• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.344-347
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• 2004

The amount of coal ash has been increasing and development of effective use is urgently needed. Various by-products and waste are expected to be used as resources from the point of reduction in environmental load. This is an experimental study to compare the properties of high volume coal ash concrete using the reclaimed coal ash. For this purpose, authors have started work to develop a production method of hardening coal ash concrete. Laboratory tests show that the optimum mixture of coal ash concrete can be determined from multiple regression analysis. According to test results, it was found that the compressive strength of the concrete can be determined by a single curve. And it is obtained from the analysis of the results tested for concrete with the ratio of total power to water and amount of land reclamation ash.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.789-792
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• 1999

Reinforced concrete structures covered creek for road vehicle located in urban areas have been experiencing corrosion of concrete and reinforcing steel caused by $H_2S$ gases generated by anaerobic bacterial. H2S gases react with oxygen and water to form sulfuric acid ($H_2SO_4$). This acid chemically attacks concrete, and sulfate ions penetrate into the concrete, causing rebar corrosion. In this work, to determine the conditions of RC culvert boxes which were constructed in the 1970s, various tests were conducted, including carbonation depth, compressive strength, half-cell potential measurements, and XRD analyses. Results indicated that the concrete deterioration was caused by sulfate attack and rebar corrosion. This paper discusses the evaluation on the durability of reinforced concrete structures covered creek for road vehicle.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.445-448
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• 2003

Polymer concrete using wastes PET recycled resin that is, in general, more excellent mechanical properties than portland cement concrete. A lot of works are carried out about short-term properties of polymer concrete, however, little work has done to define their long-term properties, that is, sustain load such as creep. In this study will show the data that can long-term behavior of polymer concrete by short term creep test of polymer concrete that was affect to the temperature and the time to predict to long-term creep behavior. Then prediction equation was similar tendency that was comparing to short-term creep test and long-term creep test.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.05a
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• pp.87-88
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• 2011

High absorptance of lightweight aggregate make a hard product, work, quality management ect. for making low absorptance property, lightweight aggregate is coated by an organic matter and that way remarkably showed to decrease the absorptance by pre-study. but first, we would need a check to fit into the concrete which both fresh concrete and hardened concrete. In this study, mechanical property change of coated lightweight aggregate concrete was analysed by compared experiment with coated lightweight aggregate concrete and non-coated aggregate concrete.

• Structural Engineering and Mechanics
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• v.37 no.1
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• pp.1-15
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• 2011

The response of concrete to transient dynamic loading has received extensive attention for both civil and military applications. Accordingly, thoroughly understanding the response and failure modes of concrete subjected to impact or explosive loading is vital to the protection provided by fortifications. Reactive powder concrete (RPC), as developed by Richard and Cheyrezy (1995) in recent years, is a unique mixture that is cured such that it has an ultra-high compressive strength. In this work, the concrete cylinders with different steel fiber volume fractions were subjected to repeated impact loading by a split Hopkinson Pressure Bar (SHPB) device. Experimental results indicate that the ability of repeated impact resistance of ultra-high-strength concrete was markedly superior to that of other specimens. Additionally, the rate of damage was decelerated and the energy absorption of ultra-high-strength concrete improved as the steel fiber volume fraction increased.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.475-480
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• 1999

Recently domestic building market in the face of 3D, in addition to construction cost increase, materials lack problems and opening a building market to foreign countries, is trying to find out the efficient ways of overcoming these problems. So the necessity to study the permanent form is urgent to escape the problems of constructing human power economy, cost down, noises problem, environmental prevention and efficacy of form work to technical improvement will contribute a practical permanent form in field through economic evaluation of permanent form. In this paper, we compared wood form cost with permanent form cost(made form polymer or fly ash) for frame work

• Proceedings of the Korea Concrete Institute Conference
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• 1995.10a
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• pp.293-298
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• 1995

This study experimentally evaluate the bonding performance of repair and strengthening materials. It is very important problem to justify bonding properties between repair and strengthening materials and old concrete. Many previous research and investigation showed that bonding strength of reinforcing materials determines the strengthening effect and the durability of repair work. Therefore, menifestation of bonding properties and the improvement of bonding performance of repair and strengthening materials are very important. In order to improve the perforamnce of repair work, it needs to investigate the behavior of bonding materials, such as stress distribution along the bonding area and the long term performance of the material. The target repair methods are steel plate addition technique and repair mortar method, and the test parameters studied in this paper include epoxy thickness, bonding surface texture, and bonding area.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.21-24
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• 2006

In recent, there are a lot of problems such as shortage of construction workers, complicate progress of work and so on under RC construction. To solve these problems, the construction methods without form-work are used in the main structural members - beam, slab and stairs. However, there isn't yet form-workless system for columns. The purpose of this study was to experimentally evaluate the structural behavior of full scaled no-form system columns reinforced with steel sheet forms and angles. The main variables are 1) comparison of concrete member strength with and without reinforcement, 2) effect of L-angle.

• Structural Engineering and Mechanics
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• v.78 no.4
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• pp.403-411
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• 2021

Ties are mandated by many design guidelines and codes to prevent the progressive collapse of buildings initiated by local failures. This study develops a model to estimate catenary/cable action capacity and the required ties in continuous reinforced concrete beams to bridge above the potential failed interior columns. The developed model is derived based on virtual work method and verified using test results presented in the literature. Also, parametric investigations are conducted to estimate the required ties in continuous reinforced concrete beams supporting one-way slab systems. A comparison is conducted between the estimated tie reinforcement using the developed model and that provided by satisfying the integrity provisions of the ACI 318-14 (2014) code. It is shown that the required tie reinforcements to prevent progressive collapse using the developed model are obviously larger than that provided by the integrity requirements of the ACI 318-14 (2014) code. It has been demonstrated that the increases in the demanded tie reinforcements over that provided by satisfying ACI 318-14 (2014) integrity provisions are varied between 1.01 and 1.46.

• Computers and Concrete
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• v.27 no.3
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• pp.211-223
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• 2021

This paper presents a review of the two widespread approaches which deal with the ultimate strength design of RC slabs subjected to bending moments and torsion: The Field of Moments Method (FoMM) and the Sandwich method (SM). Special attention is paid to the ultimate strain distribution implicitly assumed when using each one of the methodologies, in particular, the yielding of the steel reinforcement. This work analyzes the initial assumption regarding ultimate strain distribution in the SM. Furthermore, this work studies the resisting moments field on which the Wood-Armer method is based, and it finds some inconsistencies. Several examples have been developed.