Effect of natural alfa fibers on cementitious composites: Characterization, optimization, and performance evaluation

This study evaluated the effect of Alfa Fibers (AFs) as reinforcement in cement mortars. In order to improve fiber-matrix compatibility, an alkaline treatment was applied before mixing. A detailed characterization was performed using Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, X-Ray Diffraction, and tensile testing to assess morphological, physical, chemical, and mechanical characteristics of AF. Moreover, a systematic optimization of fiber ratios in the blend was conducted, considering three lengths (25, 30, and 35 mm) and three contents (0.2, 0.3, and 0.4%), evaluating workability, compressive, and flexural resistance. The optimal mixture was analyzed in depth, assessing mechanical behavior, durability-related properties, and thermal conductivity compared to a control batch. The results demonstrated structural changes in the fibers induced by alkalinization, improving fiber-matrix interaction. Optimizing length and content defined the most suitable proportions for AF-Reinforced Mortar (AFRM). Regarding mechanical properties, the fiber-reinforced mix exhibited a 30.2% increase in flexural resistance and a 4.0% growth in compressive strength compared with control. The durability results highlighted a satisfactory response from AFRM. While porosity and water absorption were higher by only 9.4% and 7.7%, respectively, capillarity behaved analogously to the control mortar. Conversely, a reduction in drying shrinkage was observed over time, attributed to the presence of fibers. Thermal analysis revealed insulation efficiency by AFRM, with a 19.3% lower thermal conductivity. Overall, the findings confirm that AF can enhance the performance of mortars for construction applications. The integrated evaluation developed in this work provides an effective approach for incorporating natural fibers into cementitious composites.