• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.283-284
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• 2018

The rear side surface of tiles act have protrusions that helps secure the adhesion between the tile and the mortar for tile setting. Conventional height of the rear side usually ranges between 1 to 1.5 mm, and the molding method is classified in between press type and compression type during the manufacturing process, with most tiles being produced by the former method. In sites where adhesion failures were observed, tiles were taken to examine the cause of defect. It was determined that height was irregular at the rear side surface. Based on these findings, an experiment was conducted to determine the correlation between the rear surface and the bonding strength of tiles.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.98-99
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• 2015

In the study, based on analysing bond strength of MPC and existing rapid harding grout according to shape of cross section, early ages shape of cross section is investigated about effect on bond strength to use MPC as an emergency repair material for road defects such as the form of a pot-hole. The result, MPC is about 10% higher than the shear bond strength rapid harding grout, about 20% higher bending bond strength.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.11a
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• pp.165-166
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• 2017

The purpose of this study is to investigate the effect of tile adhesion failure due to weak adhesion with concrete admixture (FA, SP) on walls. The test specimens were divided into four types : (1) OPC 100% (2) OPC 80%+FA 20% (3) OPC 80%+SP 20% (4) OPC 60%+SP 40%, each adhered on a 650 × 650mm wall with 200mm thickness capable of attaching two insulation tiles (300 × 600mm). The tests were carried out on the four types of walls by mortar bedding application method, and after 4 weeks of curing period, adhesion strength test was carried out. The adhesion strength difference was investigated between the concrete wall with added admixture (FA, SP) and general concrete wall.

• Journal of the Korean GEO-environmental Society
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• v.23 no.12
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• pp.17-23
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• 2022

This paper analyze the precast panel retaining wall's safety factor changes based on the numerical analysis using PLAXIS 2D software. Numerical analysis conditions include construction method, nail and panel fixing method, backfill material compaction conditions, rainfall conditions. The classification according to the construction method of the precast panel retaining wall includes the top-down and bottom-up methods. The difference between the top-down and bottom-up methods is the presence or absence backfill material and the ground excavation method. The top-down method involves vertically excavating the ground and attaching the panel using mortar, but in the bottom-up method, the ground is vertically excavated and harden the backfill material. As a result of numerical analysis, the top-down method secured a higher safety factor in all cases except the rainfall conditions.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.11a
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• pp.21-22
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• 2020

This study is about high strength self-leveling mortar according to the mixing ratio of polymer. The self-leveling mortar currently released in Korea maintains a compressive strength of 40 Mpa as of 28 days. In addition, the level of bonding strength and flexural strength are kept the same. However, through this study, it is confirmed how the self-leveling mortar with a compressive strength of 60Mpa as of the 28th is shown according to the amount of polymer mixed. Experimental factors were configured according to the amount of polymer mixed, and the types of experiments were to confirm compressive strength, flexural strength, adhesion strength and flow. In addition, by confirming the early strength, a study was conducted to improve the quick workability compared to the self-horizontal mortar in the market.

• Journal of the Korea Concrete Institute
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• v.15 no.3
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• pp.462-469
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• 2003

This paper presents an experimental study on the potential durability enhancement of infrastructures repaired by a sprayed high ductile fiber-reinforced cementitious composite (ECC). For this study, a PVA-ECC which exhibits sprayable properties in the fresh state and tensile strain-hardening behavior in hardened state was sprayed and tested. The experimental results show that the sprayed ECC exhibits mechanical properties with strain capacity comparable to the cast ECC with the same mix design. During loading, the crack widths of ECC are tightly controlled with an average of 30${\mu}m$. It is also revealed that when sprayed ECC is used as a repair material, ductility represented by deformation capacity at peak load of repaired beams in flexure are obviously increased in comparison to those of commercial prepackaged mortar (PM) repaired beams. In addition to high delamination resistance, the significant enhancement of energy absorption capacity and crack width control in ECC repair system suggest that sprayed ECC can be effective in extending the service life of rehabilitated infrastructures.

• Journal of the Korea Institute of Building Construction
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• v.15 no.3
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• pp.299-306
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• 2015

In construction materials area, many research on polymer for cement-based materials have been conducted. In spite of these research, general research scope is limited to the normal strength range, and thus in this research, for both normal and high strength range mixtures, the strength and mechanical properties of high strength cement mortar incorporating Vinyle Acetate-Ethylene(VAE) type powder polymer are evaluated. As a result of experiment, in the case of high strength mixture, as the amount of VAE polymer addition was increased the compressive and flexural strengths were decreased while the tensile and bonding strengths were increased because of the formation of the polymer membrane inside of the mortar matrix.

• Journal of the Korean Recycled Construction Resources Institute
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• v.12 no.3
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• pp.314-321
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• 2024

Due to the depletion of natural aggregate resources, the use of recycled aggregates became an urgent issue. Microcracks generated during production of recycled aggregate and cement paste attached to the surface of aggregate have been the biggest obstacles to promote the use of recycled aggregate. To alleviate such problem, this study attempted the spray and immersion treatment of recycled fine aggregate using mono-ammonium phosphate solution, which is known to be effective for reducing the pH of recycled aggregate. The changes in physical properties before and after treatment were observed, and the compressive strength of mortar specimen was evaluated. According to the experimental results, the absorption capacity of the recycled fine aggregate increased with reduction in pH after mono-ammunium phosphate treatment. Calcium hydroxide and ettringite was removed, and skeletal density of recycled fine aggregate increased due to the formation of hydroxyapatite. Despite the increase in absorption capacity, the compressive strength of the mortar increased and it seems to be associated with the increase in adhesion strength at the interface between cement paste and recycled fine aggregate. When the concentration of ammonium monophosphate aqueous solution was excessive (immersion: 15% and 20%, spraying 20%), the compressive strength of the mortar decreased, which seemed to be related to the increase in the absorption capacity caused by the the excessive dissolution of the hydration products such as portlandite and ettringite.

• Journal of the Korea Concrete Institute
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• v.23 no.5
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• pp.675-682
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• 2011

Recently, in retrofit of RC structures using FRP (Fiber Reinforced Polymer), researches about Near-Surface-Mounted Rertofit (NSMR) method have been widely performed. In NSMR, FRP bar is normally inserted in the slit formed in the cover concrete and then bonded by using epoxy mortar. In this paper, the bond characteristic of NSMR using FRP plate instead of bar was studied experimentally. Fracture behavior is observed from bond test using the parameters of embedment length, shear key, and FRP plate layer. In addition, an equation to predict the splitting strength of NSMR using FRP is proposed using the test result. The results showed that when the longer embedment length and more layers of FRP are used, the higher bond strength is achieved. There was a good co-relationship between the test and calculated results using the proposed equation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.37-43
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• 2020

The seismic reinforcement ratio of SOC facilities, such as domestic roads and railroads, is 96%. Out of approximately 7 million buildings as of 2016, only 0.51 million buildings with seismic performance were secured. Although the proportion of masonry structures is 38.8% of the total buildings, there is almost no seismic resistance, only 2.0%. To solve the problem in Korea, government-level seismic measures are being promoted, but the situation is insufficient. Overseas, the UBC research team in Vancouver, Canada, has developed and used EDCC to reinforce the seismic performance of masonry buildings. EDCC is a construction material that can secure concrete ductility capability by mixing fibers and secure deformation resistance of concrete through bridging action. It is necessary to examine various materials because EDCC is not used as a spray type of secure seismic reinforcement. In this study, as part of the research and development of spraying materials to improve the durability of masonry buildings, this study examined the spraying characteristics of fiber-reinforced mortar according to fiber use and the viscosity change according to the use of thickener. As a result, the working performance of the fiber-reinforced mortar for seismic reinforcement was improved when using 1% fiber and 1% thickener.