Woodwool cement is usually produced as boards in thicknesses of 2.5 to 15 cm, but can also be produced as structural blocks. Reinforcing the thickest boards with round wooden battens produces a material with good structural properties. Woodwool cement is also used as an ingredient in some sandwich boards, glued or heated together with layers of polystyrene, polyurethane, rockwool or foamglass.
Woodwool cement is resistant to rot. It has a weak alkaline content of about pH 8.5; mould needs a pH of 2.5-6 to develop. Woodwool can therefore be used as foundation wall insulation. The woodwool should be laid on the inside, because running water in the earth will wash away the cement in the long term. The sound absorption qualities, when it is not rendered, are very good, and the boards are suitable for use as acoustic cladding.
The product is a simple mixture of woodwool and cement. Natural acids in the wood shavings have to be rinsed out first, either by boiling or in a solution of sodium waterglass or calcium chloride. Alternatively, the shavings can be left in the open air to oxidize for about a year.
Woodwool cement consists of 45-65% cement by weight. The role of the cement is therefore quite decisive in an environmental evaluation, since cement implies high energy use and emissions of carbon dioxide, etc. in production. Woodwool cement products cannot be recycled as material or burned for energy recycling. Boards that are mechanically fixed can, in principle, be re-used whole. Waste is almost inert.
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