Environmental Impact on the Behavior of CFRP Sheet Attached to Concrete

Abstract

Carbon fiber-reinforced polymer (CFRP) has many advantages as a construction/structural-strengthening material. However, there are still concerns regarding the long-term performance of these materials when used with reinforced concrete (RC) structures. Environmental conditions have an adverse effect on the behavior of CFRP and the bond between these sheets and concrete. Therefore, the durability of CFRP used for strengthening RC beams was evaluated under different environmental scenarios, including subjection to immersion in deicing agents, tap water, and saltwater, freeze-and-thaw cycles, and outdoor environmental changes. Laboratory tests were performed to examine the influence of these environmental scenarios on the bonding behavior between CFRP sheets and concrete in terms of deformations and modes of failure. Two types of test setups were performed in this study, namely pull-off shearing and three-point bending. Forty-two concrete prisms with CFRP were prepared and tested by using the pull-off shearing setup. It was observed that as the period of exposure increased, noticeable effects on the CFRP sheet as well as the bond stiffness were observed. Exposure to tap water had a greater impact than saltwater on the CFRP–concrete bond strength as well as the CFRP. In addition, eighteen notched concrete beams strengthened with an external CFRP were tested under three-point bending. The tap water exposure showed a 3.6% increase in the bond strength compared to the control specimen. However, the saltwater exposure showed a 10% increase.