U.S. patent application number 10/763787 was filed with the patent office on 2004-08-05 for method for making wallboard or backerboard sheets including aerated concrete.
This patent application is currently assigned to CONSOLIDATED MINERALS, INC.. Invention is credited to Bromwell, Leslie G., Gregg, Frederick Browne.
Application Number | 20040150139 10/763787 |
Document ID | / |
Family ID | 22566942 |
Filed Date | 2004-08-05 |
United States Patent
Application |
20040150139 |
Kind Code |
A1 |
Gregg, Frederick Browne ; et
al. |
August 5, 2004 |
Method for making wallboard or backerboard sheets including aerated
concrete
Abstract
A method for making wallboard or backerboard sheets which are
relatively lightweight, strong, and which have good fire
resistance, thermal insulation, and sound absorbing properties
includes forming core material having opposing first and second
major surfaces and comprising aerated concrete, securing at least
one face layer on at least one of the first and second major
surfaces of the core material, and cutting the core material and at
least one face layer secured thereto into a plurality of wallboard
or backerboard sheets. The provision of aerated concrete for the
core provides many key advantages over conventional gypsum
wallboard sheets, and/or conventional backerboard sheets, such as
gypsum greenboard or cementitious backerboard, for example. In one
class of embodiments, the method may further include curing the
core material prior to securing the at least one face layer
thereto. In another class, the method may further include curing
the core material after securing the at least one face layer
thereto.
Inventors: |
Gregg, Frederick Browne;
(Leesburg, FL) ; Bromwell, Leslie G.; (Auburndale,
FL) |
Correspondence
Address: |
Christopher F. Regan
Allen, Dyer, Doppelt,
Milbrath, Gilchrist, P.A.
P.O. Box 3791
Orlando
FL
32802-3791
US
|
Assignee: |
CONSOLIDATED MINERALS, INC.
Leesburg
FL
|
Family ID: |
22566942 |
Appl. No.: |
10/763787 |
Filed: |
January 23, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10763787 |
Jan 23, 2004 |
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10079732 |
Feb 21, 2002 |
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6682617 |
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10079732 |
Feb 21, 2002 |
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09680720 |
Oct 6, 2000 |
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6409855 |
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60158172 |
Oct 7, 1999 |
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Current U.S.
Class: |
264/333 ;
257/E21.244; 264/158 |
Current CPC
Class: |
B32B 2307/304 20130101;
Y10T 156/1734 20150115; E04F 13/148 20130101; Y02W 30/91 20150501;
B28B 1/50 20130101; Y02W 30/92 20150501; Y10T 156/1097 20150115;
B32B 2307/3065 20130101; B32B 13/04 20130101; E04C 2/049 20130101;
C04B 2111/00629 20130101; B32B 13/14 20130101; B32B 38/0004
20130101; B32B 5/18 20130101; E04F 13/16 20130101; C04B 28/18
20130101; E04C 2/043 20130101; C04B 2111/0062 20130101; C04B
2111/27 20130101; B32B 2305/08 20130101; C04B 2111/00612 20130101;
B28B 11/04 20130101; E04F 13/141 20130101; Y02W 30/97 20150501;
Y10T 428/249969 20150401; B32B 2307/718 20130101; C04B 28/02
20130101; C04B 2111/28 20130101; C04B 2111/40 20130101; H01L
21/31053 20130101; B32B 2038/0076 20130101; C04B 40/02 20130101;
B32B 2419/00 20130101; C04B 38/02 20130101; C04B 28/184 20130101;
B32B 13/08 20130101; B32B 2307/7246 20130101; E04C 2/04 20130101;
C04B 2201/20 20130101; C04B 28/02 20130101; C04B 20/0048 20130101;
C04B 38/02 20130101; C04B 40/024 20130101; C04B 28/02 20130101;
C04B 14/06 20130101; C04B 18/08 20130101; C04B 20/0048 20130101;
C04B 22/064 20130101; C04B 38/02 20130101; C04B 40/024 20130101;
C04B 38/02 20130101; C04B 28/02 20130101; C04B 40/024 20130101;
C04B 28/02 20130101; C04B 18/24 20130101; C04B 38/02 20130101; C04B
28/02 20130101; C04B 14/42 20130101; C04B 38/02 20130101; C04B
40/02 20130101; C04B 28/02 20130101; C04B 38/02 20130101; C04B
40/024 20130101; C04B 38/02 20130101; C04B 20/0048 20130101; C04B
22/064 20130101; C04B 28/02 20130101; C04B 40/024 20130101; C04B
28/18 20130101; C04B 14/42 20130101; C04B 14/48 20130101; C04B
16/06 20130101; C04B 18/08 20130101; C04B 18/24 20130101; C04B
22/04 20130101; C04B 40/0071 20130101; C04B 40/024 20130101; C04B
28/184 20130101; C04B 14/42 20130101; C04B 14/48 20130101; C04B
16/06 20130101; C04B 18/08 20130101; C04B 18/24 20130101; C04B
38/02 20130101; C04B 40/0071 20130101; C04B 40/024 20130101 |
Class at
Publication: |
264/333 ;
264/158 |
International
Class: |
B28B 003/00 |
Claims
That which is claimed is:
1. A method for making wallboard or backerboard sheets comprising:
forming core material having opposing first and second major
surfaces and comprising aerated concrete; securing at least one
face layer on at least one of the first and second major surfaces
of the core material; and cutting the core material and at least
one face layer secured thereto into a plurality of wallboard or
backerboard sheets.
2. A method according to claim 1 further comprising curing the core
material prior to securing the at least one face layer thereto.
3. A method according to claim 1 further comprising curing the core
material after securing the at least one face layer thereto.
4. A method according to claim 1 wherein forming the core material
comprises: dispensing materials for making aerated concrete into a
mold and allowing the materials to rise and stiffen into a body;
curing the body; and dividing the cured body into a plurality of
cured sheets to serve as the core material.
5. A method according to claim 4 further comprising joining a
plurality of the cured sheets together in end-to-end relation while
advancing the cured sheets along a path of travel.
6. A method according to claim 5 wherein securing the at least one
face layer is performed while the cured sheets are advanced along
the path of travel.
7. A method according to claim 1 wherein forming the core material
comprises: dispensing materials for making aerated concrete into a
mold and allowing the materials to rise and stiffen into a body;
dividing the body into a plurality of uncured sheets; and curing
the sheets to serve as the core material.
8. A method according to claim 7 further comprising joining a
plurality of the cured sheets together in end-to-end relation while
advancing the cured sheets along a path of travel.
9. A method according to claim 8 wherein securing the at least one
face layer is performed while the cured sheets are advanced along
the path of travel.
10. A method according to claim 1 wherein forming the core material
comprises: dispensing materials for making aerated concrete into a
mold and allowing the materials to rise and stiffen into a body;
and dividing the body into a plurality of uncured sheets to serve
as the core material.
11. A method according to claim 10 further comprising curing the
uncured sheets after securing the at least one face layer
thereto.
12. A method according to claim 11 wherein the curing is after
cutting.
13. A method according to claim 1 wherein forming the core material
comprises mixing and dispensing the materials for making aerated
concrete in slurry form.
14. A method according to claim 13 wherein securing the at least
one face layer comprises receiving the aerated concrete in slurry
form thereon as the at least one face layer is advanced along a
path of travel.
15. A method according to claim 14 further comprising: permitting
the aerated concrete material to rise and stiffen prior to cutting;
and curing the aerated concrete after cutting.
16. A method according to claim 1 securing the at least one face
layer comprises securing first and second face layers on respective
first and second major surfaces of the core material.
17. A method according to claim 1 wherein the at least one face
layer comprises paper.
18. A method according to claim 1 wherein the at least one face
layer is moisture-resistant.
19. A method according to claim 1 further comprising forming the
first major surface of the core material to have beveled portions
adjacent respective opposing longitudinal side edges.
20. A method according to claim 1 wherein securing the at least one
face layer comprises securing the at least one face layer to extend
around the opposing longitudinal side edges.
21. A method according to claim 1 wherein forming the core material
comprises forming the core material with reinforcing fibers in the
aerated concrete.
22. A method for making wallboard or backerboard sheets comprising:
dispensing materials for making aerated concrete into a mold and
allowing the materials to rise and stiffen into a body; curing the
body; dividing the cured body into a plurality of cured sheets to
serve as core material having opposing major surfaces; securing at
least one face layer on at least one of the first and second major
surfaces of the core material; and cutting the core material and at
least one face layer secured thereto into a plurality of wallboard
or backerboard sheets.
23. A method according to claim 22 further comprising joining a
plurality of the cured sheets together in end-to-end relation while
advancing the cured sheets along a path of travel.
24. A method according to claim 23 wherein securing the at least
one face layer is performed while the cured sheets are advanced
along the path of travel.
25. A method according to claim 22 securing the at least one face
layer comprises securing first and second face layers on respective
first and second major surfaces of the core material.
26. A method according to claim 22 wherein the at least one face
layer comprises paper.
27. A method according to claim 22 wherein the at least one face
layer is moisture-resistant.
28. A method according to claim 22 further comprising forming the
first major surface of the core material to have beveled portions
adjacent respective opposing longitudinal side edges.
29. A method according to claim 22 wherein securing the at least
one face layer comprises securing the at least one face layer to
extend around the opposing longitudinal side edges.
30. A method according to claim 22 further comprising adding
reinforcing fibers to the aerated concrete.
31. A method for making wallboard or backerboard sheets comprising:
dispensing materials for making aerated concrete into a mold and
allowing the materials to rise and stiffen into a body; dividing
the body into a plurality of uncured sheets; curing the uncured
sheets to serve as core material having opposing first and second
major surfaces; securing at least one face layer on at least one of
the first and second major surfaces of the core material; and
cutting the core material and at least one face layer secured
thereto into a plurality of wallboard or backerboard sheets.
32. A method according to claim 31 further comprising joining a
plurality of the cured sheets together in end-to-end relation while
advancing the cured sheets along a path of travel.
33. A method according to claim 32 wherein securing the at least
one face layer is performed while the cured sheets are advanced
along the path of travel.
34. A method according to claim 31 securing the at least one face
layer comprises securing first and second face layers on respective
first and second major surfaces of the core material.
35. A method according to claim 31 wherein the at least one face
layer comprises paper.
36. A method according to claim 31 wherein the at least one face
layer is moisture-resistant.
37. A method according to claim 31 further comprising forming the
first major surface of the core material to have beveled portions
adjacent respective opposing longitudinal side edges.
38. A method according to claim 31 wherein securing the at least
one face layer comprises securing the at least one face layer to
extend around the opposing longitudinal side edges.
39. A method according to claim 31 further comprising adding
reinforcing fibers to the aerated concrete.
40. A method for making wallboard or backerboard sheets comprising:
dispensing materials for making aerated concrete into a mold and
allowing the materials to rise and stiffen into a body; dividing
the body into a plurality of uncured sheets having opposing first
and second major surfaces to serve as the core material; securing
at least one face layer on at least one of the first and second
major surfaces of the core material; cutting the core material and
at least one face layer secured thereto into a plurality of uncured
wallboard or backerboard sheets; and curing the uncured wallboard
or backerboard sheets.
41. A method according to claim 40 wherein the at least one face
layer comprises first and second face layers on respective first
and second major surfaces of the core material.
42. A method according to claim 40 wherein the at least one face
layer comprises paper.
43. A method according to claim 40 wherein the at least one face
layer is moisture-resistant.
44. A method according to claim 40 further comprising forming the
first major surface of the core material to have beveled portions
adjacent respective opposing longitudinal side edges.
45. A method according to claim 40 wherein the at least one face
layer extends around the opposing longitudinal side edges.
46. A method according to claim 40 further comprising adding
reinforcing fibers to the aerated concrete.
47. A method for making wallboard or backerboard sheets comprising:
mixing and dispensing materials for making aerated concrete
adjacent at least one face layer advancing along a path of travel;
permitting the aerated concrete materials to rise and stiffen to
define core material having first and second opposing surfaces with
the at least one face layer secured thereto; cutting the core
material and at least one face layer secured thereto into a
plurality of uncured wallboard or backerboard sheets; and curing
the uncured wallboard or backerboard sheets.
48. A method according to claim 47 wherein the at least one face
layer comprises first and second face layers on respective first
and second major surfaces of the core material.
49. A method according to claim 47 wherein the at least one face
layer comprises paper.
50. A method according to claim 47 wherein the at least one face
layer is moisture-resistant.
51. A method according to claim 47 further comprising forming the
first major surface of the core material to have beveled portions
adjacent respective opposing longitudinal side edges.
52. A method according to claim 47 wherein the at least one face
layer extends around the opposing longitudinal side edges.
53. A method according to claim 47 further comprising adding
reinforcing fibers to the aerated concrete.
54. A method for making at least one of a wallboard or backerboard
sheet comprising: forming a core having opposing first and second
major surfaces and at least one face layer thereon, said core
comprising aerated concrete.
55. A method according to claim 54 wherein the at least one face
layer comprises first and second face layers on respective first
and second major surfaces of the core.
56. A method according to claim 54 wherein the at least one face
layer comprises paper.
57. A method according to claim 54 wherein the at least one face
layer is moisture-resistant.
58. A method according to claim 54 wherein the core has a generally
rectangular shape defining a pair of opposing side edges and a pair
of opposing end edges.
59. A method according to claim 58 wherein the first major surface
has beveled portions adjacent respective opposing side edges.
60. A method according to claim 58 wherein the at least one face
layer extends around the opposing side edges.
Description
RELATED APPLICATION
[0001] The present application is based upon U.S. provisional
patent application serial No. 60/158,172 filed Oct. 6, 1999, the
entire disclosure of which is incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to the field of manufacturing
construction products, and, more particularly, to methods for
making lightweight, high-strength, fire-resistant wallboard sheet,
and/or moisture-resistant backerboard sheets.
BACKGROUND OF THE INVENTION
[0003] Wallboard sheets are widely used in building construction to
form partitions or walls of rooms, elevator shafts, stair wells,
ceilings, etc. The sheets are typically fastened to a suitable
supporting framework. The seams between sheets are covered to
provide an even wall surface. The sheets may be readily cut to size
by first scoring the face sheet, and then snapping the board about
the score line. The wall may then be painted or covered with a
decorative wall covering, if desired. Such wallboard sheets created
from a gypsum core with outer face layers of paper, sometimes
referred to as gypsum board or drywall, are well known.
[0004] Gypsum wallboard is typically manufactured by delivering a
slurry or paste containing crushed gypsum rock onto a moving sheet
of facing paper to which a second or top paper layer is then added
to form a long board line. The board line permits the slurry to
harden before being cut. The cut panels are heated in a kiln,
before being packaged for storage and shipping.
[0005] Typically, such sheets are 1/2 or {fraction (5/8)} inch
thick and in conventional sizes of 4.times.8 feet, such a gypsum
wallboard sheet may weigh about 55-70 pounds. Accordingly, handling
of such gypsum wallboards presents a significant task for
construction personnel or wallboard "hangers", particularly when
such boards are secured overhead to form a ceiling. In addition,
the fire resistance, thermal insulation and sound absorbing
properties of conventional gypsum wallboard sheets may not be
sufficient for some applications.
[0006] Another variation of gypsum wallboard is water-resistant
drywall or "greenboard". The greenboard typically includes the same
gypsum core, but includes a water-resistant facing so the water is
less likely to penetrate, stain and/or decay the wall. Greenboard
is typically used for walls in a moist or humid environment, such
as a bathroom, for example. Such greenboard is not typically
recommended as an underlayment for tile in the bathroom, for
example, since water may penetrate the grout or cracks between
adjacent tiles and deteriorate the greenboard. U.S. Pat. No.
5,552,187 to Green et al. discloses the addition of a fibrous
mat-faced gypsum board coated with a water-resistant resinous
coating for greater durability in moist environments.
[0007] Yet another related conventional wallboard product to serve
as an underlayment for wet areas is the concrete backerboard. For
example, UTIL-A-CRETE.RTM. Backerboard from Bonsal is a precast
cementitious backboard with glass mesh reinformcement. The board
includes portland cement, fiber glass mesh and lightweight
aggregate. The backerboard is more adapted to be used in areas
subject to splashing or high moisture.
[0008] While the glass mesh face layers are typically secured to
the surface of the backerboard after the core has been precast,
continuous production is also disclosed in U.S. Pat. No. 5,221,386
to Ensminger et al. In addition, the mesh or reinforcing layers
have also been embedded in the faces and edges of the
backerboards.
[0009] Unfortunately, conventional cementitious backerboards may be
more difficult to score and break to size. Moreover, since the
backerboards include a core of cement, their density is
considerably greater than even conventional gypsym wallboard.
Accordingly, manufacturers may offer the backerboards in smaller
sizes to be more readily handled by the installer, but such
increases seams between sheets and also increases costs of
installation. A typically-sized 4 foot by 8 foot sheet can weigh
well over 100 pounds, which is very unwieldy especially in confined
spaces.
SUMMARY OF THE INVENTION
[0010] In view of the foregoing background, it is therefore an
object of the invention to provide a method for making wallboard or
backerboard sheets which are relatively lightweight, strong, and
which have good fire resistance, thermal insulation, and sound
absorbing properties.
[0011] This and other objects, features and advantages in
accordance with the present invention are provided by a method
comprising forming core material having opposing first and second
major surfaces and comprising aerated concrete, securing at least
one face layer on at least one of the first and second major
surfaces of the core material, and cutting the core material and at
least one face layer secured thereto into a plurality of wallboard
or backerboard sheets. The provision of aerated concrete for the
core provides many key advantages over conventional gypsum
wallboard sheets, and/or conventional backerboard sheets, such as
gypsum greenboard or cementitious backerboard, for example.
[0012] In one class of embodiments, the method may further comprise
curing the core material prior to securing the at least one face
layer thereto. In another class, the method may further comprise
curing the core material after securing the at least one face layer
thereto.
[0013] In one particularly advantageous embodiment, forming the
core material comprises dispensing materials for making aerated
concrete into a mold and allowing the materials to rise and stiffen
into a body, curing the body, and dividing the cured body into a
plurality of cured sheets to serve as the core material. The
plurality of the cured sheets may be joined together in end-to-end
relation while advancing the cured sheets along a path of travel.
In addition, securing the at least one face layer may be performed
while the cured sheets are advanced along the path of travel.
[0014] In another embodiment, forming the core material comprises
dispensing materials for making aerated concrete into a mold and
allowing the materials to rise and stiffen into a body, dividing
the body into a plurality of uncured sheets, and curing the sheets
to serve as the core material. This embodiment may also include
joining the plurality of the cured sheets together in end-to-end
relation while advancing the cured sheets along a path of travel.
Additionally, the at least one face layer may also be secured while
the cured sheets are advanced along the path of travel.
[0015] In yet another embodiment, forming the core material
comprises dispensing materials for making aerated concrete into a
mold and allowing the materials to rise and stiffen into a body,
and dividing the body into a plurality of uncured sheets to serve
as the core material. In this embodiment, curing of the uncured
sheets occurs after securing the at least one face layer thereto.
Curing may also be performed after cutting. A high temperature
resistant face layer may be required where curing is performed
after securing of the one or more face layers.
[0016] In accordance with still another embodiment of the
invention, the method includes mixing and dispensing the materials
for making aerated concrete in slurry form, and wherein securing
the at least one face layer comprises receiving the aerated
concrete in slurry form thereon as the at least one face layer is
advanced along a path of travel. This embodiment may also include
permitting the aerated concrete material to rise and stiffen, and
curing the liquid aerated concrete after rising and stiffening. The
curing may also be after cutting.
[0017] The securing the at least one face layer may comprise
securing first and second face layers on respective first and
second major surfaces of the core material. The at least one face
layer may comprise paper, such as for a wallboard. Alternately, the
at least one face layer may be moisture-resistant for a
backerboard.
[0018] The method may also include forming the first major surface
of the core material to have beveled portions adjacent respective
opposing longitudinal side edges. Securing the at least one face
layer may include securing the at least one face layer to extend
around the opposing longitudinal side edges. In addition, forming
the core material may comprise forming the core material with
reinforcing fibers in the aerated concrete.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a schematic view of a portion of a wall structure
including the wallboard and/or backerboard in accordance with the
present invention with various layers removed for clarity of
explanation.
[0020] FIG. 2 is a perspective view of a wallboard sheet as can be
used in the wall structure of FIG. 1.
[0021] FIG. 3 is an enlarged cross-sectional view through a side
edge of the wallboard sheet as shown in FIG. 2.
[0022] FIG. 4 is a perspective view of another embodiment of a
wallboard sheet as can be used in the wall structure of FIG. 1.
[0023] FIG. 5 is an enlarged cross-sectional view through a beveled
portion of the wallboard sheet as shown in FIG. 4.
[0024] FIG. 6 is a perspective view of a backerboard sheet as can
be used in the wall structure of FIG. 1.
[0025] FIG. 7 is an enlarged cross-sectional view through a side
edge of the backerboard sheet as shown in FIG. 6.
[0026] FIG. 8 is a perspective view of another embodiment of a
backerboard sheet as can be used in the wall structure of FIG.
1.
[0027] FIG. 9 is an enlarged cross-sectional view through a beveled
portion of the backerboard sheet as shown in FIG. 8.
[0028] FIG. 10 is a flowchart for a first embodiment of a method
for making wallboard and/or backerboard sheets in accordance with
the invention.
[0029] FIG. 11 is a flowchart for a second embodiment of a method
for making wallboard and/or backerboard sheets in accordance with
the invention.
[0030] FIG. 12 is a flowchart for a third embodiment of a method
for making wallboard and/or backerboard sheets in accordance with
the invention.
[0031] FIG. 13 is a flowchart for a fourth embodiment of a method
for making wallboard and/or backerboard sheets in accordance with
the invention.
[0032] FIG. 14 is a schematic block diagram of a system for making
wallboard and/or backerboard sheets in accordance with the
invention.
[0033] FIG. 15 is a more detailed schematic diagram of a former
embodiment for the system as shown in FIG. 14.
[0034] FIG. 16 is a more detailed schematic diagram of an
alternative portion of the former embodiment as shown in FIG.
15.
[0035] FIG. 17 is a more detailed schematic of another former
embodiment and variation thereof for the system of FIG. 14.
[0036] FIG. 18 is a more detailed schematic of still another former
embodiment and variation thereof for the system of FIG. 14.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0037] The present invention will now be described more fully
hereinafter with reference to the accompanying drawings, in which
preferred embodiments of the invention are shown. This invention
may, however, be embodied in many different forms and should not be
construed as limited to the embodiments set forth herein. Rather,
these embodiments are provided so that this disclosure will be
thorough and complete, and will fully convey the scope of the
invention to those skilled in the art. Like numbers refer to like
elements throughout, and prime and multiple prime notation are used
in alternate embodiments to indicate similar elements.
[0038] The present invention is based, at least in part, upon the
recognition of the various shortcomings of prior art gypsum
wallboard and/or cementitious backerboard sheets, and the further
recognition that the use of aerated concrete as the core material
overcomes a number of the shortcomings. As it is also known
autoclaved aerated concrete is a high-quality, load-bearing, as
well as insulating building material produced in a wide range of
product sizes and strengths. The material has been used
successfully in Europe and is now among widely used wall building
materials in Europe with increasing market shares in other
countries.
[0039] Aerated concrete is a steam cured mixture of sand or
pulverized fuel ash, cement, lime and an aeration agent. High
pressure steam curing in an autoclave produces a physically and
chemically stable product with an average density being about one
fifth that of normal concrete. The material includes non-connecting
air cells, and this gives aerated concrete some of it its unique
and advantageous properties. Aerated concrete enjoys good strength,
low weight, good thermal insulation properties, good sound
deadening properties, and has a high resistance to fire.
[0040] Aerated concrete may be used in the form of panels or
individual building blocks. It has been used for residences;
commercial, industrial and agricultural buildings; schools;
hospitals; etc. and is a good material in most all climates. Panels
or blocks may be joined together using common mortar or thin set
glue mortar or adhesive. Aerated concrete has durability similar to
conventional concrete or stone and a workability perhaps better
than wood. The material can be cut or sawn and readily receives
expandable fasteners. Aerated concrete has a thermal conductivity
six to ten times better than conventional concrete. The material is
also non-rotting, non-toxic and resistant to termites.
[0041] As disclosed in U.S. Pat. No. 4,902,211 to Svanholm, for
example, aerated concrete may typically be produced as follows. One
or several silica containing materials, such as sand, shale ashes
or similar materials, as well as one or more calcareous binders,
such as lime and/or cement, are mixed with a rising or aeration
agent. The aeration agent typically includes aluminum powder which
reacts with water to develop hydrogen gas at the same time a mass
of what can be considered a calcium silicate hydrate forms. The
development of hydrogen gas gives the mass macroporosity. The
rising mass is typically contained within a mold. After rising, the
mass is permitted to stiffen in the mold forming a semiplastic body
which has low strength, but which will keep together after removal
from the mold.
[0042] After a desired degree of stiffness is achieved and the body
is removed from the mold, the body may typically be divided or cut
by wires into separate elements having the desired shape, such as
building blocks or larger building panels. The divided body is
positioned in an autoclave where it is steam cured at high pressure
and high temperature to obtain suitable strength. The body is then
advanced to a separation station where the adjacent building blocks
or panels are separated from one another. The blocks are packaged,
such as onto pallets for storage and transportation.
[0043] Referring now initially to FIGS. 1-5 a wallboard sheet 30 in
accordance with the present invention is now described. The
wallboard sheet 30 may be used to form part or all of an interior
wall structure, such as the right hand portion of the wall
structure 25 (FIG. 1). Of course, the wallboard sheet 30 could be
used for ceilings, interior partitions, elevator shafts, etc, as
will be appreciated by those skilled in the art. The wall structure
25 will typically include a frame 26 formed of horizontal and
vertical wall studs or members, 27, 28, respectively, to which the
wallboard sheets 30 are secured by suitable fasteners and/or
adhesive.
[0044] The wallboard sheet 30 includes a core 40 having opposing
first and second major surfaces 40a, 40b, respectively, and at
least one face layer on at least one of the first and second major
surfaces of the core. The core 40 includes aerated concrete. The
provision of aerated concrete for the core provides many key
advantages over conventional wallboard sheets, such as gypsum
wallboard, for example. The core 40 may be produced from a mixture
of Portland cement, quick lime, sand, aluminum powder and water,
although at least some of the sand and perhaps some of the quick
lime can be replaced by flyash. In general, the flyash may be used
as at least a partial replacement for sand in the mix, but flyash,
depending on its composition, may react with the aluminum powder in
a manner similar to quick lime to produce the micro-cellular
bubbles in the expanded aerated concrete.
[0045] In the first embodiment of the wallboard sheet 30, both
first and second face layers 42a, 42b, respectively, are adhesively
secured to the opposing first and second major surfaces 40a, 40b of
the core 40 via respective adhesive layers 43a, 43b. In other
embodiments, the adhesive may be incorporated into the face layers
and/or the surface portion of the aerated concrete core as will be
appreciated by those skilled in the art. One or both of the face
layers 42a, 42b may comprise paper, having colors and/or weights,
for example, similar to conventional gypsum wallboard paper.
[0046] The core 40 and hence the wallboard sheet 30 may have a
generally rectangular shape defining a pair of opposing side edges
31a, 31b, respectively, and a pair of opposing end edges 32a, 32b,
respectively. The first face layer 42a may extend around the
opposing side edges 31a, 31b as shown perhaps best in the enlarged
cross-sectional view of FIG. 3. In addition, the opposing end edges
32a, 32b of the core may be exposed (FIG. 2). If desired, a tape,
not shown, may be provided on the opposing ends 32a, 32b as will be
appreciated by those skilled in the art.
[0047] The aerated concrete core 40 may have a relatively low
density in a range of about 25 to 40 lbs./ft..sup.3 The core 40 and
hence the sheet 30, as well, may also have a thickness T in a range
of about 1/4 to 1 inch, a width W in a range of about three to five
feet, and a length L in a range of about five to sixteen feet.
Accordingly, even a 1 inch thick, 4 foot by 8 foot wallboard sheet
30 may have a relatively low total weight of about 60 pounds.
[0048] Referring now more particularly to the embodiment of the
wallboard sheet 30' shown in FIGS. 4 and 5, other aspects of the
invention are now explained. The illustrated wallboard sheet 30'
includes beveled portions 35a, 35b formed on the first major
surface 40a' of the core 40' adjacent respective opposing side
edges 31a', 31b'. The beveled portions 35a, 35b may facilitate the
receipt of taping and joint compound to cover the joints between
adjacent sheets 30' in the finished wall structure.
[0049] As perhaps best shown in FIG. 5, the illustrated embodiment
of the wallboard sheet 30' also includes only a single face layer
42a', although in other embodiments, a second face layer may be
applied as well. In addition, the illustrated embodiment of the
core 40' includes schematically illustrated reinforcing fibers 46.
The fibers 46 may be provided by a fibrous material, such as
cellulose or other natural or synthetic fibers, including
fiberglass, metal or other materials, to impart strength to the
core and reduce the relative brittleness of the aerated
concrete.
[0050] Another aspect of the wallboard sheet 30' is that it
includes a joint schematically illustrated by the dashed line 37
extending across the width of the sheet as may be formed during the
manufacturing thereof and as will be explained in greater detail
herein. The joint 37 can be stronger than the adjacent core
material, and without compromising the ability to score and snap
break the wallboard sheet 30' as conveniently as with conventional
gypsum wallboard. Stated slightly differently, some embodiments of
the wallboard sheet 30' may include first and second portions on
opposite sides of the joint 37 aligned in end-to-end relation at
respective opposing edges thereof, and an adhesive layer may be
used to join the opposing edges of the first and second portions
together.
[0051] The other elements of the wallboard sheet 30' indicated with
prime notation and not specifically mentioned are similar to those
elements described above with reference to the wallboard sheet 30
described above. Accordingly, these elements need no further
discussion herein. Those of skill in the art will also appreciate
that the various features of the embodiments of the wallboard
sheets 30, 30' can be mixed and/or substituted in yet further
embodiments of the invention.
[0052] Because of the relative light weight of the wallboard sheets
30, 30' including aerated concrete, shipping, handling, and
installation at a job site are facilitated. In addition, the
substitution of aerated concrete for gypsum, for example, also
offers the advantages of increased fire resistance, thermal
insulation, sound deadening, and other properties in a wall
structure formed by fastening the aerated concrete wallboard sheets
to a suitable building frame.
[0053] Returning again briefly to FIG. 1 and additionally to FIGS.
6-9, a backerboard sheet 60 in accordance with the present
invention is now described. More particularly, as shown in the left
hand portion of FIG. 1, the backerboard sheets 60 may be used where
the wall is likely to be exposed to splashing water or moisture,
such as a bathroom, and other indoor areas as will be appreciated
by those skilled in the art. The backerboard sheet 60 is also
typically used as an underlayment substrate for decorative area
tile 50 and/or border tile 51 as shown in the left hand portion of
FIG. 1. Adjacent ones of the tiles 50, 51 typically include grout
lines 52, 53 therebetween through which moisture may penetrate. In
addition, cracks may form in the grout lines or the tiles
themselves through which moisture may also penetrate.
[0054] Conventional gypsum greenboard or cementitious sheets for
such high-moisture applications suffer a number of significant
shortcomings and disadvantages as highlighted in the background of
the invention section above. The backerboard sheet 60 including a
core 70 comprising aerated concrete, and at least one
moisture-resistant face layer overcomes these shortcomings and
disadvantages.
[0055] In the first illustrated embodiment of the backerboard sheet
60, both first and second moisture-resistant face layers 72a, 72b,
respectively, are secured to the opposing first and second major
surfaces 70a, 70b of the core 70. Each moisture-resistant face
layer 72a, 72b illustratively includes a woven fiber mesh 74a, 74b
incorporated into a respective resin layer 73a, 73b. The fibers may
include at least one of glass, plastic, and metal. The
moisture-resistant face layer may have other constructions and be
formed of different moisture-resistant materials, such as those
commonly used for cementitious backerboard, and others as will be
appreciated by those skilled in the art. For example, moisture
resistant face layers include nylon, aramid resin, or metal fibers
as disclosed in U.S. Pat. No. 5,221,386 may also be used, and the
entire contents of this patent are incorporated herein by
reference.
[0056] The core 70 and hence the backerboard sheet 60 may also have
a generally rectangular shape defining a pair of opposing side
edges 61a, 61b, respectively, and a pair of opposing end edges 62a,
62b, respectively. The first face layer 72a may also extend around
the opposing side edges 61a, 61b as shown perhaps best in the
enlarged cross-sectional view of FIG. 7. In addition, the opposing
end edges 72a, 72b of the core may be exposed (FIG. 6). If desired,
a tape, not shown, may be provided on the opposing ends 62a, 62b as
will be appreciated by those skilled in the art. In addition, the
aerated concrete core 70 may have the same characteristics and
sizes as mentioned above with respect to the wallboard sheets 30,
30', for example.
[0057] Referring now more particularly to the embodiment of the
backerboard sheet 60' shown in FIGS. 8 and 9, other aspects of the
invention are now explained. The illustrated backerboard sheet 60'
includes beveled portions 65a, 65b formed on the first major
surface 70a' of the core 70' adjacent respective opposing side
edges 61a', 61b'. The beveled portions 65a, 65b may facilitate the
receipt of taping and sealing or joint compound to cover the joints
between adjacent sheets 60' in the finished wall structure.
[0058] As perhaps best shown in FIG. 9, the illustrated embodiment
of the backerboard sheet 60' also includes only a single
moisture-resistant face layer 72a', although in other embodiments,
a second face layer may be applied as well. The moisture-resistant
face layer 72a' is also illustratively directly secured to the core
70, although an incorporated resin or adhesive may be used in other
embodiments.
[0059] The illustrated embodiment of the core 70' includes
schematically illustrated reinforcing fibers 76. The fibers 76 may
be provided by a fibrous material, such as cellulose or other
natural or synthetic fibers, including fiberglass, metal or other
materials, to impart strength to the core and reduce the relative
brittleness of the aerated concrete. The fibers may also be
desirably selected to avoid attracting or retaining moisture.
[0060] Another aspect of the backerboard 60', similar to the
wallboard 30' discussed above, is that it includes a joint
schematically illustrated by the dashed line 67 extending across
the width of the sheet as may be formed during the manufacturing
thereof and as will be explained in greater detail herein. The
joint 67 can also be stronger than the adjacent core material, and
without compromising the ability to score and snap break the
backerboard sheet 60'. In other words, the backerboard sheet 60'
may include first and second portions on opposite sides of the
joint 67 aligned in end-to-end relation at respective opposing
edges thereof, and an adhesive layer may be used to join the
opposing edges of the first and second portions together.
[0061] The other elements of the backerboard sheet 60' indicated
with prime notation and not specifically mentioned are similar to
those elements described above with reference to the backerboard
sheet 60 described above. Accordingly, these elements need no
further discussion herein. Those of skill in the art will also
appreciate that the various features of the embodiments of the
wallboard sheets 60, 60' can be mixed and/or substituted in yet
further embodiments of the invention. Because of the relative light
weight of the backerboard sheets 60, 60' including aerated
concrete, shipping, handling, and installation at a job site are
facilitated.
[0062] Turning now additionally to the flowcharts of FIGS. 10-13
various method aspects for making the wallboard and/or backerboard
sheets in accordance with the invention are now described. The
method may include forming core material having opposing first and
second major surfaces and comprising aerated concrete, securing at
least one face layer on at least one of the first and second major
surfaces of the core material, and cutting the core material and at
least one face layer secured thereto into a plurality of wallboard
or backerboard sheets. The provision of aerated concrete for the
core provides many key advantages over conventional gypsum
wallboard sheets, and/or conventional backerboard sheets, such as
gypsum greenboard or cementitious backerboard, for example.
[0063] In one class of embodiments, the method may further comprise
curing the core material prior to securing the at least one face
layer thereto. In another class, the method may further comprise
curing the core material after securing the at least one face layer
thereto.
[0064] Referring now to the flowchart of FIG. 10, a particularly
advantageous embodiment is described wherein curing is performed
before adding the at least one face layer. In particular, from the
start (Block 100), the materials for making aerated concrete are
mixed and dispensed into a suitable mold at Block 102. The
materials are permitted to rise and stiffen into a body (Block
104), and the body may then be removed from the mold (Block 106).
The body having a size of about twenty feet in length, four feet in
height, and two feet in width is cured at Block 108, such as by
positioning in an autoclave as will be appreciated by those skilled
in the art. The one or more face layers can then be secured to the
cured sheets of the core material at Block 110. Thereafter, the
core material with the face layer(s) secured thereto can be cut to
the desired lengths to form the wallboard or backerboard sheets at
Block 112 before packaging/shipping (Block 114) and stopping or
ending the method at Block 116.
[0065] In other words, in this embodiment forming the core material
comprises dispensing materials for making aerated concrete into a
mold and allowing the materials to rise and stiffen into a body,
curing the body, and dividing the cured body into a plurality of
cured sheets to serve as the core material. The plurality of the
cured sheets may be joined together in end-to-end relation while
advancing the cured sheets along a path of travel. In addition,
securing the at least one face layer may be performed while the
cured sheets are advanced along the path of travel.
[0066] A variation of this method embodiment is now explained with
reference to the flowchart of FIG. 11. In this embodiment, prime
notation is used to indicated similar steps which need no further
explanation. In accordance with the illustrated embodiment of FIG.
11, the body is divided, but not separated or cut, into sheets at
Block 105, and is then cured at Block 107. Thereafter, the cured
sheets are used as the core material and to which the face layer(s)
are secured as described above. This embodiment may offer the
advantage of slightly easier cutting of the body, since it has not
been fully cured; however, the ultimate dimensional accuracy of the
sheets may be less compared to first curing the body and then
cutting the body into cured sheets. Of course, a combination of
some cutting or shaping before curing and further cutting or
shaping after curing are also contemplated by the present
invention.
[0067] Referring now more particularly to the flow charts of FIGS.
12 and 13, the second class of method embodiments, wherein the one
or more face layers are added before final curing, are now
described. It is noted that final curing using a conventional
autoclave may place relatively difficult requirements on the
characteristics of the face layers in terms of temperature
resistance and/or abrasion resistance. Accordingly, manufacturing
speed or efficiency may need to be considered in view of the
increased face layer material costs as will be appreciated by those
skilled in the art.
[0068] The first embodiment is now described with reference to the
flowchart of FIG. 12. From the start (Block 130), the materials for
making aerated concrete are mixed and dispensed into a suitable
mold at Block 132. The materials are permitted to rise and stiffen
into a body (Block 134), and the body may then be removed from the
mold and divided into uncured sheets (Block 136). The one or more
face layers may be secured to the uncured sheets at Block 138,
which can then be cured (Block 140), before being cut into desired
lengths at Block 142. The final sheets may be packaged and shipped
at Block 144 before stopping or ending the method at Block 146. Of
course, the final curing could also be performed prior to the
cutting into individual sheets as will be appreciated by those
skilled in the art.
[0069] Referring now to the flowchart of FIG. 13, yet another
embodiment of the method is now described. This embodiment is
directed to a more continuous manufacturing operation. More
particularly, from the start (Block 150) the materials for making
aerated concrete are dispensed in slurry form onto at least one
face layer (Block 152), typically as the face layer is advanced
along a conveyor, for example. The slurry may alternatively be
dipensed onto a surface, e.g. a stainless steel surface, instead of
directly onto the face layer. The dwell time on the conveyor may
desirably be sufficient to allow the materials to rise and stiffen,
and optionally cured, (Block 154) before cutting into final lengths
(Block 156). Thereafter, the sheets may be packaged and shipped at
Block 158 before stopping (Block 160). Of course in other
embodiments, it is also possible to cut the core material before
final curing. This may be especially desirably where conventional
autoclave curing is performed which may require a relatively long
dwell time in the heated chamber. However, other curing techniques,
such as the addition of microwave radiation are also contemplated
which may provide for near continuous curing of the core material
as will also be appreciated by those skilled in the art.
[0070] Of course, in all of the specifically described and
contemplated method embodiments, the securing of the at least one
face layer may comprise securing first and second face layers on
respective first and second major surfaces of the core material.
The at least one face layer may comprise paper, such as for a
wallboard. Alternately, the at least one face layer may be
moisture-resistant for a backerboard. Forming may also include
forming the first major surface of the core material to have
beveled portions adjacent respective opposing longitudinal side
edges. In addition, the at least one face layer may be secured to
extend around the opposing longitudinal side edges by the use of
simple edge wrapping guides, for example. The core material may
also be formed with reinforcing fibers in the aerated concrete.
[0071] Turning now additionally to FIGS. 14-18 various aspects of a
system for making the wallboard and/or backerboard including
aerated concrete in accordance with the invention are now
described. Starting with the overall simplified schematic diagram
of FIG. 14 an illustrated embodiment of the system 200 is now
described. The system 200 includes a mixer 210 for mixing materials
for making aerated concrete. The mixer 210 is supplied with the
starting materials for making aerated concrete from the cement
supply 201, the sand (ash) supply 202, the water supply 203, the
aluminum or other aeration agent supply 204, the lime supply 205,
and the optional reinforcing fiber supply 206. The system also
illustratively includes at least one face layer supply 215, a
former 220 downstream from the mixer 210 and connected to the face
layer supply 215. A cutter 225 is provided downstream from the
former 220. And an optional packager 230 is provided, such as to
package the wallboard or backerboard sheets onto pallets for
shipping, for example.
[0072] The former 220 is for forming core material having opposing
first and second major surfaces and comprising aerated concrete,
and for securing at least one face layer from the at least one face
layer supply 215 onto at least one of the first and second major
surfaces of the core material. As described below, in one class of
embodiments, the former 220 may further include an autoclave for
curing the core material prior to securing the at least one face
layer thereto. In another class, the former may further include an
autoclave or other curing apparatus for curing the core material
after securing the at least one face layer thereto.
[0073] One particularly advantageous embodiment of the system will
now be explained with reference to the more detailed schematic
diagram of the former 220 as shown in FIG. 15. More particularly,
the illustrated embodiment of the former 220 may include a mold 240
downstream from the mixer for receiving the materials for making
aerated concrete therein and allowing the materials to rise and
stiffen into a body 242. The former 220 also includes the autoclave
243 downstream from the mold 240 for curing the body 242. Of
course, the system would also include the necessary material
handling mechanisms and apparatus to remove the body 242 and
position it as will be appreciated by those skilled in the art.
[0074] The former 220 also includes a divider downstream from the
autoclave for dividing the cured body 242 into a plurality of cured
sheets to serve as the core material. One or more band saws 245,
for example, could be used to slice the cured body 242 into a
plurality of cured sheets 244. Other types of saws could also be
used.
[0075] The former 220 may also include a conveyor 247 and a sheet
handler 246 cooperating therewith for joining a plurality of the
cured sheets 244 together in end-to-end relation while advancing
the cured sheets along a path of travel on the conveyor.
Alternatively, the cured sheets 244 may not be joined together, but
may have already been cut in desired dimensions. The schematically
illustrated end-to-end joiner 250 can provide the adhesive,
alignment and compressive forces, if needed to insure a quality
joint. Downstream from the joiner 250, a trim/bevel station 252 can
be used to trim the upper and/or side surfaces of the sheets, and
also to form the desired beveled sides if desired.
[0076] Both the joiner 250 and trim/bevel station 252 can be
readily made from conventional equipment and need no further
discussion herein. What is noted, however, is that the aerated
concrete is readily workable unlike conventional concrete, for
example. A waste collection system may also be provided to collect
and recycle trimmed or cut material from the aerated concrete as
will be appreciated by those skilled in the art.
[0077] Downstream from the trim/bevel station 252, the former 220
also illustratively includes a securing station 253 to apply the
one or more face layers from the appropriate supplies 254, 255.
This securing station 253 can use conventional layer handling,
guiding rolls, etc. to attach the at least one face layer while the
cured sheets 244 are advanced along the path of travel. The
securing station 253 can also include the necessary guides and
rolls to roll a face layer around the longitudinal side edges as
described above.
[0078] Turning now briefly to FIG. 16 a variation of the former
embodiment described above will now be described. In this
embodiment of the former 220', the body 242' is cut or divided into
sheets 244' before positioning in the autoclave 243'. As discussed
above, while the cutting may be somewhat easier, and a more simple
wire saw 249' may be used, the resulting dimensions of the sheets
may not be as accurate. This embodiment does, however, avoid the
need for higher temperature compatible/resistant face layers. Of
course, combinations of pre-cure and post-cure shaping of the core
material may also be used.
[0079] Turning now more particularly to FIG. 17 another variation
or embodiment of a former 220" is now described. In this
embodiment, the face layers from the supplies 254", 255" are added
downstream from dividing the body 242" into uncured sheets 244" but
before positioning in the autoclave 243" for curing. As noted above
this may increase the requirements and costs for the face layers,
but may provide increased manufacturing efficiencies as will be
appreciated by those skilled in the art. As shown, uncured sheets
244" may also be passed through cutter 225" prior to the autoclave
243". Of course, the various core shaping operations may also be
performed on the uncured sheets to form beveled edges, etc.
[0080] A further embodiment of the former 220'" is described with
reference to FIG. 18. This embodiment of the system may provide for
near continuous production. In this embodiment, the former 220'"
may comprise a slurry dispenser (and spreader) 260 and a conveyor
247'" cooperating therewith for dispensing the materials for making
aerated concrete adjacent at least one face layer, such as from
supply 254'", as the at least one face layer is advanced along a
path of travel. The securing station 253'" secures the second face
layer from the supply 255'" and may wrap the edges in the
illustrated embodiment. Again, the slurry may also be dispensed
directly onto a surface, such as a stainless steel surface, instead
of onto the at least one face layer, with the first and second face
layers being secured by the securing station 253'" thereafter. In
this embodiment, the autoclave or other curing station 243'" is
downstream from the dispenser for curing the materials for making
aerated concrete. The autoclave 243'" may preferably be after the
cutter 225'", for example, but the autoclave or other curing device
may be positioned along the conveyor 247'". Typically, curing takes
between 4 and 12 hours at a temperature of about 165.degree. C. and
pressure of about 150 psi. It is expected that the time from
pouring the mixture onto the conveyor to cutting the sheet into
final lengths will vary between 20 and 50 minutes depending on the
relative percentage of cement, lime and aluminum.
[0081] In any of the embodiments, the former may secure first and
second face layers on respective first and second major surfaces of
the core material. For wallboard sheets, the at least one face
layer supply may comprise at least one paper face layer supply. For
backerboard sheets, the at least one face layer supply preferably
comprises at least one moisture-resistant face layer supply.
[0082] Other related concepts and features are disclosed in the
following copending patent applications filed concurrently herewith
and assigned to the assignee of the present invention and are
entitled WALLBOARD SHEET INCLUDING AERATED CONCRETE CORE, attorney
work docket number 64901; SYSTEM FOR MAKING WALLBOARD OR
BACKERBOARD SHEETS INCLUDING AERATED CONCRETE, attorney work docket
number 64907; and BACKERBOARD SHEET INCLUDING AERATED CONCRETE
CORE, attorney work docket number 64908, the entire disclosures of
which are incorporated herein in their entirety by reference.
[0083] It is also contemplated that the wallboard and backerboard
sheets described herein may be produced without the face layers if
sufficient strength and surface smoothness can be obtained by use
of the fibrous filler material alone, for example. However, it is
recognized that any filler material will add weight and that the
volume of fibrous material is a trade off with weight and strength
or flexibility. Thus, it may be desirable to use just enough
fibrous material to produce some slight flexibility without
addressing surface smoothing. Accordingly, many modifications and
other embodiments of the invention will come to the mind of one
skilled in the art having the benefit of the teachings presented in
the foregoing descriptions and the associated drawings. Therefore,
it is to be understood that the invention is not to be limited to
the specific embodiments disclosed, and that other modifications
and embodiments are intended to be included within the scope of the
appended claims.
* * * * *