Concrete Journal
Online ISSN : 2186-2753
Print ISSN : 0387-1061
ISSN-L : 0387-1061
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Volume 54, Issue 4
Displaying 1-16 of 16 articles from this issue
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TOPICS
  • Significance of Architectural Institute of Japan's Recommendations for Loads and Overview of 2015 Revision
    T. Takada
    2016 Volume 54 Issue 4 Pages 339-344
    Published: 2016
    Released on J-STAGE: April 03, 2017
    DOIhttps://doi.org/10.3151/coj.54.4_339
    JOURNAL FREE ACCESS
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    This commentary covers the significance for practical design of the Architectural Institute of Japan's Recommendations for Loads on Buildings revised in 2015 and includes an overview of the changes made from the previous edition, providing an introduction to, among specific types of loads, seismic loads, and the newly added tsunami loads and impact loads. In terms of their significance, these Recommendations are distinguished by the fact that they present “appropriate design load values” from the viewpoint of society, building owners, and designers, as opposed to the “minimum values” to which laws and regulations are limited to. Another distinguishing feature of these Recommendations is that they organize the various types of loads in a unified manner and that they provide load setting methods that do not depend on the design method used and the target building, along with the latest objective data.
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  • Leaching Modeling and Evolution of pH in Cementitious Materials of Radioactive Waste Repository Facilities
    Y. Tsuji, K. Nakarai, K. Haga, H. Sakamoto
    2016 Volume 54 Issue 4 Pages 345-352
    Published: 2016
    Released on J-STAGE: April 03, 2017
    DOIhttps://doi.org/10.3151/coj.54.4_345
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    This paper covers required functions and performance with regard to the performance evaluation of cementitious materials over an ultra-long term on the order of 10,000 years, discusses the need for leaching modeling and aqueous alteration evaluation of cementitious materials, and presents concepts. The positioning of leaching modeling and the state of knowledge about the aqueous alteration of cement hydrates based on a survey of the existing literature are described. Further, the results of an investigation of concrete structures in long-term contact with water, and the results of accelerated leaching tests and electrical migration tests are reported.
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  • Continuous Quality Control Method for Fresh Concrete Using Probe inside Drum
    Y. Hirofuji, A. Mohri, M. Miyamoto, M. Yamada
    2016 Volume 54 Issue 4 Pages 353-361
    Published: 2016
    Released on J-STAGE: April 03, 2017
    DOIhttps://doi.org/10.3151/coj.54.4_353
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    Continuous concrete quality control equipment is a technology introduced from overseas that consists in a measuring instrument featuring a built-in strain gauge and thermometer (hereafter, “probe”) attached inside the drum on an agitator truck, making it possible to estimate slump from concrete loading to unloading, as well as concrete temperature and loading weight. The information obtained from the probe can be grasped in real time through wireless communication, thus enabling continuous control of the quality of ready-mixed concrete during transportation. This paper provides an overview of said equipment along with application examples, examining the estimation accuracy of slump, temperature and other characteristics of various types of concrete, as well as the applicability of this technology to realtime measurement. The results show that this equipment allows highly accurate estimation of slump and temperature, and since it allows monitoring of slump and other characteristics over time, it is deemed to be useful for quality control.
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  • Study on Filling Materials Suitable for Seawater Piping Trench Closure Work at Fukushima Daiichi Nuclear Power Plant
    S. Yanai, Y. Hibi, K. Nishikouri, K. Sato
    2016 Volume 54 Issue 4 Pages 362-370
    Published: 2016
    Released on J-STAGE: April 03, 2017
    DOIhttps://doi.org/10.3151/coj.54.4_362
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    Highly contaminated water leaking from the reactor buildings and turbine buildings damaged by the 2011 Great East Japan Earthquake has accumulated in the seawater piping trenches of Fukushima Daiichi Nuclear Power Station Units 2, 3, and 4. In November 2014, work commenced to replace and remove this contaminated water by filling the trenches with filling materials, and this work was completed in December 2015. This paper summarizes the contents of this study on various filling materials, including special fillers with long-distance underwater flowability applied to the horizontal tunnel parts of the trenches.
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  • Testing and Behavior of Post-installed Anchors in Freeze-Thaw Environment
    K. Aoki, H. Nishida, H. Maeda, M. Takahashi
    2016 Volume 54 Issue 4 Pages 371-374
    Published: 2016
    Released on J-STAGE: April 03, 2017
    DOIhttps://doi.org/10.3151/coj.54.4_371
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    Testing and behavior of post-installed anchors in freeze-thaw environment is to verify the mount of pull-out (displacement) and tensile resistance when the tensile load is applied to post-installed anchor for long-term. Such testing method is not a standardization yet in Japan. In this case, the test is organized according to European Technical Approval Guideline (ETAG) and investigated at Garman independent test laboratory (KIWA). This paper delineates the testing process and the behavior of sustained tensile load in freeze-thaw environment.
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  • Report on Cooperative Experiments on Relationship between Strength and Void Ratio of Porous Concrete
    Technical Committee on Establishment of Construction and Quality Contr ...
    2016 Volume 54 Issue 4 Pages 375-380
    Published: 2016
    Released on J-STAGE: April 03, 2017
    DOIhttps://doi.org/10.3151/coj.54.4_375
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    This report introduces the results of cooperative experiments carried out by the Technical Committee on Establishment of Construction Standard and Quality Control Standards for Performance-Based Design of Porous Concrete. The Committee presents the draft proposal of a strength control method that uses a strength ratio-void ratio relation formula. The results of these common experiments verify the relationship between strength ratio and void ratio, and empirical constants for this relational formula are proposed, but each organization ought to determine appropriate empirical constants for practical application. The process that led to the present proposal is described while introducing the results of the common experiments.
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