• Title, Summary, Keyword: Tensile properties

Search Result 5,378, Processing Time 0.081 seconds

Experimental Investigations on the Flexural Behavior of One-Way Concrete Slabs Reinforced with GFRP Re-Bar Bundle (유리섬유 보강 플래스틱 Re-Bar 다발로 보강된 1방향 콘크리트 슬래브의 휨거동에 관한 실험적 연구)

  • 윤순종;김병석;유성근;정재호;정상균
    • Composites Research
    • /
    • v.16 no.3
    • /
    • pp.32-40
    • /
    • 2003
  • In recent years, the investigation on the development of fiber reinforced plastic(FRP) Re-Bar has been greatly increased due to the attractive physical and mechanical properties of FRP. The primary reason of such a tendency is in the fact that it does not ordinarily cause durability problems such as those associated with steel reinforcement corrosion. This study is an experimental investigation on the flexural behavior of one-way concrete slabs, which can be used to construct bridge deck, reinforced with GFRP Re-Bar bundle. The tensile tests of GFRP Re-Bar produced by domestic industry and third point bending tests of one-way slab specimens reinforced with GFRP Re-Bar bundle are peformed. For all slab specimens, load-deflection relations are predicted by using the ACI committee 440 and the results are compared with experimental ones. In order to establish the design criteria or guidelines of concrete flexural member reinforced with FRP Re-Bar, it is needed to evaluate the serviceability limit state as well as the strength limit state.

Preparation and Characterization of Polyurethane Waterproof Coatings Containing Fly Ash

  • Lee, Sung-Il;Kim, Duk-Bae;Yang, Go-Su;Kim, Wan-Young;Byoun, Youn-Seop;Lee, Youn-Sik
    • Elastomers and Composites
    • /
    • v.38 no.3
    • /
    • pp.243-250
    • /
    • 2003
  • Polyurethane waterproof (PW) coatings are increasingly demanded in Korea for repairing cracks on old building roofs and construction of many sporting facilities. Calcium carbonate, a common filler, is incorporated in PW compositions. In this study, PW coatings were prepared by substituting a part of calcium carbonate with fly ash. The maximum amounts of calcium carbonate which can be substituted by fly ash obtained in the cyclone and bag filter dust collectors were 20 and 10%, respectively. It was found that the curing rate of PWs ran be controlled by varying the amount of Pb-octoate catalyst. The elongations at break as well as tensile strength and tear strength of PW coatings containing fly ash could also be adjusted such that their values were comparable to those of a standard PW coating by varying relative amounts of some components. However, the amount of cadmium, mercury, and lead leached from PW coatings containing fly ash obtained from the bag filter collector exceeded the respective allowed upper limits, mainly due to the initial high contents of them in the fly ash. On the other hand, PW coatings containing fly ash obtained from the cyclone collector exhibited better mechanical properties and did not release any significant amounts of the heavy metals. Thus, it was concluded that PW coatings containing fly ash can be utilized for practical applications as long as an appropriate fly ash is used.

Drying Shrinkage and Strength Properties of Ultrarapid-Hardening Polymer-Modified Mortar Using Redispersible Polymer Powder (재유화형 분말수지를 혼입한 초속경 폴리머시멘트 모르타르의 건조수축 및 강도특성)

  • Lee, Youn-Su;Joo, Myung-Ki
    • Journal of the Korea Concrete Institute
    • /
    • v.15 no.3
    • /
    • pp.409-416
    • /
    • 2003
  • The effects of polymer-cement ratio, antifoamer content and shrinkage-reducing agent content on the air content, setting time, drying shrinkage and strength of polymer-modified mortars using redispersible polymer powder are examined. As a result, the air content of the polymer-modified mortars using redispersible polymer powder tend to decrease with increasing polymer-cement ratio and antifoamer content. Regardless of the antifoamer content, the setting time of the polymer-modified mortars using redispersible polymer powder tend to delayed with increasing polymer-cement ratio. Irrespective of the antifoamer content, the drying shrinkage of the polymer-modified mortars using redispersible polymer powder tend to decrease with increasing polymer-cement ratio and shrinkage-reducing agent content. Regardless of the antifoamer content, the flexural and tensile strengths of the ultrarapid-hardening polymer-modified mortars using redispersible polymer powder tend to increase with increasing polymer-cement ratio, and tend to decrease with increasing shrinkage-reducing agent content. However, the compressive strength of the ultrarapid-hardening polymer-modified mortars using redispersible polymer powder decrease with increasing polymer-cement ratio and shrinkage-reducing agent content.

Studies on Influence of Water-Proof Agents on the Properties of Mortar (방수제(防水劑)가 모르터의 제성질(諸性質)에 미치는 영향(影響)에 관(關)한 연구(硏究))

  • Kim, Seong Wan;Sung, Chan Yong;Kim, Sun Young
    • Korean Journal of Agricultural Science
    • /
    • v.14 no.2
    • /
    • pp.358-372
    • /
    • 1987
  • This study was performed to obtain data which can be applied to use of water-proof mortars. The data was based on the properties of water-proof mortars depending upon various mixing ratios to compare those of cement mortar. The water-proof agents used were retard and accelerate type which are being used as mortar structures. The water-proof agents, mixing ratios of cement to fine aggregate were 1:1, 1:2, 1:3 and 1:4. The results obtained were summarised as follows; 1. The results of flow test, water-cement ratio was increased with the increasing of mixing ratio. 2. The permeability were increased in poorer mixing ratio and higher water pressure. 3. The bulk density was decreased with the increasing of mixing ratio, and compressive and tensile strength were increased with increasing of the bulk density. 4. At 1:1 mixing ratio, the highest strengths were showed and strengths were decreased with the increasing of mixing ratio. 5. The absorption rates were increased in- poorer mixing ratio 6. The correlation between W/C, permeability, bulk density, compressive strength and absorption rate were highly significant as a straight line, respectively.

  • PDF

Therapeutic Effect of Hydrocolloid Membrane Containing Liriope platyphylla Extracts on the Burn Wounds of SD Rats (맥문동 혼합 하이드로콜로이드막의 제조 및 화상치료 효능평가)

  • Lee, Eun Hae;Go, Jun;Kim, Ji Eun;Koh, Eun Kyoung;Song, Sung Hwa;Sung, Ji Eun;Park, Chan Kyu;Lee, Hyeon Ah;Hwang, Dae Youn
    • Journal of Life Science
    • /
    • v.25 no.5
    • /
    • pp.523-532
    • /
    • 2015
  • A variety of previous pharmacological studies have suggested Liriope platyphylla (L. platyphylla) may exert beneficial biological effects on inflammation, diabetes, neurodegenerative disorder, obesity, constipation, and atopic dermatitis. In addition, hydrocolloid membranes (HCMs) have attracted attention in dermatological care, including in the treatment of scleroderma skin ulcers, cutaneous ulcers, permanent tympanic membrane perforations, pressure sores, and decubitus ulcers in the elderly. To investigate the therapeutic effects of HCM containing an aqueous extract of L. platyphylla (HCM-LP) on second-degree burn wounds, their physico-chemical properties were analyzed and the therapeutic effects were observed in SD rats after treatment with HCM-LP for 14 days. Significant declines in tensile strength (38.4%) and absorptiveness (46.3%), as well as an increase in surface roughness (38.1%) were detected in HCM-LP compared with that of HCM. In SD rats with burned skin, the wound diameter was shorter in the HCM-LP treated group than in the GZ group on post-surgical day 14, while the significant improvements in scar tissue reduction, epithelium regeneration, angiogenesis, and extracellular matrix deposition were observed in the HCM-LP-treated group during all experimental periods. Overall, these results suggest HCM-LP may accelerate the process of healing the burn injury skin of SD rats through the regulation of angiogenesis and connective tissue formation.

Analysis of the Physicochemical Properties and Antioxidative Activity of Napa Cabbage Pickle (저장기간 동안 배추 피클의 이화학적 특성 및 항산화 활성 분석)

  • Son, Hae-Reon;Oh, Sun-Kyung;Bae, Sang-Ok;Choi, Myeong-Rak
    • Journal of Life Science
    • /
    • v.26 no.11
    • /
    • pp.1275-1281
    • /
    • 2016
  • The principal objective of this fundamental research was to analyze the physicochemical properties the and antioxidative activity of Napa cabbage pickle (NCP) for development of low-salt pickles. NCP-1 was a smaller than NCP at amount soy sauce (10%). The pH of NCP and NCP-1 were $4.51{\pm}0.15$, $4.85{\pm}0.08$ immediately after preparation. The pH of NCP and NCP-1 was reduced to $4.08{\pm}0.05$ and $4.31{\pm}0.12$ over time during 60 days of storage. The acidity of the NCP and NCP-1 immediately after preparation were 0.51% and 0.38% and increased to 0.67% and 0.56% after 60 days of storage. The salinity for the NCP ranged from 1.71-2.22% and NCP-1 ranged from 1.18-1.63%. The L value, which indicates the lightness, was the highest at day 0 and the lowest at 60 day. The tensile strength value of NCP was $10.9{\pm}0.05kgf/cm^2$ and NCP-1 in $11.84{\pm}0.11kgf/cm^2$ at day 0 and then significantly decreased with time in storage. The cutting force of NCP was $1004{\pm}7.12gf/cm^2$ and NCP-1 in $845{\pm}5.27gf/cm^2$ at day 0, which increased over time in storage. The overall acceptability of NCP was the highest at day 30, but the overall acceptability of NCP-1 was the highest at day 45. NCP-1 extracts at day 60 showed the highest antioxidant activity of 66.04%, whereas the NCP extract at day 0 showed the lowest antioxidant activity of 45.41%. These results showed that depending on the content of the seasoning pickle difference in the antioxidant activity. Thus, the best pickled Napa cabbage is determined by a smaller amount soy sauce in NCP-1, and the results could provide a basis for improving the availability and quality of Napa cabbage.

Effect of Antimicrobial Microperforated Film Packaging on Extending Shelf Life of Cluster-type Tomato (Lycopersicon esculentum Mill.) (천연 항균물질 미세천공필름 포장이 송이토마토의 품질에 미치는 영향)

  • Lee, Youn-Suk;Lee, Young-Eun;Lee, Jung-Soo;Kim, Young-Shik
    • Horticultural Science & Technology
    • /
    • v.29 no.5
    • /
    • pp.447-455
    • /
    • 2011
  • To investigate the effects of the improvement of postharvest quality on fresh tomato, antimicrobial microperforated (AMP) films were prepared and their antimicrobial abilities were observed. AMP films were made by coating different types of natural antimicrobial agents such as cinnamon, clove, and clary sage essential oils into microperforated (MP) films. Cinnamon essential oil of 10% (v/v) has proven to be very effective as inhibitor of the mold growth on tomato, compared to the clove and clary sage essential oils. Quality changes of fresh tomatoes packed using the natural AMP films (AMP10 and AMP30) and MP films (MP10 and MP30) during storage were evaluated. Total microbial growth, weight loss, firmness, lycopene content, and decay rate as the major quality parameters were monitored over 9 days at $15^{\circ}C$. The oxygen transmission rates and mechanical properties between the natural AMP and MP films were also compared. There was no significant difference in change of oxygen transmission rate, tensile strength and elongation between the AMP and MP films. For storage studies, the freshness of tomato packaged in AMP30 film was higher than that in OPP film (the control), MP10, MP30, and AMP10 films. Especially, AMP30 film exhibited high efficiency compared to the control for tomato decay during storage periods. Based on the results, the microperforation and antimicrobial properties of the packaged films may significantly affect the maintenance of an optimum gas composition within the package atmosphere for increasing the storage life and quality of produce. They were also effective on the inhibition of microbial growth by controlled release of antimicrobial agent at an appropriate rate from the package into the tomato. Natural antimicrobial agent coating microperforated films could use potential functional package as a method of extending the freshness of postharvest tomato for storage.

Edible Films from Protein Concentrates of Rice Wine Meal (주박 단백질 농축물로부터 가식성필름의 제조)

  • Cho, Seung-Yong;Park, Jang-Woo;Rhee, Chul
    • Korean Journal of Food Science and Technology
    • /
    • v.30 no.5
    • /
    • pp.1097-1106
    • /
    • 1998
  • Biodegradable edible films were prepared from rice protein concentrates (RPC) made from rice wine meal by alkaline extraction and isoelectric precipitation. The effect of film forming solution pH and plasticizers were studied, and cross-linkers were added to improve mechanical properties and water vapor permeabilities (WVP) of films. Films could be formed within pH $8{\sim}11$ with tensile strength (TS) of 4.3{\sim}5.7\;MPa$. Films produced under pH 11 had the highest TS (5.7 MPa) and the lowest WVP $(0.44\;ng{\cdot}m/m^2{\cdot}s{\cdot}Pa)$. Added glycerol, polyethylene glycol 200 (PEG) and its mixture (GLY:PEG=50:50) as plasticizers also affected the mechanical properties and WVP of films. TS and elongation at break (E) of films at various plasticizer levels were $5.5{\sim}1.0\;MPa$ and $3.6{\sim}24.3%$, respectively. At the same plasticizer concentration, the highest TS was observed when glycerol was used whereas the highest E was measured when mixture was used as plasticizer. WVPs of films with thickness of $60\;{\mu}m$ were $0.39{\sim}0.54\;ng{\cdot}m/m^2{\cdot}s{\cdot}Pa$. WVP of films decreased as the ratio of glycerol/PEG 200 was decreased, and WVP increased as the total amount of plasticizer added to the films increased. Film strength was improved by the addition of small amount of sodium hydrogen sulfate, succinic anhydride, ascorbic acid and citric acid, whereas TS of films containing $0.5{\sim}2.0%$ of NaCl and $CaCl_2$ were lower than those without the salts. The highest TS (6.3 MPa) was achieved with films containing 0.1% of succinic anhydride.

  • PDF

An Experimental study on the Engineering Properties of Concrete with Rice-Husk Ash (왕겨재를 혼입(混入)한 콘크리트의 공학적(工學的) 특성(特性)에 관(關)한 실험적(實驗的) 연구(硏究))

  • Sung, Chan Yong;Yoo, Byong In;Kim, Kyung Tae;Jung, Hyun Jung;Kim, Young Ik
    • Korean Journal of Agricultural Science
    • /
    • v.24 no.2
    • /
    • pp.207-217
    • /
    • 1997
  • This study was performed to evaluate the engineering properties of rice-husk ash concrete using normal portland cement, natural aggregates and rice-husk ash. The following conclusions were drawn; 1. The unit weight was in the range of $2,216{\sim}2,325kgf/m^3$, the weights of those concrete were decreased 1~6% than that of the normal cement concrete, respectively. 2. The highest strength was achieved by 10% rice-husk ash filled rice-husk ash concrete, it was increased 8% by compressive strength, 17% by tensile strength and 18% by bending strength than that of the normal cement concrete, respectively. 3. The ultrasonic pulse velocity was in the range of 3,252~4,016 m/s, which was showed about the same compared to that of the normal cement concrete. The highest ultrasonic pulse velocity was showed by 10% rice-husk ash filled rice-husk ash concrete. 4. The dynamic modulus of elasticity was in the range of $242{\times}10^3{\sim}306{\times}10^3kgf/cm^2$, which was showed about the same compared to that of the normal cement concrete. The highest dynamic modulus was showed by 10% rice-husk ash filled rice-husk ash concrete. 5. The static modulus of elasticity was in the range of $185{\times}10^3{\sim}275{\times}10^3kgf/cm^2$, which was showed about the same compared to that of the normal cement concrete. The poisson's number of rice-husk ash concrete was less than that of the normal cement concrete. The dynamic modulus was increased approximately 11~30% than that of the static modulus. 6. The durability was increased with increase of the content of rice-husk ash. The durability was increased 1.3 times by 10% rice-husk ash, 1.6times by 20% rice-husk ash filled concrete than that of the normal cement concrete. respectively.

  • PDF

Fracture Pattern and Physical Property of the Granodiorite for Stone Resources in the Nangsan Area (낭산일대에 분포하는 화강섬록암 암석자원의 열극체계 및 물리적 특성)

  • Yun, Hyun-Soo;Hong, Sei-Sun;Park, Deok-Won
    • The Journal of the Petrological Society of Korea
    • /
    • v.16 no.3
    • /
    • pp.144-161
    • /
    • 2007
  • The studied Nangsan area is widely covered by the Jurassic biotite granodiorite, which is mainly light grey in color and medium-grained in texture. Results of the regional fracture pattern analysis for the granodiorite body are as follows. Strike directions of fractures show three dominant sets in terms of frequency order. The sets are in an order of a (1) $N80^{\circ}{\sim}90^{\circ}E$ (1st-order)>(2) $N70^{\circ}{\sim}80^{\circ}E$ (2nd-order)>(3) $NS{\sim}N10^{\circ}E$ (3rd-order). Spacings of the fractures are mostly predominant in less than 200 cm. Therefore, the granodiorite of the area has more potential for non-dimensional stones than dimension ones. And orientations of vertical quarrying planes can be also divided into two groups in terms of frequency $N14^{\circ}W{\sim}N16^{\circ}E$ (1st-order) and (2) $N78^{\circ}E{\sim}N88^{\circ}E$ (2nd-order). The orientations of the two groups are more or less different from those of the regional fracture patterns. These can be mainly attributed to the preferred orientations of microcrack developed in the quarries. Of physical properties, specific gravity, absorption ratio, porosity, compressive strength, tensile strength and abrasive hardness are 2.65, 0.28%, 0.73%, $1,628kg/cm^2,\;100kg/cm^2$ and 31, respectively. Contrary to the porosity, both granites of the Nangsan and Sogrisan areas show almost similar values of the abrasive hardness. These can be explained by the differences of Qz+Af modes, which can be regarded as an index for abrasive resistance. Meanwhile, it is anticipated that comprehensive understanding of the orientations of vertical quarrying planes and characteristics of various physical properties will be utilized as an important information for stone resources.