The feasibility study of wood and agricultural waste materials for the development of thermal insulating materials

Abstract

Currently, wood and agricultural wastes are used for biofuel production thus providing short-term benefits. The use of these waste materials in the production of thermal insulating materials would bring long-term benefit and contribute to the current energy performance of buildings. The objective is to test loose-fill thermal insulating materials from wood and agricultural waste. The raw materials for the experimental studies were as follows: straw shives, wood bark, wood sawdust and fibre hemp shives. The physical properties of the wood and agricultural waste were determined according to: thermal conductivity - EN 12667 and EN 12939; long-term water absorption - EN 12087; water vapour transmission - EN 12086. The thermal properties of waste were evaluated by thermogravimetric (TGA) measurements and calorimetric bomb method. It is determined that, depending on the type of waste (straw shives, wood bark, wood sawdust and fibre hemp shives), the bulk density can vary from ~ 80 kg/m3 to ~216 kg/m3 while thermal conductivity – from 0.0445 W/(m∙K) to 0.0574 W/(m∙K). Test results show that all waste are characterized by sudden water absorption. During the 24 hours after immersion, waste particles absorb approximately ~200 wt.% of the whole water, while water vapor resistance factors is up to ~3.3. The results from the combustion heat test show similar results for all waste materials ~18 Mj/kg. TGA method in nitrogen and air atmosphere shows that all materials without flame retardants loose most of their mass (70 wt.%) at second and third heating stages at temperature of 400°C. The wood and agricultural waste materials are characterized by a high calorific value; therefore, it is necessary to process them with flame-retardants in order to use them in building construction industry. The obtained numerical values of properties for wood and agricultural waste materials show that they can be used as effective fillers for thermal insulating composite materials.