• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.6
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• pp.176-181
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• 2018

Concrete structures are degraded physically and chemically due to various reasons after construction. Because the deterioration of concrete structure reduces the service life, reasonable repair and maintenance techniques are needed. Recently, in order to efficiently repair concrete structures, many researches on hybrid repair materials having improved adhesion performance have been carried out actively. In this study, we developed a hybrid repair material containing rapid hardening cement, PVA powder, nylon fiber, and latex to improve adhesion and water-tightness of existing concrete. The compressive strength, drying shrinkage and the adhesion strength test were carried out to evaluate the performance of the repair material. In addition, the flexure bond performance was evaluated before and after repair. From the results, the bending strength was 110% ~ 150% in all specimens except for the specimen containing only the rapid hardening cement, and all the specimens behaved with the existing concrete in the crack pattern generated by the bending strength.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.2
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• pp.41-48
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• 2018

Carbonation is one of the major detrimental factors to the reinforced concrete structures owing to penetration of atmospheric CO2 through the micro pores, thereby it reduces the durability of the concrete. The maintenance periods and cost for concrete according to the coefficient variation of different finishing materials is documented in literature. However, it is required to carry out the systematic and well planned studies. Therefore, keeping them in mind, surface repair was carried out to the carbonated concrete and the maintenance cost was calculated to measure the durability life after repair with different variable. The deterministic and probabilistic methods were applied for durability and repair cost of the concrete. In the existing deterministic model, the cost of repair materials increases significantly when the concrete structure reaches its service life. In present study using a stochastic model, the maintenance period and cost was evaluated. According to obtained results, there was no significant difference in the number of maintenance of the coefficient variation. The initial durability has a great influence on the maintenance time and cost of the structure. Unlike the deterministic model, the probabilistic cost estimating model reduces the number of maintenance to the target service life expectancy.

• Computers and Concrete
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• v.7 no.3
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• pp.249-269
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• 2010

Managing and reusing knowledge in engineering and construction sectors can lead to greater competitive advantage, improved designs, and more effective management of constructed facilities. The use of Information Technology (IT) in design and construction can exploit strategic opportunities for new ways of integration, sharing and facilitating information and knowledge in any field of engineering. The integrating of separate areas of IT can be used to bring a group of experts and specialists in any field of engineering closer together by allowing them to communicate and exchange information and expertise that facilitate knowledge capture, sharing, and reuse. A lack of an advisory management system and a need to marshal all available data in a common format has indicated the need for an integrated engineering computing environment to investigate concrete repair problems. The research described in this paper is based upon an evaluation management system (EMS) which comprising a database management system (REPCON) alongside visualisation technologies and evaluation system (ECON) is developed to produce an innovative platform which will facilitate and encourage the development of knowledge in educational, evolution and evaluation modes of concrete repair. This allows us to create assessment procedures that will allow the current condition of the concrete structure and its components to be expressed numerically using a confidence level (CL) so as to take the best course of action in the repair and maintenance management. The explained rating system, which is related to structural integrity and serviceability of the structure, allows the confidence level to be determined by visual inspection and the descriptive information and pictures taken from an available REPair of CONcrete (REPCON) database.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.817-822
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• 2002

The problem of the crack which occures from the reinforced concrete structure could be caused by the complexed factors. When the crack happen, it caused fatal blemish to manage and maintain the structure such as structural problem, licking, spalling, viewing Even though they study and work hard to solve this kind of problem in the world, there are no countermeasure for perfect prevention of crack. After the crack checked out, a method of repair-reinforcement has been studied and operated actively, Generally, occurance of the crack in the concrete structure could be taken as granted, no need to mention the damage from the crack, domestic construction try to hide it rather than repair basically, In many cases the construction amount for repairing the crack has to be made in the construction area and the amount is very expensive. To save the repaing fee, companys repair it under the meeting of their desire. it can be expected for the effection of the construction. For this reason, we compare a new injection method to solve the demerits of the present method, to save and use the merit of the present method.

• Proceedings of the Korea Concrete Institute Conference
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• 1990.10a
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• pp.179-184
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• 1990

This paper presents the recent repair and maintenance techniques of R/C structures in Korea. This paper consists of four parts : the first part introduces the current diagmosis techniques, the second one includes the repair methods and the third one classifies the repair material. Finally a repair case of the R/C structure in a chemical plant in Korea was introduced.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.414-417
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• 1996

It is the aim of this study to introduce the performance and application of new repair system for the exterior wall by durability failure caused carbonation and salt damage. The elementary performance of this repair system is as follows. (1) Al the layer in the repair are cement based, same with the mother concrete (2) this repair system use SBR admixture (3) This cement and mortar powder for this repair system are premixed and ready to use just adding admixture at the job site.

• International Journal of Concrete Structures and Materials
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• v.18 no.3E
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• pp.207-211
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• 2006

This paper presents an experimental study on the repair performance of sprayed engineered cementitious composites(ECC) serving as a repair material. Sprayable ECC, which exhibit tensile strain-hardening behavior in the hardened state and maintain sprayable properties in the fresh state, have been developed by using a parallel control of micromechanical design and rheological process design. The effectiveness of sprayable ECC in providing durable repaired structures was assessed by spraying the ECC and testing them for the assessment. The experimental results revealed that, when sprayed ECC were used as a repair material, both load carrying capacity and ductility represented by the deformation capacity at peak load of the repaired flexural beams were obviously increased compared to those of commercial prepackaged mortar(PM) repaired beams. The significant enhancement in the energy absorption capacity and tight crack width control of the ECC repair system treated with wet-mix spraying process suggests that sprayed ECC can be effective in extending the service life of rehabilitated infrastructures.

• Journal of the Korea Concrete Institute
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• v.17 no.4 s.88
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• pp.637-643
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• 2005

Reinforced concrete beams or slabs are often strengthened or repaired using polymer modified cement concrete Stresses can develop in the structure by ambient temperature changes because thermal coefficients of the repair material and the existing concrete are typically different. Especially, shear stress often causes debonding of the interface. In this study, a rational procedure was developed where anchors can be designed in strengthened or repaired concrete members to prevent debonding at the interface. The current design procedure considers thicknesses and elastic moduli of the repair material and existing concrete, ambient temperature change, length, and beam-vs.-slab action. The procedure is also applicable to stresses developed by differential drying shrinkage.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2001.10a
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• pp.193-197
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• 2001

The growth in concrete structures repair has prompted major efforts to develop high early strength concrete. The internal or external restraint of thermal shrinkage movements could thus generate tensile stresses in concrete structures if it is used rapid setting repair concrete. Restrained shrinkage and thermal stresses could produce microcracks in concrete which increase its permeability and accelerate its long-term deterioration under weathering and load effects. This study aims at evaluation and increase of the engineering properties of high early strength concrete using regulated set cement.

• International Journal of Concrete Structures and Materials
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• v.2 no.1
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• pp.3-8
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• 2008

Polymer-cement composites are known repair materials. The aim of this work is to investigate the influence of various amount of dispersion of carboxylated styrene-butadience copolymer on the selected mechanical properties of polymer-cement concrete (PCC) and on its adhesion to ordinary concrete. The compressive, flexural and tensile strengths as well as frost resistance and fracture resistance of the composites are tested. Adhesion strength of PCC to ordinary concrete, as one of most important performance of good repair material is evaluated and analyzed using three test methods. The results obtained in standard pull-off test are compared with the two other tests. The first one, which is an adaptation of WST (wedge splitting test) characterizes crack propagation in the plane of bond created during repair. In the second test the resistance to shear is a measure of adhesion strength.