Strengthening projects using carbon fiber have been implemented in several structures in Chile, such as buildings, stadiums, hospitals, and-very successfully-bridges. This document introduces the techniques implemented for the superstructure and infrastructure of bridges that are under threat of operational load, seismic activity or collapse. For infrastructure in particular, the application of carbon fibers in Lautaro Bridge, Maule Region, Chile, is presented. This structure was affected by the earthquake of February 27, 2010; it sustained damage on some of its piers. This paper shows the application of carbon fiber to concrete piers as a solution to the aforementioned threats. It also looks into the strengthening technique using carbon fiber applied to the Alhue Bridge, located in the O’Higgins Region. The strengthening of this structure is a response to problems related to an increase of load demand, modification of standards and regulation requirements, as well as a repair and prevention measure against damage or defects caused by seismic activity. In the case of the Alhue Bridge, an important increase of load demand was registered at the end of the 20th and start of the 21st centuries, which damaged the structural system of the deck, making the bridge vulnerable to exceeding heavy loads. Through this investigation, it is possible to extend the application of carbon fiber on slabs as a solution to the aforementioned threats, referencing its construction process through strengthening projects carried out in the country.