• Title/Summary/Keyword: shrinkage property

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An experimental study on shrinkage and crack resistance of Hwang Toh concrete mixed with PET fiber (PET보강섬유를 혼입한 황토콘크리트의 건조수축 및 균열저항성에 관한 실험적 연구)

  • Kim, Hyun-Young;Kim, Sung-Bae;Yi, Na-Hyun;Han, Byung-Goo;Kim, Jang-Ho
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.04a
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    • pp.797-800
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    • 2008
  • To decrease the usage of cement, the pozzolan reaction materials are used as a mineral admixture. Hwang Toh which is broadly deposited in Korea is well known as a environment friendly material and the activated Hwang Toh which has the property of pozzolan reaction is practically used as a mineral admixture of concrete. PET fiber which is made by recycled PET bottle controls micro crack in concrete. But the study about concrete mixed with reinforcing fiber is not enough and the property of Hwang Toh concrete mixed with PET fiber is more complicated case. So this study performed drying shrinkage experiment to analyse mechanical property of Hwang Toh concrete mixed with PET fiber.

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Appearance, stretch, and clothing pressure changes in nylon SCY knitted fabric by structure (Nylon SCY 편성물의 편성조직에 따른 외형, 신장특성 및 의복압 변화)

  • Sang, Jeong Seon;Park, Myung-Ja
    • Journal of the Korea Fashion and Costume Design Association
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    • v.21 no.4
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    • pp.17-26
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    • 2019
  • This research aims to obtain useful data on the development of compression garment products with high-stretch knitted materials. Using nylon SCY, four specimens were knitted. Then, appearance (width, length, weight, thickness), stretch property (stretch, recovery) and clothing pressure were measured and their interrelation was analyzed. In the comparison of appearance features, yarn floating caused shrinkage in both course and wale directions of the specimens. Yarn overlapping by tucking caused a release in the course direction and shrinkage in the wale direction. Also, structural change was affected by the weight and thickness change of the knitted fabric. In the analysis of fabric stretch, yarn floating reduced the extension in course direction and increased that in wale direction of the knitted fabric. However, yarn overlapping reduced the elongation in both directions. In the analysis of recovery, yarn floating and overlapping raised fabric recovery in both directions, and tuck structure was superior to float in recovery. In the analysis of clothing pressure, 'Plain-Float' structured fabrics showed a higher clothing pressure than 'Plain' and the clothing pressure value of 'Plain-Tuck' was lower than that of 'Plain'. As for the correlation between fabric appearance, stretch property, and clothing pressure, the appearance change in course direction had a major influence on the clothing pressure. The shrinkage of appearance led to a decrease in stretch and an increase in clothing pressure.

Prediction of Mechanical Property of Glass Fiber Reinforced Polycarbonate and Evaluation of Warpage through Injection Molding (유리섬유로 강화된 폴리카보네이트의 기계적 물성예측 및 사출성형을 통한 휨의 평가)

  • Moon, Da Mi;Choi, Tae Gyun;Lyu, Min-Young
    • Polymer(Korea)
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    • v.38 no.6
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    • pp.708-713
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    • 2014
  • Most plastics products are being produced by injection molding process. However, mold shrinkage is inevitable in injection molding process and it deteriorates dimensional quality through deflections and warpages. Mold shrinkage depends upon the material property of resin as well as injection molding condition. In this study, material property of resin has been predicted for glass fiber reinforced polycarbonate to control the warpage, and computer simulation of injection molding has been performed using predicted property. It was observed that the deflection of part decreased by the glass fiber reinforced resin. In order to verify the validity of this method and confidence of results, experiments of injection molding were performed. The results of experiments and computer simulations showed good agreement in their tendency of deflections. Consequently, it was concluded that the method of designing the material property of resin conducted in this study can be utilized to control the dimensional accuracy of injection molded products.

An Experimental Study on the Creep Behavior and Crack Resistance of Hwang-toh Concrete Mixed with Recycled-PET Fiber (재생 PET 섬유가 혼입된 황토 콘크리트의 크리프 거동과 균열저항성에 관한 실험적 연구)

  • Kim, Sung-Bae;Jay Kim, Jang-Ho;Han, Byung-Goo;Hong, Geon-Ho;Song, Jin-Gyu
    • Journal of the Korea Concrete Institute
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    • v.21 no.3
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    • pp.265-273
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    • 2009
  • There have been numerous studies to develop eco-friendly concrete. The attempt to reduce the amount of cement used is suggested as one of the solutions for eco-friendly concrete. To decrease the usage of cement, the pozzolan reaction materials are used as a mineral admixture. Hwang-toh, which is broadly deposited in Korea is a well known environment friendly material and the activated hwang-toh, which has the property of pozzolan reaction, is alternatively used as a mineral admixture of concrete. The purpose of this study is to investigate the drying shrinkage of hwang-toh concrete mixed with recycled PET fiber. Therefore, drying shrinkage experiments are performed to analyze mechanical property of hwang-toh concrete mixed with recycled PET fiber. Test results showed that the drying shrinkage is controlled by hwang-toh admixture and PET fiber.

Strength and Crack Resistance Properties of Fiber Reinforced Concrete Mixed with Recycled PET Fiber (재생 PET 섬유가 혼입된 섬유 보강 콘크리트의 강도 및 균열저항 특성)

  • Kim, Sung-Bae;Kim, Hyun-Young;Yi, Na-Hyun;Kim, Jang-Ho Jay
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.14 no.1
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    • pp.102-108
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    • 2010
  • The main objective of this study was to evaluate the effect of recycled PET (RPET) fiber made from waste PET bottles to examine application on concrete member. To evaluate the reinforcement effect of RPET fiber in concrete member, experimental tests were performed, such as mechanical property tests (compressive strength, modulus of elasticity and splitting tensile strength) and drying shrinkage test. In mechanical property tests, compressive strength and modulus of elasticity in concrete mixed with RPET fiber gradually decreased, but splitting tensile strength gradually increased as volume fraction of fiber increased. In drying shrinkage test, free drying shrinkage increased. In restrained case, in contrast, crack occurrence was delayed because of tensile resistance increase by RPET fiber. The comparison of RPET and PP fiber added concrete specimen's properties showed that two materials had similar properties. In conclusion, RPET fiber is an alternative material of PP fiber, even finer for its excellence in eco-friendliness due to the recycling of waste PET bottles and its possible contribution to the pollution declination.

Autogenous Shrinkage of Very-Early Strength Latex-Modified Concrete with Latex Contents (라텍스함량 변화에 따른 VES-LMC의 자기수축)

  • Park, Won-Il;Choi, Pan-Gil;Yun, Kyong-Ku;Lee, Bong-Hak
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.11 no.3
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    • pp.1059-1065
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    • 2010
  • Very-early strength latex-modified concrete (VES-LMC) was developed for the purpose of fast-track overlay of a concrete bridge deck under heavy traffic, concentrated on the workability, durability, and strength gain so that it can be opened to the traffic only three hours after its placement. The mixture of VES-LMC might accompany very high heat of hydration at early-age because of its inherent rapid hardening property and could have susceptibility to autogenous shrinkage because of its relatively low water-cement ratio. This study evaluated the effect of the latex-cement ratio(L/C) both of the constant and variable slumps on the autogenous shrinkage of VES-LMC by carrying out simple temperature rise test and early-age shrinkage experiment. Test results are as follows: The latex contributes on the enhancement of the concrete durability but has little effect on its hydration and the accompanied heat of hydration in VES-LMC. Autogenous shrinkage increased with the increase in latex-cement ratio at variable slumps and its pattern followed regularly a logarithmic increase. However, the influence of water-cement ratio and latex-cement ratios for the test specimens at constant slump on early-age autogenous shrinkage property was found to be minor due to the simultaneous effect of the two experimental variables.

Early Age Properties of HPC Columns under Construction-Site Conditions

  • Yun, Ying-Wei;Jang, Il-Young
    • International Journal of Concrete Structures and Materials
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    • v.2 no.1
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    • pp.63-68
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    • 2008
  • High performance concrete (HPC) is widely used in civil engineering due to its high durability and low permeability etc. Compared with ordinary concrete, HPC may develop much higher AS (autogenous shrinkage) at early age due to the relative low water cement (w/c) ratio and adding of mineral admixtures, which is one of the main reasons for early age micro-cracking of HPC structures. This paper studies the early age property of HPC columns under similar construction-site surroundings by embedded strain transducers. Results show that for HPC structure, early-age autogenous shrinkage especially within the first day after concrete pouring is pretty large. AS within the first day are 60% larger than those for 14 days in this research for all specimens. Therefore it should be taken into account for structure durability. By comparison of PHPC (plain HPC column) and RHPC (reinforced HPC column) specimens, the effects of reinforced bars on AS and temperature distribution have been analyzed. Also the influence of w/c ratio on AS is demonstrated.

Durable Press Finishing of Silk/Cotton Fabrics with BTCA ( I ) - Effect of Treating Conditions on Physical Properties - (BTCA에 의한 실크/면 교직물의 DP 가공 (I) - 물리적 특성에 미치는 처리 조건의 영향 -)

  • 이문철;조석현
    • Textile Coloration and Finishing
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    • v.14 no.1
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    • pp.43-50
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    • 2002
  • Silk/Cotton fabrics were treated with butanetetracarboxylic acid(BTCA) to improve crease recovery and anti-shrinking properties at various curing temperatures and pH values. We investigated the effects of finishing conditions on add-on of BTCA, bending property(E, 2HB), wrinkle recovery angle, shrinkage, and dyeing properties. The Add-on of BTCA increased with increasing curing temperature and concentration. Crease recovery was improved with decreasing shrinkage. Maximum add-on of BTCA was showed at pH 2.5. In case of dyeing and mercerization, silk side treated with BTCA was more flexible than untreated, whereas cotton side was more stiff. In dyeing after mercerization, B and 2HB values were higher and K/S values were doubled nearly. The hand of fabric improved with decreasing B and 2HB by the BTCA treatment. BTCA treatment after reactive dyeing improved crease recovery, and caused no change of color difference. However, BTCA treatment after reactive dyeing didn't improve crease recovery, whereas B and 2HB were decreased considerably by the treatment.

Durable Press Finishing of Silk/Cotton Fabrics with BTCA(2) - The Evaluation of Physical Properties of Silk/Cotton Fabrics Treated with BTCA by HPLC Analysis - (BTCA에 의한 실크/면 교직물의 DP 가공(2) - HPLC에 의한 BTCA 처리 실크/면 교직물의 물리적 특성 평가 -)

  • 조석현;이문철
    • Textile Coloration and Finishing
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    • v.14 no.3
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    • pp.19-25
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    • 2002
  • Silk/cotton fabrics were treated with butanetetracarboxylic acid(BTCA) under various treating conditions such as concentration, treated time and curing temperatures. Bending property, tensile strength, wrinkle recovery angle, and shrinkage were measured. The BTCA concentration in the saponfication mixture was measured by an isocratic HPLC equipped with the strong cationic exchange column Aminex HPX-87-H and a UV detector. The detected concentration of BTCA was shown in silk side much more than that of cotton side. The bending and shrinkage properties were improved at minimum curing condition and the lower concentration of BTCA. Tensile strength decreased with increasing concentration of BTCA, curing temperature and treated time, while wrinkle recovery angle increased.

The Control Methods of Crack on Concrete with Fiber reinforced and Finishing (섬유종류 및 마감방법에 따른 무근콘크리트의 균열제어 방법)

  • Lee, Tae-Gyu;Kim, Gyu-Yong;Kang, Yeon-Woo;Kim, Soon-Mook;Kim, Soo-Bong;Jung, Jae-Yung
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2014.05a
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    • pp.260-261
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    • 2014
  • When press concrete with high W/B was hardened, it should consider a crack to make stress by drying shrinkage. For control of crack, wire-mesh used to reinforce concrete in site. Actually, it reported failure case in lack of quality control. This study conducted experiment to apply fiber reinforced press concrete. it was evaluated on fresh property, compressive strength and shrinkage crack of press concrete with fiber.

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