EFFECT OF FREEZE-THAW ACTION ON ACOUSTIC EMISSION CHARACTERISTICS OF SELF-COMPACTING LIGHTWEIGHT AGGREGATE CONCRETE

To study the acoustic emission (AE) characteristics of self-compacting lightweight aggregate concrete (SCLC) under uniaxial compression after freeze-thaw action, 0, 50 and 100 rapid freeze-thaw tests are carried out on self-compacting lightweight aggregate concrete specimens without air entraining agent. The results show that: with the increase of freeze-thaw cycles, the uniaxial compressive stress-strain curves of the specimen tend to be complete, and the peak stress decreases significantly. The peak frequency of AE is mainly located in the four 'dominant frequency bands' of 15 kHz-45 kHz, of 85 kHz-105 kHz, of 235 kHz-255 kHz and of 285 kHz-320 kHz, corresponding to the compression of pre-existing cracks or pore in concrete, the cracking of aggregate/paste interface reinforcement layer, the penetration fracture of coarse aggregate and the cracking of mortar, respectively. Under the action of uniaxial compression, the freeze-thawed specimens undergo the alternating transformation between tensile cracks and shear cracks, and finally form the main crack which leads to failure. Freeze-thaw action and the variation of stress level have a great influence on the distribution of AE signal source. With the increase of stress level, AE signal tends to be active and gathers on the fracture surface of the sample.