Evaluating the impact of coatings and chemical treatments on the tensile behavior of natural fibers

Vegetal fibers are gaining interest in the construction industry as sustainable alternatives to synthetic materials in structural composites. However, their variable mechanical properties and lower durability often limit their effectiveness, particularly in fiber–matrix adhesion and overall structural performance. This study investigates the impact of alkali treatments and graphene coatings on the tensile behavior of hemp and Spanish broom fibers, with a specific focus on treatment duration rather than concentration levels. Sodium hydroxide (NaOH) treatments were applied to remove non-cellulosic components, followed by graphene coatings to enhance fiber strength and durability. The results indicate that alkali treatment improves fiber surface roughness and fibrillation, thereby enhancing mechanical interlocking with the matrix. Graphene coatings further contribute to tensile strength and stiffness, particularly for Spanish broom fibers, which maintain integrity after treatment. These findings highlight the potential of chemically treated and graphene-coated vegetal fibers as viable reinforcements in mortar based composite materials, providing enhanced mechanical performance and environmental sustainability. • Tensile tests are carried out on hemp and Spanish broom fibers. • Effect of alkali treatments duration on fiber tensile properties is assessed. • Effect of graphene coating on treated fiber tensile properties is assessed. • Results show significant improvements in fiber tensile properties with graphene coating.