Issues Related to Durability of Frp Reinforcement for Rc Structures Exposed to Accelerated Ageing

Corrosion of steel reinforcement in an aggressive environment constitutes a serious problem for many reinforced concrete (RC) structures. Fiber-reinforced polymers (FRP) rebars represent a potential solution to this situation. Even if FRP reinforcement shows a good resistance to electro-chemical corrosion, long-term behavior must be investigated and proven. The mechanical properties of FRP rods are primarily related to fiber type and content, but an aggressive environment may cause damage to the resin allowing chemical and physical agents to attack the fibers. The cementitious environment and external agents may affect the long-term mechanical performance of FRP reinforcement. The pore water in concrete is highly alkaline (pH = 13.5) and may reduce significantly the mechanical properties of fibers such as those made of glass. At the same time freeze-thaw cycles, moisture absorption, and thermal cycles may produce resin cracking and accelerate stress corrosion mechanisms. All these effects may be accelerated by the presence of applied load. In this project, an experimental procedure is proposed to study the long-term behavior of FRP rods used in RC structures. Accelerated ageing and physicomechanical characterization were conducted for five types of FRP rods under two types of conditioning regimens. The correlation between the tensile test results, apparent horizontal shear strength, and gravimetric measurements allowed to determine the changes in properties due to fiber and resin degradation, as a result of the accelerated aging. Electronic microscopy investigations (SEM) were carried out to highlight the damage mechanisms at the fiber-matrix interface. Micelli, F. and A. Nanni, “Issues Related To Durability Of FRP Reinforcement for RC Structures Exposed to Accelerated Aging,” Proc., ASC 16 Annual Conference Virginia Tech, Blacksburg, VA, Sept. 9-12, 2001, M.W. Hyer and A.C. Loos, Eds., Paper 056, 12 pp. CD-ROM