Journal of Advanced Concrete Technology
Online ISSN : 1347-3913
Volume 16 , Issue 4
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Scientific paper
  • Yosuke Ito, Shinji Kawabe, Satoshi Ohba
    2018 Volume 16 Issue 4 Pages 170-178
    Published: April 26, 2018
    Released: April 27, 2018

    Heating mortar block system for melting snow utilizes electromagnetic waves of frequency 2.45 GHz and this system has a feature of quick snow removal and maintainability compared with conventional ways to remove snow. In this study, the influence of Base layer thickness on the capability of electromagnetic waves absorption was clarified and the efficiency of heating mortar block system through electromagnetic waves is improved. The followings are obtained. (1) Thickness of the base layer of sand mortar causes prominent electromagnetic waves absorption at specific frequency (hereinafter called “peak”) with periodicity. (2) It is possible to adjust the thickness of heating mortar blocks to have a peak. (3) The heating capability should be evaluated by the return loss when the sand mortar is placed under the slag mortar. [This paper is the extended version of Ito et al. (2017)]

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  • Nolan Wesley Hayes, Qiang Gui, Ammar Abd-Elssamd, Yann Le Pape, Alain ...
    2018 Volume 16 Issue 4 Pages 179-190
    Published: April 26, 2018
    Released: April 27, 2018

    A large-scale testing program on alkali silica reaction (ASR)-affected concrete structural members without shear rein-forcement representative of structural members found in nuclear power plants is presented. Three concrete specimens, designed to experience a free expansion rate of approximately 0.15% per year were fabricated and placed within a controlled environmental chamber (38 ± 1°C (100 ± 2°F) and 95 ± 5% relative humidity (RH)). Sixty-four (64) embed-ded transducers and twelve (12) long-gauge fiber-optic sensors provide evidence of strong anisotropic expansion and oriented ASR-induced cracking resulting from the confinement effect caused by the reinforcement layout and addi-tional structural boundary conditions. Surface cracking is not indicative of internal ASR-induced damage/expansion.

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