Interfacial bonding enhancement on the epoxy adhesive joint between engineered bamboo and steel substrates with resin pre-coating surface treatment

As a green and natural engineering material, bamboo is going to be vastly used in constructions, as well as it needs to be bonded with other materials for composite application. This study applied a resin pre-coating (RPC) method on the epoxy adhesive joint between engineered bamboo and steel substrates and experimentally investigated the beneficial effect of the RPC method on the bonding property of epoxy joints. The diluted resin solution was made by dissolving resin in acetone, and three mixing concentrations by weight were prepared as 5 wt%, 10 wt% and 20 wt%. The test results showed that RPC treatment obviously increases the shear strength and energy of the epoxy joint, while the degree of the effect depends on the resin solution concentration. Moreover, the RPC method also improves the failure mode of the epoxy joint from adhesive fracture along the steel bonding interface to mixed mode of structure fracture in engineered bamboo and adhesive fracture in both adhesive interfaces, as well as increases the failure surface roughness. The working mechanism of RPC treatment is that the resin solution could take sticky epoxy adhesive penetrate into the micro-openings along the bonding surface zone and remove the bonding defects, and thereby, it enhances the interlocking effect between substrate and adhesive as well as improves the rupture strength of engineered bamboo near the bonding interface zone. Finally, it improves the bonding property of epoxy adhesive joint between engineered bamboo and steel.