• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.1
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• pp.21-28
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• 2017

The steel-plate concrete(SC) is used in a form of module assembly construction in the outer wall of nuclear-power plant and LNG containment. Since the steel-plate concrete modules are generally manufactured from the plant, the weight of SC has significantly effect on the total construction cost in the aspect of shipment. Therefore, the use of lightweight aggregates concrete(LWAC), which fill the inside of SC module can be a solution. However, the amount of used lightweight aggregates(LWA) is limited in the use of current concrete mixing process due to the concrete quality problems and it also determines the allowable minimum density of LWAC. In this research, the preplaced casting method is applied because of increasing the volume fraction of LWA significantly, which results from the producing process of pre-packing the LWA in the formwork and filling the interstitial voids between LWA using cement paste grout. The density and compressive strength of selected preplaced LWAC were $1,600kg/m^3$ and 30MPa and it was applied for the mock-up specimens of SC panel. It was used for the 3-point bending test for evaluating its structural performance. The results show that the preplaced LWAC can reduce the density of concrete with the adequate mechanical and structural performance.

• Journal of the Korea Institute of Building Construction
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• v.15 no.2
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• pp.177-183
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• 2015

In this study, the thermal conductivity, physical and mechanical properties of lightweight aggregate concretes with hollow micro sphere(HMS) are experimentally examined as a basic research for the development of structural insulation concrete. As the results of this experiment, in the case of concrete mixed with HMS, the value of slump has been reduced, so it is found that the dosage of superplasticizer should be increased. As the replacement ratio of HMS increases, it has shown that the compressive strength is somewhat decreased due to the low interfacial adhesion strength of HMS. But the thermal conductivity is found to be greatly improved with the replacement ratio of HMS increases, the thermal conductivity of HMS shows the lower value of 68% at lightweight aggregate concrete and 32% of normal concrete. Also it is found that the compressive strength is decreased and thermal conductivity is increased as the water-cement ratio increases. The most outstanding for insulation performance is observed when using 20% of HMS and 50% of water-cement ratio.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.05a
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• pp.188-189
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• 2014

Recently, structural system of apartment building is changing from wall type to column type to accommodate various life styles of residents in Korea. Reinforced-concrete bearing wall structures have been mainly used in apartment construction since 1980's. It is impossible to remove the bearing wall in case of remodeling a house, so that the lightweight wall is needed to apply to the column type structure of the Long Life Housing. Therefore, the purpose of this study is to evaluate the construction performance of the wall. Constructibility reviews are performed throughout interview survey from builders who charge with managing the construction of the lightweight wall in field. This paper present that constructor prefer the bearing wall rather than the lightweight wall because of the schedule delay, difficulty of management, and lack of skilled labor. The results indicate what we should improve on the lightweight wall from now on.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.56-60
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• 2007

Nowadays shear wall structural system is gradually changing to framed structure. For this reason, lightweight panel is increasingly being used as separating walls. One of design methods to obtain high transmission loss is double panel. To predict the acoustic performance of double panel, prediction of transmission loss of single panel must be performed, previously. In this study, the predicted values for four single panels were compared with the measured values. The result shows the arithmetical average deviations(100Hz to 3150Hz) between the predicted and measured transmission loss were in range between 1.1dB and 3.9dB. The predicted values were generally lower than measured values above critical frequency. The single-number quantities, $R_W+C$, were predicted in range between 36dB to 38dB, and the differences of single-number quantities between the predicted and measured value were within 1dB.

• Structural Engineering and Mechanics
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• v.81 no.5
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• pp.551-563
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• 2022

Bolted connector could be an alternative to replace the conventional welded headed stud in steel-ultra high performance concrete (UHPC) lightweight composite structures. In this paper, a novel demountable bolted shear connector, consisting of a high-strength bolt (HSB) and a specially-designed nut which is pre-embedded in a thin UHPC slab, is proposed, which may result in the quick installation and disassembly, due to the mountable, demountable and reusable features. In order to study the shear behavior of the new type of bolted shear connector, static push-out tests were conducted on five groups of the novel demountable bolted shear connector specimens and one group of conventional welded headed stud specimen for comparison. The effect of the bolt shank diameter and aspect ratio of bolt on failure mode, shear stiffness, peak slip at the steel-UHPC interface, shear strength and ductility of novel bolted connectors is investigated. Additionally, design formula for the shear strength is proposed to check the suitability for assessment of the novel demountable bolted shear connectors.

• Journal of the Korea institute for structural maintenance and inspection
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• v.2 no.4
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• pp.186-193
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• 1998

The purpose of this research is to seek properties of flowing light-weight aggregate concrete and possibility of application. The experimental analysis results by using light-weight aggregate and industrial waste such flyash, furnace slag are as follow. 1) The research shows that flowing light-weight aggregate concrete of slump 23~27cm, slump flow 58~69 cm is possible, but material segregation is appeared above slump 26.5cm and slump flow 65 cm. 2) If mixing ratio of flyash is increase, strength deterioration is about 25 % in early age. It showed that effectiveness of long time strength improvement because strength manifestation ratio is above 95% in a long term. 3) This research showed possibility of substitution of blast furnace slag because strength deterioration by using mixing of furnace slag was appeared small deterioration range as below 10 %. 4) Each experimental compressive strength ratios were 77 %(1st week), 86 %(2nd week), 109 %(8th week), 115 %(13th week), 125 % (26th week) on the basis of 28 days. If mixing ratio of flyash is increase, long term strength increase ratio is improved.

• Korean Journal of Agricultural Science
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• v.23 no.1
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• pp.39-50
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• 1996

The normal cement concrete is widely used material to build the construction recently, but it has a fault to increase the dead load on account of its unit weight is large compared with strength. So, many engineers are continuously searching for new materials of construction to provide greater performance at lower density. Many studies were carried out on the lightweight aggregate concrete in foreign country in the latter half of the 19th century, therefore lightweight aggregate concrete has been used successfully for many years for structural members. The main purpose of the work described in this paper were to establish its physical and mechanical properties of no-fines lightweight concrete using synthetic lightweight coarse aggregates. Test results are summarized as follows ; The water-cement ratio was shown less than 33% in use synthetic lightweight coarse aggregates, unit weights of synthetic lightweight concrete was shown less than $1,800kg/m^3$ and compressive strength was higher than $200kg/m^2$. And the pulse velocity was more than 3,000m/sec. The relationship of compressive strength between unit weight and pulse velocity was shown to be approximately linear.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.5
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• pp.85-92
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• 2016

The eight mixes and artificial soil aggregates were prepared for evaluating the practical application of lightweight foamed concrete as soil aggregates. The main parameter was unit binder content ranged between from 100 to $800kg/m^3$. In lightweight foamed concrete, flow, slurry and dried density, and compressive strength at different ages were measured. In Artificial soil aggregates crushed from lightweight foamed concrete, particle size distribution, pH, coefficient of permeability, cation exchange capacity(CEC), and ratio of carbon to nitrogen(ratio of C/N), were measured. The test results showed that flow, slurry and dried density, and compressive strength at different ages of lightweight foamed concrete increased with the increasing of unit binder content. Compressive strength at age of 28, of lightweight foamed concrete with unit binder of more than $500kg/m^3$, was more than 4 MPa. The ammonium phosphate immersion time of more than age of 3, was effective to decrease pH of artificial soil aggregates. In addition, artificial soil aggregates was evaluated as high class in terms of cation exchange capacity(CEC), while satisfied with value of ratio of carbon to nitrogen(ratio of C/N) recommended by landscape specification.

• Journal of the Korea Concrete Institute
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• v.26 no.3
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• pp.247-254
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• 2014

Strain properties of concrete member which acts as an important factor in the stability of the concrete structure in the event of fire, significantly affected the characteristics of the coarse aggregate, which accounts for most of the volume. For this reason, there are many studies on concrete using artificial lightweight aggregate which has smaller thermal expansion deformation than granite coarse aggregate. But the research is mostly limited on concrete using clay-based lightweight aggregate. Therefore, in this study, the high temperature compressive strength and elastic modulus, thermal strain and total strain, high temperature creep strain of concrete was evaluated. As a result, remaining rate of high-temperature strength of concrete using lightweight aggregate is higher than concrete with general aggregate and it is determined to be advantageous in terms of structural safety and ensuring high-temperature strength from the result of the total strain by loading and strain of thermal expansion. In addition, in the case of high-temperature creep, concrete shrinkage is increased by rising loading and temperature regardless of the type of aggregate, and concrete using lightweight aggregate shows bigger shrinkage than concrete with a granite-based aggregate. From this result, it is determined to require additional consideration on a high temperature creep strain in case of maintaining high temperature like as duration of a fire although concrete using light weight aggregate is an advantage in reducing the thermal expansion strain of the fire.

• Magazine of the Korea Concrete Institute
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• v.8 no.4
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• pp.149-159
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• 1996

Recent advances in material technology has accelerated the development of higher strength concretes using lightweight manufactured aggregates.Concretes with these chnractcristics are designable since the reductiun of dead loads and the increase in load capacity can oflix substantial cost reductions. Alt,hough thesc rharackristics are very desirable, very little information is availablc to the structural rivic;~~,cher about the properties of highstrength lightweight concrete. In general, shear strength of reinforced concrete beams is dependent on the compressive strength of concrete. the longitudinal steel ratio, the shear span to the depth ratio and shear reinforcement. In this study. eight single reinforced high strength lightweight concrete beams were tested to investigate their behavior and to determine their ultimate shear strengths.The variables studied in this investigation are shear span to effective depth ratio a/d = 1.5. 2.5, 3.5 and 4.5 : vertical shear reinforcement ratio ${\rho}_8= 0%$ and 1.136%. Test results were analyzed and compared with strengths predicted by ACI code equation. Zsutty's equation. As the results, ACI Eq.(ll-3) and ACI Eq.(ll-6) are conservative for high strength lightweight concrete beam. Also Zsuttyrs Eq. is conservative for beams except short beams. (a/d= 1.5)