Abstract
In this study, high-strength concrete containing hooked-end steel or amorphous metallic fibers was fabricated, and the electrical conductivity and electromagnetic shielding effectiveness were evaluated after 28 and 208 days based on considerations of the influences of the moisture content. Amorphous metallic fibers, which have the same length and length/equivalent diameter ratio as hooked-end steel fibers, were favored for the formation of a conductive network because they can be added in large quantities owing to their low densities. These fibers have a large specific surface area as thin plates. The electromagnetic shielding effectiveness clearly improved as the electrical conductivity increased, and it can be expected that the shielding effectiveness will approach the saturation level when the fiber volume fraction of amorphous metallic fibers exceeds 0.5 vol.%. Meanwhile, it is necessary to reduce the amount of moisture to conservatively evaluate the electromagnetic shielding performance. In particular, when 0.5 vol.% of amorphous metallic fibers was added, a shielding effectiveness of >80 dB (based on a thickness of 300 mm) was achieved at a low moisture content after 208 days. Similar to the electrical conductivity, excellent shielding effectiveness can be expected from amorphous metallic fibers at low contents compared to that provided by hooked-end steel fibers.
Highlights
The rapid development of information and communication technology has increased the use of electronic devices, thereby causing electromagnetic wave pollution [1,2,3]
Amorphous metallic fibers form an excellent conductive network at a lower content compared to that formed by hooked-end steel fibers because the former have a larger specific surface area and quantity at the same content
Compared to PP0.15AM0.5, the other specimens exhibited significantly reduced electrical conductivity and shielding performance owing to the reduction in moisture content caused by long-term aging
Summary
The rapid development of information and communication technology has increased the use of electronic devices, thereby causing electromagnetic wave pollution [1,2,3]. Many studies have been conducted on carbon-based materials, such as CNTs and graphene, as mixing materials for electromagnetic wave shielding owing to their large specific surface area, low density, and excellent mechanical and electrical properties, but they have shortcomings, such as high production cost and low dispersibility [13,14,15]. In the case of typical steel fibers, their heavy weight still increases the self-weight of the structure, but their actual application is difficult owing to the corrosion problem [21,22] Their small specific surface area and high density make it difficult to construct continuous conduction paths, and the complex manufacturing processes, such as casting and hot and cold rolling, are not favorable in terms of carbon dioxide emissions [23]. The effects of the content and specific surface area of fibers on the electrical conductivity and electromagnetic shielding effectiveness were examined, and the relationship between the electrical conductivity and electromagnetic shielding effectiveness was analyzed within the scope of this study
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