Concrete Journal
Online ISSN : 2186-2753
Print ISSN : 0387-1061
ISSN-L : 0387-1061
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Volume 51, Issue 6
Displaying 1-13 of 13 articles from this issue
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TOPICS
  • Experimental Study on Seismic Retrofitting Technology that Complements Existing Pile Foundations with Soil-Cement Columns made with Cementitious Solidification Material
    K. Tomisawa, T. Maki, T. Watanabe, T. Sasaya
    2013 Volume 51 Issue 6 Pages 499-506
    Published: 2013
    Released on J-STAGE: June 01, 2014
    DOIhttps://doi.org/10.3151/coj.51.499
    JOURNAL FREE ACCESS
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    Inadequate seismic performance of foundations during an earthquake causes excessive response displacement of the superstructure, which may degrade the functions of the entire structure. Thus, like the seismic reinforcement of superstructures and substructures, reinforcement measures are considered necessary for the existing foundations of structures that could not be provided with the required seismic performance, including liquefaction countermeasures. Consequently, as a reasonable seismic retrofitting technology for foundations in soft ground or liquefied ground, composite piles that provide soil-cement columns made with cementitious solidification material around pile foundations were researched and developed. Composite piles differ from conventional foundation seismic reinforcement methods that integrate reinforcement piles, reinforcement material or soil-cement columns with the substructure in that they represent a technology that aims to secure seismic performance of existing pile foundations solely through the reaction force of soil densification columns, and they are considered advantageous in terms of executability and cost. A series of large-scale experiments on the practical application of composite piles was conducted and findings on their seismic performance centering on the energy absorption effect are reported.
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  • Physical Properties of Crushed Stone Powder Influencing the Properties of Concrete
    T. Fumoto
    2013 Volume 51 Issue 6 Pages 507-514
    Published: 2013
    Released on J-STAGE: June 01, 2014
    DOIhttps://doi.org/10.3151/coj.51.507
    JOURNAL FREE ACCESS
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    Aggregate produced by crushing stone or waste always contains powder. When this powder is mixed in a part of the aggregate and for the effective resources, it influence the properties of the concrete. Given that there is a variety of powder materials and manufacturing methods, there is a need to clarify the physical properties of powder that affect the properties of concrete. With particular focus on crushed stone powder, this paper outlines the my research applied to paste, mortar and porous concrete. As a result, it is determined that the filling factor, particle shape, and fine surface irregularities of crushed stone powder have an influence on the dispersion state of crushed stone powder and the flowability of the paste, and that crushed stone powder behaves as a part of the paste with respect to the flowability and drying shrinkage of the paste.
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