Effect of fibers surface treatments on the mechanical and thermal properties of composites reinforced by eco-friendly fibers

This paper deals with the enhancement of thermal insulation of building construction materials by the incorporation of treated natural fibers (posidonia oceanica and esparto grass). The surface treatment of the natural fibers aimed at the improvement of the adhesion between fibers and construction material matrices. Untreated and treated posidonia oceanica and esparto grass fibers have been characterized through Fourier Transform Infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. The obtained results indicated a clear change in the surface morphology, enhancement in the crystallinity, and modification in the chemical structure of the treated posidonia oceanica and esparto grass fibers in comparison with untreated fibers. Experimental investigations have been carried out to examine the effect of the incorporation of treated posidonia oceanica and esparto grass fibers on the interfacial adhesion with matrices, the compressive strength of cement and gypsum composite samples compared to those with untreated fibers and their thermal properties. Results indicated, on the one hand, an improvement of the interfacial adhesion and compressive strength of matrices filled with treated fibers compared to those filled with untreated fibers. On the other hand, results have shown a clear reduction in thermal diffusivity, thermal conductivity, and bulk density of composites with the addition of treated fibers compared to those of composites without fibers. Finally, the treated posidonia oceanica and esparto grass utilized can replace conventional synthetic fibers and will be an interesting alternative that would solve simultaneously environmental and energy concerns.