Mechanical properties of structural fiber-reinforced concrete

The research analyzes the effect of structural synthetic fibers (1.5% by volume) on the physical and mechanical properties of concrete. Mixtures with and without fibers were prepared following NMX standards and ACI 211 method, evaluating slump, unit mass, temperature, and compressive, flexural and tensile strengths at 7, 14, 28 and 45 days. The fibers reduced the slump, decreasing the workability, but did not significantly modify the unit mass or temperature, indicating a more cohesive and segregation-resistant mix. The compressive strength increased 10.7% with respect to the design and 5% with respect to the mix without fibers, due to the better distribution of stresses. In flexure, the increase was 11.6% at 45 days, since the fibers delay the formation of cracks and allow higher stresses before failure. In tension, the reinforced concrete showed an average increase of 9.1%, reaching 12.1% at 45 days, although its effect is limited at high loads. Keywords: reinforced concrete, structural synthetic fibers, mechanical properties, strength, durability.