VTT Technical Research Centre of Finland examined, as part of the EU’s Reffibre project, whether new industrial applications could be developed for various types of sludge and fly ash generated by the paper and board industry. Laboratory tests showed that these side streams can replace up to 50% of oil-based polypropylene. They can be used as a raw material in plastic composites made using injection moulding and extrusion.

Large quantities of various side streams are created during the manufacture of paper and cardboard. Part of these can be used instead of natural aggregates as a raw material in concrete or asphalt, or in construction. Large amounts of side streams still end up in landfills and incineration.

Side streams could be used to lower composite manufacturing costs, reduce the environmental impacts of production, and lower the total amount of waste. This would also reduce the production of oil-based plastics.

Laboratory tests showed that 50% of the raw-materials in injection-moulded composite could come from paper and board industry side streams. The amount of side streams has an effect on the product’s properties: strength, stiffness, heat resistance, appearance and the texture of the surface.

During the project, Plastec Finland Oy and Wiitta Oy produced floor tiles and storage containers, of which side-streams accounted for 30%. New applications are continually being sought – in the future, they may include pallets and crates, for example.

The possible legal restrictions still have to be explored prior to the product-specific use of side-streams in composites.

VTT coordinated the Reffibre project (No. 604187), which formed part of the EU's Seventh Framework Programme, during 2013-2016. In addition to VTT, Technische Universität Darmstadt, Papiertechnische Stiftung, Instituto Tecnológico del Embalaje, Transporte y Logstica, Bumaga BV, Confederation des Industries Papetieres Europeennes CEPI Aisbl, Vrancart S.A. Adjud, Alucha SL, Papierfabrik Utzenstorf AG and Holmen AB participated in the project. The side streams used for the study were obtained from European companies.