Statistical Characterization of Fracture in CFRP-Concrete Interfaces Due to Wet-Dry Cycling

The experimental fracture mechanics Single Contoured-Cantilever Beam (SCCB) specimen was implemented to evaluate environmentally conditioned concrete-CFRP interfaces. Fracture studies were conducted on specimens having undergone 10, 20 and 30 cycles of alternate wetting and drying. Half of the 24 conditioned specimens studied were placed in a 10% sodium sulfate solution (pH = 6.2-6.5) and half were soaked in sodium hydroxide (pH = 12) to simulate naturally occurring acidic and alkaline field exposure-conditions, respectively. At the end of each target age, SCCB fracture testing was conducted. Two approaches were used in determining the fracture toughness of the CFRP-concrete interface bond that depend on the proper identification of loads reaching a critical state, P-c. In the first, the topmost, or "head", -initiation and -arrestment loads were averaged, and in the second, the mean of the entire "set" of initiation and -arrestment loads was taken. This raw-data was then reduced by a statistical-based method from which a range of permissible critical loads was designated. The final G(Ic) values cited are based on an averaging of this refined data. Considerable degradation of the CFRP-concrete interface bond resulted especially for cases of latter-stage cycling in the aggressive sodium-sulfate and -hydroxide solutions.