Concrete Journal
Online ISSN : 2186-2753
Print ISSN : 0387-1061
ISSN-L : 0387-1061
Volume 58 , Issue 3
Showing 1-11 articles out of 11 articles from the selected issue
  • S. Urano, Y. Nakata, S. Yanai, C. Hashimoto
    2020 Volume 58 Issue 3 Pages 209-216
    Published: 2020
    Released: March 01, 2021

    Various issues related to pumping concrete with concrete pumps have been pointed out. These include the occurrence of accidents and the lack of a unified pumping load calculation method. The Committee on Concrete Pumping Technologies, which gathers information on the latest trends in pumping technology, conducted as a safety study an analysis of accidents involving pumping and a survey on the status of conveying pipe management methods. Further, as an investigation of pumping plans, the Committee conducted a survey on issues related to pumping planning, and regarding pumpability, it conducted a survey on differences in this regard among the concrete-related guidelines of academic societies. Based on the “Report of the Committee on Concrete Pumping Technologies”, published in June 2019, which presents the results of two years of activities by the Committee, this paper describes the findings.

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  • T. Koyama, K. Ito, H. Jinnai
    2020 Volume 58 Issue 3 Pages 217-222
    Published: 2020
    Released: March 01, 2021

    The Architectural Institute of Japan's “Recommendation for Practice of Hot Weather Concreting”, which consists of guidelines for measures against various problems that affect concreting in hot environments, was revised in July 2019. This paper first lays out the climatic characteristics of increasingly hot summer environments, then gives the background of the revisions that have been made since the establishment of this Recommendation, and the main points of revision in each chapter.

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  • H. Yamada, H. Katahira, H. Watanabe
    2020 Volume 58 Issue 3 Pages 223-228
    Published: 2020
    Released: March 01, 2021

    Drying shrinkage of concrete is influenced by various factors such as the materials used, mix proportions, construction conditions, environmental conditions, and shape. In recent years, much attention has been paid to the fact that concrete using coarse aggregate that conforms to the JIS standard experiences excessive drying shrinkage strain. It has been reported that the effect of the coarse aggregate used is greater than the effect of unit water content, which has long been held to be a major factor for drying shrinkage of concrete. Based on the above, a method for measuring the drying shrinkage rate of coarse aggregate using a wire strain gauge has been established and the relationship between the drying shrinkage rate of concrete and various quality indicators of coarse aggregate has been clarified through an investigation focusing on the drying shrinkage characteristics of coarse aggregate. This paper reports the results of reorganizing the data acquired so far.

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