Metallic cement and its application in electrothermostriction
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This thesis provides the first report of metallic cement paste and its application in electrothermostriction. The metallic cement paste contains 0.36 vol.% steel fibers (diameter 8 μm, length 6 mm), in addition to silica fume. The metallic character is shown by linear increase of the electrical resistivity with increasing temperature from 25 to 65°C, low electrical resistivity (2.7 Ω.cm, percolation), and high electromagnetic reflectivity. The paste exhibits temperature coefficient of electrical resistivity 0.004/°C. Electrothermostriction allows electrically activated actuation of an object. The abovementioned metallic cement is used as a planar heating element to actuate a plain mortar block that is cementitiously bonded to it. By applying DC electric power 21 W (voltage 2.8 V and current 7.4 A) for 105 s, this work attained in the mortar in-plane strain 1 × 10 -4 (6 × 10 -4 /°C, which is large compared to the thermal expansion coefficient 1 × 10 -5 /°C).