• Title/Summary/Keyword: 재생 특성

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Evaluation of Permanent Deformation Characteristics of Recycled Asphalt Concretes Made by Improved Binder-Rejuvenation (바인더 회생방식을 개선한 재생 아스팔트 콘크리트의 소성변형 특성 연구)

  • Kim Kwang-Woo;Kweon Oh-Sun;Doh Young-Soo
    • International Journal of Highway Engineering
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    • v.8 no.1 s.27
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    • pp.1-13
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    • 2006

  • This paper is one of the studies for developing new methodologies for improving performance of hot-mix recycled asphalt mixtures. The objective of this study is to evaluate rut-resistance characteristics of recycled asphalt mixture which was prepared by newly developed mixing method. The new mixing method provided more sufficient rejuvenation of old binder of reclaimed asphalt pavement (RAP), making homogeneous binder viscosity level in a recycled mixture. Two aggregates (gneiss and granite), two RAP contents (15% and 30%) and two contents (none and 6%) of polymer modifier (LDPE) were used. Recycled mixture was prepared with two methods; method A and method F. To examine difference of binder oxidation level by type of material within a recycled mixture, Gel-permeation chromatography(GPC) analysis was performed on the binders mixed with coarse aggregates and matrix separately. Laboratory tests were performed for evaluation of rut resistance characteristics of each recycled mixture and these includes wheel tracking (WT) test and Kim test. Rut depth and dynamic stability were obtained from WT test and deformation strength $(S_D)$ was obtained from Kim test. The results of regression analysis was shown that correlation $(R^2)$ of F mixing mixtures was higher than one of A mixing mixtures. Therefore, F mixing mixtures showed more consistent rut resistance than h mixing mixtures.

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Comparing Laboratory Responses of Engineered Emulsified Asphalt and Foamed Asphalt Mixtures for Cold In-place Recycling Pavement (현장 상온 재생 아스팔트 포장을 위한 고점착 유화 아스팔트 혼합물과 폼드 아스팔트 혼합물의 반응특성 비교)

  • Kim, Yong-Joo Thomas;Lee, Ho-Sin David
    • International Journal of Highway Engineering
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    • v.12 no.1
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    • pp.79-86
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    • 2010

  • Cold in-place recycling (CIR) using emulsified asphalt or foamed asphalt has become a more common practice in rehabilitating the existing asphalt pavement due to its cost effectiveness and the conservation of paving materials. As CIR continues to evolve, the engineered emulsified asphalt was developed to improve the field performances such as coating, raveling, retained stability value and curing time. The main objective of this research is to compare the laboratory responses of the engineered emulsified asphalt (CIR-EE) mixtures against the foamed asphalt (CIR-foam) mixtures using the reclaimed asphalt pavement (RAP)materials collected from the CIR project on U.S. 20 Highway in Iowa. Based on the visual observation of laboratory specimens, the engineered emulsified asphalt coated the RAP materials better than the foamed asphalt because the foamed asphalt is to create a mastic mixture structure rather than coating RAP materials. Given the same compaction effort, CIR-EE specimens exhibited lesser density than CIR-foam specimens. Both Marshall stability and indirect tensile strength of CIR-EE specimens were about same as those of CIR-foam specimens. However, Marshall stability and indirect tensile strength of the vacuum-saturated wet specimens of CIR-EE mixtures were higher than those of CIR-foam mixtures. After four hours of curing in the room temperature, the CIR-EE specimens showed less raveling than the CIR-foam specimens. On the basis of test results, it can be concluded that the CIR-EE mixtures is less susceptible to moisture and more raveling resistant than CIR-foam mixtures.

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성체줄기세포와 난치병 진료의 전망

  • O, Il-Hwan
    • Health and Mission
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    • s.4
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    • pp.17-19
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    • 2005

  • 줄기세포는 난치병에 걸렸을 때 장기의 기능을 담당할 수 있는 세포를 재생해 낼 수 있게 한다. 줄기세포는 근래에 "21세기판 불로초"로 불리며, 무한히 증식 될 수 있는 자기 재생능, 정상염색체 유지 및 다양한 세포로의 분화 등 놀라운 특성으로 난치병, 노인성 질환 치료를 위한 치료제로 활용 중이다.

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