Characterization of biomass-based materials for building applications: The case of straw and olive tree waste

Vegetable fibers are more and more frequently used in building materials because of their low carbon footprint and their suitability as hygrothermal panels and acoustic absorbers. In particular, as vegetable materials have high carbon sequestration capacity, any use that prevents their incineration (e.g. the natural end-of-life for most pruning wastes), represents an essential contribution to reduction of CO2 emissions. For the above reasons, several researches promote the revival of sustainable building materials made of biomass. In this study, the hygrothermal and acoustical properties of materials suitable for buildings, made with vegetable fibers, are investigated. Straw fibers and olive tree-pruning residues were mixed with sodium silicate solution binders to create high performance insulating panels. Tests carried out in the laboratory allow a correlation between physical and microstructural properties. They evaluated thermal properties, such as thermal conductivity and thermal diffusivity, as well as the hygric performances of the materials, such as sorption isotherm and water vapor permeability. Moisture diffusivity and moisture buffer value were also estimated. Furthermore, sound absorption measurements were carried out. A final comparison between the new panels and one insulating material (EPS) on the market was discussed based on a numerical simulation using Wufi® software.