Note: Descriptions are shown in the official language in which they were submitted.
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INSULATING CEMENTITIOUS MIXTURE AND METHOD OF USE
Backyround_Of The Invention
1. field of The Invention
This invention relates to cementitious mixtures and their
use, and more particularly, but without limitation, to light-
weight or insulating cementitious mixtures, structures formed
therefrom and methods of use thereof.
2. Description Of The Prior Art
Lightweight materials with good thermal insulating Schick-
teristics are desirable for use in building panels, and in par-
tickle-, tilt-up wall panels. use of lightweight aygreyates in
concrete have been used for such purposes, and the American
Society for Testing and materials has published ASTM
Specification C322 entitled "Lightweight Aygreyates For
Insulating Concrete". This specification covers lightweight
aggregates intended for use in concrete not exposed to weather,
in which the prize consideration is the thermal insulating pro-
petty of the resulting concrete. One problem with such materials
is that the insulating art greatly reduces the compressive
strength of the concrete.
Specifically, vermiculite has been used in cementitious mix-
lures. Fox example, STYMIE Specification C332, Group I cove-s one
of two general types of lightweight aggregates, particularly
aggregates prepared by expanding products such as pullout or Yen-
maculate. The vermiculite in such aygreyates provides the then-
met insulating characteristics and is also used specifically
because it will readily absorb and hold liquid water by capillary
penetration. A material purporting to conform with ASTM Spew
C332, Group I is sold under the name "Zonolite Insulating
Concrete" by W. R. Grace Company.
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The strength of lightweight insulating concretes is not surf-
fishnet to be suitable lo- exterior surfaces. Also, the Yen-
maculate in such materials will still adsorb water which is
unsatisfactory for exterior surfaces
Tune use of polypropylene fibers to reinforce cementitious
mixtures is disclosed in United States Patent 3,591,395 to
Zonsveld et at. Such fibers are sold under the name of "Forte
Fibre" by Forte Fibre, Inc.
Summary Of The Invention
The present invention provides a cementitious mixture
comprising a coated, insulating aggregate, a fibrous material and
cement, and also provides a hardened material formed by mixing
the cementitious mixture with water and a method of making a
lo building panel with such material.
The coated, insulating aggregate used in the mixture is Yen-
maculate coated with a film of water-repellent material, such as
asphalt. The asphalt-coated vermiculite allows the hardened
material to have a surface suitable for exterior surfaces and
acts to provide a greater compressive strength than normal ins-
feting concretes However, the water-repellent feature of the
coated vermiculite has prevented its use in a cementitious mix-
lure with water added. Accordingly, water-repellent vermiculite
may not be used in conventional cementitious mixtures; the
fibrous material utilized in the present invention must also be
present.
The preferred fibrous material is made of polypropylene, and
the polypropylene fibers utilized in the mixture are collated,
fibrillated, polypropylene fibers which form a fine lattice, or
mesh, when mixed with cement and water. The fibers were dove-
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loped originally to inhibit shrinkage and cracking in concrete.
In addition to strengthening the material, the polypropylene
fibers bind and distribute the water-repellent vermiculite in the
mixture of the resent invention.
S Tests indicate the preferred mixture has significantly
greater compressive strength than previous standard vermiculite-
cement mixtures, mixtures utilizing standard vermiculite with
polypropylene fibers, and a vermiculite, cement and sand mixture
recommended for increased strength by a manufacture. of standard
vermiculite.
The water-repellent film coveting the vermiculite reduces the
number of sharp edges which results in lower stress con-
- cent rations in the dried cement, thus lessening the likelihood of
crack propagation which increases compressive strength. It is
also theorized that the ductile, resilient nature of water-
repellent coatings such as asphalt increases the ability of the
material to withstand load.
The mixture of the present invention also results in a better
surface finish than standard vermiculite insulating concretes,
and is durable enough to be used for floors and exterior sun-
faces as well as interior walls.
In utilizing the mixture in a wall panel, a prefabricated,
load-bearing frame is filled with the mixture which hardens into
a solid panel. Insulating material may be placed in thy center
of the frame and enclosed by the hardened material. In a pro-
furred embodiment of the frame, all structural members of the
frame have a substantially C-shaped cross section opening
inwardly. Intermediately spaced vertical support members also
have such a cross-sectional configuration.
A method of manufacture of a prefabricated building panel is
disclosed in which a perimeter lip is formed around each side of
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the frame. The frame, with the lips attached, is laid on a
smooth sup face and is partially filled with the hard enable
material made from the mixture of the present invention. The
insulating layer is then installed, and additional hard enable
material is added to fill the center of the frame. After her-
dining, the panel may be lifted to a vertical position by lifting
means.
Calculated R values for the wall panel made in accordance
with the invention indicate excellent insulating characteristics,
and flame spread tests show excellent fire resistance.
An object of the present invention is to provide an improved
cementitious mixture.
Another object is to provide such an improved cementitious
mixture for forming a hardened, lightweight, insulating material.
Ann additional object of the invention is to provide a light-
weight insulating concrete suitable for exterior surfaces.
Another object of the invention is to provide a lightweight
insulating concrete having great compressive strength kirk-
teristics than previously known lightweight insulating concrete.
Steele another object is to provide a material with excellent
thermal insulating characteristics for use in building panels
Another object is to provide a building panel material that
is more resistant to fire than conventional concrete.
A further object is to provide a method of using such a
cementitious mixture in a building panel utilizing a load-beariny
frame
Additional objects and advantages of the invention will
become apparent as the following detailed description of the pro-
furred embodiment is read in conjunction with the accompanying
drawings which illustrate such preferred embodiments.
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Brief Description Of The Drawings
FIG. 1 illustrates a building wall having a surface panel
formed by hardening the mixture of the present invention
FIG. 2 is a horizontal cross section taken along lines 2-2 in
FIG. 1.
FIG. 3 is a vertical cross section taken along lines 3-3 in
FIG. 1.
FIG. 4 shows a horizontal cross-sectional view illustrating a
method of making a building panel utilizing the mixture of the
present invention.
Detailed Description Ox The Preferred Embodiments
The cementitious mixture of the present invention comprises a
coated, lightweight aggregate, a fibrous material and cement.
This dry mixture may be admixed with water to form a hard enable
material which, when hardened, is lightweight, has desirable
thermal insulating characteristics, and is suitable for wall
structures and also floors and exterior surfaces.
The coated, lightweight aggregate used in the present invent
tin is a water-repellent vermiculite. This vermiculite is not
the water-absorbing material used in previously known mixtures
for insulating concretes. Instead, the vermiculite used is an
expanded vermiculite which has been coated with a film of water-
repellent material, preferably, but not limited to, a bituminous
material such as asphalt. This greatly reduces the water-holdin~
capacity of the vermiculite, and the treated material sheds
water. Normally, water-repellent vermiculite is immiscible in
water, and when mixed with cement and water will simply float to
the top before the mixture hardens. In fact, prior to this
invention, the art has taught that water-repellent vermiculite
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should not be mixed with water or a cement-water mixture, because
conventional mixtures require a water-absorbing material
A water-repellent vermiculite suitable for use in the present
invention, and a method of manufacturing such vermiculite, are
described in United States Patent No. 2,824,022 to Siesta. One
such material is available under the name "Masonry Zonolite" from
W. R. Grace Company. This water-r0pellent vermiculite has been
used in the past as a fill insulation in wall openings such as
in masonry walls, where there is a danger of water leakage that
would damage water-absorbing, or other hydrophillic, insulation.
The fibrous material utilized in the mixture of the present
invention preferably consists of collated, fibrillated, pulpier-
pylon fibers such as those which have been developed by Forte
Fibre, Inc. to be added to concrete mixtures to inhibit shrinkage
and cracking, although it is not intended that the invention be
limited to these materials. These fibers are formed into pro-
stressed lattice bundles. When the fibers are added to the mix,
the mixing action causes the bundles to open to a fine lattice,
or mesh, form. The mixing also causes the fibers to spread unit
firmly through the mix. The fibers are designed to act to rein-
force potential crack zones by strengthening microscopic flaws in
the connect
In addition to strengthening the hardened material, the pro-
sent invention utilizes the polypropylene fibers to bind and
distribute water repellent vermiculite in a mixture of cement and
water as it is mixed and cured to a hardened mass, preventing the
vermiculite from floating to the top. This allows the water-
repellent vermiculite to be used despite the contrary teachings
of the art. Thus the polypropylene fibers are utilized in a
novel manner, and a method of mixing water-repellent vermiculite
with cement and water is made available. The advantages of such
a mixture will be evident after studying the test results
disclosed herein.
Collated, fibrillated, polypropylene fibers are manufactured
in a variety of lengths and are known to be available in lengths
from 3/4 inch to 2 1/2 inches, It has been found by experiment
station that longer lengths of fibers will better hold the water-
repellent vermiculite. In a preferred embodiment, the average
length of the fibers is approximately 2 1/2 inches, but the pro-
sent invention is not limited to fibers of such length
To reduce the possibility of cracking of the hardened material, a non-shrinking Port land cement is utilized in the pro-
furred embodiment. However-, a mixture can be made utilizing the
fibers and water-repellent vermiculite in standard cements as
lo well, and wherefore, the present invention is not limited to non-
shrinking Poland cement.
In preparing the mixture to make the hardened material, the
dry mixture of coated aggregate, fibrous material and cement is
mixed with water in the manner of any conventional cemen~itious
mixture. A mixing time of approximately 10 to 30 minutes is pro-
fireball, although other times may be suitable depending on the
degree of agitation and the relative concentration of the come
pennants of the mixture.
For the dry mixture, the range of the concentrations of the
components as a percentage by weight of the combined vermiculite,
fiber and cement believed to be satisfactory are as follows:
Wate--repellent vermiculite Approximately 9% to So%
Polypropylene fibers Approximately 0.7% to 2g
Cement Approximately 43% to 89%
The ratio of dry~mixture-to-water by weight ranges from
approximately 1:2.3 to 1:10.2, depending upon how we a mixture
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is desired. It is possible that mixtures outside these ranges
may also achieve satisfactory results, and wherefore, it is not
intended that the present invention be limited by the range of
dry mixtures or the dry-mixture-to-water ratios listed above.
S As a result of many tests, a preferred dry mixture for the
present invention has been empirically determined. The con-
cent ration of the various components in the preferred dry mixture
is as follows:
Approximately 17.3~ by weight of asphalt-coated, expanded
vermiculite
Approximately 1.4% by weight of collated, fibrillated,
polypropylene fibers
Approximately 81.3~ by weight of non-shrinking Port land
cement
This dry mixture is mixed with water to form a hard enable
material. The preferred dry-mixture to-water weight ratio range
is approximately 1:4.3 to 1:7.2 with approximately 1:5,8 con-
ridered optimum, but other ratios may also achieve satisfactory
results.
Using the material concentration relationships of the pro-
furred mixture, approximately one cubic yard of hardened material
it obtained by a dry mixture containing approximately 20 pounds
of water-reuellent vermiculite, approximately 1.6 pounds of
polypropylene fibers and approximately 94 pounds of non-shrinking
Port land cement, and then mixing with water. Approximately 60 t
100 gallons (500.5 to 834.2 pounds) of water may be used, but
preferably, approximately 80 gallons (667.4 pounds) of water are
used with the mixture.
Coarse aggregates, such as sand or gravel, as are commonly
used in cementitious mixtures, may be added to the mixture of the
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present invention as desired to provide different textures and
for additional strength of the hardened material.
Tests indicate that the preferred mixture of the present
invention results in a hardened material of significantly greater
compressive strength than previously known vermiculite-cement
mixtures. Table I shows the results from one series of tests
after an aging time of seven days, and Table II shows data on the
same materials after an aging time of twenty-four days. In
Tables I and II, the materials for the test samples are ides-
I lifted as follows:
A - the preferred mixture of the present invention
B - vermiculite insulating concrete following the Yen-
maculate manufacturer's recommendations and ASTM
Specification C332, Group I, using normal, expanded Yen-
maculate and no polypropylene fibers
C - the standard vermiculite insulating concrete in test
material B with the addition of polypropylene fibers
D - the mixture in test material B with sand added as recomb
mended by the manufacturer of the vermiculite for
increasing the strength of the material
TABLE I
Age Time: 7 days
Test Compressive Strength,
Material Pounds Per Cubic Inch
A 380
B 160
C 160
D 185
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TABLE II
Age Time: 24 days
Test Compressive Strength,
Material Pounds Per Cubic Inch
_ _ _ _ _
A 620
B 215
C 280
D go
Table III shows results on the preferred mixture performed in
another series of tests. Samples 1 and 2 in Table III indicate
,.
separate tests on the same material after aging 24 days.
TABLE III
_
Test Material
Age Time Compressive Strength,
DavsPounds Per Cubic Inch
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6 478
24 (Sample 1) 548
24 (sample 2) 584
As can be seen, both series of tests showed comparable
compressive strength for the test samples made from the material
of the present invention.
The water-repellent film covering the watar-repellent Yen-
maculate reduces the number of sharp edges on the vermiculite
particles. When mixed with the cement, the smoother edges of the
water-repellent vermiculite result in reduced stress con-
cent rations in the cement, thus reducing the likelihood of
crack propagation which increases compressive strength. It is
theorized that the ductile, resilient nature so some water-
repellent coatings such as asphalt results in an increased Abe-
lily of the hardened material to withstand loading. It is Allis
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theorized that the heat of hydration generated as the cement sets
causes the asphalt coating to become tacky which helps bind the
vermiculite to the hardening cement. At any rate, the present
invention results in a vermiculite-cement material with
demonstrably greater strength than previously known in the art.
Another positive result of the present mixture is a better
surface finish. Standard vermiculite insulating concrete has a
chalky, powdery surface when hardened and is not durable enough
for exterior surfaces. Material formed from the mixture of the
present invention has no chalky finish. In addition to being
stronger, the material has a smoother and slicker finish when
dried. Nails can be driven into the surface and it can be sanded
and varnished. Surface features can be routed and carved into
the finished surface easily. The finished surface is durable and
can be used as a floor surface as well as for wall or ceiling and
roof surfaces. The material is also satisfactory for exterior
surfaces as well as interior surfaces
Referring now Jo the drawings, and particularly FIG. 1, a
prefabricated wall panel utilizing the mixture of the present
invention is generally designated by the numeral 10. A load-
bearing frame 12 is filled with the mixture which, when cured or
aged, hardens into a solid panel 14.
Frame 12 is of substantially rectangular configuration having
a pair of vertical columns 16 and an upper horizontal beam I and
a lower horizontal beam 20 defining a panel-shaped central
opening 21. Intermediate vertical support members 22 may be
fixedly installed in central opening 21 between horizontal beams
18 and 20 as necessary. Frame 12 and vertical support members 22
thus form a load-bearing structure before the mixture it poured
to form panel 19. In this wall panel, the hardened material is
I
not actually required as a load bearing component of the stuck-
lure, but does help contain and brace vertical support members
22.
Prior to pouring the mixture, such items as electrical recap-
S lade boxes 24 and reinforcing bar 26 may be placed in the freemen a manner commonly known in the art. Electrical conduit (not
shown) connected to receptacle boxes 24 and lifting means 28 may
also be preinstalled.
Referring now to the horizontal cross-section view of FIG. 2,
it can be seen that a layer of insulating material 30 is placed
between vertical columns 16 and the adjacent vertical support
member 22 and also between adjacent vertical support members 22.
As shown in FIG. 3, insulating layer 30, such as thermal or sound
insulation, extends vertically between lower horizontal beam 20
and upper horizontal beam 18.
Referring again to FIG. 2, each vertical column 16 has a
substantially C-shaped cross section having a transverse member
32 with a first flange 34 perpendicular to transverse member 32
at opposite ends thereof and extending inwardly with respect to
frame 12. At an end of each of these first flanges 34 opposite
transverse member 32 is a second flange 36. Second flanges 36
extend toward one another and are substantially parallel to
transverse member 32~ Thus each vertical column 16 defines a
longitudinal channel 38 which opens toward central opening 21 of
frame 12
Similarly, as shown in FIG. 3, horizontal beams lo and I
each have a transverse member 40, first flanges 42 and second
flanges 44 to define a longitudinal channel 46 which opens toward
central opening 21 of frame 12.
Refrying again to JIG. 2, it can be seen that vertical sup-
port members 22 also have a substantially C shaped cross-
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sectional configuration, similar to that of vertical columns 16,
except that vertical support members 22 are smaller. Each Yen-
tidal support member 22 has a transverse member 48, first flanges
50 extending perpendicularly from the transverse member and a
second flange 52 at an end of firs flange 50 opposite transverse
member 48. Second flanges 52 extend toward one another and are
substantially parallel to transverse member 48. Each vertical
support member 22 thus defines a longitudinal channel 54, and the
opening direction of the channel is purely arbitrary. Transverse
member 48 of vertical support member 22 is dimensioned such that
it will fit between second flanges 44 of horizontal beams 18 and
22, as best shown in FIG. 3.
Referring now to FIG. 4, the method of manufacture of the
prefabricated building panel utilizing the mixture of the present
invention will be explained. Angle iron piece 56 has a first
flange 58 which is temporarily attached to the external surface
of it flanges 34 of both vertical columns 16. First flanges
58 of angle iron piece 56 are outwardly disposed with respect Jo
frame 12. A second flange 60 of angle iron piece 56 thus extends
transversely away from frame 12. Similar angle iron pieces (not
shown) are temporarily attached to first flanges 42 of horizontal
beams 18 and 20. All the angle iron pieces are joined at the
corners of frame 12 such that second flanges 60 form a perimeter
lip 62 around each side of the frame, outwardly spaced from inner
perimeter edge 64 of frame 12.
Frame 12, with lip 62 attached to each side thereof, is laid
flat on a smooth surface 66 such that it rests on one of said
lips. Central opening 21 of frame 12 is partially filled with
the mixture of the present invention to form a first hardened
layer 68. Note that longitudinal channels 38 of vertical columns
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16, longitudinal channels 46 of horizontal beams 18 and 20, and
longitudinal channels 54 of vertical support members 22 are par-
tidally filled with the mixture, thus tying and interlocking fist
layer 68 into the load-beariny structure. If reinforcing bar 26
is used, first layer 68 is preferably sufficient to totally
enclose the reinforcing bar. Also electrical receptacle boxes 24
and interconnecting conduit are installed prior to pouring the
hard enable material.
Insulating layer 30 is placed on hardened layer 68 in central
opening 21 of frame 12 as herein before described. Additional
reinforcing bar 26 is installed as desired, and the mixture is
poured on top of insulating layer 30 up to a level even with a
top surface 70 of upper angle iron lip 62 to form a second her-
dined layer 72. This also fills the remaining portion of long-
tudinal channels 38, 46 and 54 to tie and interlock second layer
72 into the load-bearing structure. Before second layer 72 her-
dens completely, it can be textured as desired in a manner known
in the art.
After hardening, angle iron pieces So are removed. Thus,
hardened layers 68 and 72 are wormed to have a transverse eye 74
which extends away from frame 12 as best shown in JIGS. 2 and 3.
once the pouring and hardening processes are complete, panel
10 can be lifted to a vertical position by lifting means 28 and
installed in a building as desired.
US The wall panel described above is but one embodiment of a
building panel utilizing the mixture of the present invention,
and it should be understood that the mixture can be used in many
other building structures previously known in the art to provide
a stronger, more durable panel than normal lightweight insulating
concrete.
I
A coarse aggregate, such as gravel, may be included in the
mixture to provide a rock-wall finish on the wall panel described
above. Other coarse aggregates may also be used for color, sun-
face finish and strength as desired.
although using wate--repellent vermiculite, the present
invention retains the advantage of the excellent thermal ins-
feting characteristics of standard vermiculite concrete mixtures.
For example, but not by way of limitation, calculated R
values fox a building panel of the embodiment described above,
wherein the insulating layer is a thermal insulation, and having
the indicated transverse dimensions, are as follows:
Inside air film 0.68
3" thick, first hardened layer 7.~0
2" thick, urethane thermal insulation layer 12.00
3" thick, second hardened layer 7.20
Outside air film 0.17
.. . . ... _ _ _ _
Total R Value 27.25
Another wall panel, utilizing no insulating layer in the
center, would have a calculated R value as follows:
Inside air film 0.68
8" thick, hardened layer 19.20
outside air film 0.17
Total R Value 20.05
Obviously, even without an additional thermal insulating
layer in thy center, the material of the present invention has
excellent thermal insulating characteristics.
Flame spread tests conducted in accordance with ASTM
Specification Eye, "Flame Spread Tests of Insulating Concrete
Panels," show excellent fire resistance for the hardened material
made from the mixture of the present invention. The tests were
conducted on a solid four-inch thick panel having no insulating
layer embedded therein. The results were as follows:
Flame Spread: 0
Smoke Developed: 0
S Ignition: None
There was some charring. However, the material did not
explode and break up as conventional concrete will do when sub-
jetted to such testing.
It can be seen that the vermiculite cementitious mixture of
the present invention, the hardened material formed by mixing the
dry mixture with water and curing, the method of manufacturing a
wall panel utilizing the mixture, and other methods of use of the
mixture, are well adapted to carry out the objects and attain the
ends and advantages mentioned, as well as those inherent therein.
While presently preferred embodiments of the mixture, methods of
use of the mixture, and of a building panel, have been described
for the purposes of this disclosure, numerous changes in the mix-
lure and the construction and arrangement of parts in the
building panel can be made by those skilled in the art. All such
changes are encompassed within the scope and spirit of this
invention as define by the appended claims.
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