The flexural behavior of bridge concrete slab sections that were subjected to a level of cracking and were later repaired with carbon fiber reinforced polymers (CFRP) was evaluated in order to study the possibility of using this type of strengthening in existent bridge slabs in Costa Rica.Three concrete slabs were built: the first was a control specimen (which was not strengthened with CFRP) and the two others were meant to evaluate the effect of CFRP strengthening. The loading scheme consisted in placing the slabs on three simple supports and applying two concentrated loads, in order to generate positive and negative moment regions. The slabs meant for strengthening were initially loaded with an 80% of their ultimate strength with the purpose of generating cracks that needed repairing. The cracks whose crack widths exceeded 0.3 mm were repaired by epoxy injection and then the two slabs were strengthened with CFRP in the positive and negative moment regions. Finally the three specimens were loaded until failure.The slabs reinforced with CFRP were 36% stronger than the control slab, which suggests that this type of strengthening can be used in existing bridge slabs in the country. Additionally, the experimental results obtained in this project were compared with the experimental results from the project of Carranza (2017) and both projects had similar results, with difference percentages varying between 10% and 14%.Se evaluó el comportamiento a flexión de secciones de losas de puentes de concreto que fueron sometidas a un estado de agrietamiento y posteriormente reparadas con polímeros reforzados con fibras de carbono (CFRP). Se construyeron tres losas de concreto: un espécimen de tipo control (sin refuerzo con CFRP) y dos especímenes para evaluar el refuerzo con CFRP. El esquema de carga consistió en colocar las losas sobre tres apoyos simples y aplicar dos cargas puntuales que generasen momento positivo y negativo. Se sometieron las losas por reforzar a un 80% de su carga última para generar agrietamiento que requiriese reparación. Se repararon las grietas cuyos anchos de grieta superaron los 0.3 mm mediante inyección de epóxico y se reforzaron los dos especímenes con CFRP en las zonas de momento positivo y negativo. Finalmente se cargaron los tres especímenes hasta la falla. Se obtuvo que las losas reforzadas con CFRP fueron 36% más resistentes que la losa control. Además se compararon los resultados experimentales de este proyecto con los resultados de la investigación de Carranza (2017). Se concluyó que ambas investigaciones dieron resultados similares, con porcentajes de diferencia entre un 10% y 14%.