U.S. patent application number 10/574299 was filed with the patent office on 2007-11-22 for block-type building stone used as a construction material for walls.
Invention is credited to Wilfried Blocken.
Application Number | 20070266656 10/574299 |
Document ID | / |
Family ID | 34424325 |
Filed Date | 2007-11-22 |
United States Patent
Application |
20070266656 |
Kind Code |
A1 |
Blocken; Wilfried |
November 22, 2007 |
Block-Type Building Stone Used As A Construction Material For
Walls
Abstract
The invention relates to a block-type component that is used as
a construction material for walls, e.g., noise barriers and walls
of buildings. The component comprises an exterior and an interior,
in addition to a three-ply construction including the following
layers: an external layer, which consists of stone or concrete and
forms the exterior, a central layer of insulating mortar with a
high degree of thermal insulation, comprising at least 70% by
volume (in relation to the volume of the central layer) of
reprocessed, granular polyurethane and cement as the binding agent,
and an internal layer that preferably contains cement as the
binding agent, the layer forming the interior.
Inventors: |
Blocken; Wilfried;
(Schalkhoven, BE) |
Correspondence
Address: |
MCCARTER & ENGLISH LLP;CITYPLACE I
185 ASYLUM STREET
HARTFORD
CT
06103
US
|
Family ID: |
34424325 |
Appl. No.: |
10/574299 |
Filed: |
October 1, 2004 |
PCT Filed: |
October 1, 2004 |
PCT NO: |
PCT/EP04/10954 |
371 Date: |
March 22, 2007 |
Current U.S.
Class: |
52/286 ;
52/747.12 |
Current CPC
Class: |
E04B 2002/0269 20130101;
E04C 1/40 20130101; C04B 28/02 20130101; C04B 28/02 20130101; C04B
2111/52 20130101; B32B 2419/02 20130101; B32B 2305/70 20130101;
E04B 2002/0208 20130101; B32B 13/04 20130101; C04B 2111/00612
20130101; B32B 2307/304 20130101; C04B 16/082 20130101; C04B
2103/004 20130101; E04B 2002/0267 20130101 |
Class at
Publication: |
052/286 ;
052/747.12 |
International
Class: |
E04B 1/00 20060101
E04B001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 2, 2003 |
DE |
103 46 520.0 |
Sep 9, 2004 |
DE |
10 2004 044 003.4 |
Claims
1. A block-type building stone as a building material for walls
such as soundproof walls and building walls, the building stone
comprising: an outside face; and an inside face; and a
three-layered structure, three-layered structure including an outer
layer forming the outside face, a middle layer made from insulating
mortar with high thermal performance that has at least 70 volume
percent (related to the volume of the middle layer of recycled,
granular polyurethane and cement as a binder, and an inner layer
that forms the inside face and preferably comprises cement as the
binder.
2. The block-type building stone as set forth in claim 1, wherein
the width of the middle layer is greater than the width of the
outer layer and is eater than the width of the inner layer,
preferably that the middle layer has a thickness that is at least
twice, more specifically three times, the thickness of the outer
layer, the inner layer or the outer layer and the inner layer.
3. The block-type building stone as set forth in claim 1, wherein
the outer layer is thinner than the inner layer.
4. The block-type building stone as set forth in claim 1, wherein
the concrete from which the outer layer is made is a standardized
concrete such as CEM I 52.5, CEM I 42.5, or CEM I 32.5.
5. The block-type building stone as set forth in claim 1, wherein
the middle layer comprises 90-94 volume percent of recycled hard
polyurethane that has been shredded to form a mixture of powder and
granules having a grain size of less than 8 mm and 6-10 volume
percent of cement, more specifically, 92 volume percent of recycled
hard polyurethane and 8 volume percent of cement, each relative to
the volume of the middle layer.
6. The block-type building stone as set forth in claim 1, wherein
the thickness of the outer layer ranges between 4 and 15 cm, more
specifically between 8 and 12 cm.
7. The block-type building stone as set forth in claim 1, wherein
the middle layer, the inner layer or the middle layer and the inner
layer have an open pore structure.
8. The block-type building stone as set forth in claim 1, wherein
the building stone comprises an upper face and a bottom face and at
least one projection on the upper face, and the bottom face defines
a recess that is at least as large as the at lease one projection
on the upper face and conforms to the shape of the at least one
projection.
9. The block-type building stone as set forth in claim 1, wherein
the building stone comprises a front and a rear end surface that
are both level.
10. The block-type building stone as set forth in claim 1, wherein
the outside face, the inside face or the outside face and the
inside face are level surfaces.
11. The block-type building stone as set forth in claim 1, wherein
the building stone is 0.4 to 2.5 m in length.
12. The block-type building stone as set forth in claim 1, wherein
a strip-shaped material, more specifically, a rubber-type material,
is provided that is interposed between two superposed block-type
building stones.
13. The block-type building stone as set forth in claim 1, wherein
the outer layer, the inner layer or the outer layer and the inner
layer have no gaps.
14. A method of manufacturing a block-type building stone as set
forth in claim 1 comprising the steps of: introducing a bottom
layer into a water permeable mould to form an outer layer or an
inner layer; mixing cement, polyurethane and water to produce a
pourable mixture; pouring the mixture onto the bottom layer already
formed in the mould to produce a middle layer; observing a waiting
time wherein the cement does not yet harden and water flows out of
the mould so that the layer thickness of the middle layer is
reduced by at least 0.5% preferably by 2 to 5%; and applying an
upper layer to form the inner layer or the outer layer.
15. The method as set forth in claim 14, wherein at least one of
(i) the middle layer is applied onto the bottom layer while the
bottom layer is still fresh, (ii) the upper layer is applied onto
the middle layer while the middle layer is still fresh and (iii)
the middle layer is applied onto the bottom layer while the bottom
layer is still fresh and the upper later is applied onto the middle
layer while the middle layer is still fresh.
16. The method as set forth in claim 15, wherein the upper layer is
applied by pressing parts such as bricks, or rubble stones, into
the still fresh middle layer.
17. The method as set forth in claim 14, wherein, using normal
hardening cement, the waiting time is at least 30 minutes and at
most 5 hours.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is the U.S. National Phase of International
Application No. PCT/EP2004/010954, filed Oct. 1, 2004, which claims
priority to German Application No. DE 10 2004 044 003.4, filed Sep.
9, 2004, and German Application No. DE 103 46 520.0, filed Oct. 2,
2003, the contents of which are expressly incorporated by reference
in their entirety as part of the present disclosure.
BACKGROUND
[0002] The invention relates to a block-type building stone used as
a construction material for walls such as soundproof walls and
building walls. The building stone has an outside face and an
inside face.
[0003] The objective is to indicate a building stone that absorbs
in the best possible way any kind of sound and is as little sound
permeable as possible. The building stone should reflect as little
sound as possible, at least on its inside face. The building stone
finds application in conjunction with any kind of sound sources
that are to be insulated against the environment such as a
residential zone, so for example sound sources in industrial firms,
sports centers and the like. An acoustic insulation may also be
carried out inside a building. Generally, the building stone is
intended to be used for external applications such as free-standing
walls and outer building walls.
[0004] Block-type building stones are generally known. There also
exist building stones made from layers, for example lightweight
concrete building stones with a middle layer of foam such as
polystyrene. For interior construction, polystyrene covered gypsum
plasterboards are known.
SUMMARY OF THE INVENTION
[0005] It is the object of the invention to indicate a block-type
building stone and a method of manufacturing same out of which
walls can be built in a fast and simple manner and which comprises
least possible sound permeability and highest possible sound
absorption.
[0006] This object is solved by a block-type building stone
comprising an outside face, an inside face and a three-layered
structure. The three-layered structure includes an outer layer
forming the outside face, a middle layer made from insulating
mortar with high thermal performance that has at least 70 volume
percent (related to the volume of the middle layer) of recycled,
granular polyurethane and cement as a binder, and an inner layer
that forms the inside face and preferably comprises cement as the
binder. The block-type building stone is manufactured by first
introducing a bottom layer into a water permeable mould to form
either the outer layer or the inner layer. Next, cement,
polyurethane and water are mixed together to produce a pourable
mixture that is poured onto the bottom layer already formed in the
mould to produce the middle layer. Next, a waiting time is observed
wherein the cement does not yet harden and water flows out of the
mould so that the layer thickness of the middle layer is reduced by
at least 0.5%, preferably by 2 to 5%. Upon the expiration of the
waiting period, an upper layer is applied; the upper layer forms
the layer (outer layer or inner layer) not already formed by the
bottom layer.
[0007] As noted above, the building stone is made from three
different layers. The inner layer and/or the outer layer is either
a continuous layer or a layer consisting of discrete larger parts
such as e.g., bricks, ordinary stones, quarry stones, stone slabs
(also marble, granite). In this case, the larger parts are pressed
into the middle layer where they preferably adhere thanks to the
cement of the middle layer. In use, these layers are positioned
substantially vertically so that sound, which propagates
substantially parallel to the earth's surface, is forced to pass
through one layer after the other. Each layer has its own task to
complete with regard to minimizing noise. It is preferred that the
outer layer has the highest specific weight among the three layers;
it is more specifically responsible for blocking the sound. The
middle layer has the lowest specific weight among the three layers
and is responsible for damping. Preferably, the inner layer has a
specific weight between that of the outer layer and that of the
middle layer; it is responsible for absorption. The interfaces
between the layers are also beneficial for the purpose of
utilization because the transmission properties of sound change at
the interfaces.
[0008] The building stone further has outstanding thermal
insulating properties. This is more specifically due to the middle
layer, which has a very low thermal conductivity of typically 0.05
W/m0K. This provides the building stone with a beneficial double
function. It is light-weighted and easy to handle. It is also
suited for do-it-yourselfers.
[0009] The inner layer is formed from mineral grains without
superfines. As a result, it has open pores. The irregular grain
structure reduces sound reflection from the surface thereof. The
pore volume is preferably configured such that no water is allowed
to accumulate within the structure of the inner layer so that frost
damage and weed growth are prevented.
[0010] The middle layer is preferably chosen to be quite thick. In
any case, it contributes little to the overall weight of the
building stone so that said building stone can be configured to be
quite large whilst still having a reasonable overall weight. It is
preferred that the thickness of the middle layer be at least twice
the thickness of the inner layer and/or the thickness of the outer
layer. For the outer layer, one chooses a thickness that is
beneficial to sound blocking without said outer layer determining
too much the overall weight of the building stone. It has been
found that layer thicknesses ranging from 4-14 cm are advantageous.
The inner layer is preferably at least as thick as the outer layer
and is preferably slightly thicker than the outer layer. For the
inner layer, a coarse grain size ranging from 1 to 4 mm such as
flint has prove advantageous.
[0011] In a preferred developed implementation, the middle layer
comprises 90-94 volume percent of recycled hard polyurethane that
is shredded to form a mixture of powder and granules having a grain
size of preferably less than 8 mm and 6-10 volume percent of
cement, more specifically 92 volume percent recycled hard
polyurethane and 8 volume percent cement, each time related to the
volume of the middle layer (24).
[0012] The block-type building stone preferably comprises an upper
face and a bottom face. At least one projection is provided on the
upper face and the bottom face comprises at least one recess that
is at least the size of the projection on the upper face and
conforms to the shape thereof. This allows for easy matching of the
building stones during stacking. Continuous joints are avoided.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Other features and advantages of the invention will become
more apparent upon reviewing the appended claims and the following
non restrictive description of embodiments of the invention, given
by way of example only with reference to the drawing. In said
drawing:
[0014] FIG. 1 is a perspective illustration of a building stone of
the invention;
[0015] FIG. 2: is a front view of a building stone in a second
embodiment;
[0016] FIG. 3: is a perspective illustration of a building stone
that is in parts a sectional view with the section line being
transverse to the longitudinal direction, in a third embodiment of
the building stone;
[0017] FIG. 4: is a front view of a building stone in a fourth
embodiment;
[0018] FIG. 5: is a front view of a building stone in a fifth
embodiment;
[0019] FIG. 6: is a front view of a building stone in a sixth
embodiment;
[0020] FIG. 7: is a perspective illustration of a mould for
manufacturing the building stone;
[0021] FIG. 8: is a top view on a top layer constructed from
bricks;
[0022] FIG. 9: is a top view on a top layer constructed from rubble
stones; and
[0023] FIG. 10: is a section taken along the section line X-X in
FIG. 9.
DETAILED DESCRIPTION OF THE INVENTION
[0024] The building stone of FIG. 1 has an outer layer 20 made from
self-compacting concrete. The specific weight typically is 2,400
kg/m.sup.3. At least 200 kg, preferably 300 kg, of cement are used
per cubic meter. Said outer layer is a flat right parallelepiped of
about 5 cm thick. The outer layer 20 forms an outside face 22 of
the building stone. In use, this outside face is turned away from a
noise source.
[0025] The outer layer 20 is adjoined with a middle layer 24. It is
made from a material that has been described in U.S. Pat. No.
5,904,763. This material has a quite low specific weight and, more
specifically, a very low thermal conductivity. The disclosure of
U.S. Pat. No. 5,904,763 is fully incorporated herein by reference
and pertains to the disclosure of the present application.
[0026] On its inside face, the middle layer 24 is adjoined with an
inner layer 26. This layer also is flat and in the form of a right
parallelepiped. The inner layer 26 forms an inside face 28 of the
building stone. The inner layer 26 has a specific weight ranging
from about 1,950 to 2,050 kg/m.sup.3. At least 100 kg of cement are
used per cubic meter. A fraction of 200 to 250 kg cement is better.
The inner layer has no zero fraction. The building stone further
has a front end surface 30 and a rear end surface 32. The two end
surfaces are identically built, the distinction between front and
rear has only been made to better associate them with the FIGS.
[0027] In the exemplary embodiment shown in FIG. 1, the outer layer
20 and the inner layer 26 have the same thickness. The middle layer
24 has a thickness of about 15 cm, it thus is three times the
thickness of the outer layer 20 or of the inner layer 26. The
thickness W of the building stone is about 25 cm, the length L
ranges from about 30-250 cm, the height H is about 30 cm.
[0028] All three layers 20, 24, 26 are cement bound. This same type
of bond also promotes the adhesion between the various layers.
Further, the environmental stability of the building stone is
substantially determined by the cement bond. Finally, the cement
bond permits to keep the cost of manufacturing the building stone
low.
[0029] The building stone of FIG. 1 has almost but not exactly the
shape of a right parallelepiped. On the upper face, there is
provided a tongue 34 that has a constant cross section and extends
over the entire length L of the building stone. The cross section
of the tongue is trapezoidal. The tongue 34 is only formed in the
region of the middle layer 24; it extends over almost the entire
width thereof. On the one hand, it is defined on either side toward
the top by short inclined surfaces 36 sloping upward at an angle of
30.degree. each. These inclined surfaces 36 commence at the
interface between the middle layer 24 and a respective one of the
adjacent layers 20 and 26. On the other hand, the tongue 34 is
substantially bounded by a main surface 38 that is located above a
terminating surface 46 of the outer layer 20 and inner layer 26, at
a distance from said terminating surface ranging from between 0.5
and 8 cm, typically from between 2-5 cm.
[0030] In the bottom face of the building stone there is formed,
corresponding to the tongue 34, a groove 40 that substantially
conforms to the shape of the tongue 34. Also, the groove 40 is
located in the middle layer 24 only and takes the entire width
thereof. It also extends over the entire length L. The groove 40
preferably has dimensions that are slightly larger than the tongue
34, which makes it possible to provide, between groove 40 and
tongue 34 of superposed building stones, a free space to dispose a
glue, a mortar 42 (see FIG. 3) or an intermediate layer 44 (see
FIG. 4). By way of example, a free space of about 3 mm is provided
on all sides between the groove 40 and the tongue 34.
[0031] The tongue 34 and the groove 40 permit to achieve in a known
way a shape association of superposed building stones. When the
building stones are being superposed, the level terminating
surfaces 46 of the respective one of the outer layer 20 and of the
inner layer 26 come into surface contact. The outside faces 22 and
the inside faces 28 of superposed building stones are aligned.
[0032] The building stones can be stacked one upon the other
without having to glue or join them together by any other means.
However, an adhesive or another binder may be interposed. This
means may be provided between tongue 34 and groove 40 but it may
also be provided between the terminating surfaces 46 of superposed
outer layers 20 and inner layers 26 respectively. Direct, immediate
contact between the respective terminating surfaces of the outer
layers 20 and the inner layers 26 of superposed building stones is
preferred, though. It is preferred that a binder is only applied
onto the main surface 38 of the tongue 34.
[0033] In principle, a projection like the tongue 34 and a
corresponding recess like the groove 40 need not be provided. If
they are provided, they need not have the concrete shape as
illustrated; there may also be provided isolated, cylindrical
projections having mating recesses provided on the bottom face, and
so on. Here, prior art mating projections and prior art mating
recesses may be utilized.
[0034] Even if it is advantageous to have the projections and the
recesses located in the region of the middle layer 24 only, this is
not a limitation; the projections could as well be provided only in
the layers 20 and/or 26 or also in these layers.
[0035] The projections and mating recesses permit to avoid direct,
rectilinear joints between superposed building stones. This permits
to generally improve sound insulation.
[0036] FIG. 2 shows quite small a building stone of an overall
thickness W of about 12.5 cm. The outer layer 20 of concrete such
as CEM I 52.5 is about 2.5 cm thick. Other concrete qualities such
as B25/35 for example are possible. The inner layer 26, which is
built from mineral grain with a granularity of 2-5 mm, has the same
thickness. The middle layer 24 has a thickness W of about 7.5 cm.
The stone has a height H of 20 cm and an overall length L of 60 cm.
Such a stone can be lifted by hand, meaning no hoists are needed.
The groove 40 on the bottom face is 2 cm deep, the tongue 34 on the
upper face protrudes 1.7 cm upward. The inclined surfaces 36 of the
tongue 34 are at an angle of 45.degree..
[0037] In the exemplary embodiment of FIG. 3, there is illustrated
a stone with an overall width W of about 25 cm, a height H of about
20 cm and a length L of about 40 cm. In this exemplary embodiment
as well outer layer 20 and inner layer 26 have the same thickness.
The thickness is about 5 cm. The remaining thickness is filled out
by the middle layer 24. It is made from 80 volume percent of
processed, shredded hard polyurethane and of cement as a binder. As
shown in FIG. 3, an about 3 mm thick layer of mortar 42 is applied
onto the main surface 34, said mortar layer providing a connection
with a building stone that is placed on top of the building stone
illustrated.
[0038] The building stone of FIG. 4 has an overall width W of about
50 cm and a height H of 40 cm. It is available in three different
lengths L, namely of 0.6 m, 1.2 m and 1.8 m. The outer layer 20 and
the inner layer 26 again have the same thickness of about 10 cm,
with the remainder of the overall thickness, about 30 cm, being
filled out by the middle layer 24. This layer is made from
recycled, shredded hard polyurethane in a fraction of at least 85
volume percent (related to the middle layer) and from cement.
Again, there is a groove 40 in the bottom face, said groove having
a depth of 4 cm, and a tongue 34 on the upper face protrudes 3.7
cm. On said tongue 34, namely on the main surface 38 thereof, there
is placed an intermediate layer 44 in the form of a rubber strip of
approximately 3 mm thick. This allows for filling out the gap
between tongue 34 and groove 40 of two superposed building stones.
The acoustic and thermal properties improve simultaneously, with
the building stones being finally fixed with respect to each other
by the intermediate layer 44. If the rubber used for the
intermediate layer 44 is a foam rubber, the thickness may be
slightly more than 3 mm. If the intermediate layer 44 is
compressible, its elastic properties can be made use of.
[0039] In the embodiment of FIG. 5, the building stone has a width
of 60 cm; the height thereof is about 48 cm. There are different
lengths, with the overall lengths available being 0.6 m, 1.2 m, 1.8
m and 2.4 m. The thickness of the outer layer 20, which is about 12
cm, is slightly smaller than the thickness of the inner layer 26.
The middle layer is about 36 cm thick; it is made from 90 to 94
volume percent of recycled, shredded hard polyurethane, with the
remainder being cement. It more specifically consists of 92 volume
percent recycled, shredded hard polyurethane with a grain size of
less than 10 mm, preferably of less than 8 mm, and 8 volume percent
of cement.
[0040] In the embodiment of FIG. 5, the tongue 34 protrudes quite
far upward, with the main surface 38 of the tongue 34 being located
5.7 cm above the terminating surfaces 46 of the outer layer 20 and
the inner layer 26. The groove 40 is configured accordingly to have
a depth of about 6 cm.
[0041] The exemplary embodiment of FIG. 6 shows quite wide a
building stone, with the overall width W being approximately 75 cm
and the height H about 60 cm. In this case also, the available
overall lengths L are 0.6, 1.2, 1.8 and 2.4 m. The thickness of the
outer layer 20 and of the inner layer 26, which have the same
thickness, is about 15 cm, with the thickness of the middle layer
24 being accordingly 45 cm. The inside depth clearance of the
groove 40 is about 8 cm, the height of the tongue 34 about 7.7 cm.
This building stone is suited for self-supporting soundproof walls
that can be stacked sufficiently high without needing additional
supporting means. Connection means between stacked building stones
need not be provided. This facilitates assembly and disassembly of
a soundproof wall.
[0042] FIG. 7 shows a mould 48 for manufacturing the building
stones. During manufacturing, the layers are formed with an
orientation that is different from the one used in subsequent
application. The respective layers are horizontal, meaning that
they are lying on top of each other in the mould once the building
stone is finished. Generally, manufacturing starts with forming the
outer layer 20, although it is also possible to proceed in reverse
and to first build the inner layer 26.
[0043] As shown in FIG. 7, there is provided a suited mould 48 that
already provides the shape of the tongue 34 and of the groove 40.
Put another way, the mould 48 has the hollow space dimensions of
the finished building stone. The mould 48 is open toward the top
only where there is located either the inner layer 28 or the outer
layer 22, which is preferred. The respective upper face is produced
by processing it accordingly, for example by leveling it at the
upper edge of the mould 48. Later, the mould can be opened at a
suited location (not shown) in order to remove the finished
building stone; an end wall of the mould may be removed for
example.
[0044] For manufacturing the building stone, the mould is first
filled to the extent needed for the incline of a respective one of
the groove 40 and the tongue 34 to be achieved. The corresponding
layer is leveled. FIG. 7 shows several surfaces that are formed by
the mould on the finished building stone (not shown in FIG. 7),
namely e.g., 32, 34, 36, 38; this is to facilitate the
understanding. If the need arises, the outer layer 20 may be
compacted.
[0045] Next, the middle layer 24 is introduced before the lowermost
layer has hardened. The thickness of this layer is also naturally
limited by the mould, which is apparent from the tapering incline
of a respective one of the tongue 34 and the groove 40. The
material of the middle layer 24 is filled up to this level.
Finally, the topmost layer, which preferably is the inner layer 26,
is applied, with the middle layer 24 not yet being hardened. This
permits to achieve a beneficial connection between the layers.
[0046] For manufacturing the middle layer, recycled, granular
polyurethane, cement and water are intimately blended together,
with water being added until the mixture is pourable. Generally,
more water is added than is needed for hardening. When the prepared
mixture is filled in for forming the middle layer, the surface of
the middle layer levels out and water starts to flow out of the
mould. It is allowed to rest for a while, this time being referred
to as waiting time herein after. The waiting time should not be so
long to allow the cement of the middle layer to harden. During the
waiting time, water is flowing out and the cement starts to
crystallize. The thickness of the layer diminishes. After typically
1 to 2 hours, generally between half an hour and five hours,
shrinking of the middle layer is observed. The layer thickness is
typically reduced by 2 to 2.5%. The water flowing out of the mould
is clean and virtually no cement is swept along by the water
flow.
[0047] The shrinking of the middle layer 24 is a process that is
typical for the invention. Initially, the middle layer 24 has
sufficient water to be capable of leveling and arranging itself on
its own. What is particularly notable thereby is that virtually no
cement is swept along by the water flowing out of the mould. The
mould needs not be particularly fine-meshed to prevent cement from
being swept along by the water flow. The water permeable mould only
has to have openings small enough to prevent any fraction of
polyurethane from passing through the holes.
[0048] The middle layer is typically produced in the following way.
100 liters of polyurethane and 20 liters of cement (ordinary blast
furnace slag cement) are filled, together with 50 liters of water,
into a compulsory mixer such as a job mixer or a screeding machine.
The components are carefully blended. Then, 100 liters of
polyurethane, 20 liters of cement and 50 liters of water are added
once more. They are sufficiently blended. The mixture obtained is
pourable. It exhibits the setting or shrinking that is
characteristic for the invention.
[0049] Another possibility is to first dry blend polyurethane and
cement and to add water only then. It is for example possible to
dry blend 100 liters of polyurethane and 20 to 25 liters of cement
in a screeding machine prior to adding water. Typically, the water
is added in a fraction of about 50% of the volume fraction of the
polyurethane.
[0050] It is preferred to also wait for a while after the lower
layer has been introduced into the mould. If the lower layer
consists of concrete, shrinking is observed after a while. As
already described in the steps described with regard to the middle
layer 24, the time until shrinking occurs is dependent on the type
of cement used. With rapid cement, the shrinking time is reduced.
It is advantageous to pour the middle layer 24 onto the lower layer
while the lower layer is still fresh but the cement has already
started to harden, meaning the crystallization has already
started.
[0051] Typically, the lower layer and the middle layer are
continuous, meaning they show no gaps. The upper layer may also be
configured in the same way but it may also be configured to have
gaps. This will be explained with reference to the FIGS. 8 and
9.
[0052] In FIG. 8, bricks 50 or tiles are pressed at regular
intervals into the middle layer 24; they form the outer layer 20.
Upon pressing them into the middle layer 24, the material thereof
rises slightly in the gaps between the discrete bricks 50 but does
not reach the front face of the bricks 50. The bricks 50 are
retained by the cement binder of the middle layer 24 so that no
additional binder needs to be added. Still, additional binder may
be added and it is for example also possible to apply a thin
hardening layer of mortar, of glue or the like onto the middle
layer 24 and to press the bricks 50 into the applied layer.
[0053] In the implementation as shown in the FIGS. 9 and 10, quite
large rubble stones 52 are pressed into the still fresh but already
set middle layer 24. They form the outer layer 20 and, at their end
sides, the outside face 22. In this case as well, the material of
the middle layer 24 rises in the gaps between the stones 52. This
can be discerned from FIG. 10.
[0054] Concrete, open concrete, bricks 50, stucco, madder plaster
(in German: Krapputz), exposed aggregate concrete, paving, plaster,
lamellae and any type of natural and prefabricated stones such as
marble slabs, concrete, paving stones, granite blocks, quarry
stones 52 can be used as the outer layer 20.
* * * * *