Concrete, a widely utilized construction material, is prone to sudden failure and has limited energy absorption upon yielding. The incorporation of short discrete fibers has shown significant promise in addressing these challenges. Fiber-reinforced concrete finds application in various scenarios. Fibers are added to concrete to reduce cracking, enhance physical properties, reduce drying shrinkage, improve strength and toughness, extend service life, decrease water bleeding, reduce concrete permeability, and enhance construction value. Sisal, a natural fiber known for its high mechanical efficiency, is used as reinforcement in a cement-based matrix. This research focuses on the structural, morphological, and mechanical aspects of reinforced concrete slabs containing varying proportions of sisal fibers, ranging from 1 to 2% by weight of cement. The inclusion of sisal fibers alters the concrete flow, aligning with findings from prior studies. Notably, an alkaline treatment using NaOH was conducted, removing impurities and reducing lignin and cellulose content. This treatment, as observed in SEM images, enhanced the surface morphology of the coarser sisal fibers, leading to increased tensile strength in the samples. Additionally, the mechanical properties, including strength parameters and tensile stress, exhibited improvements with the incorporation of sisal fibers. These findings highlight the potential benefits of sisal fibers in enhancing concrete strength and mitigating brittle fractures.