The architectural heritage of the colonial period in Mesoamerica was built primarily with stones from local quarries. In Mexico, 10 colonial cities have been declared UNESCO World Heritage Sites, where stone blocks joined or covered with lime mortar were widely used. In some cases, walls were constructed with uncarved stones covered and grouted with mortars. This construction technique, derived from European treatises by Alberti, Palladio, and Vitruvius, was adapted by builders in the Americas. Consequently, lime mortars were modified to suit local conditions and required mechanical resistance, elasticity, durability, color compatibility, and adhesion to stone. A major challenge in seismic zones is minimizing cracking while increasing flexural strength and elasticity. This study analyzed lime mortars reinforced with natural fibers, including cotton, lamb¿s wool, hair, and chicken feathers, to determine their behavior under compressive, flexural, adhesive, and direct tensile stresses, as well as modulus of elasticity. Nondestructive tests, including ultrasonic pulse velocity, colorimetry, effective porosity, and sorptivity, were also conducted. All tests were performed at 1473 days. Results indicated significant improvements in mechanical properties compared with unreinforced mortars, demonstrating that natural fiber reinforcement enhances performance and durability, supporting its use in the preservation and restoration of historic masonry.
