• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 한국건설관리학회 2007년도 정기학술발표대회 논문집
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• pp.113-118
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• 2007

In this study, we select a site adopting real composite precast concrete method. Estimating real construction cost and imaginary cost appling reinforced concrete method in the site, we compare the costs. Through using high intensity concrete and prestressed concrete, amount of concrete is reduced more than 50% but there isn't big gap in material cost. In the main construction cost of composite precast concrete method, the material cost with production cost and transportation cost are in that, joints and topping concrete are account for 90%. But in case of reinforced concrete, labor cost spent at concrete steel bar and form is account for 30%. In the cost of attached, compared with composite precast concrete method, the reinforced concrete method taken in big portion by temporary work and scaffolding is twice as much as composite precast concrete method in construction cost. Therefore, economic efficiency is excellent reducing 11% total cost of composite precast concrete method from the reinforced concrete method.

• Proceedings of the Korean Institute of Building Construction Conference
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• 한국건축시공학회 2015년도 춘계 학술논문 발표대회
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• pp.40-41
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• 2015

The purpose of this study is to develop advaced furture type of concrete which utilizes transpart plastic types of fiber replacing previously used high price optical fiber and porous type of steel mold to induce its mass production. New type of concrete solved problems of construction and economy can make it easily their application to construction market.

• Computers and Concrete
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• 제32권6호
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• pp.595-606
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• 2023

Dune sand (DS) has been widely used as a partial replacement for regular sand in concrete construction. Therefore, investigating its mechanical properties is critical for the analysis and design of structural elements using DS as a construction material. This paper presents a comprehensive investigation of the mechanical properties of DS concrete, considering different replacement ratios and strength grades. Regression analysis is utilized to develop strength prediction models for different mechanical properties of DS concrete. The proposed models exhibit high calculation accuracy, with R² values of 0.996, 0.991, 0.982, and 0.989 for cube compressive strength, axial compressive strength, splitting tensile strength, and elastic modulus, respectively, and an error within ±20%. Furthermore, a stress-strain relationship specific to DS concrete is established, showing good agreement with experimental results. Additionally, nonlinear finite element analysis is performed on concrete-filled steel tube columns incorporating DS concrete, utilizing the established stress-strain relationship. The analytical and experimental results exhibit good agreement, confirming the validity of the proposed stress-strain relationship for DS concrete. Therefore, the findings presented in this paper provide valuable references for the design and analysis of structures utilizing DS concrete as a construction material.

• Proceedings of the Korea Concrete Institute Conference
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.363-366
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• 2005

When widening or repairing concrete deck slab, there is a joint inevitably. However, joining-construction method have following problem, that is the additional stress in existing part of bridge resulting from the specific process of joining-construction and the difference of amount of shrinkage between new and existing bridge. On this study, compared shrinkage stress of the direct joining construction method with the indirect joining construction method, and concluded the proper substitution rate of expansion cement. The rate of replacement was proper at $10\%$. but more than $15\%$, concrete had excessive expansion and weeker compressive strength. The time of placing closure concrete, considering the shinkage stresses and creep, was suitable in $45\~60$ days after placing the new concrete deck slab.

• Proceedings of the Korea Concrete Institute Conference
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• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
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• pp.563-564
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• 2009

Ultra-High Performance Concrete (UHPC) compared to normal concrete is exhibiting extremely high strength characteristics with compressive strength and tensile strength reaching 200MPa and 15MPa, respectively. The mechanical characteristics of UHPC can be thus exploited advantageously in the construction of structure through the reduction of the cross-sectional area and fabrication of slim and light-weight of the structural members. In the case where the structural member is made of UHPC, the occurrence of crack can be prevented by releasing the restraint provided by the form in due time. This research performs parametric study of the failure characteristics of concrete such as failure energy and softening curve suggested by the viscous crack model approximating the failure of concrete. The scope of this research contains the results of tests performed to investigate the strength of UHPC during early elapsed time.

• Proceedings of the Korean Institute of Building Construction Conference
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• 한국건축시공학회 2018년도 춘계 학술논문 발표대회
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• pp.4-5
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• 2018

Recently, high-strength concrete used for shortening the construction time of high-rise building construction, Concrete pumping technology is emerging as the core technology of high-rise buildings. In this paper, we have started to study the use of electromagnetic field as a method to increase the efficiency of the lubricating layer between the inside of the pipe and concrete, which has been established as the most important factor determining the pumping performance. The pumping performance improvement effect of concrete strength was verified and basic research was carried out to utilize it as a method to increase the efficiency of pumping in field application. In the related work, the effect of the electromagnetic field was verified by conducting a mock-up performance evaluation (horizontal 300 m) of the pumping force by the concrete strength.

• Proceedings of the Korea Concrete Institute Conference
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.823-828
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• 2002

Concrete used up to date semipermanent architecture material but now day concrete early deterioration emboss social issue because of construction structure and environmental factor. so, many study of deterioration concrete construction improve durability used impregnation alkalization agent. Impregnation alkalization agent deterioration concrete construction spray infiltration or diffusion improve alkali and filler inter minuteness void elaborateness constitution concrete. but many study of harding concrete change inter minuteness void that Is insufficiency also, To study of method recover shape impregnation alkalization agent apply deterioration concrete construction. impregnation alkalization agent infiltration according to test of porosity, premeameter, absorption.

• Proceedings of the Korea Concrete Institute Conference
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• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
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• pp.287-292
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• 1997

Recent economic growths have accelerating much construction activities of various infrastructures, such as Express railway, Long-span bridges, Multi-story Buildings and etc. Reinforcement steel corrosion to be inevitably caused under the progress of these construction activities have been on and off serious problems in the site, which could incur another tragedic accident to us suffering from safety-ignorance disease. Thus, it is strongly requested to develop probable innovative products which could remove corrosive materials on rebars and also protect steel corrosion of reinforced concrete structures in the construction site. Hydro-Seal and Steel-Seal could solve these problems currently faced with in the construction site. The objective of this research is to experimentally evaluated the effect of Hydro-Seal and Steel-Seal in reinforced concrete structures, of which usage might affect the bond strength between steel and concrete, long-term compressive strength of concrete, corrosion resistance and etc. Related test results show that appropriate dosage of Hydro-Seal and Steel-Seal in reinforced concrete structures didnot affect physical properties of reinforced concrete structures.

• Proceedings of the Korean Institute of Building Construction Conference
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• 한국건축시공학회 2017년도 추계 학술논문 발표대회
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• pp.128-129
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• 2017

Concrete properties alone cannot provide satisfactory waterproof performance because concrete can generate cracks due to possible problems in design, construction and curing process, and various environmental factors. Therefore, concrete structures require installing waterproofing layers for concrete protection and various types of construction methods are currently being applied. The purpose of this study is to investigate the concrete strength changes when waterproofing admixtures are mixed into the concrete. The results of flexural strength testing confirmed that the initial strength of concrete specimens with the admixtures was lower than that of the concrete specimen without the admixture based on different curing periods.

• Structural Engineering and Mechanics
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• 제45권6호
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• pp.837-851
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• 2013

In construction industry, strength is a primary criterion in selecting a concrete for a particular application. The concrete used for construction gains strength over a long period of time after pouring the concrete. The characteristic strength of concrete is defined as the compressive strength of a sample that has been aged for 28 days. Neither waiting for 28 days for such a test would serve the rapidity of construction, nor would neglecting it serve the quality control process on concrete in large construction sites. Therefore, rapid and reliable prediction of the strength of concrete would be of great significance. On this backdrop, the method is proposed to establish a predictive relationship between properties and proportions of ingredients of concrete, compaction factor, weight of concrete cubes and strength of concrete whereby the strength of concrete can be predicted at early age. Multiple regression analysis was carried out for predicting the compressive strength of concrete containing Portland Pozolana cement using statistical analysis for the concrete data obtained from the experimental work done in this study. The multiple linear regression models yielded fairly good correlation coefficient for the prediction of compressive strength for 7, 28 and 40 days curing. The results indicate that the proposed regression models are effectively capable of evaluating the compressive strength of the concrete containing Portaland Pozolana Cement. The derived formulas are very simple, straightforward and provide an effective analysis tool accessible to practicing engineers.