Concrete Journal
Online ISSN : 2186-2753
Print ISSN : 0387-1061
ISSN-L : 0387-1061
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Volume 51, Issue 2
Displaying 1-15 of 15 articles from this issue
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  • Post-Construction Quality Verification of In-Place Reinforced Concrete
    K. Nakarai, I. Kurashige, T. Kishi
    2013 Volume 51 Issue 2 Pages 153-158
    Published: 2013
    Released on J-STAGE: February 01, 2014
    DOIhttps://doi.org/10.3151/coj.51.153
    JOURNAL FREE ACCESS
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    Subcommittee on Post-Construction Quality Verification of In-Place Reinforced Concrete (JSCE 335) under Concrete Committee of Japan Society of Civil Engineers (JSCE) published the state-of-the-art report on the non-destructive inspection technique for measuring the quality of cover concrete of completed structures and the system for verifying durability of the structures based on the measured quality. Firstly, the significance of the implementation of the inspection was clarified by the review of the process of design, construction and maintenance. Then, a guideline for verifying the quality of cover concrete by the non-destructive inspection method such as air permeability test or water absorption test on site was proposed. In addition, the other guideline for improving the quality of cover concrete during the construction was proposed. Finally, the future of the durability design, prediction and maintenance utilizing the post-construction quality verification was discussed.
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  • Freezing-thawing Resistant Recycled Concrete using Recycled Aggregate Class M
    H. Katahira, A. Koyama, H. Watanabe
    2013 Volume 51 Issue 2 Pages 159-164
    Published: 2013
    Released on J-STAGE: February 01, 2014
    DOIhttps://doi.org/10.3151/coj.51.159
    JOURNAL FREE ACCESS
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    According to the former JIS A 5022, which describes technical requirement of recycled concrete using recycled aggregate class M, the scope of application of recycled concrete using recycled aggregate class M was limited to the underground structures which are not affected by freezing-thawing action. However, JIS A 5022 was revised in 2012, so that the new test method which can evaluate the freezing and thawing resistance of recycled coarse aggregate has been introduced. The freezing and thawing resistant recycled concrete using recycled aggregate class M is specified in the revised JIS A 5022, which extends applicability of recycled concrete using recycled aggregate class M to concrete members which suffer from freezing-thawing action.
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  • Mix Performance and Mechanical Properties of High Strength Concrete using Blast Furnace Slag Fine Aggregate
    D. S. Shi, Y. Masuda, M. Abe, T. Kage
    2013 Volume 51 Issue 2 Pages 165-172
    Published: 2013
    Released on J-STAGE: February 01, 2014
    DOIhttps://doi.org/10.3151/coj.51.165
    JOURNAL FREE ACCESS
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    In this study, mix performance and mechanical properties of concrete using blast furnace slag fine aggregate were studied by experiment. As ordinary strength concrete, it is necessary that the water content and the chemical admixture content of concrete using blast furnace slag fine aggregate would be increased than river sand concrete in order to gain uniform workability of fresh concrete. However, the mix performance of high strength concrete using blast furnace slag fine aggregate is same as high strength concrete using river sand by using chemical admixture. As same as concrete using river sand, the strength of concrete using blast furnace slag fine aggregate will increase with decrease of water-cement ratio and the compressive strength can exceed 100N/mm2. At early age, the compressive strength of concrete using blast furnace slag fine aggregate is lower than river sand concrete. Under long term curing, the increasing rate of compressive strength of ordinary strength concrete using blast furnace slag fine aggregate will be higher than river sand concrete, but this increasing rate will be lower when the strength of concrete was high. Young's modulus of concrete using blast furnace slag fine aggregate is greater than concrete using river sand, and Young's modulus of concrete using mixed fine aggregate is middle of concrete using river sand and using blast furnace slag. The drying shrinkage of concrete that used blast furnace slag as fine aggregate is less than concrete that used natural river sand as fine aggregate when the mix proportion condition of concrete was identical.
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  • Development of the Retrofitting Method using Arch Shaped Steel Plate for the Beams of Existing Railway Viaducts
    Y. Maeda, T. Kuroiwa, T. Tadokoro, Y. Tanimura
    2013 Volume 51 Issue 2 Pages 173-180
    Published: 2013
    Released on J-STAGE: February 01, 2014
    DOIhttps://doi.org/10.3151/coj.51.173
    JOURNAL FREE ACCESS
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    Railway viaducts have been constructed since the end of the Taisho period in urban areas, and many of them have been used up to now. The reinforcement work of the beam may be necessary from the viewpoint of seismic capacity and durability in such viaducts. Therefore, we developed the reinforcement method effective in both flexural strengthening and shear reinforcing for the beams using arch shaped steel plates. In this paper, we introduce the outline of reinforcement method and the result of cyclic loading tests, and propose a design method.
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