Research was performed into the use of hemp shive as a fast-growing and carbon-storing agricultural waste material in the production of particleboard for the construction industry. Hemp shives were acquired and prepared for board production with the use of milling and sieving to reach two target groups with 0.5 mm to 2 mm and 2 mm to 5.6 mm particle size ranges. The cold pressing method was used to produce hemp boards with Kleiberit urea formaldehyde resin as a binder. The boards were made as 19 mm thick single-layer parts with a density range of 300 ± 30 kg/m3, which qualifies them as low-density boards. Exploratory samples were made using milled hemp fibers with higher density. Additional components such as color pigments and wood finishes were added to test improved features over raw board samples. Tests were performed to determine moisture contents, density range, structural properties, and water absorption amounts. Produced board bending strength reached 2.4 MPa for the coarser particle group and thermal conductivity of 0.057 ± 0.002 W/(mK). The results were compared with existing materials used in the industry or in the development stage to indicate options of developed board applications as indoor insulation material in the construction industry.

Abstract. In recent years the popularity of ecological and renewable materials has grown. Aware of the limited resources as well as availability of local resources and economic grounds, the attention is paid to the development of new materials. Currently, there is a political as well as a societal demand for products that require less energy for the manufacturing process and are easy to recycle with less impact on environment. In comparison with concrete, wood-geopolymer emits less CO 2 , it is environmentally friendly and made from available local resources. Therefore, the geopolymer composites obtained from clay, sodium silicate and wood particles or fiber could be one of the solutions. Geopolymers are inorganic polymers that are formed by the polymerization reaction of silico-aluminate and silico-oxide. In this case, the geopolymer is formed from clay, which is mined in Latvia (silico-aluminate) and water glass (silico-oxide). The wood-geopolymer was made by mixing geopolymer with softwood particles. The aim of the research was to develop a wood-geopolymer composite material and to evaluate its optimal composition and properties. The study defined the impact of the compound on the mechanical and physical properties (bending strength, compressive strength, modulus of elasticity, swelling and thermal conductivity) of the wood-geopolymer composite. The current paper presents mechanical properties of different composition and treatment methods of wood-geopolymer. As a part of the research the geopolymer and wood geopolymer thermal conductivity was compared. The results have shown that there is a correlation between the wood-geopolymer density and the thermal conductivity. The same correlation was observed between the wood-geopolymer density and the mechanical strength.