Concrete Journal
Online ISSN : 2186-2753
Print ISSN : 0387-1061
ISSN-L : 0387-1061
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Volume 39, Issue 4
Displaying 1-8 of 8 articles from this issue
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  • Outline of Standard Specification for Concrete Structures [Maintenance] JSCE 2001
    T. Miyagawa, H. Morikawa
    2001 Volume 39 Issue 4 Pages 3-9
    Published: April 01, 2001
    Released on J-STAGE: April 26, 2013
    DOIhttps://doi.org/10.3151/coj1975.39.4_3
    JOURNAL FREE ACCESS
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    The first edition of Standard Specification for Concrete Structures [Maintenance] was published by the Japan Society of Civil Engineers in January 2001. This paper describes the background and features of the new specification. Especially, a basic concept of performance verification for existing concrete structures, and, scenario for lifetime of concrete structures are explained briefly.
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  • Maintenance of existing concrete structures and professional engineers for maintenance
    T. Uomoto
    2001 Volume 39 Issue 4 Pages 10-13
    Published: April 01, 2001
    Released on J-STAGE: April 26, 2013
    DOIhttps://doi.org/10.3151/coj1975.39.4_10
    JOURNAL FREE ACCESS
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    At present, tremendous amount of concrete structures are now being used in Japan. There are many deteriorated structures that have been in use for more than 50 years since 20's of Syowa era. One of the most important works, for the concrete engineers from the 21st century, is to maintain these existing concrete structures. To deal with the problem, Japan Concrete Institute has started a program from this year to promote and evaluate professional engineers for maintenance.
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  • The Effects of the Trace Elements in Cement on the Environment
    T. Ugajin
    2001 Volume 39 Issue 4 Pages 14-19
    Published: April 01, 2001
    Released on J-STAGE: April 26, 2013
    DOIhttps://doi.org/10.3151/coj1975.39.4_14
    JOURNAL FREE ACCESS
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    This paper discusses the effects of trace elements in cement, especialy water-soluble hexavalent chromium on environment through investigation and experimentation. In the cases of bleeding water from fresh concrete and the water that washed some tools in construction site, the concentrations of hexavalent chromium occasionally exceed the regulations for waste water. However, popular guards taken to protect construction workers against strong alkalinity originally, are also available to protect them against hexavalent chromium. Concerning the leachability of hexavalent chromium from hardened concrete, there is no result exceeding environmental quality standards for soil pollution. From the experimental results assumed green cut, cocreting under water and pile concreting in site, we found that there is no serious problem that some water contained hexavalent chromium leached from concrete affect environment.
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  • Development of Aggregate Materials Using Construction By-Products An Application for Concrete Noise Barriers
    Y. Momi.yama, J. Uchida, T. Shitama, H. Mizuguchi
    2001 Volume 39 Issue 4 Pages 20-26
    Published: April 01, 2001
    Released on J-STAGE: April 26, 2013
    DOIhttps://doi.org/10.3151/coj1975.39.4_20
    JOURNAL FREE ACCESS
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    The purpose of this study is to develop concrete aggregate that is utilized some kinds of sludge and plastic wastes occurring in construction and maintenance management on expressways. In this study, sludge was derived from sand-made sludge, and plastic wastes were derived from plastic seats for agriculture. These sludge and plastic wastes were kneaded and mixed with addition made by cement in order to produce aggregate for concrete. By investigating/analyzing each characteristics of construction by-products and plastic wastes as concrete aggregate, concrete noise barrier is found out to be suitable for their application product. By comparing with ordinary concrete noise barrier, this recycling noise barrier can realize the cost reduction of about 15%.
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  • The Estimation Method of Concrete in Structures by Small Size Cores
    K. Terada, Y. Tanigawa, A. Nakagome, H. Sawara
    2001 Volume 39 Issue 4 Pages 27-32
    Published: April 01, 2001
    Released on J-STAGE: April 26, 2013
    DOIhttps://doi.org/10.3151/coj1975.39.4_27
    JOURNAL FREE ACCESS
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    In this study, estimation method for strength of concrete in structures with small size cores whose diameter is from 18 to 26 mm is investigated. The strength of concrete in structures is estimated by this method by using the strength gap between small size cores and standard size cores which are 100 mm diameter and 200 mm height. In the present paper, the results of the basic experiments are described, and the summary of the process of the estimation method with small size cores is explained.
    Furthermore, the estimating method to several existing structures is applicated.
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  • [title in Japanese]
    [in Japanese], [in Japanese], [in Japanese]
    2001 Volume 39 Issue 4 Pages 34-38
    Published: April 01, 2001
    Released on J-STAGE: April 26, 2013
    DOIhttps://doi.org/10.3151/coj1975.39.4_34
    JOURNAL FREE ACCESS
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  • [title in Japanese]
    [in Japanese], [in Japanese], [in Japanese], [in Japanese]
    2001 Volume 39 Issue 4 Pages 39-43
    Published: April 01, 2001
    Released on J-STAGE: April 26, 2013
    DOIhttps://doi.org/10.3151/coj1975.39.4_39
    JOURNAL FREE ACCESS
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  • [title in Japanese]
    [in Japanese], [in Japanese]
    2001 Volume 39 Issue 4 Pages 61-64
    Published: April 01, 2001
    Released on J-STAGE: April 26, 2013
    DOIhttps://doi.org/10.3151/coj1975.39.4_61
    JOURNAL FREE ACCESS
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