To Monitor Fracture Behaviors in Four-Point Cyclic Bending Tests of Low-Activated High Alumina Concrete and Standard Concrete RC Beams Using Acoustic Emission Technique

Abstract

In this study, acoustic emission monitory (AE) was used to observe and evaluate the mechanical behavior of two kinds of RC beam members, made of low-activation concrete and normal concrete, by general four-point bending test and cyclic four-point bending test. During the loading, acoustic emissions due to cracking, shearing, rubbing, de-bonding or interlocking could be monitored and recorded using a real-time high sampling rate DAQ system and proper sensors; besides, beam displacement, cracking situation and loading were also measured simultaneously. The experiment goals included: (1) to observe the damage mechanisms of the beams under bending test and their corresponding AE performance; and (2) to observe the material fracture and corresponding AE in the beams under the cyclic bending test of 0.5Hz (periodic dynamic condition). After experiments, the fracture history of the beam under general loading test could be revealed through the comparison for the chronicled AE signal density and load/strain data. The damage on beam under the cyclic test could be analysed through the chronological comparison for the cumulative sum of AE signal counts obtained for different test periods and stages. Both the irreversibility on fracture mechanism (affected by the Kaiser effect) and the “remainder toughness” could be discussed through the quantitative analysis on AE characteristics for two different beams. They might relate to the durability and toughness of material for beam.