Morphological and structural analysis of treated sisal fibers and their impact on mechanical properties in cementitious composites

Sisal fibers are used as an ecological reinforcement in composites. This article will first study the effect of the different treatments on the morphological properties of the fibers. Then, it will focus on the effect of sisal fibers incorporation in cement mortar. After the various treatments, the results of the scanning electron microscopy showed morphological changes in the fiber's outer surface. X-ray diffraction revealed that treated fibers have a higher crystallinity index compared to untreated ones. The variation of the spectrum in FTIR spectroscopy was consistent with previous results seen in XRD and SEM analyzes. Finally, the ATG of the sisal fiber also showed that the fiber's treatment increased its thermal resistance. In terms of mechanical and physical properties, the addition of 4% sisal fibers by mass of cement led to a decrease in its density and an increase in its porosity. A decrease in the compressive and flexural strength of the mortars was observed, but in the same time, satisfactory results were observed for the elastic modulus of the composite with treated sisal fibers and immersed in paraffin oil. •In term of physical properties, the addition of 4% fiber by mass of cement led to a decrease in the density of the mortar due to the increase in its porosity.•The decrease in flexural and compressive strengths of composites based on sisal fibers compared to the cement mortar is due to the above-mentioned factors.•The results of elasticity modulus of composite mortars with sisal fibers treated with NaOH and immersed in paraffin oil showed a slight (minimal) difference (3%) compared to the elasticity modulus of cement mortar.