Civil Engineering Reference
In-Depth Information
Figure 14.13: Woodwool slabs reinforced with round rods combine high
thermal insulation values with structural integrity.
Source: Gaia Lista, 1990
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 insulation qualities, when it is not rendered, are very good, and the boards
are suitable for use as acoustic cladding.
A woodwool slab that has been cast into concrete or rendered has a lower insu-
lation value, because the surface spaces will be filled with mortar. The effective
insulation value of the rendered woodwool slab is the same as a 1 cm thinner
board which has not been rendered. Boards with finer woodwool have a better
insulation value than those with a coarser surface.
Woodwool cement consists of 65 per cent cement (by weight). To evaluate this
material environmentally, the role of cement must be considered (see 'Additives
in cement', p. 97). It is also used as part of some sandwich boards, glued or heat-
ed together with layers of polystyrene, polyurethane, rockwool or foamglass.
These products have high insulation values, but have to be carefully handled as
waste if they contain plastic.
Pure woodwool cement products cannot be recycled as material or burned for
energy recycling. Boards which are mechanically fixed to a surface can, in prin-
ciple, be re-used. Waste is almost inert and can be used as loose fill.
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