Debonding behavior and meso-mechanical properties of CFRP-concrete interface under atmospheric acidic deposition

In this study, the meso-mechanical properties and debonding mechanism of CFRP-concrete interface under atmospheric acidic deposition were investigated. Firstly, debonding failure mode, ultimate load/displacement, strain distribution, and bond-slip relationships under different corrosion time were obtained and analyzed via the single shear test. A new bond-slip model for corroded CFRP-concrete interface was proposed. The relationships between bond properties and damage of concrete were discussed. Secondly, meso-mechanical properties of cement mortar, epoxy resin, and interphase were characterized via nanoindentation method. Elastic moduli of different phases under different corrosion time were investigated and discussed. Finally, a FE model was built to simulate the interface's debonding behavior. Adhesive shear stress and stiffness degradation were utilized to describe the debonding process of CFRP-concrete interface. The results indicated that the bond properties of CFRP-concrete interface increased slightly in initial corrosion stage (0-5 days), then decreased gradually with the development of interfacial damage. The bond strength, fracture energy of the specimens after 50 days of corrosion were 44.1 % and 60.3 % lower than those of uncorroded specimens, respectively. Average elastic modulus of interphase after 50 days of corrosion was 32.1 % lower than that of uncorroded samples, which revealed the deterioration mechanism of bond behavior from meso-scale to macro-scale. The bond-slip model and FE model built in this paper can be utilized to predict the debonding behavior of CFRP-concrete interface. This study can provide theoretical support for CFRP-reinforced structures under atmospheric acidic deposition environment.