Concrete Journal
Online ISSN : 2186-2753
Print ISSN : 0387-1061
ISSN-L : 0387-1061
Volume 57 , Issue 6
Showing 1-11 articles out of 11 articles from the selected issue
  • K. Yokozeki, M. Hisada
    2019 Volume 57 Issue 6 Pages 419-425
    Published: 2019
    Released: June 01, 2020

    The Japan Society of Civil Engineers (JSCE)ʼs Standard Specifications for Concrete Structures “Test Methods and Specifications” were revised in October 2018 for the first time in five years. The “Test Methods and Specifica tions” volume is a specification document that covers concrete-related quality standards and test methods. It is composed of two parts, namely a compilation of JSCE standards and related standards, and JIS standards. Under the design/construction and maintenance system for performance verification type structures, qualified performance evaluations are required, and test methods and specifications play an important role toward the fulfillment of this requirement. This paper describes newly added five standards and sixty revised standards of the 2018 edition of the Standard Specifications for Concrete Structures “Test Methods and Specifications” and provides an outline of revised materials.

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  • S. Asamoto, S. Okazaki, I. Kurashige, N. Chijiwa, Y. Kawabata
    2019 Volume 57 Issue 6 Pages 426-432
    Published: 2019
    Released: June 01, 2020

    In the case of mass concrete, rich-mixture prestressed concrete, steam cured precast concrete, and hot weather concrete, the temperature in the concrete due to internal and external factors can be as high as 60°C to 80°C. Focusing on the practical risks by the high temperatures of 60°C to 80°C, the Technical Subcommittee on the Investigation into the Effects of High Temperature on Concrete Performance and Characteristics (Committee No. 352) of the Japan Society of Civil Engineers discussed the topics and required research when the concrete structures are exposed to the high temperature, from the two aspects of the macro performance requirements for design and construction, and the physicochemical micro-characteristics organically related to the macro performance. This paper organizes the design and construction-related concepts in the field of civil engineering related to exposure to high temperatures, presents an overview of the results of the Subcommittee's activities, and outlines the required approach for understanding the effects of exposure to high temperatures on concrete performance, and related design issues.

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  • S. Komatsu, Y. Kondo, N. Ikawa, C. Hashimoto
    2019 Volume 57 Issue 6 Pages 433-440
    Published: 2019
    Released: June 01, 2020

    Based on the assumption that workers can be made to learn correct test methods by having them understand the importance of adhering to the work items specified in the Japanese Industrial Standards (JIS) and properly understand ing the mechanism of measuring equipment, workers were made to conduct the slump test, air content test, and compressive strength test under conditions deviating from those specified by JIS. Two types of concrete were used, with respective slump of 21 cm and 12 cm. The findings included the facts that the timing of lifting of the slump cone can decrease the measured slump value of fresh concrete by up to 3.0 cm, that the finishing method of the samples placed in the air content tester can cause the measured air content value to vary by up to 1.5%, and that tumbling of specimens prior to concrete hardening can cause reduction in compressive strength by approximately 7% by the material age of 28 days.

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