Concrete Journal
Online ISSN : 2186-2753
Print ISSN : 0387-1061
ISSN-L : 0387-1061
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Volume 30, Issue 2
Displaying 1-5 of 5 articles from this issue
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  • Prospects and Problems of Self-Placable Concrete
    Hajime Okamura, Kazumasa Ozawa
    1992 Volume 30 Issue 2 Pages 5-14
    Published: February 01, 1992
    Released on J-STAGE: April 26, 2013
    DOIhttps://doi.org/10.3151/coj1975.30.2_5
    JOURNAL FREE ACCESS
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    The self-placable concrete, which can be filled in the formwork without using vibrators, can enhance the reliability of concrete structures and may promote a modernization of construction industry such as automated, rapid and safe construction works. In this paper, are described the background of the development of the concrete system and its future prospects and problems to be solved. The self-placable concrete, called High Performance Concrete, which can enhance the durability of concrete independently of site worker's skillfullness, was developed in the Concrete Laboratory in the department of Civil Engineering of the University of Tokyo. The key point of producing the self-placable concrete is how to design the mix proportion, considering the properties of the used materials. There are problems to be solved for practical application, which are related to important things for the concrete technology in future. Those are that quality specification of cement for such kind of concrete should be made, that production system and quality control system in a ready-mixed concrete factory should be built and that automated construction system at the site should be developed.
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  • Control and Research for Shrinkage Crack of RC Building Walls
    Mitsuo Koyanagi
    1992 Volume 30 Issue 2 Pages 15-22
    Published: February 01, 1992
    Released on J-STAGE: April 26, 2013
    DOIhttps://doi.org/10.3151/coj1975.30.2_15
    JOURNAL FREE ACCESS
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    Cracks in reinforced concrete walls are caused by restrained volume change, cold joint of non-filling up concrete, and expanding with steel corrosion, etc. This paper descrives the actual state and how to control on restrained volume change. Cause of “Cracks occurred by volume change” is divided into drying shrinkages of concrete and thermal shrinkages of heat and temperature changes. Crackes in buildings are due to these combined factors. Investigations and studies reports about these cracks factors are introduced. Are offered datas about cracks mechanism and how to control.
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  • Slipform Method in Severe Cold Seasons
    A. Ueda, K. Tanaka, S. Sakurai, K. Suga
    1992 Volume 30 Issue 2 Pages 23-30
    Published: February 01, 1992
    Released on J-STAGE: April 26, 2013
    DOIhttps://doi.org/10.3151/coj1975.30.2_23
    JOURNAL FREE ACCESS
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    Construction of the tower in DDI Nagano Network Center had to be finished concreting by slip form work from February till March in severe cold seasons of the year 1991, for process of this tower construction was restricted. But adopting slip form work in this environment put under a taboo, because strength of concrete was not expected below freezing point and a counterplan for resistance of frost damage after slipping form was difficult. And we had adopted Anti-Freeze Concrete Additive which was effective to quickening strength and resistance of frost damage, recently this one is expect to using for a counterplan of winter concrete. This report describes the effects of Anti-Freeze Concrete Additive and the results concerning execution control of this Tower.
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  • Design and Construction of Complex Cable-Stayed Bridge for Ikuchi Bridge
    Chikara Miyashita, Toru Fujiwara
    1992 Volume 30 Issue 2 Pages 31-45
    Published: February 01, 1992
    Released on J-STAGE: April 26, 2013
    DOIhttps://doi.org/10.3151/coj1975.30.2_31
    JOURNAL FREE ACCESS
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    Ikuchi Bridge is a complex cable-stayed bridge with a central span length of 490 m which is located the Onomichi-Imabari route (Nishi Seto Expressway) in the Honshu-Shikoku Bridge Project. The main girder is a steel-concrete mixed structure as the first case adopted in Japan which consists of a steel girder for center span and prestressed concrete (PC) girder for both side spans. This report summarizes the outline of the design and construction of the bridge, completed in December 1991. Special remarks to the fundamental design concepts and the constructive features on connection part between steel girder and PC girder, and also stress and geometrical control in the tolerance against plastic deformations due to the influence of creep and shrinkage occurring on PC side span girders are reported.
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  • [title in Japanese]
    1992 Volume 30 Issue 2 Pages 14
    Published: 1992
    Released on J-STAGE: April 26, 2013
    DOIhttps://doi.org/10.3151/coj1975.30.2_14
    JOURNAL FREE ACCESS
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    [in Japanese]
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