U.S. patent application number 09/829256 was filed with the patent office on 2002-11-21 for asymmetrical concrete backerboard and method for making same.
Invention is credited to Dinkel, Jeffrey.
Application Number | 20020170648 09/829256 |
Document ID | / |
Family ID | 25253981 |
Filed Date | 2002-11-21 |
United States Patent
Application |
20020170648 |
Kind Code |
A1 |
Dinkel, Jeffrey |
November 21, 2002 |
Asymmetrical concrete backerboard and method for making same
Abstract
The present invention is a backerboard having a fiberglass mesh
on one side, and a impervious reinforcement membrane on the other
side. The backerboard incorporates a low density, high compressive
strength concrete core having an upper principal surface and a
lower principal surface. The upper principal surface of the core is
covered by a fiberglass mesh reinforcement layer, itself covered
and bonded to the core by a thin layer of Portland cement. The
lower principal surface of the backerboard is covered with a high
tensile strength, impervious reinforcement membrane.
Inventors: |
Dinkel, Jeffrey; (Marietta,
GA) |
Correspondence
Address: |
TROUTMAN SANDERS LLP
BANK OF AMERICA PLAZA, SUITE 5200
600 PEACHTREE STREET , NE
ATLANTA
GA
30308-2216
US
|
Family ID: |
25253981 |
Appl. No.: |
09/829256 |
Filed: |
April 9, 2001 |
Current U.S.
Class: |
156/44 ; 156/243;
52/600 |
Current CPC
Class: |
B32B 13/12 20130101;
B32B 2307/7265 20130101; Y10T 442/171 20150401; Y10T 29/49623
20150115; Y10T 29/49629 20150115; B32B 37/20 20130101; E04C 2/06
20130101; B32B 13/08 20130101; B32B 2315/06 20130101; E04C 2/26
20130101; B28B 19/0092 20130101; B32B 13/02 20130101; B32B 2305/08
20130101; B32B 37/24 20130101; B32B 13/14 20130101; B28B 23/0006
20130101; B32B 2315/085 20130101; Y10T 442/2066 20150401 |
Class at
Publication: |
156/44 ; 156/243;
52/600 |
International
Class: |
B32B 031/12; B29B
007/00 |
Claims
What is claimed is:
1. A construction element for use as an underlayment or backerboard
comprising: (a) a core having an upper principal surface and a
lower principal surface; and (b) an impervious membrane on the
lower principal surface of the core; the core including alkaline
resistant fibers.
2. The construction element of claim 1, the alkaline resistant
fibers being chopped reinforcement fibers randomly dispersed in the
core.
3. The construction element of claim 2, the impervious membrane
comprising a reinforced polymer membrane.
4. The construction element of claim 2, the impervious membrane
comprising waterproof paperboard.
5. The construction element of claim 2, the impervious membrane
comprising spunbonded olefin.
6. The construction element of claim 2, the impervious membrane
comprising an alkaline resistant dense polymer fiber mat.
7. The construction element of claim 2, the cement core comprising
Portland cement and an additive selected from the group consisting
of expanded shale, expanded clay, sintered clay, pumice, slag,
calcium carbonate, slate, diatomaceous slate, perlite, vermiculite,
scoria, volcanic cinders, tuff, diatomite, sintered fly ash,
industrial cinders, gypsum, foam beads and glass beads.
8. A construction element for use as an underlayment or backerboard
comprising: (a) a core having an upper principal surface and a
lower principal surface; (b) a pervious upper reinforcement
material on the upper principal surface of the core; (c) an upper
coating in communication with the upper principal surface of the
core and the pervious upper reinforcement material; and (d) an
impervious membrane on the lower principal surface of the core.
9. The construction element of claim 8, the impervious membrane
comprising a reinforced polymer membrane.
10. The construction element of claim 8, the impervious membrane
comprising waterproof paperboard.
11. The construction element of claim 8, the impervious membrane
comprising spunbonded olefin.
12. The construction element of claim 8, the impervious membrane
comprising an alkaline resistant dense polymer fiber mat.
13. The construction element of claim 8, the cement core comprising
Portland cement and an additive selected from the group consisting
of expanded shale, expanded clay, sintered clay, pumice, slag,
calcium carbonate, slate, diatomaceous slate, perlite, vermiculite,
scoria, volcanic cinders, tuff, diatomite, sintered fly ash,
industrial cinders, gypsum, foam beads and glass beads.
14. A construction element for use as an underlayment or
backerboard comprising: (a) a cement core having an upper principal
surface and a lower principal surface; (b) a pervious reinforcement
layer on the upper principal surface of the core; (c) a cement
slurry binding the reinforcement layer to the upper principal
surface of the core; and (d) a high tensile strength, impervious
moisture barrier membrane bound to the lower principal surface of
the core.
15. The construction element of claim 14, the cement core
comprising Portland cement and an additive selected from the group
consisting of expanded shale, expanded clay, sintered clay, pumice,
slag, calcium carbonate, slate, diatomaceous slate, perlite,
vermiculite, scoria, volcanic cinders, tuff, diatomite, sintered
fly ash, industrial cinders, gypsum, foam beads and glass
beads.
16. The construction element of claim 14, the core comprising
Portland cement and alkaline resistant fibers.
17. The construction element of claim 16, the alkaline resistant
fibers being chopped reinforcement fibers randomly dispersed in the
core.
18. The construction element of claim 14, the pervious
reinforcement layer comprising a fiberglass mesh with an alkaline
resistant coating, the fiberglass mesh of the pervious
reinforcement layer selected from the group consisting of woven
fiberglass and fiberglass skrim.
19. The construction element of claim 14, the impervious moisture
barrier membrane comprising an alkaline resistant dense polymer
fiber mat.
20. A method of manufacturing a construction element for use as an
underlayment or backerboard comprising the following steps: (a)
conveying a sheet of impervious reinforced membrane through a core
station; and (b) depositing at the core station a core material on
the impervious reinforced membrane; the core material including
alkaline resistant fibers; the impervious reinforced membrane
acting as a carrier sheet.
21. The method of manufacturing according to claim 20, the alkaline
resistant fibers being chopped reinforcement fibers randomly
dispersed in the core.
22. The method of manufacturing according to claim 21, the
impervious reinforced membrane comprising a reinforced polymer
membrane.
23. The method of manufacturing according to claim 21, the
impervious reinforced membrane comprising waterproof
paperboard.
24. The method of manufacturing according to claim 21, the
impervious reinforced membrane comprising spunbonded olefin.
25. The method of manufacturing according to claim 21, the
impervious reinforced membrane comprising an alkaline resistant
dense polymer fiber mat.
26. A method of manufacturing a construction element for use as an
underlayment or backerboard comprising the following steps: (a)
conveying a sheet of impervious reinforced membrane through a core
station; (b) depositing at the core station a core material on the
impervious reinforced membrane; and (c) layering a pervious
membrane atop the core material such that the core material is
sandwiched between the pervious membrane and the impervious
membrane the impervious reinforced membrane acting as a carrier
sheet throughout the manufacturing process.
27. The method of manufacturing according to claim 26, further
comprising the step of screeding the core material to reduce the
thickness of the core material on the impervious reinforced
material.
28. The method of manufacturing according to claim 27, said step of
screeding smoothing out an upper surface of the core material.
29. The method of manufacturing according to claim 26, further
comprising the step of compacting the core material on the
impervious reinforced membrane.
30. The method of manufacturing according to claim 26, further
comprising the step of bathing the pervious membrane in a binding
agent prior to layering the pervious membrane on the core
material.
31. The method of manufacturing according to claim 26, further
comprising the step of cutting the construction element into
panels.
32. The method of manufacturing according to claim 26, the
impervious reinforced membrane comprising a reinforced polymer
membrane.
33. The method of manufacturing according to claim 26, the
impervious reinforced membrane comprising waterproof
paperboard.
34. The method of manufacturing according to claim 26, the
impervious reinforced membrane comprising Tyvek.RTM..
35. A method of manufacturing a construction element for use as an
underlayment or backerboard comprising the following steps: (a)
conveying a sheet of impervious reinforced membrane through the
steps of the method of manufacturing; (b) depositing a core
material from a core material hopper to the conveyed impervious
reinforced membrane; and (c) screeding the core material on the
conveyed sheet of impervious reinforced membrane with a screed; (d)
compacting the core material on the conveyed sheet of impervious
reinforced membrane with a compactor; (e) bathing a conveyed
pervious reinforced membrane through a bath of cement; and (f)
layering the pervious reinforced membrane on the core material on
the conveyed sheet of impervious reinforced membrane; and (g)
cutting the manufactured construction element into panels.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates generally to a composite structural
panel, and more particularly to an asymmetrical concrete
backerboard having fiberglass mesh reinforcement on one side, and
an impervious reinforcement membrane on the opposite side of the
board.
[0003] 2. Description of Related Art
[0004] The conventional backerboard is made up of a rectangular
panel of solid concrete, the concrete core, having both major
surfaces covered with fiberglass. The fiberglass adds strength to
the board, and provides only limited resistance to water
penetration through the board. Concrete backerboards are used
extensively in the construction of interior and exterior floors,
walls and ceilings. The concrete backerboard is a superior
substrate or underlayment for stucco, ceramic tile, marble, and
other tile-like surfaces located in wet areas, such as shower walls
and bathtub surrounds, and building exterior walls.
[0005] Typically, the concrete core of the backerboard is a low
density, high compressive strength, concrete core. The fiberglass
mesh reinforcement layers overlay both major faces of the core,
with each of these pervious fiberglass layers themselves covered
with a thin layer of Portland cement. Backerboards have textured
cementitious surfaces that provide for a high strength bond with
mastics and Portland cement mortars that are used to adhere tile to
the substrate in wet areas.
[0006] While the conventional backerboard is generally stable and
water resistant, it is not an ideal construction panel for use in
wet environments due to several inherent limitations. For example,
it is generally recommended by backerboard manufactures, and
required by most building codes, to use an additional impervious
moisture barrier behind the backerboard. Thus, contractors are
forced to install the backerboard and separate moisture barrier in
the field, at the construction site. Use of a impervious barrier
membrane with the backerboard provides protection for the wood or
steel structures under or behind the backerboard, and contains the
moisture in the wet area. Examples of commonly used moisture
barriers are felt paper, Tyvek.RTM., spunbonded olefin and
polyethylene.
[0007] An exemplary patent in this field includes U.S. Pat. No.
3,284,980 to Dinkel disclosing a precast panel of cement and
aggregate reinforced with a skin membrane of fibrous material.
Backerboard manufacturing techniques include a lightweight
aggregate core faced on each side or face with a fiberglass mesh
material bathed in a slurry of neat cement and pressed against the
aggregate core, such that when the neat cement and the aggregate
core are cured, there is provided a composite, fiberglass mesh
reinforced, cementitious panel. U.S. Reissue Pat. No. Re32,037 to
Clear is a method for manufacturing cementitious reinforced panels
and illustrates a concrete panel 11 having reinforcement layers 12,
13 and a polyethylene layer 20 adjacent one of the layers 12, 13.
Layers 12 and 13 are described as mesh reinforcing elements,
preferably constituting fiber mesh like pervious webs, each
entrained in hydraulic cement. Layer 20 is a carrier sheet placed
under reinforcing element 12 during manufacture. Yet, such methods
of constructing backerboards are not only deficient because they
produce an inferior wet-area panel, but also because they require
the use of a carrier sheet.
[0008] It is evident from the prior art that an improved
backerboard and method of constructing such an improved backerboard
is needed. It can be seen that there is a need for a backerboard
having at least one waterproof surface that can be delivered
ready-made to the construction site, and a method for producing
such a backerboard without resort to a carrier sheet.
BRIEF SUMMARY OF THE INVENTION
[0009] Briefly described, in a preferred form, the present
invention is a backerboard having a fiberglass mesh on one side,
and an impervious moisture barrier membrane on the other side. Such
an asymmetrical backerboard design (the two major surfaces of the
core having differing moisture-resistant layers, providing
different moisture-resistant properties) incorporates numerous
advantages over the conventional backerboard design, including
having lower manufacture costs, having a waterproof panel
deliverable on-site, and having a simplified manufacturing process
by eliminating the use of a carrier sheet or web.
[0010] The present asymmetrical backerboard comprises a low
density, high compressive strength concrete core having an upper
principal surface and a lower principal surface. The upper
principal surface of the core is covered by a fiberglass mesh
reinforcement layer, itself covered and bonded to the core by a
thin layer of Portland cement. Alternatively, if the core itself
comprises a sufficient amount of randomly dispersed fiberglass
fibers, the addition of the fiberglass mesh reinforcement layer may
not be required. The lower principal surface of the backerboard is
covered with a high tensile strength, impervious moisture barrier
membrane.
[0011] The present backerboard construction eliminates the prior
art necessity of the on-the-construction-site application of a
moisture barrier behind the backerboard. It exhibits all of the
structural, bonding and workability properties of conventional
backerboards, and provides advanced water resistance.
[0012] The present method of constructing the backerboard dispenses
with the prior art requirement of a carrier sheet or web. In a
preferred embodiment of the invention, the panel is manufactured by
the concurrent steps of running a continuous pervious reinforcement
web through a web coating bath and then removing excess bath
therefrom, and running a continuous impervious reinforcement web
through a set of pinch rollers and atop a conveyor belt.
[0013] Core material is dispensed upon the impervious web via a
hopper, and the combination of impervious web and core material run
through a screed. The core material is then compacted. The bathed
pervious web is then fed onto the top of the core material, forming
a sandwich of, from bottom to top, impervious web, core material
and pervious web. The composite is then cut into panels.
[0014] It is thus an object of the present invention to provide an
asymmetrical backerboard and a method for making such a board.
[0015] Further, it is an object of the present invention to provide
a construction panel having at least one major surface which is
highly resistant to the penetration of water.
[0016] These and other objects, features, and advantages of the
present invention will become more apparent upon reading the
following specification in conjunction with the accompanying
drawing figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a front sectional view of a prior art
backboard.
[0018] FIG. 2 is a side view of FIG. 1.
[0019] FIG. 3 is a front sectional view of the present asymmetrical
backboard according to a preferred embodiment of the present
invention.
[0020] FIG. 4 is a side view of FIG. 3.
[0021] FIG. 5 is a block diagram of a preferred construction method
for the backerboard of FIG. 3.
[0022] FIG. 6 illustrates the manufacture of the backerboard of
FIG. 3.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] The components of the present invention are referenced
herein as follows:
1 NO. COMPONENT NO. COMPONENT 10 Prior Art Backerboard 48 Core Feed
Hopper 12 Concrete Core 52 Screed 14 Fiberglass Mesh Reinforcement
54 Compaction Station 16 Layer of Portland Cement 56 Compaction
Roll 20 Present Asymmetrical Backerboard 58 Bath 22 Concrete Core
62 Roller Assembly 24 Upper Principal Surface of Core 64 Doctor
Assembly 26 Lower Principal Surface of Core 66 Drag Bar 28 Upper
Reinforcement Material 72 Step of Feeding 32 Upper Coating 74 Step
of Depositing 34 Impervious Membrane 76 Step of Screeding 40
Present Manufacturing Process 78 Step of Compacting 42 Roll of
Impervious Membrane 82 Step of Bathing 44 Pinch Roller Assembly 84
Step of Layering 46 Conveyor Belt 86 Step of Cutting
[0024] It should be noted that as used herein the term "pervious"
defines a property of a material, that property enabling free water
to penetrate through a material, and that the term "impervious"
defines a property of a material, that property being highly
resistant against enabling free water to penetrate through a
material. An impervious material may enable water vapor to
penetrate through a material.
[0025] Referring now in detail to the drawing figures, wherein like
reference numerals represent like parts throughout the several
views, FIGS. 1 and 2 illustrate a conventional backerboard 10
comprising a low density, high compressive strength, concrete core
12. A layer of fiberglass mesh reinforcement 14 covers both major
faces of the core 12, with each of these pervious fiberglass layers
themselves 14 covered with a thin layer 16 of Portland cement.
[0026] As shown in FIGS. 3 and 4, The present invention 20
comprises a core 22 having an upper principal surface 24 and a
lower principal surface 26, an upper reinforcement material 28 in
contact with the upper principal surface 24 of the core 22, an
upper coating 32 in communication with the upper principal surface
24 of the core 22 and the upper reinforcement material 28, and an
impervious membrane 34 covering the lower principal surface 26 of
the core 22.
[0027] The core 22 can comprise low, medium and high slump
concrete. The concrete preferably includes Portland cement and
lightweight fillers and/or aggregates of, for example, expanded
shale, expanded clay, sintered clay, pumice, slag, calcium
carbonate, slate, diatomaceous slate, perlite, vermiculite, scoria,
volcanic cinders, tuff, diatomite, sintered fly ash, industrial
cinders, gypsum, foam beads, glass beads and the like. Other
additives that can be mixed with the Portland cement include
lightweight sand and alkaline resistant fibers such as chopped
reinforcement fibers, randomly dispersed in the core 22.
[0028] The upper reinforcement material 28 is preferably pervious
and comprises woven fiberglass mesh or fiberglass skrim with an
alkaline resistant coating. Alternatively, the reinforcement
material 28 can be a polymer fiber mat. In yet another embodiment,
the upper reinforcement material 28 can, in essence, be made a part
of the core 22, such that the addition of a separate layer of upper
reinforcement material is not necessary. For example, the core 22
can comprise a sufficient amount of alkaline resistant fibers
wherein an upper reinforcement material layer need not be an
additional element of the present backerboard 10.
[0029] The upper coating 32 can be a Portland cement slurry being
either neat or foamed. The slurry can comprise fine aggregate
and/or filler material.
[0030] The impervious membrane 34 preferably comprises a polymer
membrane, for example, a fiber mat, Tyvek.RTM., Typar.RTM., brand
spunbonded olefin, or a layer of waterproofed paper or cardboard.
The impervious membrane 34 can specifically include an alkaline
resistant dense polymer fiber mat.
[0031] Manufacture
[0032] The present manufacturing process 40 (as shown left to right
in FIGS. 5 and 6) incorporates a first feeding step 72 of running a
continuous roll 42 of the impervious membrane 34 out through a
pinch roller assembly 44. The impervious membrane 34 is at that
point supported and conveyed by a conveyor belt 46.
[0033] In a second depositing step 74, the membrane 34 is conveyed
beneath a core material dispense hopper 48, through which the
cementitious core mix of the core 22 if fed onto the membrane 34.
Hopper 48 can include elements (not shown), for example, a metering
gate for controlling the amount of mix laid onto the membrane
34.
[0034] A third screeding step 76 of the present manufacturing
process includes reducing the thickness of the core mix. The
conveyor belt 46 carries the membrane 34/core mix composite through
screed 52 to reduce the thickness, and smooth out the upper
surface, of the core mix. Thereafter, in a fourth compacting step
78, the conveyor belt 46 moves the membrane 34/core mix composite
into a compaction station 54 that can include a compaction roll 56
that which serves to compact the core mix against the impervious
membrane 34. This compaction increases the density of the core and
enhances the bond of the membrane 34 to the core mix.
[0035] In a fifth bathing step 82, a roll of the upper
reinforcement material 28 is run through a bath 58 of the upper
coating 32, and in a sixth layering step 84, the upper
reinforcement material 28 is laid down on the core mix. A roller
assembly 62 can serve to draw the upper reinforcement material 28
through the bath 58 and a doctor assembly 64 can remove any
excessive slurry from the material 28. A drag bar 66 can be
positioned above the material 28 which drags against its upper
surface, thereby serving to urge core mix on the upper surface of
the material 28 into the interstices of the material 28 and through
the material 28. In a final cutting step 86, the backerboard is
then cut downstream (not shown) into panels.
[0036] The present manufacturing process 40 has great advantages
over the prior art processes. During the manufacture of the
standard concrete backerboard, with cementitious surfaces on both
sides, the conventional forming conveyor must be protected from
contact with the bottom of the core/pervious (as opposed to the
present invention's impervious membrane 34) surface while in its
plastic state. This is accomplished by the use of a form, a carrier
sheet or a disposable carrier web. These forms and carrier sheets
are treated with a release agent and remain with the backerboard
until it has hardened, at which time the form or carrier sheet is
separated from the backerboard, cleaned and recoated with release
agent to be reentered into the forming operation. In the case of
manufacturing with a carrier web, the web is treated with a release
agent and is dispensed onto the forming conveyer where the
backerboard is formed on the carrier web. This web remains with the
backerboard until it hardens at which time the carrier web is
removed and disposed.
[0037] The present invention avoids the carrier sheet problem by
providing a backerboard with a cementitious surface on only one
side, and a high tensile strength impervious membrane 34 on the
other side. Manufacturing this improved backerboard with the
membrane 34 on the bottom side eliminates the need for a form, a
carrier sheet, a release agent or a carrier web. The impervious
membrane 34 which is incorporated into the present backerboard
composite, essentially becomes a non-disposable carrier web. The
manufacturing process thus is greatly simplified by ridding the
process and equipment required to treat the carrier or form with
release agent, dispensing the carrier or form into the forming
process, separating the carrier or form from the backerboard,
cleaning the carrier or form, retreating the carrier or form with
release agent, and/or dispensing of and disposing of the carrier
web. Additionally the cost of the impervious high tensile strength
membrane 34 is approximately one-forth (1/4) of the cost of vinyl
coated fiberglass mesh with comparable tensile strength.
[0038] While the invention has been disclosed in its preferred
forms, it will be apparent to those skilled in the art that many
modifications, additions, and deletions can be made therein without
departing from the spirit and scope of the invention and its
equivalents as set forth in the following claims.
* * * * *