Effect of Fiber Treatments on the Mechanical Properties of Sisal Fiber-Reinforced Concrete Composites

The mechanical behavior of fiber-cement composites is significantly influenced by the interfacial bonding between the fiber and the cement matrix. However, natural fibers are less chemically compatible with the cement matrix. As a result, it is essential to modify the surface of natural fibers to achieve good fiber-matrix interfacial bonds. In the current study, sisal fibers intended for use as a reinforcement in concrete matrices were alkali treated with NaOH solutions (2%, 5%, and 10%) for 12 hrs, 24 hrs, and 48 hrs. Water absorption, tensile strength, and surface morphological changes in fibers were studied. The effect of fiber treatment on the concrete was also assessed by measuring its slump, compressive strength, flexural strength, and toughness. Alkali treatment was discovered to reduce the water absorption capacity of sisal fiber. On the contrary, fiber surface morphology and mechanical properties improved up to a point and then gradually declined. The addition of treated sisal fiber considerably increases concrete’s flexural strength and toughness. However, an insignificant change in compressive strength was observed.