Volume 5, Issue 6 (November 1977)
Acoustic Emission of Plain Concrete
When a specimen of engineering material is subjected to external loads, stress waves known as acoustic emissions are induced. A unique characteristic of many engineering materials that emit acoustical energy is that upon reloading the specimen does not emit acoustical energy until the magnitude of loading exceeds the prior maximum loading. This investigation was undertaken to determine if this characteristic could be used to disclose the loading history of plain portland cement concrete. The test results show that the unique characteristic is very temporary and therefore cannot be used to determine the prior maximum loading on a concrete specimen. Within a matter of hours concrete subjected to loading within its elastic limit recovers, and acoustical energy may again be released by reloading.