The deterioration of concrete structures is a major concern to the infrastructure community. Typical sources of deterioration may include aging, increased service load, and environmental damage. Structural rehabilitation using carbon fiber reinforced polymer (CFRP) sheets has recently attracted attention to the infrastructure community because of the superior strengthening effects in comparison to conventional repair methods. The CFRP sheets may be bonded on the deteriorated concrete structure using bonding agents to enhance load-carrying capacity. The most important consideration in such a strengthening method may be the long term durability under harsh environmental conditions. Furthermore, premature debonding of bonded CFRP sheets may also cause significant losses of the strengthening effects. Although extensive research has been reported on the debonding mechanism of CFRP sheets, there is still lack of understanding on the durability of CFRPs subject to low temperature effects. This book mainly focused on the durability performance of concrete members strengthened with CFRP sheets subjected to harsh environments.