mechanical and chemical properties according to the curing method. As a result of this experiment, NSC realized outstanding strength for water curing and steam curing. It means that it has a good possibility as substitution of cement. From now on, it can be used for structure satisfying specific standard. We expect to find a substitution of outstanding cement by progressing continuous research making the best use of pros and cons according to the curing method.
Hydration and Insulation Characteristics of a Ground Granulated Blast Furnace Slag Based Non-Sintered Cement Using Circulating Fluidized Bed Combustion Ash as a Activator
Lee, Seung-Heun ; Lee, Gang-Hyuk ; Yoo, Dong-Woo ; Ha, Ju-Hyung ; Cho, Yun-Gu ;
Journal of the Korea Concrete Institute, volume 27, issue 3, 2015, Pages 245~252
DOI : 10.4334/JKCI.2015.27.3.245
As people have more interest in environment-friendly structures recently, many researchers are actively researching non-sintered cement in Korea and other countries. Non-sintered cement shows various characteristics of its reaction products and hardeners, depending on the kind of alkali activators. Thus, this study manufactures ground granulated blast furnace slag based non-sintered cement binder by using circulating fluidized bed combustion ash, which is a kind of industrial byproduct, as a stimulant, and investigated its hardening characteristics and hydration, depending on the rate of circulating fluidized bed combustion ash. Besides, this study investigated its insulation property according to the weight lightening of non-sintered cement. As a result, ettringite and C-S-H were mainly formed in the hydration, and it was possible to manufacture a non-sintered cement hardener over 50 MPa. Lastly, it was possible to manufacture a non-sintered cement hardener in a thermal conductivity level of
when the compressive strength was 10 MPa for weight lightening.
Correlation Between Tensile Strength and Compressive Strength of Ultra High Strength Concrete Reinforced with Steel Fiber
Bae, Baek-Il ; Choi, Hyun-Ki ; Choi, Chang-Sik ;
Journal of the Korea Concrete Institute, volume 27, issue 3, 2015, Pages 253~263
DOI : 10.4334/JKCI.2015.27.3.253
Ultra-high strength concrete which have 100 MPa compressive strength or higher can be developed applying RPC(Reactive Powder Concrete). Preventing brittle failure under compression and tension, ultra-high strength concrete usually use the steel fibers as reinforcements. For the effective use of steel fiber reinforced ultra-high strength concrete, estimation of tensile strength is very important. However, there are insufficient research results are available with no relation between them. Therefore, in this study, correlation between compressive strength and tensile strength of ultra-high strength concrete was investigated by test and statistical analysis. According to test results, increasing tendency of tensile strength was also shown in the range of ultra-high strength. Evaluation of test results of this study and collected test results were carried out. Using 284 splitting test specimens and 265 flexural test specimens, equations suggested by previous researchers cannot be applied to ultra-high strength concrete. Therefore, using database and test results, regression analysis was carried out and we suggested new equation for splitting and flexural tensile strength of steel fiber reinforced ultra-high strength concrete.
The Reduction of Maximum Hydration Temperature in Cement Paste Using Calcium Silicate Hydrates and Glucose
Moon, Hoon ; Kim, Hyeong-Keun ; Ryu, Eun-Ji ; Jin, Eun-Ji ; Chung, Chul-Woo ;
Journal of the Korea Concrete Institute, volume 27, issue 3, 2015, Pages 265~272
DOI : 10.4334/JKCI.2015.27.3.265
In this study, a method to reduce temperature rise due to hydration in mass concrete is investigated. It is to use retarder (glucose) for reducing heat of hydration and to use calcium silicate hydrate (C-S-H) for compensating the retardation effect due to its role as a nucleation seed. For this purpose, the temperature rise of cement paste due to hydration was measured and the effect of using both C-S-H and glucose on setting and 28-day compressive strength of mortar specimens was investigated. According to the experimental results, using C-S-H and glucose caused the reduction in the maximum temperature but accelerated the time to reach the maximum temperature compared to that of retarded cement paste using glucose. In addition, using C-S-H and glucose did not show significant effect on 28-day compressive strength of mortar specimens, indicating that the method shown in this study can be a successful alternative to control maximum temperature rise in mass concrete.
The Strength and Drying Shrinkage Properties of Alkali-Activated Slag Mortars as the Particle Size of Blended Fine Aggregate
Kim, Tae Wan ;
Journal of the Korea Concrete Institute, volume 27, issue 3, 2015, Pages 273~281
DOI : 10.4334/JKCI.2015.27.3.273
In this paper, the performance of alkali-activated slag cement (AASC) is assessed in terms of compressive strength and drying shrinkage, using three different types of silica sand and river sand. The sand type has an important influence on the properties of AASC mortar. Three silica sands (SS1, SS2 and SS3) and river sand (RS) were considered. Three series of blended sands have been tested. A first series (S1) with RS and SS1, a second series (S2) with RS and SS2 and third series (S3) with RS and SS3 with a different blended ratios. The result shows a very significant influence of the blended sand on the AASC mortar properties. The compressive strength and drying shrinkage related with the particle sizes and blended ratios of sands are investigated considering blended sand properties like fineness modulus (FM) and relative specific surface. The type and blended ratio of sand seems to have very significant and important consequences for the mix design of the AASC mortar.
Flexural Strength of Hybrid Steel Fiber-Reinforced Ultra-High Strength Concrete Beams
Yang, In-Hwan ; Kim, Kyoung-Chul ; Joh, Chang-Bin ;
Journal of the Korea Concrete Institute, volume 27, issue 3, 2015, Pages 283~290
DOI : 10.4334/JKCI.2015.27.3.283
This paper proposes a method for predicting flexural strength of hybrid steel fiber-reinforced ultra-high strength concrete beams. It includes an experimental test framework and associated numerical analyses. The experimental program includes flexural test results of hybrid steel fiber-reinforced ultra-high strength concrete beams with steel fiber content of 1.5% by volume. Tensile softening characteristics play an important role in the structural behavior of steel fiber-reinforced ultra high performance concrete. Tension softening modeling is carried out by using crack equation based on fictitious crack and inverse analysis in which load-crack mouth opening displacement relationship is considered. The comparison of moment-curvature curves of the numerical analysis results with the test results shows a reasonable agreement. Therefore, the numerical results confirms that good prediction of flexural behavior of steel fiber-reinforced ultra high strength concrete beams can be achieved by employing the proposed method.
Hysteretic Behavior Evaluation of a RC Coupling Beam using a Steel Fiber and Diagonal Reinforcement
Oh, Hae Cheol ; Lee, Kihak ; Han, Sang Whan ; Shin, Myoungsu ; Jo, Yeong Wook ;
Journal of the Korea Concrete Institute, volume 27, issue 3, 2015, Pages 291~298
DOI : 10.4334/JKCI.2015.27.3.291
In this paper, a bundled diagonal reinforcement using high performance steel fiber was proposed to enhance the construct ability and seismic performance. Experiments of coupling beam was composed of four specimens and the hysteretic behavior evaluated for reverse cyclic loading to specimens using high performance steel fiber. The main variables of the experiment is a amount of stirrup and bundled reinforcement, depending on whether the mix of steel fiber. Specimen which criteria was applied 100% of stirrup and bundled diagonal reinforcement of ACI318 criteria. With this, by appling same diagonal reinforcement, two specimens were created by adjusting stirrup of 75%, 50%. So, a total of four specimens were produced. When coupling beam was placed concrete, this experiment was mixed in a content of steel fiber 1%. All the specimens were produced by aspect ratio 3.5(l/h=1050/300) to a half-scale. In this result, two specimens as reduced to stirrup of 75%, 50% was no significant difference in the strength, stiffness and energy dissipation capacity, respectively compared to the stirrup of 100%.
Shear Friction Strength based on Limit Analysis for Ultra-High Performance Fiber Reinforced Concrete
Lee, Ji-Hyung ; Hong, Sung-Gul ;
Journal of the Korea Concrete Institute, volume 27, issue 3, 2015, Pages 299~309
DOI : 10.4334/JKCI.2015.27.3.299
Ultra High Performance Fiber Reinforced Concrete (UHPFRC) is distinguished from the normal concrete by outstanding compressive and tensile strength. Cracked normal concrete resists shear by aggregate interlocking while clamped by transverse reinforcement, which is called as shear friction theory. Cracked UHPFRC is expected to have a different shear transfer mechanism due to rather smooth crack face and post-cracking behavior under tensile force. Twenty-four push-off specimens with transverse reinforcement are tested for four different fiber volume ratio and three different ratio of reinforcement along the shear plane. The shear friction strength for monolithic concrete are suggested by limit analysis of plasticity and verified by test results. Plastic analysis gives a conservative, but reasonable estimate. The suggested shear friction factor and effectiveness factor of UHPFRC can be applied for interface shear transfer design of high-strength concrete and fiber reinforced concrete with post-cracking tensile strength.
Evaluation of Flexural Behavior of Reinforced Concrete Beams Using Alkali Activated Slag Concrete
Lee, Kwang-Myong ; Seo, Jung-In ;
Journal of the Korea Concrete Institute, volume 27, issue 3, 2015, Pages 311~317
DOI : 10.4334/JKCI.2015.27.3.311
Cement zero concrete produced by alkali-activators and industrial by-products such as slag instead of cement, enables to solve the environmental pollution problems provoked by the exhaustion of natural resources and energy as well as the discharge of carbon dioxide. However, researches on the cement zero concrete are still limited to material studies and thus, study on the structural behavior of relevant members is essential to use the cement zero concrete as structural materials. This paper aims to evaluate experimentally and analytically the flexural behavior of RC beams using 50 MPa alkali activated slag concrete. To achieve such a goal, flexural tests on three types of RC beam specimens were conducted. A nonlinear analysis model is proposed using the modulus of elasticity and stress-strain relationship of alkali activated slag concrete. The analysis results obtained by the proposed model agree well with the experimental results, which could verify the validity of the proposed model.