Study of toughness and thermal properties of bio-composite reinforced with diss fibers for use as an insulating material

•Effect of diss fibers rate on mechanical and thermal properties of cementitious composite.•The incorporation of diss fibers in cement matrix makes the composite lighter and improves its insulating capacity.•Enhancement of Toughness of diss fibers based composites under flexion and compression.•The composites could be classified as structural and insulating material according to RILEM classification. This study investigates the performances of a new material composed of cement binder and natural vegetal diss fibers. The main goal is to use a locally abundant plant (diss) as a substitute for aggregates, in order to produce a lightweight material with excellent thermal insulation. Three composites with diss fiber content of 20%, 25% and 30% by weight of cement were produced, and their thermal and mechanical performances were experimentally investigated. At first, the flexural strength, toughness index, compressive strength and toughness energy of the composites were examined. Then, thermal properties in terms of conductivity, diffusivity and effusivity were evaluated for the three composites. The results show that incorporating a large amount of diss fibers in the cement matrix causes an increase in the porosity of the composite and consequently a reduction in density. The high porosity of the composites causes a significant reduction in compressive strength. However, the toughness of the composites in the post-cracking stage is significantly enhanced. Under three-point loading, the diss-fiber-reinforced composites exhibit pseudo-ductile post-peak behavior with high values of toughness index (I5). The low density is accompanied by an improvement in the composites’ thermal performance, with a significant decrease in thermal conductivity, thermal diffusivity and thermal effusivity. According to RILEM, the developed composites could be classified as lightweight insulating materials and can be used in non-load bearing walls and insulating fillers.