Valorization of Posidonia-Oceanica leaves for the building insulation sector

Abstract

A new bio-composite material appropriate for building thermal insulation is proposed. The hydrophilic, thermal, and mechanical properties of composites made with Posidonia-Oceanica leaves, are experimentally investigated. The effect of two different sizes of fibers (natural and crushed leaves) as well as the effect of the chemical treatment (1% sodium hydroxide) are studied. For this purpose, different parallelepipedic specimens of dimensions 270 × 270 × 30 mm3 (thermal properties tests) and 160 × 40 × 40 mm3 (mechanical properties tests) were prepared by varying densities of leaves (0, 5, 10, 15, 20, and 30% by volume). In comparison to the fiber size effect, the results reveal that fiber loading has a significant impact on the mechanical and thermal characteristics of composites. Alkali treatment can improve the compressive and flexural strength of bio-composites. The novel bio-composites have low thermal conductivity (0.09 W.m−1K−1 when 30% of reduced size Posidonia-Oceanica leaves were loaded into the reference mortar) and acceptable mechanical performances. Results also show (1) The addition of treated fiber improves the ductility of the material. (2) The fracture toughness is 75% greater than reference mortar. (3) The use of crushed fibers decreases the composite’s mechanical strengths. (4) The flexural strength decreases with the fibers content and increase after 1% sodium hydroxide treatment. It can be concluded that the proposed bio-composite can be employed as thermal insulation material.