• Proceedings of the Korea Concrete Institute Conference
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• 한국콘크리트학회 1998년도 가을 학술발표대회 논문집(III)
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• pp.785-790
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• 1998

Ground Penetrating Radar (GPR) is a powerful tool with a wide range of applications in the nondestructive testing of concrete. It's useful for the detection of steel bars and delaminations embedded inside concrete, nondestructively. The purpose of this study is to detect a reinforced bar embedded inside concrete and to determine the range of application using GPR. A concrete specimen used for this study has a 25mm diameter steel bar and it's dimensions are 1,000 mm (L)× 1,000 mm(W)×280 mm(D). The advantages and limitations of GPR in these applications for concrete are also discussed.

• Proceedings of the Korea Concrete Institute Conference
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.529-532
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• 2001

In this paper, rust-protection performance of concrete using ground granulated blast-furnace slag are discussed. 4 kinds of W/B in combination with 3 kinds of replacement ratio of ground granulated blast-furnace slag and 2 kinds of chloride ion contents of are selected as experimental parameters. According to the experimental results, as the replacement ratio of ground granulated blast-furnace slag is increased, the corrosion area of steel bar tends to be decreased. However, as the autoclave cycle and chloride ion contents are increased, the corrosion area of steel bar is increased. In conclusion, when the replacement ratio of ground granulated blast-furnace slag is 50%, the strength and rust-protection performance appear to be most excellent.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2007년도 정기총회 및 학술발표대회
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• pp.433-436
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• 2007

We analyzed the sloped ground safety factor, which is not presented in the design specification, using a computational analysis program L-Pile Plus 13.8. To achieve this we chose a required parameter set and a level ground safety factor presented in the design specification, and then determined its values comparing with the change of the safety factor according to the parameter. Using these parameters, we estimated the sloped ground safety factor for the slope of 35 degrees considering the improvement value of the slope presented in the design specification. As a result of this analysis, we obtained the smaller safety factor by about 0.7 times than the case of the level ground and verified that a number of concrete poles fail to assure 1 degree of the safety factor. We, therefore, concluded that an adjustment of the embedment depth is required in the case of the sloped ground.

• Computers and Concrete
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• 제31권4호
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• pp.327-335
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• 2023

The most popular building material, concrete, is intrinsically linked to the advancement of humanity. Due to the ever-increasing complexity of cementitious systems, concrete formulation for desired qualities remains a difficult undertaking despite conceptual and methodological advancement in the field of concrete science. Recognising the significant pollution caused by the traditional cement industry, construction of civil engineering structures has been carried out successfully using Geopolymer Concrete (GPC), also known as High Performance Concrete (HPC). These are concretes formed by the reaction of inorganic materials with a high content of Silicon and Aluminium (Pozzolans) with alkalis to achieve cementitious properties. These supplementary cementitious materials include Ground Granulated Blast Furnace Slag (GGBFS), a waste material generated in the steel manufacturing industry; Fly Ash, which is a fine waste product produced by coal-fired power stations and Silica Fume, a by-product of producing silicon metal or ferrosilicon alloys. This result demonstrated that GPC/HPC can be utilised as a substitute for traditional Portland cement-based concrete, resulting in improvements in concrete properties in addition to environmental and economic benefits. This study explores utilising experimental data to train artificial neural networks, which are then used to determine the effect of supplementary cementitious material replacement, namely fly ash, Ground Granulated Blast Furnace Slag (GGBFS) and silica fume, on the compressive strength, tensile strength, and modulus of elasticity of concrete and to predict these values accordingly.

• Earthquakes and Structures
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• 제6권1호
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• pp.1-18
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• 2014

The main focus of this paper is the analysis of the different components of the variability for strong ground motions recorded from earthquakes produced by the Vrancea subcrustal seismic source. The analysis is performed for two ground motion prediction equations: Youngs et al. (1997) and Zhao et al. (2006), recommended within the SHARE project for the Vrancea subcrustal seismic source and which are proposed in the work of Delavaud et al. (2012) and graded best in Vacareanu et al. (2013c). The first phase of the analysis procedure consists of a grading procedure. In the second phase, the single station sigma procedure is applied for both attenuation models in order to reduce some parts of ground motion models' variability produced by the ergodic assumption. The strong ground motion database which is used throughout the study consists of over 400 accelerograms recorded from 9 Vrancea intermediate-depth seismic events. The results of the single station sigma analysis show significant reduction of the standard deviations, especially in the case of the Youngs et al. (1997) attenuation model, which is also graded better than the other selected GMPE.

• Proceedings of the SAREK Conference
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.58-63
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• 2009

A ground-loop heat exchanger for the ground source heat pump system is the core equipment determining the thermal performance and initial cost of the system. The size and performance of the heat exchanger is highly dependent on the ground thermal properties - the ground effective thermal conductivity, the borehole thermal resistance and the undisturbed ground temperature. Nowadays, precast concrete piles using steel reinforced precast concrete piles - energy piles - are used to reduce the installing cost of the ground-loop heat exchanger. We were carried out some tests to investigate the effects of some parameters such as borehole length, grouting materials and U-tube configuration of the energy piles. 4 concrete piles, each measuring $250mm{\sim}400mm$ in diameter and approx. 10m in length, and rigged with single spiral and 3 U-tube loop of $16mm{\times}2.3mm$ PB piping. The thermal response tests were conducted using a testing device for 4-different ground-loop heat exchangers. During the heating period, the energy piles absorb the heat of 0.89kW to 1.37kW.

• Tunnel and Underground Space
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• 제20권1호
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• pp.58-64
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• 2010

GLI model was verified to consider the interaction between a ground and a tunnel lining and to rationally reduce the ground load acting on the secondary lining(concrete lining) of a tunnel. In this study, the economy and the construction condition of tunnel concrete linings designed by a conventional frame model at Lot O of OO line were highly enhanced through a field design change using GLI model. For a few safe considerations, not only about 50% saving of reinforcing steel could reduce the material cost but also the wide space between bars could make it easy to pour concrete mix without voids. There was large saving effect of reinforcing steel for poor ground conditions because Terzaghi's load used in the conventional frame model produces too much high loads for those conditions.

• Proceedings of the Korean Geotechical Society Conference
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.87-96
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• 2010

PAP method is a combined measures which consist a anchored retaining wall method with permanent ground anchors and vertical precast concrete panels, step by step on the slope surface. And soil is back filled between slope and vertical precast panels. Therefore, this method is more effective than any other ground anchor reinforcing methods of slope stability, for example cross type concrete block ground anchor or buttress concrete block ground anchor method. Because of increasing effective anchor force and green tree planting.

• Journal of the Korea institute for structural maintenance and inspection
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• 제6권2호
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• pp.195-202
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• 2002

Urbanization and development of industry makes people concerned about quality of circumstances. Problems of vibration are on the rise. Vibration makes inhabitants feel unpleasant and involves structural damage. The purpose of this study is to assess damage of reinforced concrete structures due to ground motions as the parameters of frequency, duration time and aspect ratio of structures are changed. Ground motions were modeled as sine waves. To compare sine waves with real ground motions, two cases are selected; one is blast loading case and the other is earthquake loading. It was intended to provide means to assess R/C structure damage due to ground motions.

• International Journal of Concrete Structures and Materials
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• 제18권2E호
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• pp.125-132
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• 2006

Waste glass has been increasingly used in industrial applications. One shortcoming in the utilization of waste glass for concrete production is that it can cause the concrete to be weakened and cracked due to its expansion by alkali-silica reaction(ASR). This study analyzed the ASR expansion and strength properties of concrete in terms of waste glass color(amber and emerald-green), and industrial by-products(ground granulated blast-furnace slag, fly ash). Specifically, the role of industrial by-products content in reducing the ASR expansion caused by waste glass was analyzed in detail. In addition, the feasibility of using ground glass for its pozzolanic property was also analyzed. The research result revealed that the pessimum size for waste glass was $2.5{\sim}1.2mm$ regardless of the color of waste glass. Moreover, it was found that the smaller the waste glass is than the size of $2.5{\sim}1.2mm$, the less expansion of ASR was. Additionally, the use of waste glass in combination with industrial by-products had an effect of reducing the expansion and strength loss caused by ASR between the alkali in the cement paste and the silica in the waste glass. Finally, ground glass less than 0.075 mm was deemed to be applicable as a pozzolanic material.