A Fracture Mechanics Approach for Interface Durability of Bonded FRP to Concrete


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Title: A Fracture Mechanics Approach for Interface Durability of Bonded FRP to Concrete

Author(s): J.F. Davalos, S.S. Kodkani, I. Ray, and D.M. Boyajian

Publication: Special Publication

Volume: 230


Appears on pages(s): 1465-1480

Keywords: durability; external bonding; fracture toughness; FRPconcrete; interface

Date: 10/1/2005

Externally bonded GFRP fabrics are being increasingly used for seismicretrofit and rehabilitation of concrete structures, due to their high strength to weightratio and low cost in comparison to carbon and aramid fibers. However, glass fibers arevulnerable to attack caused by harsh environmental weathering conditions such asfreezing-thawing, wetting-drying, and exposure to alkaline and acidic environments.Concerned with durability, this study is based on fracture mechanics to evaluate theinterface durability of GFRP bonded to Normal Concrete (NC) and High-PerformanceConcrete (HPC). Three types of specimens are evaluated: (1) newly bondedunconditioned specimens, (2) environmentally conditioned specimens, and (3)correspondingly base-line companion specimens. Two types of environmental ageingprotocols are defined: (1) freeze-thaw cycling under in calcium chloride, used tosimulate the deleterious effect of the deicing salts; and (2) alternate wetting and dryingin sodium-hydroxide, used to simulate the alkalinity due to the presence of concretepore water. Durability of the interface is characterized based on the critical strainenergy release rate, under Mode-I loading, and weight and strain measurements.Considerable degradation of the interface bond is observed with increasingenvironmental cycling period.