• Journal of the Korean Geotechnical Society
• /
• v.23 no.10
• /
• pp.65-72
• /
• 2007

Large-scale direct shear tests were conducted in order to investigate both the shear strength of soil itself and the friction behavior at the interface of soil/geosynthetics in respect of efficiency in this study. Sand, crushed stone and three types of geotextile (i.e. one woven geotextile and two nonwoven geotextiles) were used in the experimental program. The considered interfaces for the evaluation of interface shear strength in this study included sand/sand, crushed stone/crushed stone, sand/woven geotextile, crushed stone/woven geotextile, crushed stone/nonwoven geotextile-A and crushed stone/nonwoven geotextile-B. The results showed that the efficiency of 84% was obtained at the interface of sand/woven geotextile compared with the shear strength of sand itself (i.e. sand/sand interface). The efficiencies of 74%, 83% and 72% were obtained at the interface of crushed stone/nonwoven geotextile-A, crushed stone/nonwoven geotextile-B and crushed stone/woven geotextile, respectively compared with the shear strength of crushed stone itself (i.e. crushed stone/crushed stone interface).

• Journal of the Korean Geosynthetics Society
• /
• v.3 no.2
• /
• pp.3-11
• /
• 2004

Fabric Foam systems provide a variety of flexible bank protection for open channels and hydrulic structures. The structural performance and durability of conventional bank protection materials such as concrete, gravel, riprap and vegetation can be significantly improved by confining the materials within the cells of Fabric Foam system. This paper presents the results of field and laboratory tests carried out to evaluate the performance of new Fabric Foam System as a Bank Protection. The results of the tests confirmed effect of Fabric Foam System in Bank Protection.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.26 no.6A
• /
• pp.1033-1039
• /
• 2006

The purpose of this study are to evaluated bond, flexural properties and control of plastic shrinkage cracking of crimped type synthetic fiber with amplitude 6 mm and height 1.8 mm reinforced cement based composites. Bond and flexural test were conducted in accordance with the JCI-SF 8 and JCI SF-4 standard, respectively. The plastic shrinkage cracking test was conducted for evaluating the effect of fiber in reducing shrinkage cracking in cement based composites. Test results indicated that the crimped typel synthetic fibers performed significantly better than the straight type fiber in terms of interface toughness and pullout load and the crimped type synthetic fibers improved the flexural toughness of concrete. Also, the increasing the crimped type synthetic fiber volume fraction from 0.00% to 1.00% improved the plastic shrinkage cracking resistance. Specially, the effect of control of plastic shrinkage cracking is excellent at the more than 0.5% fibre volume fraction.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.9 no.4
• /
• pp.602-608
• /
• 2021

Recently, research and development has been conducted to impart high performance and functionality to concrete materials by mixing various reinforcing materials into the matrix. Ductile fiber reinforced concrete using a large amount of fibers shows a distributed multiple cracking behavior, and various studies are being conducted on this material. However, research is focused on static behavioral analysis but studies on cyclic behaviors are not sufficient. In this study, beams were made of ductile fiber reinforced concrete with various fiber contents, and static and fatigue flexural tests were performed. As a result, the effect of fiber content on the flexural behavior was analyzed. Also, the applied load level and fatigue life relationship of ductile fiber reinforced concrete was proposed. Concrete with high ductile property could be achieved with a fiber content of 2%. When 0.5% fiber was more added, the maximum flexural strength was similar, but the flexural toughness is nearly doubled. On the other hand, there was no significant difference in the fatigue life of these two mixtures.

• Journal of the Korean Geotechnical Society
• /
• v.16 no.4
• /
• pp.107-116
• /
• 2000

In this study, the permeability reduction in the soil-filter systems due to clogging phenomenon was evaluated. An extensive research program was performed using two typical weathered residual soils which were sampled at Shinnae-dong and Poi-dong area in Seoul. Two separate simulation tests with weathered residual soil were performed: one was the filtration test(cross-plane flow test); and the other was the drainage material in the field. The compatibility of the sol-filter system was investigated with emphasis on the clogging phenomenon. The hydraulic behaviour of the soil-filter system was evaluated by changing several testing conditions. Also, experimental results of the permeability reduction are compared with the results obtained from the theoretical model which can monitor the spatial variation of the permeability with time.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.8 no.4
• /
• pp.545-552
• /
• 2020

This study evaluated the support performance of fiber-net integrated shotcrete in tunnel support system developed for the purpose of improving constructability and stability while fully performing its mechanical performance as a tunnel support materials by four-point bending test, two-dimensional numerical analysis, and cross-sectional analysis. As a result of evaluating the flexural performance through a four-point bending test, in the case of fiber-net reinforced shotcrete, the tensile performance of fiber-net resulted in a continuous increase in load after crack occurrence, unlike steel fiber reinforced shotcrete. Also, the results of the tunnel cross-sectional structure analysis for ground conditions and the cross-sectional analysis of fiber-net and steel fiber reinforced shotcrete showed that sufficient support performance can be exhibited even if the thickness of fiber-net reinforced shotcrete was reduced compared to the previous one. Additionally, through these results, the support pattern of fiber-net integrated shotcrete in tunnel support system, which can be applied efficiently to the construction sections requiring higher stability among the rock mass class III, was proposed.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.33 no.4
• /
• pp.1665-1673
• /
• 2013

Recently, the interest and demand on free formed structure providing aesthetic value as well as functionality has been increasing. Formwork has numerous advantages such as high strength, convenience, accuracy and good quality of surface roughness. Nevertheless, it increases construction cost and period to build complex shapes. For these purpose, deposition construction systems such as Contour Crafting and Concrete Printing have been developed with active collaboration between university and industry by applying the rapid prototyping technology to the construction industry in USA and England. Since there has been no related research in Korea, the possibility of spin-off technology and its fusion cannot be expected. In this paper, design elements including mechanical system and control system related to automatic deposition construction system prototype for constructing a free curved structure without mold are described. As for an appropriate material for the system, fiber reinforced mortar was selected by experiments on compressive strength, fluidity, viscosity and setting time. By performing transfer and extrusion experiments, the possibility of the development of deposition construction system was demonstrated. Based on this research results, it is required to keep the automatic deposition construction system improve and extend it into the new application area in construction industry.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.6A
• /
• pp.861-872
• /
• 2008

Concrete-filled glass fiber reinforced polymer tubes are often used for marine structures with the benefit of good durability and high resistance against corrosion under severe chemical environment. Current research presents results of a comprehensive experimental investigation on the behavior of axially loaded circular concrete-filled glass fiber reinforced polymer tubes. This paper is intended to examine several aspects related to the usage of glass fiber fabrics and filament wound layers used for outer shell of piles subjected to axial compression. The objectives of the study are as follows: (1) to evaluate the effectiveness of filament winding angle of glass fiber layers (2) to evaluate the effect of number of GFRP layers on the ultimate load and ductility of confined concrete (3) to evaluate the effect of loading condition of specimens on the effectiveness of confinement and failure characteristics as well, and (4) to propose a analytical model which describes the stress-strain behavior of the confined concrete. Three different types of glass fiber layers were chosen; fabric layer, ${\pm}45^{\circ}$ filament winding layer, and ${\pm}85^{\circ}$ filament winding layer. They were put together or used independently in the fabrication of tubes. Specimens that have various L:D ratios and different diameters have also been tested. Totally 27 GFRP tube specimens to investigate the tension capacity, and 66 concrete-filled GFRP tube specimens for compression test were prepared and tested. The behavior of the specimens in the axial and transverse directions, failure types were investigated. Analytical model and parameters were suggested to describe the stress-strain behavior of concrete under confinement.

• Proceedings of the Korean Society of Dyers and Finishers Conference
• /
• 2012.03a
• /
• pp.92-92
• /
• 2012

나노필라멘트 섬유는 직편물 등으로 구조/용도 다양화 가능하다. 나노필라멘트 섬유는 소재특유의 닦음성, 흡착성, 고밀도 특성 등을 활용하여 직편물의 형태로 다양한 용도 개발이 가능하며, 나노기술을 접목시킨 새로운 기능성과 고성능 섬유 소재 개발을 통한 자동차 분야의 개발 트랜드인 고급화, 경량화, 고성능화 추진을 위해 연료전지, 신슐레이터, 고성능 필터, 시트나 도어트림, 헤드라인과 같은 인테리어류와 전자 분야의 제조원가 절감, 공정 단순화를 위해 프린터 토너, 하드디스크 연마제, 다용도 No Dust Cleaner 등의 개발, 의료/바이오 분야의 혈액필터, 수술용 보호제, 창상억제제(유착 방지막), 항균마스크, 의료용 약물전달 시스템 및 환경 분야의 정수/공기 정화 시스템, 건축 토목용 보강제, 고(高)인성 콘크리트, 폐수처리용 슬러리 담체(Matrix) 등 다양한 분야로 용도 개발이 가능하다. 본 연구는 나노필라멘트의 다양한 분야로의 용도 개발 적용의 기초연구로서, 부직포 상으로 얻어지는 나노섬유 제조기술의 단점인 직경의 불균일, 물리적 특성의 한계와 필라멘트가 아닌 단섬유로 인해 발생하는 용도 및 상품 개발에의 제한성을 개선하기 위하여 연속적으로 필라멘트를 생산가능한 해도형 복합방사 방법을 도입하여 개발한 장섬유 필라멘트 형태의 해도형 나노 섬유 소재를 활용하는 것으로 방사된 SDY 형태의 나노필라멘트 섬유를 제직상에서의 작업성 용이 및 직물의 벌키성 증대와 Crimp성을 향상 시켜 터치감 및 후가공에 용이할 수 있도록 DTY를 제조함에 있어 기존 일반 POY사에서의 DTY공정과는 달리 소재의 특성 즉, 해도사의 해성분 및 도성분의 후공정을 감안하여 최적의 Crimp는 발현하되 단면의 형상을 유지할 수 있는 다양한 사가공 조건을 설정 하고 이에 따라 가공사를 생산하여 공정조건에 따른 가공사의 물성 및 수축특성을 비교 분석 하여 염색 및 후가공시 소재의 물성 및 수축특성이 미치는 영향성을 살펴보고자 하였다.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.26 no.6C
• /
• pp.385-393
• /
• 2006

Soil nailing is a reinforcement method used for stabilizing excavated walls or slopes. Due to its much advantages such as ease of construction and economical efficiency, use of soil nailing is increased. However, the soil nail has much disadvantages for use in urban area. The soil nail needs to be installed inevitably beyond private land boundary, which causes rent for use. For this reason, removable soil nailing system was developed. However, the removal rate of this system is just about 50￠¦70%. To resolve this problem, the Fiber Reinforced Plastic (FRP) soil nailing system which does not need to be removed and allows for the installation beyond private land, is developed. In this paper, through theoretical and experimental studies in laboratory and field such as prototype tests, pullout tests, we evaluate the stability and behavior characteristics of the FRP soil nailing system. And, numerical analyses using FLAC2D were performed with respect to various soil conditions, where prototype test for excavation wall and pullout tests were carried out. As a result of this study, the FRP soil nailing systems show similar behavior characteristics with those of removable soil nailing system. Finally, considering the serviceability and mechanical stability of FRP soil nailing systems, it is enough to be used as a good alternative of general soil nailing system.