• Advances in concrete construction
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• v.15 no.6
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• pp.377-389
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• 2023

In this study, an improved modular arch system with the lower arch space composed of a precast arch block and an outrigger was proposed as an underground culvert, and its applicability and structural behaviors were confirmed. This modular arch culvert structure with vertical walls was designed using precast blocks and by adjusting the placement spacing of concrete blocks to the upper part form an arch shape and the lower part form a vertical wall shape, based on previously researched modular arch systems. Owing to the vertical wall of the proposed modular arch system, it is possible to secure a load-carrying capacity and an arch space that can sufficiently resist the earth pressure generated from the backfill soil and loading on the arch system. To verify the structural characteristics, and applicability of the proposed modular precast arch culvert structure, a full-scale modular culvert specimen was fabricated, and a loading test was conducted. By examining its construction process and loading test results, the applicability and constructability of the proposed structure were analyzed along with its structural characteristics. In addition, its the structural predictability and safety for the applicability were evaluated by comparing the construction process and loading test results with the FE analysis results.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.720-728
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• 2009

This thesis is results of numerical analyses about test results of discharge capacity apparatus using penetration method. Applicability of numerical approach with FEM technique, using Cam-clay model, was confirmed by analyzing the results of standard consolidation test before analyzing test results of discharge capacity apparatus using penetration method. Thus, input parameters for the model was convinced to be appropriate. For numerical analyses about test results of discharge capacity apparatus using penetration method, identical initial and loading conditions during tests were applied to simulate test results correctly. Effects of ground disturbance resulted from installment of vertical drains on the behaviors of consolidation were also simulated. Applicability of numerical approach was investigated by comparing test results with numerical ones. As results of them, both of consolidation settlement were found to be in good agreements so that its applicability was confirmed. As results of numerical estimation, degree of consolidation with the condition of considering smear zone was found to be delayed, compared with results without smear zone. On the other hands, parametric numerical analyses of changing parameters related to smear zone such as permeability and size of smear zone and permeability of vertical drain were also carried out.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.1333-1342
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• 2010

It required excessive cost and effort to evaluate the quality of shotcrete mix for field test. Also, due to a myriad of field variables, it is difficult to get a standardized result for field test. And it is impossible to simulate the shotting process for indoor test. In this study, in order to overcome these problems, we developed a standardized Shotcrete Shotting Test Machine. Using this machine we performed shotcrete quality test and estimated the applicability of developed Shotcrete Shotting Test Machine by comparing with the results of field test.

• International Journal of Highway Engineering
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• v.16 no.4
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• pp.21-33
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• 2014

PURPOSES: The purpose of this study was to break away from the workforce method using cold-mix asphalt mixtures and has a constant quality and has develop repair materials of pre-production asphalt-precast types. METHODS: The selection of the repair material was determined as the results obtained through physical properties of materials and the field applicability. In case of repair materials, values obtained through Marshall stability test & the dynamic stability test & retained stability test as well as the site conditions was considered. In case of adhesive, test results were obtained through examination of the bond strength(tensile, shear) and the field applicability of the adhesive was examined through combined specimens to simulate field applications. RESULTS : According to the results of laboratory tests, in the case of repair materials, Marshall stability and dynamic stability, retained stability of cold-mix reaction type asphalt mixture is the highest. In the case of adhesive, two-component epoxy-urea has a very high bonding strength(tensile, shear) was most excellent. According to the results of field tests, when epoxy-urea was excellent workability. Also, the repair body through actual mock-up test did not occur large deformation and fracture after 12 months. CONCLUSIONS : A suitable repair material is cold-mix reaction type mixture of asphalt-precast, a suitable adhesive is a two-component epoxy-urea.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.601-604
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• 2006

Reinforcement corrosion is the most important durability problem of reinforced concrete structures. One of the important factors affecting the steel corrosion is carbonation. However, existing carbonation test takes several months to obtain the results. Therefore, in this study, new rapid carbonation test equipment for concrete was developed and its applicability was investigated. The testing period can be reduced by increasing $CO_2$ concentration up to 100% in the equipment. It is found from the test results that the carbonation depth of concrete specimens tested for 2 weeks was $3{\sim}5$ times greater than that of specimens tested by existing test method. In conclusion, it would be possible to get the reliable test results enough to evaluate the durability of concrete structures in a short-period.

• Proceedings of the KSR Conference
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• 2003.10b
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• pp.141-145
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• 2003

Step-by-step laboratory performance test and repetitive improvement of KRRI rail fastening system show that it has the similar capability as other fastening systems that have been globally used. In this study, for the evaluation of field applicability, construction and rolling-stock operation test of KRRI rail fastening system are performed. Through this approach, comparison against the service criteria of foreign countries are made.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.3166-3171
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• 2011

The design standard for the thickness of reinforced roadbed is divided into high-speed and conventional railroad because dynamic characteristics of train loadings differ depending on the train speed. Due to the national plan for increasing the train speed for both conventional and new railroad lines, it is necessary to examine the applicability of concrete tracks and feasibility of the train speed increase on the conventional lines with the current thickness of the reinforced roadbed. In this study, a real-scale test was performed to monitor the dynamic characteristics of the reinforced roadbed with a thickness of 20cm and the train speed of 200km/h, 300km/h, and 400km/h. The test results were then compared with the design code to investigate the applicability of the conventional reinforced roadbed when the trains operate with higher speed.

• International Journal of Highway Engineering
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• v.19 no.2
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• pp.7-15
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• 2017

PURPOSES : Infiltration of moisture, polluted material, and deicer into concrete, accompanied by freeze and thaw can cause significant deterioration of concrete pavement. In order to protect concrete from deterioration, it is necessary to prevent the infiltration of these concrete external materials. The moisture-repellent agent, which is a surface treatment and maintenance material added to concrete structures to render them water resistant, has advantages such as prevention of water infiltration and security against air permeation. Nano-coat, which is referred to as silicon hydride, is typically used as a moisture-repellent agent. Therefore, in this study, an attempt is made to use penetration-type Nano-coat as an alternative in order to evaluate its applicability through environmental resistance tests. METHODS : This study aimed to evaluate the applicability of penetration-type Nano-coat, which can provide water repellency to concrete, in concrete pavements, through various environmental resistance tests such as freezing and thawing resistance, chloride ion penetration resistance, and surface scaling resistance tests. The applicability of penetration-type Nano-coat was demonstrated based on the specification of KS F 2711, KS F 2456, and ASTM C 672. RESULTS :In the case of penetration-type Nano-coat applied on sound concrete, an increase in concrete durability was demonstrated by the negligible chloride ion penetrability and the absence of scaling, as revealed by visual observation of the surface, after 50 cycles of scaling resistance test. In addition, test result of the application of penetration-type Nano-coat on deteriorated concrete established that concrete surface pretreated by grinding provided improved durability than non-treated concrete. CONCLUSIONS :This study indicates that penetration-type Nano-coat is applicable as an effective alternative, to increase the durability of concrete structures. In addition, it was known that pretreatment of deteriorated concrete surface, such as grinding, is required to improve the long-term performance of concrete pavement.

• Journal of Korean Society of Rural Planning
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• v.5 no.1 s.9
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• pp.45-55
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• 1999

The applicability of resistivity cone for contaminant investigation in farm land was examined in laboratory and in-situ. To verify the resistivity variations in sand with contaminants, laboratory experiment used soil resistivity test box was performed. Heavy metal and others ions were appeared steep variations in low concentration. Pilot test results were the same as laboratory test results. In the in-situ test used resistivity cone, resistivities of waste landfill layer were low than the common soil layers and resistivities had been difference with concentration of contaminant components. Therefore contaminant investigation in farm land using resistivity cone was expected very effective.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.11a
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• pp.21-22
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• 2018

In this study, the characteristics of the Mock-up test were reviewed to analyze the applicability of the coal gasification slag (CGS) from the integrated gasification combination Cycle (IGCC) to the concrete fine aggregate. The analysis shows that CGS and crushed sand mix is the best combination of CGS combined with about 50 % of CGS based on the effects of promoting liquidity and strength. This is expected to be a positive factor in securing the strength and flexibility of concrete given the optimal mix of CGS, and may also contribute to the improvement of quality.