• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.527-530
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• 2005

Shotcrete have become a deterioration which is used in the underground such as groundwater and soil in sulfate ion. Sulfate attack on concrete structures in service is not widespread, and the amount of laboratory-based research seems. to be disproportionately large. In this study, immersion test using $Na_2SO_4$ solution($1,2,5\%$) was performed to evalute the resistance of shotcrete. From the results of the immersion test for 112 days of exposure. In order to understand the deterioration mechanism due to seawater attack, test using scanning electron microscopy(SEM) analysis and X-ray diffraction showed that the deterioration mechanism due to sulfate attack in shotcrete.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1291-1298
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• 2005

Shotcrete for the support of tunnel can contact with groundwater. The hazardous components in the groundwater cause the corrosion of shotcrete. Also, the hazardous components may deteriorate the engineering properties of shotcrete, such as compressive strength, bond strength, and flexural strength. The more the effect of the hazardous components on the shotcrete may increase, the more the stability of tunnel structure may decrease. It was analyzed to find the hazardous components in the ground water. The uniaxial compressive strength test, XRD, SEM were conducted to evaluate the durability and corrosion of shotcrete. These tests were performed on shotcrete specimens at 2, 4, 8, and 16 weeks. The specimens were immersed in various chemical solutions including hazardous components after the specimens were made at the construction site.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.622-628
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• 2004

In general, Reinforced Slopes by Shotcrete are difficult to inspect because of stiff Slope and highly Working Area. So the Inspection Techniques are needed by the Non-contact and Non-destructive. On this Study, Appling the safety method to finding the weak zones(cavity area, dampness area, etc.) by using the Infrared Thermal Technique That is detecting the Detail Thermal Difference on the Surface of Reinforced Slopes by Shotcrete.

• 한국터널공학회:학술대회논문집
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• 2005.04a
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• pp.259-261
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• 2005

The needs of improving the performance of wet shotcrete has become one of the most important issues in the tunnel field. The aim of this paper is to research the construction method of reinforced shotcrete using structural polymer fiber which exhibits a high quality in toughness and durability for the support of tunnel.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.373-378
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• 2003

The cement-based composites have relatively low tensile strength and toughness. The fiber addition is one of the most important ways of increasing the toughness of concrete. The steel fibers have been used conventionally in the shotcrete of tunnel lining. Recently, the structural synthetic fibers were developed and used frequently in some actual tunnel shotcreting in foreign countries. Now types of synthetic fibers have been developed in this study. The purpose of this study is to explore the strength and toughness characteristic of the concrete reinforced with synthetic fibers developed in this study. The result were compared with those of steel fiber reinforced concrete. It is seen that the performance of synthetic fiber reinforced concrete is good as much as that of steel fiber reinforced concrete, while the synthetic fibers have advantages in corrsion resistance and economy.

• Journal of Industrial Technology
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• v.33 no.A
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• pp.93-99
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• 2013

Shotcrete has been referred to as gunite, pneumatically applied mortar or concrete, sprayed concrete or mortar. There are sound reasons why sprayed mortar is one of the best portland cement based material for repairing old concrete structures. However, it is difficult to find the research results on the latex-modified mortar nevertheless on the impact of air onto the fresh and hardened properties of latex-modified mortar. So, the main experimental program included strength test, slump test, rapid chloride permeability test, image analysis for air void system, and chemical attacks with the main experimental variables of latex content, fine aggregate content, water-cement ratio, and air foamer content.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.48-57
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• 2009

The quality control of tunnel support construction is very important to maintain a long term stability of tunnel. Especially, steel fiber reinforced shotcrete should be necessary to investigate practically the condition of quality control in the construction site. In order to perform this study, the design criteria and specifications relevant to steel fiber reinforced shotcrete are reviewed. And the comparison is made between the bearing capacity of the several shotcrete layers, based on the equivalence of the bending moments. Eight tunnel construction sites are also investigated carefully to examine and analyse the characteristics of steel fiber reinforced shotcrete especially including strength and mixing condition of steel fiber. Based on the results, it is founded the items to be improved in the future. In addition, the modification program for the specifications of steel fiber reinforced shotcrete is suggested.

• Journal of the Korean Ceramic Society
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• v.45 no.6
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• pp.350-357
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• 2008

The use of shotcrete-sprayed concrete for the support of underground excavations was pioneered by the civil engineering. Now, for the nuclear wastes disposal plant in our country, watertightness of shotcrete is one of the very important properties. This study evaluated the watertightness of shotcrete using cement mineral accelerator with watertightness materials for the long-term watertightness. In this study, for improvement of watertightness of shotcrete, it used two types of obtainable at a store. Watertightness tests of shotcrete were performed the water absorption coefficient, permeability, porosity and hydrates variation. In a shotcrete containing watertightness materials, watertightness of shotcrete was improved about $15%{\sim}65%$ rather than plain shotcrete.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.1162-1167
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• 2004

From the early 1980's, the New Austrian Tunnelling Method (NATM) has been developed as a one of the standard tunneling method in Korea. Owing to the results of many researches, the practical problems of shotcrete has been improved for a last decade. However, the excess amount of rebound still remains one of the critical problems in shotcrete technology. In order to improve for this rebound problem, recently developed cement mineral accelerator has been successfully applied to several NATM tunnels in Korea. An experimental investigation was carried out in order to verify the rebound characteristics of wet-mix Steel Fiber Reinforced Shotcrete (SFRS) with powder types cement mineral accelerator. Mortar setting test, SEM analysis, bonding test under spring water condition and rebound test were conducted. From the result, wet-mix SFRS with cement mineral acelerator exhibited excellent bonding characteristics even spring water condition and less rebound ratio compared to the conventional liquid accelerator.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.845-848
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• 2008

In this study, through the Batch Plant in field which is carrying out in the country, this research is going to grope the development of Ready-mixed Shotcrete that can improve the construction of shotcrete, and long-term durability. Accordingly, in this study, the Batch Plant in field which is only for shotcrete will be chosen in random so that can be aware the problems of the Batch Plant in field, and when the results come out, the shotcrete system will be prepared that is based on the results of rsearch, and also can be used in preparation index of shotcrete. Moreover, the results will be able to improve an efficent tool that can increase shotcrete quality.