By using a newly developed Real-Time AE Spectrum Analyzer, the mechanism of microcracking process and fracture formation of cement mortar was investigated.
This system consists of a newly developed high-speed pipelined FFT (Fast Fourier Transform) processor, and a data acquisition and data compression circuit which is specially designed for the AE signal processing.
The object of AE spectrum analysis is to obtain informations on the microcracking process, and to clarify the relation between microstructure and mechanical properties in cement mortar.
A notched three points bending test by JSME standard was used.
During deformation and fracture process, seven kinds of AE power spectra are detected.
Cracking formation of mortar are shown as follows.
(1) Two kinds of AE events with low energy correspond to debonding at the interface between cement paste and coarse aggregates such as sand particles.
(2) Three kinds of AE events with low-middle energy correspond to the fracture path into cement paste parts by the above mentioned debonding.
(3) The others of two kinds with low-high energy correspond to extension of microcracks through the cement paste parts.
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