Boards can be made of domestic waste for use as chipboard-like under-layers for different finishes on walls and floors. Several products have been developed, all primarily using the fibre fractions of the waste materials.
One alternative is produced from used beverage cartons containing polyethylene. The cartons are sorted, shredded, heated and cut into 5 mm particles. The material is then spread into sheets, compressed, heated again and pressed between two plates. The polyethylene content in the material melts, acting as a glue to bond the board, thus making it durable. The board is then cooled in a cooling press and pressed once again to strengthen it.
Another alternative is produced mainly from worn corrugated paper containers that are mixed with water and ground up in a hydra-pulper. The slurry is poured into moulds. Any remaining water is removed under heat and pressure, creating sheets without the need of any additional adhesives. One face is strengthened with 'honeycomb' patterned ribs. Two sheets are then laminated together to form boards approximately 19 mm thick using polyvinyl-acetate glue (PVAC).
Different textile fibres with mixed composition can be used for producing composite panels in the same way as with chipboard, where the dry mass is mixed with glue in portions of 10-15% and exposed to heat and pressure (Gomes etal., 2007). Smaller amounts of stronger fibres, such as sisal, are added to provide extra strength.
Tests are also being conducted to produce boards from unsorted mixed rubbish. The rubbish is crushed and ground. Metals are separated out by electromagnets and the rest is dried at 140 °C to a moisture content of 3-5%. Centrifuging removes the heavier fractions in the rubbish. The heavy part is returned to waste and the light rubbish, being mainly paper, plastic and food leftovers, is mixed with about 50% wood pulp. The mixture is then glued under pressure.
The use of waste as a raw material is optimal, environmentally speaking. However, some of the products may contain contaminants from plastics and other materials, which can affect the indoor climate. There is also a risk of emissions from binding agents and fungicides that may have been used. Most waste products can be used as raw materials for the production of building boards, although usually at a slightly lower level of quality. Useless waste must be deposited at controlled tips or energy-recycled.
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