Complex Study of the Composite Building Material Based on Flax Straw Organic Waste: Hygrothermal and Physicochemical Properties

Abstract The focus of this study is on the hygrothermal and mechanical properties of the elaborated insulating composite based on flax straw. Flax straw is considered as an agricultural waste of organic origin, which has a high sorption capacity and a low thermal conductivity potential due to its natural porosity. Investigations on sorption moisture, thermal conductivity and mechanical properties under laboratory conditions have allowed us to develop a perspective building material suitable for use in ‘green’ construction, especially in rural areas, due to the relative accessibility of the base component. Liquid glass is proposed as a binder. The optimal composition of the filler and binder, sorption moisture, thermal conductivity and surface mapping of the proposed material were investigated. The thermal conductivity reached a minimum value of 0.0728 W m −1 K −1 at relative humidity of 50% during desorption, which is highly competitive to the values for conventional insulation materials on an organic basis. The binder was visually distributed evenly over the surface according to the SEM analysis. Corresponding to the spectral analysis by chemical elements, Na and SiO 2 in total showed 17.69% quantity volume on the composite surface of 2–5 μm in depth. Graphical Abstract