MICRO-DAMAGE CHARACTERISATION OF CONCRETE STRUCTURES BASED ON ACOUSTIC EMISSION

摘要

Microcracking may provide a source of damage and generally leads to degradation and deterioration of concrete structures. The purpose of this paper is to review and identify various damage characteristics of concrete structures due to cracking which arises under various different loading conditions. Acoustic emission technique was employed to identify the progress of cracking. A comprehensive experimental program has been set up and several series of test members were tested. The cracking damages under tensile, flexural and pullout loadings have been identified and characterized. It is seen that the amplitudes and energy level of Acoustic Emission (AE) events are found to be relatively small for bond cracking damages and large for tensile cracking damages. The internal microcracks are progressively developed ahead of an actual crack and the present study clearly exhibits this damage mechanism for various types of cracking in concrete. The amplitude-versus-event relations by acoustic emission have been derived to identify the cracking damages of concrete under different loading conditions. The AE characteristics due to corrosion of rebar in concrete are also addressed. The present study will allow more realistic damage assessment of concrete structures through monitoring of internal cracking based on acoustic emission. The microdamages of concrete containing nano-sized materials will also be discussed.