EXPERIMENTAL STUDY ON BOND BEHAVIOR BETWEEN NSM CFRP RODS AND STONE FOR COMPOSITE STONE BEAMS

It is a new technique to embed near-surface mounted (NSM) CFRP rods in a stone beam to improve the flexural performance of the beam, and it can be used for retrofitting existing stone structures. 26 pull-out specimens were tested to investigate the bond behavior between CFRP rods and the stone. The main experimental parameters were the diameter of CFRP rod, the bonded length and the thickness of epoxy cover. Test results indicate that there are three typical failure modes, namely tensile rupture of CFRP rod, CFRP rod-epoxy interface-interfacial failure and fracture in the stone along the groove corner. The failure mechanism is influenced by the bonded length, the thickness of adhesive cover and the diameter of CFRP rod. An epoxy cover thicker than 0.5Db has no significant influence on the ultimate load of pull-out specimen. The ultimate load of pull-out specimen increases with the increase of bonded length, whereas the average bond strength decreases with the increase of bonded length. The basic anchorage length is related to the diameter of CFRP rod, which is 30Db and 35Db respectively for bars with diameter of 5mm and 7mm.