Journal of Advanced Concrete Technology
Online ISSN : 1347-3913
ISSN-L : 1346-8014
16 巻 , 1 号
  • Rungrawee Wattanapornprom, Tetsuya Ishida
    2018 年 16 巻 1 号 p. 18-35
    発行日: 2018/01/18
    公開日: 2018/01/19
    ジャーナル フリー

    The deterioration of concrete structures in airborne chloride environments is a common problem, as attested by the large number of concrete structures in coastal areas that are in need of repair due to corrosion of steel reinforcement. Thus, to prolong the service of concrete infrastructure in marine environments, deterioration from airborne chloride should be carefully considered. However, the amount of airborne chloride is influenced by numerous factors including wind direction, wind speed, wave height, obstacles, and distance from the seashore, and the concentration of airborne chloride varies by time and location. Besides actual exposure conditions, chloride ingress depends also on the environmental condition. In order to design the concrete structures, one must consider the amount of airborne chloride, concrete qualities, and the environmental conditions. Consequently, this research aims to develop a comprehensive system that can predict chloride ingress in concrete structures by considering airborne chloride intensity at the specific locations and times, based on determination of the amount of airborne chloride generated by breaking waves and transported by wind flow. The proposed methodology can determine the chloride penetration into concrete structures in various marine environments. The numerical framework has been verified through on-site measurements to confirm its validity.

  • Koki Makita, Yoshifumi Uda, Hiroshi Yoshikado, Koji Mori, Yuichi Sato, ...
    2018 年 16 巻 1 号 p. 36-45
    発行日: 2018/01/25
    公開日: 2018/01/27
    ジャーナル フリー

    Drop-weight tests and static loading tests of RC frames made of polypropylene fiber-reinforced concrete are conducted to observe shock resistance performance and residual ductility. Experimental variables are fiber content and mass of the drop weight. In the impact test, the maximum drifts of the specimens are proportional to the mass of the drop weight although several collisions occur due to rebounding and the maximum acceleration is not always increased as the mass increases. In a static loading test, the initial stiffness is improved and crack lengths in the hinge areas of the columns are reduced by mixing the polypropylene fibers.

  • Yuya Takahashi, Yasushi Tanaka, Koichi Maekawa
    2018 年 16 巻 1 号 p. 46-60
    発行日: 2018/01/23
    公開日: 2018/01/23
    ジャーナル フリー

    To estimate the remaining life of existing RC bridge decks damaged by alkali silica reaction (ASR), multi-scale numeri-cal analysis with chemo-hygral model is integrated with visual inspection data at site. First, the applicability of the poro-mechanical models for ASR expansion in the multi-scale frame are examined with the experiments of the real scale RC slabs and the model is validated to bring about fair prediction of the 3D anisotropic expansion and the fatigue life of the slabs. Second, visually inspected cracks on bottom surfaces of RC decks are converted to space-averaged strains, and the magnitude of ASR is estimated from the vertical deformation, based on which the internal pre-stress and the damage fields are re-produced by numerical predictor-corrector cycles, and the remaining life of ASR damaged RC bridge decks is fairly estimated. By conducting sensitivity analyses in terms of ASR-gel volumes and cracks, allowable error range of site inspection data is clarified to meet the requirement of asset management.

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