The construction sector is one of the most polluting due to the high CO2 emissions generated during cement production. Therefore, it is necessary to experiment with new materials with a lower carbon footprint that improve the mechanical performance and durability of concrete. In this investigation, cement was replaced by metakaolin, and glass fibers were added by weight of the binder. In a concrete with a water to binder ratio of 0.56, fresh state tests such as slump and temperature were performed. Concrete specimens were also cast for compression, tensile and flexural mechanical tests. The main results showed that the mixture with 15% metakaolin and 1% glass fibers exhibited the best performance in flexural and tensile tests. On the other hand, the highest compressive strength was achieved with the use of 10% metakaolin without glass fibers. Based on the research, it is observed that the use of both materials improves the performance of concrete, even with the reduction in the amount of cement.