Mesoscopic study on axial compressive damage of steel fiber reinforced lightweight aggregate concrete

•The failure mechanism of SFLWCs under axial compression test was studied.•The variation of AE parameters was analyzed.•Two statistical methods (Ib-value and RA value) have been analyzed.•The frequency bands of SFLWCs were investigated. The main purpose of this study was to reveal the failure mechanism and fiber reinforcing mechanism of steel fiber reinforced lightweight aggregate concrete (SFLWC) under uniaxial compression loading. The variation of acoustic emission (AE) parameters from the initial damage to final failure was analyzed. The statistical analysis methods of AE data were used for determining micro- and macro-cracking, as well as identifying the cracking modes (tensile cracking and shear cracking). The results showed that AE signals were positively correlated with the variation of stress. Micro-steel fiber could significantly reduce the density and intensity of AE signals. The frequency bands of SFLWCs were mainly distributed in four ranges: 15–45 kHz, 85–105 kHz, 235–255 kHz and 285–320 kHz, which corresponded to the compression of pre-existing cracks or pores in concrete, the fracture failure of aggregate/paste interface reinforcement layer, the penetration fracture of aggregate and the cracking of mortar, respectively. With the increase of micro-steel fiber dosage, the three-dimensional distribution of AE signal source became more dispersed, which indicated that the addition of steel fiber could disperse the internal damage of lightweight aggregate concrete (LWC) and prevent the local brittle fracture caused by stress concentration.