Civil Engineering Reference
In-Depth Information
the sound of steps. It is hard-wearing,
and very suitable for workshops. It is
easy to repair and tolerates alkalis and
oils, but expands in response to damp
and water and should not be washed
down. The cubes are usually 4-10 cm
high. The proportion of length to
breadth should not exceed 3:1. Off-
cuts from a building site can be used.
The cubes are laid in sand, and the
joints are filled with cork or sand and
then saturated in linseed oil. On indus-
trial premises it is usual to dip them in
warm asphalt before setting them.
Figure 15.24: Batten flooring under construction.
Timber boarding
There are, in principle, three types
of boarding made from ground tim-
ber: fibreboard, chipboard and cork
sheeting. Plywood boards are usually made of larger wood sheets glued togeth-
er. Fibreboard and chipboard are almost exclusively used as underlay on either
floors or walls. On floors, they can provide the base for a 'floating' wooden floor
or soft floor coverings; on walls and ceilings they can provide a base for wallpa-
pering, hessian or paint. Certain products are delivered from factories with these
finishes already mounted. Cork sheeting is usually placed on this sort of board-
ing and is often coated with a protective layer of polyvinyl chloride. Veneer
products are often exposed when used in false ceilings, etc.
Fibreboard for covering is produced in porous, semi-hard or hard variations
from wood fibre. The porous products are glued by their own glue which is devel-
oped through heating. The same principle is usually also applied for the semi-hard
and hard boards. Some products have up to 1 per cent phenol glue added. Cork
sheeting is made from broken up bark from the cork oak. This, too, could utilize its
own glue, but phenol or urea formaldehyde glue is often used. Chipboard is pro-
duced from ground timber waste with 10 per cent by weight of urea formaldehyde
glue added. The veneer is made of thin veneer sheets which are glued onto each
other. The usual glue is urea formaldehyde at 2 per cent by weight.
Low quality raw material is used for chipboard in particular. Even timber
from demolition sites can be used. The timber for fibreboard has to be rela-
tively fresh so that the natural glues are available. The quality of timber for
veneers needs to be medium to good. The phenol and urea formaldehyde
glues that are used are based on coal-tar. Fibreboard manufacture has a very
high consumption of primary energy; other products use much less.
