Influence of technological factors on sapropel/wood chips composite

Organic lake sapropel was used as a binder to create a composite for thermal insulation and construction. To obtain good composite properties, the sapropel itself and the contact zones between the sapropel and the filler were modified. To improve the adhesion of wood chips to sapropel, the chips were treated mechanically, thermally, and chemically to roughen and uneven the surface and impart hydrophobic properties. To improve the adhesion properties of sapropel, it was mechanically cleaned and activated to increase its surface area, reduce impurities that destroy the contact zones, and increase the number of active bonds. To optimise the properties of the composite, the wood chip-to-sapropel ratio, the pressure applied to the mixture, and the use of a hydrophobizer and a flame retardant were varied. Binder amounts ranging from 8 to 72% by mass of sapropel relative to wood chips were used to bind the composite. It was found that the amount of sapropel determines the composite's density, thermal conductivity, and compressive strength. The optimal ratio among material density, thermal conductivity, and compressive strength was determined. It was found that using 32% sapropel by mass of wood chips yields a composite density of 251 kg/m 3 , a compressive stress at 10% deformation of 141 kPa, and a thermal conductivity coefficient of 0.0586 W/(m·K). Using 5% of expanded graphite, a non-combustible composite was obtained, and the use of natural linseed oil and calcite lime reduced the composite's water absorption from 12% to 1.7%.