Note: Descriptions are shown in the official language in which they were submitted.
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FIRE-INSULATING WALL COVE1IVIG RIM A PREPA TIO ' METHOD
r R SZU4E
The present invention relates to a fire-insulating wall
covering and to a method for preparing same. The present
invention relates particularly to a fire-insulating and
preferably also sound-absorbing wall covering which meets
currently stringent requirements in respect of fire-
insulating properties. Such a fire-insulating wall covering
can be applied in tunnels, underground spaces such as
shopping centres and the like.
Fire-insulating wall coverings known at the present time
do not fully satisfy the stringent requirements in respect of
fire-insulating properties.`In the case of a fire load on
such a wall covering, for instance for 120 minutes, and a
temperature on the fire side lying in the range of 1100 to
1350 C for these two hours, these fire-insulating properties
mean, among other things, that this wall covering insulates
against fire such that on the side of the wall covering
remote from the fire the temperature remains relatively low,
and particularly below 225 C, preferably below 200 C.
The wall covering must moreover have good sound-
absorbing properties and is asbestos-free.
The invention has for its object to provide such a fire-
insulating and sound-absorbing wall covering as well as a
method for preparation thereof. It is noted here that the
wall covering can be applied per se, but is preferably
applied as wall covering arranged on a supporting layer, for
instance a concrete layer which can optionally be
strengthened with a reinforcement. The underlying layers are
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thus protected against high temperatures.
This is achieved according to the invention with a fire-
insulating wall covering comprising a cured mixture of:
i) 5-20% by weight mineralized wood fibre;
ii) 20-60% by weight sand with an Si02 content of less
than 5% by weight and a greywacke content of at
least 30% by weight; and
iii) 20-50% by weight cement.
The fire-insulating wall covering is in fact based on a
cured cement plate having incorporated therein a specific
type of wood fibre and a specific type of sand.
The applied wood fibre for inter alia sound absorption
is a mineralized wood fibre. Such a mineralized wood fibre is
obtained by bringing wood fibres into contact with a solution
of aluminium sulphate. The wood fibres are generally obtained
from residual wood which is processed in different steps to
form wood fibre with a moisture content of about 15-25% (atro
basis). The aluminium sulphate is added in a quantity of
about 2.5% relative to the wood fibre and supplemented with a
quantity of water, whereby the moisture percentage rises to
about 100% (atro). The obtained wood fibres, which are thus
covered with aluminium sulphate, are the mineralized wood
fibres applied in the fire-insulating wall covering according
to the invention.
The applied aluminium sulphate is of standard chemical
quality.
The sand is a specific sand type since it is less than
5% by weight Si02. The sand further contains at least 30% by
weight greywacke. Greywacke is a type of stone containing
feldspar, apatite and the like. Clay mineral may also be
present. It is a clastic sedimentary rock with a density of
for instance 2.6 kg per m3. The greywacke can be applied in
different grain size distributions (or combinations), where
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the grain size distribution is such that the average particle
size can be around 1 mm, 4-8 mm, 11-16 mm.
The cement used is generally a portland cement, in
particular a portland slag cement.
For an optimum fire-resistant property the wall covering
preferably has a content of mineralized wood fibre of
preferably 7-15% by weight, more preferably 10-15% by weight.
By selecting the content of mineralized wood fibre subject to
the desired properties, not only is an optimum fire-resistant
property obtained but also an optimum sound-insulating
property. It is striking in this respect that use is made of
a component based-. 'on wood fibre to obtain fire-resistant
properties.
The fire-insulating wall covering preferably contains
35-50% by weight sand, while the Si02 content is preferably
lower than 2.5% by weight, more preferably lower than 2% by
weight. By opting for a relatively low Si02 content in
combination with*an optimal choice of the quantity of
greywacke, (preferably at least 50% by weight), optimum fire-
insulating properties are obtained and the fire breakthrough
can be extended a very long time and far beyond the test time
(2 hours).
A fire-insulating wall covering is-found to suffice well
in practice if it preferably contains
i) 10-15% by weight mineralized wood fibre;
ii) 35-50% by weight sand with an Si02 content smaller
than 2% by weight and a greywacke content greater
than 50% by weight; and
iii) 25-40% by weight cement.
The best properties are obtained if in this case the
cement is a low-chromate cement.
The fire-insulating and fire-resistant properties of the
wall covering can be further improved if the mineralized wood
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fibres and/or the side of the wall covering to be exposed are
provided with an impregnation which further improves the fire
resistance and/or the durability of wood fibres. Such an
impregnating agent is for instance the impregnating agent
described in the German patent application 197 27998. This
impregnating agent is preferably applied to the mineralized
wood fibres in a quantity of 0.1-1% by weight, more
preferably 0.1-0.5% by weight. In the case the wall covering
is arranged on a wall to be exposed, it is recommended to
apply the impregnating agent in a quantity of 30-500 gram per
m2, preferably 100-250 gram per m2.
The fire-insulating wall covering according to the
invention can in principle be formed on-site and cured on-
site in a mould. It is however also possible for pre-cured
plates to be taken to the location of use.
If the fire-insulating wall covering has an insufficient
strength in itself and insufficient bearing capacity, it is
recommended to arrange such a fire-insulating wall covering
on a supporting layer, for instance a concrete layer or
concrete plate.
In that case the fire-insulating wall covering can be
formed on an already present concrete plate and attached
thereto using connecting means. Another option is to arrange
finished fire-insulating wall coverings on a prepared support
layer using fixing means. Use is made in this case of
openings arranged in the fire-insulating wall covering for
arranging the fixing means and of plugs of fire-insulating
wall covering to cover the fixing means.
In the case that a plurality of plates of fire-
insulating wall covering according to the invention are
applied, this results in joints. For optimal retention of the
fire-insulating properties at the position of the joint, it
is recommended to make use of an offset joint and to fill
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this joint with either fire-insulating wall covering in
uncured form or with another fire-insulating seal.
A good fire-insulating wall covering is generally
obtained according to the invention if relative to the cured
5 weight are mixed 5-20% by weight mineralized wood fibre, 30-
60% by weight sand with an Si02 content smaller than 5% by
weight and a greywacke content of at least 30% by weight; and
20-50% by weight cement, and 10-30% by weight water is then
added, whereafter the mixture is cured to form the fire-
insulating wall covering. Wall thicknesses of 10 to 500 mm
are generally possible.
Mentioned and other features of the fire-insulating wall
covering according to the invention and of the method for
preparing such a fire-insulating wall covering will be
further elucidated hereinbelow with reference to two
embodiments, which are only given by way of example without
the invention being deemed limited thereto.
Figures 1 and 3 each show a perspective view of a space
provided with a fire-insulating wall covering; and figures 2
and 4 each show a cross-section at the position of details II
and IV respectively of figures 1 and 3.
For the preparation of the fire-insulating wall
covering, use is made per m3 of:
- 12% by weight mineralized wood fibre
- 32% by weight portland slag cement
- 42% by weight sand (Si02 content smaller than 5% by
weight, greywacke content 42% by weight)
- 0.01% by weight pigment (chromium oxide)
- 0.1% by weight impregnating agent (DE 197 27998)
- residual water.
This mixture is placed in a mould provided with
profiles, recesses for fixing points, rebates and joints. The
mass is vibrated, pressed and finally released onto a ground
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in order to cure. The formed plate is optionally sprayed at
this moment with impregnating agent. Such a plate is applied
in the embodiment shown in figures 1 and 2.
In another embodiment the fire-insulating wall covering
according to the invention for curing is arranged, for
instance in a curved mould, onto a support layer of concrete
already arranged therein. After curing these structural parts
can be applied in for instance the embodiment according to
figures 3 and 4.
In another embodiment, preformed fire-insulating wall
coverings according to the invention are placed in a mould
after being provided with coupling means for coupling to the
concrete layer to be arranged. Use is for instance made of
wood screw bolts which protrude out of the surface and which
will be taken up in the concrete layer to be arranged on this
wall covering. Via the coupling means an optimal attachment
is thus obtained between the concrete layer on the one hand
and the wall covering according to the invention on the
other.
Figure 1 shows a tunnel 1 provided with a concrete
bearing structure 2 with fire-insulating wall coverings 3
according to the invention fixed thereto. Fixing means 4 are
covered with conical plugs 5. Wall coverings 3 are mutually
separated by a joint 6.
Figure 2 shows a detail in cross-section of the
structure of this tunnel wall which is provided with wall
coverings 3 according to the invention. Wall covering 3 is
arranged in the concrete bearing structure 2 using fixing
means 4, in this case cotter bolts 7. This bearing structure
2 is further provided with a reinforcement 8.
As shown in figure 2, joint 6 is an offset joint which
is filled, wholly or only in the two straight joint parts,
with a fire-insulating seal 9, optionally a mass of the
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insulating wall covering according to the invention still to
be cured.
Figures 3 and 4 show a pedestrian passage 10, for
instance in an underground station. Use is made in this case
of wall plates 12 and 13 which are preformed and set up in
situ. Wall plates 12 and 13 once again comprise a concrete
support structure and a wall covering 14 according to the
invention. Wall covering 14 is provided with wood screw bolts
onto which is poured the concrete bearing structure 11,
10 which is also provided with a reinforcement 8.
In both cases the wall coverings 3 and 14 according to
the invention are found to satisfy the stringent requirements
made in respect of fire-insulating properties. When exposed
to a temperature regime as according to the table below, it
15 was found that on the side of such a 100 mm wall covering
remote from the fire the temperature remains below 120 C, and
is even close to a temperature lying between 100 and 110 C.
Time Temperature
(min) ('C)
0 20
3 890
5 1140
10 1200
30 1300
60 1350
90 1300
120 1200
