Damage process and performance of PVA fiber-reinforcedalkali-activated slag mortar plate under bending

The effects of unoiled polyvinyl alcohol(PVA)fiber with four different volume fractions of 0%, 1.0%, 1.5% and 2.0% on the bending properties of alkali-activated slag(AAS)mortar plates were studied. Meanwhile, the acoustic emission(AE)technique and a high-speed camera were utilized to detect the crack development over the complete damage process, and the scanning electronic microscopy(SEM)was used to observe the fiber-matrix interface. Test results show that PVA fibers play a significant role in the toughness improvement of AAS plates. However, the enhancing effect of PVA fibers on the bending behaviour of AAS plates at 120 d is not as remarkable as at early ages. It is observed that the failure process of the PVA fiber-reinforced alkali-activated slag plate can be divided into three stages: elastic stage, main crack formation stage and post-peak load stage. Observations on the fracture surface of specimens indicate that the deterioration process of specimens under bending changed from fiber pull-out at 3 and 28 d to fiber fracture at 120 d.