Science and Technology of Energetic Materials

Vol.65, No.1 (2004)

Research paper

Acoustic emission monitoring during breakage of a mortar specimen by expansive cement agent (*in Japanese)
Hisaaki Fukui, Tsuyoshi Ishida, and Naoto Ohsaka


Breaking rocks and concrete accompanies ultrasonic waves called acoustic emission. Since generation and extension of cracks causes the acoustic emission, their locations help to clarify the breaking mechanism. In this paper, the breaking mechanism of a 200 mm cubic mortar specimen by rapid type of expansive cement agent was investigated by locating acoustic emissions. At the first stage when expansive pressure of the cement agent increased gradually, acoustic emissions were distributed around the center hole of the specimen in which the cement agent was filled. At the second stage while the expansive pressure started to increase intensively and reached its maximum, they clustered near a surface on the one side of the specimen, in contrast to the distribution near the center hole at the first stage. Finally, at the third stage while visual cracks appeared and separated the specimen completely, they distributed along the cracks.

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