Experimental investigation on interfacial bonding performance between cluster basalt fiber and cement mortar

To fully understand the action mechanism of basalt fiber (BF) in matrix, so that basalt fiber reinforced concrete (BFRC) can be more widely used in engineering, it is necessary to study the bonding performance between BF and matrix. The interfacial bonding performance between cluster basalt fiber (CBF) and cement mortar were investigated by fiber pull-out test, acoustic emission (AE) technology and digital image correlation method (DICM). The failure modes and surface micro-morphology of pulled-out fibers were analyzed by scanning electron microscope (SEM). The results indicate that as the BF bundle quantity and fiber embedded depth increase, pull-out load increases obviously, while calculated bond strength decreases significantly. Specimens with double BF bundle and larger fiber embedded depth can absorb more interfacial rupture energy. More hydrate particles on the surface of pulled-out BF bundles under higher pull-out load. The variation rules of AE energy and accumulated ring count can accurately predict different test stages. The peak frequencies of AE signal are mainly concentrated in the bands of 0–100 kHz, 200–300 kHz and 420–480 kHz. The changing trend of interface strain can be accurately expressed by the change rule of surface strain. This paper provides a new idea for studying the bonding performance between fiber and matrix.