Insights on the adhesive properties and debonding mechanism of CFRP/concrete interface under sulfate environment: From experiments to molecular dynamics

Carbon fiber reinforced polymer (CFRP)-reinforced concrete structures serving in the marine environment are susceptible to sulfate attack, and the CFRP/concrete interface becomes the most vulnerable due to adhesive degradation. In this paper, the influences of the sulfate on the adhesion of the CFRP/concrete interface are investigated by combination of experiments and molecular dynamics simulation. Macro experiments show that the debonding between CFRP and concretes generally results from the adhesive failure at the epoxy/concrete interface. As the corrosion age increases, the maximum shear stress of the interface decreases gradually and tends to transfer to the non-loading side. Meanwhile, both of the fracture energy and adhesive strength of the CFRP/concrete interface is reduced due to the sulfate attack. Besides, molecular dynamics simulations reveal the micro-adhesive mechanism of the epoxy/calcium silicate hydrate (C-S-H) interface, and offer an atomic explanation for the sulfate environment weakening the adhesion of epoxy/C-S-H interface. Expectantly, this study can promote a comprehensive understanding of sustainable and durable CFRP-reinforced concrete. (C) 2020 Published by Elsevier Ltd.