Experimental and simulative study of bonding properties on fiber/epoxy interfaces by digital image correlation (DIC) technique and molecular dynamics

Abstract

Fiber/epoxy interfacial bonding properties play a vital role in the utilization of fiber reinforced polymer (FRP) bars in concrete because almost all durability deficiencies of FRP-reinforced concrete are attributed to the failure of the fiber/epoxy/concrete interface. This study aims to study the evolution of fiber/epoxy debonding under a simulated concrete pore solution environment, combining a self-developed debonding device and the digital image correlation (DIC) technique. The bonding degradation mechanism of the fiber/epoxy interface was revealed by molecular dynamics (MD) simulation. The results show that the interfacial bonding property between glass fiber (GF) and epoxy was superior to that of basalt fiber (BF), and a more significant bonding degradation was observed in BF after the corrosion of water and chloride ions due to the reduction in the number of H-bonds caused by partial replacement of Si by Al, as concluded from MD simulation. Moreover, the bond stresses of GF and BF were reduced to approximately 15% and 12% after 28 days of corrosion in the simulated concrete pore solutions, respectively. Meanwhile, the reduction in bond strength was more significant in the simulated concrete pore solution of seawater and sea sand concrete (SWSSC).