Abstract: The steel fiber was aligned by applying a uniform magnetic field to the steel fiber reinforced geopolymer mixture. The aligned steel fiber reinforced geopolymer notched beam was prepared. The acoustic emission of the beam specimen was monitored throughout the test. The effect of fiber orientation on the bending performance of geopolymer beam and the acoustic emission characteristics of the failure process was investigated in this study. The results show that the mechanical properties of aligned steel fiber reinforced geopolymer, including bending strength, crack opening displacement and fracture energy at peak load, are notably higher than those of hybrid steel fiber reinforced geopolymer. The load curve of aligned steel fiber reinforced geopolymer shows obvious sawtooth fluctuation after peak load. In the ascending branch of sawtooth fluctuation, the amplitude of acoustic emission is less than 70 dB, which corresponds to low energy rate and low wave strike rate. In the descending branch of sawtooth fluctuation, a small number of wave hits with amplitude greater than 70 dB and energy over 90% of total energy appeared. It is therefore inferred that two microscopic loss mechanism of matrix cracking and fiber pull-out dominate alternately in the process of sawtooth fluctuation.
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2021, Vol. 35 
