Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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ORGANOMINERAL PASTE AND METHOD OF USE
AS CONSTRUCTION MATERIAL
TECHNICAL FIELD
The invention relates to organomineral pastes as well
as to methods of use of pastes as construction materials.
BACKGROUND OF THE INVENTION
There are numerous known construction materials based
on hydraulic binders and more particularly cement, such as
building blocks, concrete products, outside coatings, fire
protection materials, and ground surface coverings.
However, all of these materials experience extensive
shrinkage, which leads to the presence of cracks. This
shrinkage is due to the evaporation of the water in the
finished products.
Clay bricks, which are obtained by molding, are also
known construction materials. Brick manufacture, however,
entails a cooking step.
There is also a known process for recycling airborne
ash which is also known as fluidized bed ashes from blast
furnaces and heating stations, wherein the airborne ash is
mixed with other construction materials in order to make
road coverings, for example. However, compositions
presently containing airborne ash cannot be used as
'construction material because they do not have the
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necessary mechanical properties such as strength.
Accordingly, a need remains for a construction material which
utilizes recycled materials, does not show immediate signs of
evaporation and which does not require cooking steps in
manufacturing to produce.
DETAILED DESCRIPTION OF THE INVENTION
The invention is based on the use of waste, in particular
waste coming from the manufacture of paper, for the manufacture of
construction materials as diverse as bricks, building blocks,
concrete products, outside coatings, fire protection materials and
ground surface coverings.
The invention aims to overcome the previously described
disadvantages by providing an organomineral paste that is
characterized by the fact that it is obtained by mixing a
suspension of cellulose fibers and/or cellulose waste and/or
primary sludge from papermaking and/or wastepaper with a
suspension of lime, to which mixture an aqueous solution of
sulfate and hydrogen peroxide is added.
More precisely, the mixture includes approximately or about
1 part by weight of the cellulose fibers and/or cellulose waste
and/or primary sludge from papermaking and/or wastepaper and
between approximately 0.7 and 0.8 parts by weight of lime and
between approximately 10 and 12 parts by weight of water. The
aqueous solution is obtained by mixing approximately 1 part by
weight of iron sulfate with between approximately 2.5 and 3 parts
by weight of water and between approximately 0.6 and 0.7 parts by
weight 130- volume [ ~ 33 wt%] hydrogen peroxide. Herein lime is
intended to include both calcium oxide (Ca0), as well as Calcium
Hydroxide ( Ca ( OH ) 2 ) .
According to one characteristic of the paste of the
invention, the mixture is obtained by mixing 1 part by
weight of primary sludge from papermaking with 0.75 parts
A
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by weight of lime and 11 parts by weight of water. The
aqueous solution is obtained by the mixing of 1 part by
weight of iron sulfate with 2.7 parts by weight of water
and 0.65 parts by weight of 130-volume hydrogen peroxide.
According to another characteristic of the paste of
the invention, the weight ratio of the mixture to the
solution is between 7:1 and 8:1. More precisely, the
weight ratio of the mixture to the solution is 7.65:1.
The paste of the invention can also contain airborne
ash and a hydraulic binder. In this case it is comprised
of a mixture of approximately 1 part by weight of actual
paste with between approximately 0.9 and 1.3 parts airborne
ash and between approximately 0.01 and 0.02 parts by weight
hydraulic binder.
A preferred paste contains 1 part by weight of actual
paste, 1.1 parts by weight of airborne ash, and 0.01 parts
by weight hydraulic binder. The preferred hydraulic binder
of the invention is cement.
The use of the paste in the manufacturing of a
construction material is also an object of the invention.
In effect, it has been found that a suspension of
cellulose fibers, cellulose waste and waste from the
primary sludge of the papermaking process or wastepaper
disposal process, in water, to which a suspension of lime
and a solution of iron sulfate and hydrogen peroxide are
added, allows one to obtain a homogeneous organomineral
paste that can be used in the manufacture of a construction
material with thermal insulation, sound insulation, and
fire resistance properties.
The organomineral paste of the invention is obtained
by a process which includes two steps:
1. pulping of the waste by mixing of approximately 1
part by weight cellulose fibers and/or cellulose waste
and/or primary sludge from papermaking and/or wastepaper
with between approximately 0.7 and 0.8 parts by weight of
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lime and between approximately 10 and 11 parts by weight of
water, and
2. mixing of the pulped waste obtained in the
preceding step with a solution obtained by mixing of
approximately 1 part by weight of iron sulfate with between
approximately 2.5 and 3 parts by weight of water and
between approximately 0.6 and 0.7 parts by weight of 130-
volume hydrogen peroxide.
Preferably, in the first step 1 part by weight of the
suspension of cellulose fibers and/or cellulose waste
and/or primary sludge from papermaking and/or wastepaper is
mixed with 0.75 parts by weight of lime and 11 parts by
weight of water. The solution used in the second step is
obtained by mixing approximately 1 part by weight of iron
sulfate with approximately 2.7 parts by weight of water and
approximately 0.65 parts by weight of 130-volume hydrogen
peroxide.
In the second step approximately 7 and 8 parts by
weight of the mixture obtained in the first step is mixed
with approximately 1 part by weight of the solution of iron
sulfate described in the second step. Preferably, 7.66
parts by weight of the mixture obtained in the first step
is mixed with 1 part by weight of the solution of iron
sulfate described in the secornl step.
In a preferred embodiment of the invention, primary
sludge is used from the papermaking process rather than
cellulose fibers and/or cellulose waste because, in this
case, the use of large pulpers for pulping this waste can
be avoided, and it is sufficient to use a conventional
mixer. However, the paste obtained cannot be used as
construction material because it is difficult to mold, for
example, in the form of bricks or building blocks, and
because it contains a large quantity of water and must
therefore be dried with heat. Furthermore, when dried, the
paste of the invention requires excessive shrinkage for it
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to be usable.
In order to avoid the problem of shrinkage, and still
obtain a construction material that can be sprayed or
floated, with good mechanical properties, the organomineral
paste according to the invention is used in a mixture with
a hydraulic binder such as cement.
In order to obtain a product which can be molded in
the form of bricks, building blocks, or curbstones or any
moldable concrete product, waste which one generally wishes
to recycle, such as airborne ash, is added to the paste
according to the invention with the hydraulic binder. Such
ash may come from blast furnaces and/or from heating
stations. The airborne ash acts as a liquefier and
plasticizer and gives the composition of the invention,
properties of molding ability which are due to the airborne
ash. Due to the low density of the paste of the invention,
resulting from its inclusion of modified cellulose fibers,
the product obtained has excellent sound and heat
insulation and fire resistance properties.
Surprisingly, it has been discovered that a very small
quantity of hydraulic binder, on the order of approximately
5% by weight of the total composition, is sufficient to
give the final construction material obtained from the
paste of the invention suffici2-nt mechanical properties so
that it can be used as it is. Obviously, greater
quantities of hydraulic binder may be used as desired.
Furthermore, with 5% by weight hydraulic binder, the
shrinkage after 7 days of drying is less than 200 ~m per
meter. This result compares with a shrinkage of greater
than 1,000 ~m per meter in the case of mortars, and up to
4,000 ~Cm per meter in the case of a microconcrete after 7
days of drying.
Tests of mechanical strength performed on construction
materials obtained by simple drying of the paste of the
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invention in open air show that there is a noncleavage
fracture which allows the construction material to be used
in seismic risk zones.
The construction material obtained from the
composition according to the invention retains all of its
properties when the composition is obtained by mixing of
approximately 1 part by weight of the cellulose paste with
between approximately 0.9 and 1.3 parts by weight of
airborne ash and between approximately 0.02 and 0.01 parts
by weight of cement. A preferred composition is, however,
obtained by mixing 1 part by weight of the cellulose paste
with 1.1 parts by weight of airborne ash and 0.01 parts by
weight of cement.
The airborne ash can be replaced by pozzolana or any
other equivalent material. However, a preferred
composition includes airborne ash from coal heating
stations known as "fluidized bed ashes."
Additionally, other sulfates may be used instead of
iron sulfate, including aluminum sulfate, potassium
sulfate, sodium sulfate, calcium sulfate, and ammonium
sulfate .
Various additives known in the field of construction
materials can be added to the composition of the invention
such as coloring agents . White cement can be used as a
hydraulic binder in order to give the desired color to the
final material.
The invention will now be described by means of a
preferred example of the composition according to the
invention, which is given only for the sake of illustration
and not for limiting the invention.
Example.
300 kg primary sludge from papermaking is mixed with
225 kg lime and 3,300 kg water. The mixture is stirred to
keep the cellulose fibers from settling; mixed with a
solution composed of 115 kg ferrous iron sulfate, 310 kg
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water, and 75 kg 130-volume hydrogen peroxide. The
hydrogen peroxide transforms the ferrous iron sulfate into
ferric iron sulfate.
The resultant organomineral paste is homogenous and
contains a high water weight. The presence of this high
water weight provides the advantage of not requiring the
addition of more water during the manufacture of the actual
construction material, i.e. the addition of the hydraulic
binder and of the airborne ash.
In order to obtain a construction material according
to the invention, one mixes the cellulose paste obtained
above with 2,162 kg fluidized bed ash and 217 kg cement.
A composition is obtained which can be molded in any form,
such as bricks, curbstones, etc., with a very low degree of
shrinkage with drying. Drying can advantageously be
natural, done in the air at ambient temperature and
pressure. The resultant material exhibits good thermal
conductivity, good compressive, tensile strength, and has
a low density. This composition can also be used as a
coating, which can be sprayed or floated. It can contain
a water-retaining substance such as methylcellulose,
hydroxyethylcellulose, and carboxymethylcellulose, a
waterproofing agent such as silicone, a calcium or
magnesium stearate, or any other additive for the purpose
of giving other particular properties to the composition of
the invention, as are known in the field, such as gypsum,
calcium sulfate, a ~ natural or synthetic resin, a
plasticizer, or an air entraining agent.
