Microstructure, thermo-physical and mechanical properties of green biocomposite based on gypsum and alfa stipa tenacissima fibers

This paper presents an experimental and theoretical investigation of the thermo-physical and mechanical properties of gypsum-based composites reinforced with different percentage of Alfa fibers of 40 mm length. Samples containing 0.5%, 1%, 1.5%, and 2% fiber by weight were prepared and analyzed. The analysis of the results indicates that increasing the Alfa fibers content from 0 to 2% caused a decrease in compressive strength. This reduction can be attributed to the increase in both the size and the number of pores resulting from the addition of fibers. A clear improvement in flexural strength was observed with the addition of 1.5% of Alfa fibers. The incorporation of 2% by weight of Alfa fibers into the plaster matrix considerably reduced the density and enhanced the thermal insulation properties. The thermal conductivity of the most insulating composite was 0.142 W/m·K. A modeling application showed good agreement with the experimental results. From a microstructural point of view, the surface of Alfa fibers improved the fiber-matrix adhesion. In the light of these results, the developed composite can be used as an insulating and structural plasterboard material in buildings according to the functional classification proposed by RILEM.