Note: Descriptions are shown in the official language in which they were submitted.
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The invention resides in a roof structure; a
composite panel for building constructions, and in a
process for promoting adhesion of a cementitious material
to a foam material. More particularly the invention
resides in a composite building panel comprising a main
body portion of a closed cell generally smooth skinned
foam material having along at least one surface thereof a
protective cementitious facing material adhered thereto;
such panels being particularly adapted for use in roofing
and curtain wall construction.
Particularly preferred results are obtained
with a styrene-butadiene-1,3 copolymer modified portland
cement which is a shrinkage compensating portland cement
and wherein such cement contains sufficient reinforcement
to provide restraint against expansion.
U. S. Patent 3,411,256 discloses and claims
roofing structures of the general type as utilized herein.
Such prior known structures consist essentially of a roof
support means having a roof deck, the roof deck having an
upper surface and a lower surface, the upper surface of
the roof deck supporting a water impermeable membrane
having its lower face generally adjacent the roof deck, a
closed cell foam insulating layer adjacent the upper face
of the water permeable membrane, such foam insulating
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layer being comprised of a plurality of individual closed
cell foam insulating members defining fissures between
adjacent members, and a protective layer of an inorganic
material, such as mortar, disposed on the surface of the
insulating members. Such prior known roofing structures
- suffer, however, from ineffective bonding of the pro-
tective layer to the surface of the insulating members
with resultant delamination of such layers during normal
handling and/or exposure to the elements. Such delamination
is believed to be due primarily to the poor bond of the
protective layer to closed cell, generally smooth skinned
foam insulation, taken with the normal shrinkage of the
prior known protective layers, resulting in the development
of stress at the foam-mortar interface. Another factor
believed to be a cause of such delamination is temperature
cycling during cure of the protective layer due to the
differences in the coefficient of expansion between the
foam and mortar.
Significantly improved resistance to delamination
of the protective layer from the foam layer is achieved
by utilizing roof structures of the type as described in
U.S.P. 3,411,256, where a water or vapor barrier layer is
placed on a roof deck, a waterproof closed cell, generally
smooth skinned foam insulation is placed over the water
barrier layer and a cementitious protective layer is
placed on the foam insulation wherein the cementitious
protective layer is modified by a styrene-butadiene-1,3
copolymer.
The invention resides in a composite building
panel comprising a main body portion of a closed cell,
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generally smooth skinned foam material having adhered
along at least one surface thereof a protective cementi-
tious facing material consisting essentially of an admix-
ture of portland cement, mineral aggregate and from 5 to
25 percent based on the weight of said cement of a styrene-
-butadiene-1,3 copolymer having a styrene to butadiene
weight ratio of 30:70 to 70:30, water in amount of from
25 to 65 percent based on the weight of said cement, and
based on the weight of said copolymer, (a) from 2 to 10
percent of non-ionic surfactant, (b) from 0.75 to 7.5
percent of anionic surfactant, at least about 15 percent
of which is a sodium alkyl sulfate in which the alkyl
group contains 9 to 17 carbon atoms, and (c) from 0.1 to
5 percent of a polyorganosiloxane foam depressant based
on the weight of active polyorganosiloxane, the sum of
(a) and (b) not exceeding about 11 percent by weight of
said copolymer and the weight ratio of (a) to (b) being
within the range of about 0.7:1 to 10:1.
The invention also resides in a building panel
comprising a main body portion of a closed cell, generally
smooth skinned styrene polymer foam material having a
surface containing one or more regions having indentations
therein, said surface having applied thereto a substantially
continuous binder coating of a styrene-butadiene copolymer
latex consisting essentially of a styrene-butadiene-1,3
copolymer having a styrene to butadiene weight ratio of
about 30:70 to 70:30, and based on the weight of said
copolymer, (a) from about 2 to about 10 percent of non-
-ionic surfactant, (b) from about 0.75 to 7.5 percnet of
anionic surfactant, at least about 15 percent of which is
.,? ~
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sodium alkyl sulfate in which the alkyl groups contain 9
to 17 carbon atoms, the sum of (a) and (b) not exceeding
about 11 percent by weight of said copolymer and the
weight ratio of (a) to (b) being within the range of about
0.7:1 to 10:1, and adhered to said binder coating a pro-
tective cementitious facing material, a portion of which
is contained in said indentations, said facing material
consisting essentially of an admixture of portland cement,
mineral aggregate and from about 5 to about 25 percent
based on the weight of said cement of a styrene-butadiene-
-1,3 copolymer having a styrene to butadiene weight ratio
of about 30:70 to 70:30, water in amount of from about 25
to 65 percent based on the weight of said cement, and
based on the weight of said copolymer, (a) from about 2 to
about 10 percent of non-ionic surfactant, (b) from about
0.75 to 7.5 percent of anionic surfactant, at least about
15 percent of which is a sodium alkyl sulfate in which the
alkyl group contains 9 to 17 carbon atoms, and (c) from
about 0.1 to 5 percent of a polyorganosiloxane foam depres-
sant based on the weight of active polyorganosiloxane, the
sum of (a) and (b) not exceeding about 11 percent by weight
of said copolymer and the weight ratio of (a) to (b) being
within the range of about 0.7:1 to 10:1.
The invention also resides in a process for
promoting the adhesion of the cementitious material to
the surface of the foam material to form a building
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panel, said process comprising the sequential steps of
(1) applying to said foam material surface a substantially
continuous coating of a thermoplastic styrene-butadiene
copolymer latex consisting essentially of a styrene-
butadiene-1,3 copolymer having a styrene to butadiene
weight ratio of about 30:70 to 70:30, and based on the
weight of said copolymer, (a) from about 2 to about 10
percent of non-ionic surfactant, (b) from about 0.75
to 7.5 percent of anionic surfactant, at least about
15 percent of which is sodium alkyl sulfate in which
the alkyl groups contain 9 to 17 carbon atoms, the sum
of (a) and (b) not exceeding about 11 percent by weight
of said copolymer and the weight ratio of (a) to (b)
being within the range of about 0.7:1 to 10:1, (2) applying
the cementitious material to the coated surface prior
to substantial dehydration of said coating, and (3) allowing
said cementitious material to harden.
The invention also resides in a roof structure
consisting essentially of a roof support means having a
roof deck, the roof deck having an upper surface and a
lower surface, the upper surface of the roof deck supporting
a water or vapor impermeable membrane, the impermeable
membrane having an upper face and a lower face being gener-
ally adjacent the roof deck, and a plurality of the building
panels disposed adjacent the upper face of the water
impermeable membrane, the foam material in said plurality
of panel members defining fissures between adjacent members
and wherein the surface of said foam insulating layer
adjacent said cementitious protective layer contains a
plurality of individual indentations therein said indentations
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containing a portion of said cementitious protective layer.
The invention also resides in a roof structure
consisting essentially of a roof support means having a
roof deck, the roof deck having an upper surface and a
lower surface, the upper surface of the roof deck support-
ing a water or vapor impermeable membrane, the impermeable
membrane having an upper face and a lower face being gen-
erally adjacent the roof deck, a closed cell generally
smooth skinned water impermeable styrene polymer foam in-
sulating layer disposed adjacent the upper face of the
water impermeable membrane, said insulating layer compris-
ing a plurality of insulating members said members defining
fissures between adjacent members, and a protective layer
of an inorganic material disposed on the surface of the
insulating members remote from the roof decX, the improve-
ment consisting of (1) utilizing as said protective layer
an admixture of a portland cement, mineral aggregate, from
about 5 to about 25 percent based on the weight of said
cement of a styrene-butadiene-1,3 copolymer having a
styrene to butadiene weight ratio of about 30:70 to 70:30,
water in amount of from about s25 to 65 percent based on
the weight of said cement; and based on the weight of said
copolymer, (a) from about 2 to about 10 percent of non-
-ionic surfactant, (b) from about 0.75 to 7.5 percent of
anionic surfactant, at least about 15 percent of which is
sodium alkyl sulfate in which the alkyl group contains
9 to 17 carbon atoms, and (c) from about 0.1 to 5 percent
of a polyorganosiloxane foam depressant based on the weight
of active polyorganosiloxane, the sum of (a) and (b) not
exceeding about 11 percent by weight of said copolymer and
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the weight ratio of (a) to (b) being within the range of
about 0.7:1 to 10:1, and (2) wherein the surface of said
insulating layer adjacent said protective layer contains
a plurality of individual indentations therein, said
indentations containing a portion of said protective layer.
The basic roof structure designs as contemplated
by the present invention are schematically set forth in
Figures 1 and 2 of U.S.P. 3,411,256. A wide variety of
materials may be employed in the preparation of such roofs,
e.g. the roof deck or roof support means may be prepared
from steel, wood, laminated wood, cardboard, cement,
asbestos board, planking and the like. The roof deck may
be supported in any convenient manner such as being firmly
affixed to the rafters by means of nails, screws or bolts.
The roof decking may be of panels and readily inserted
into suitable recesses in a framework and prepared by like
methods well known to the art. The water impermeable
membrane may comprise or consist of a wide variety of water
impermeable materials including conven-
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tional asphaltic and bituminous compositions employed
for roofing as well as laminates of the bituminous
material with fibrous products such as roofing felt
employing organic or inorganic fibers. Beneficially
such felt and bituminous materials may be applied in
alternating layers to provide a water impermeable membrane
of the desired thickness and mechanical strength to re-
sist movement of the roof deck and associated supporting
structure. In certain instances, a water or vapor impermeable
membrane can be formed of synthetic resinous film or sheet
such as polyethylene, polyvinyl chloride, polyurethane,
butyl rubber, polyisobutylene and the like with or without
the presence of vapor impermeable materials such as
aluminum foil, which is adhered to the roof deck by a suit-
able adhesive. One or more layers of such material may
be employed depending on the characteristics which are
desired from the finished structure.
The foam insulating layer, employed in the practice
of the present invention, is a closed cell, generally
smooth skinned material which is substantially water
impermeable. Particularly beneficial and advantageous
are cellular plastic foams of a closed cell configuration
including styrene polymer foams, styrene-acrylonitrile
copolymer foams and styrene-methylmethacrylate copolymer
foams, polyvinylchloride foams, polyurethane foams, poly-
ethylene foams, phenolic foams and other water impermeable
materials available in cellular foam form which are well
known to the art. Exemplary of such other materials which
may be used are the ceramic foams and foam glass.
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For obtainment of optimum bonding with the herein
described latex modified cementitious protective layer,
the prescribed foam insulation layer is beneficlally
provided with indentations along one or more surfaces,
such indentations being of a wide variety of shapes, sizes
and frequency. More particularly, the surface of the
closed cell foam may be punched, drilled, stamped, milled,
routed, scored or cut to provide such indentations. Further
heated projections of varying configuration may be used to
form indentations by melting a portion of such foam in-
sulation. A particularly useful means for placing indentations
in the closed cell foam insulation is to pass such foam
along a forwarding roll having longitudinal projections
thereon. This method is particularly useful for placing
indentations in styrene polymer foam due to the inherent
resiliency of such foam material. Thus, such foam is
initially compressed under a projection, having a sub-
stantially square contact area, then pushed in a forward
direction. The resulting combination of compression and
resiliency causes the foam to tear away from the edge of
the initial hole, thereby making a hole larger in diameter
at the bottom than at the top. The shape of the hole thus
resembles a trapezoid with the short parallel side of the
hole opening at the foam surface.
Particularly useful cementitious protective
layers utilized by the present invention are comprised
essentially of an admixture of a shrinkage compensating
portland cement, mineral aggregate, from 5 to 25 percent
based on the weight of said cement of a styrene-butadiene-1,3
copolymer having a styrene to butadiene weight ratio of
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30:70 to 70:30, water in the amount of from 25 to 65
percent based on the weight of said cement; and based on
the weight of said copolymer, (a) from 2 to 10 percent of
nonionic surfactan', (b) from 0.75 to 7.5 percent of
anionic surfactant, at least 15 percent of which is a
sodium alkyl sulfate in which the alkyl group contains 9
to 17 carbon atoms, and (c) from 0.1 to 5 percent of a
polyorganosiloxane foam depressant based on the weight of
active polyorganosiloxane, the sum of (a) and (b) not
exceeding 11 percent by weight of the copolymer and the
weight ratio of (a) to (b) being within the range of
0.7:1 to 10:1; and reinforcement to provide restraint
against expansion.
The shrinkage compensating cements utilized are
as follows:
Type K: This is a mixture of portland cement
compounds, anhydrous calcium sulfoaluminate (4Ca0.3A12O3.SO3),
calcium sulfate (CaSO4), and lime (CaO). The anhydrous
calcium sulfoaluminate is a component of a separately
burned clinker that is interground or blended with port-
land cement clinker. Alternatively, it may be formed
simultaneously with the portland clinker compounds.
Type M: Either a mixture of portland cement,
calcium aluminate cement and calcium sulfate or an inter-
ground product made with portland cement clinker, calcium
aluminate clinker and calcium sulfate.
Type S: A portland cement containing a large
tricalcium aluminate content and modified by an excess
of calcium sulfate above usual amounts found in other
portland cements.
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The styrene-butadiene-1,3 copolymer latexes
employed can be prepared in accordance with known
procedures. For example, the styrene and butadiene
monomers can be mixed in the proportions corresponding
to the composition of the desired copolymer in water con-
taining an emulsifying agent or agents and heated with
agitation in the presence of a peroxide catalyst to
initiate copolymerization as known in the art.
The concentration of the styrene-butadiene-1,3
copolymer solids in the cement composition is, however,
critical for the obtainment of the desired combination
of properties required by the present invention. In this
regard, concentrations less than 5 percent based on the
weight of cement used, do not provide improved mechanical
properties such as flexibility, abrasion resistance, and
adherence. Further, total latex solids concentrations
in excess of 25 percent based on the weight of cement
significantly reduce the mechanical properties of the
composition.
Utilization of such copolymer latexes in conventional
portland cement, mortar compositions is known, e.g. as
disclosed in USP 3,043,790.
If the modified shrinkage compensating cement
compositions are not properly restrained, they literally
expand themselves apart so that their potential strength
is seriously impaired or totally lost. In general, any
conventional reinforcing material such as, for example,
deformed bar, rods, or wire mesh, in the proper amounts
and properly installed will provide restraint sufficient
to maintain compositional strength and integrity. Fiber
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reinforcing materials, such as steel fibers or alkali
resistant glass fibers, also provide sufficient restraint.
Fibrous types can be added to the composition during the
mixing stage and hence, will be evenly dispersed and be-
come an integral constituent of the composition. These
fibers are randomly oriented and will provide three
dimensional restraint.
It has been found that the combination of alkali
resistant glass fiber reinforcement and the herein pre-
scribed latex modification creates an unexpectedly
beneficial effect.
It has also been found that properly restrained
modified shrinkage compensating cement compositions possess
significantly increased freeze-thaw resistance, flexural
strengths and water absorption characteristics.
The amount of water employed in preparing the
shrinkage compensating cement compositions is also important
with regard to providing compositions of optimum workability.
In this regard at least 25 percent water, based on the
weight of expansive cement, is required with an amount
from 35 to 65 percent being preferred.
Some or all of the non-ionic and anionic sur-
factants employed in the cement compositions of the invention
can be present while effecting copolymerization of the
styrene and butadiene. Ordinarily, however, it is preferred
to follow the practices used in making styrene-butadiene
emulsions for use in preparing latex paints. Thus, some
but not necessarily all of the anionic surfactant is
introduced to aid in effecting the desired dispersion and
emulsification in carrying out the copolymerization of
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butadiene and styrene, and the non-ionic surfactant is
subsequently added to stabilize the resulting polymer
dispersion. The polyorganosiloxane foam depressant and
such additional quantities of non-ionic surfactant and
anionic surfactant, as are required to complete the cement
composition, are subsequently introduced.
Illustrative of non-ionic surfactants are,
for example: fatty acid esters such as glycerol mono-
stearate, diethyleneglycol laurate, propyleneglycol mono-
stearate, sorbitol monolaurate, and pentaerythritol mono-
stearate, acid derivatives of ethylene oxide products such
as the reaction product of six moles of ethylene oxide with
one of oleic acid; condensation products of ethylene oxide
with alcohols such as stearyl alcohol; and condensation
products of ethylene oxide with phenols, naphthols, and
alkyl phenols such as di-t-butylphenoxynonaoxyethylene-
-ethanol. Preferred are the condensation products of
ethylene oxide with alkyl phenols.
Illustrative of anionic surfactants are, for
example: the alkyl aryl sulfonates such as dodecylbenzene
sodium sulfonate; sulfate derivatives of higher fatty
alcohols (i.e., alcohols of at least nine carbon atoms
and ordinarily not more than seventeen carbon atoms) such
as sodium lauryl sulfate; the sulfonated animal and vegeta-
ble oils such as sulfonated fish and castor oils; sulfonated
acyclic hydrocarbons; and the like. As pointed out here-
tofore, at least 15 percent of the anionic surfactant com-
ponent of the cement additive of the invention should be
a sodium higher alkyl sulfate such as sodium lauryl sulfate
and preferably the anionic surfactant component consists
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of a mixture of an alkyl aryl sulfonate surfactant and
such sodium alkyl sulfate.
Illustrative of the polyorganosiloxanes are
the condensation products resulting from polymerization
of organo silane diols, as represented by the formula
R R
HO- SiO - S OH
R' R'
n
where R and R', in the above formula, represent organic
radicals such as alkyl, aryl, aralkyl and alkaryl or
heterocyclic groups, and n is one or more. Also useful
are polymerization products of organo silane diols in the
presence of an organo silane monol, and condensation pro-
ducts obtained from mixtures of organo silane triols, diols,
and monols.
Preferably the organo substituent of the siloxanes
is lower alkyl (i.e., methyl, ethyl, propyl), cyclohexyl
or phenyl. Most preferably it is methyl, and accordingly,
the preferred polyorganosiloxanes are those which are
condensation products of methyl silicols, and most preferably
condensation products of dimethyl silane diol.
Polyorganosiloxanes are commercially available
in several forms which are designated in the trade as
"silicone fluids", "silicone emulsions" and "silicone com-
pounds", the latter being siloxanes modified by the addition
of a small percentage of finely divided silica or other
inert divided solid. Any of these forms can be used in
the practice of this invention.
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It has further been found to be beneficial,
for purposes of obtaining optimum adhesion of the
cementitious facing material to the foam surface to coat
the foam surface with a substantially continuous coating
of the styrene-butadiene-1,3 latex, as described supra,
prior to the application of the cementitious facing material.
In this regard, the latex coating is preferably not
substantially dehydrated prior to application of the
cementitious material.
The aggregate employed in the cementitious
protective layer may be any conventionally employed
manufactured aggregate or naturally occurring mineral
aggregate, such as sand and a mixture of sand with gravel,
crushed stone, or equivalent materials.
The cement compositions are made by simply adding
the additives to the expansive cement with mixing to obtain
a cement mix of desired flow and consistency.
While it is generally convenient to prepare the
cement compositions as a unitary product by pre-combining
the styrene-butadiene copolymer, non-ionic and anionic
surfactant, and polyorganosiloxane foam depressant, and
then introducing the resulting mixture into the cement-
-aggregate mixture in making cement, mortar, or concrete
mixes, it will be understood, of course, that it is not
necessary that all the various components of the additive
be so premixed. For example, equivalent cement, mortar,
or concrete mixes are obtained by separate addition of
the requisite quantity of styrene-butadiene copolymer
emulsion containing sufficient of the anionic and non-
-ionic surfactants to avoid coagulation of the latex, the
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polyorganosiloxane foam depressant and such additional
non-ionic and anionic surfactants as are necessary.
In preparation of the roof structures of the
present invention, usually the water resistant membrane
is applied to the roof deck, for example by applying a
layer of bituminous material thereto, applying a suitable
roofing felt to the bituminous material and providing the
repeated applications of roofing felt and bituminous
material until a suitable membrane is formed.
Advantageously the foam insulating layer is
joined to the water impermeable membrane by the use of
the same or a different bituminous composition employed
in preparing the water resistant membrane while the
bituminous material is in a heat plastified condition.
Pressing planks or sheets of the heat insulating material
into the bituminous layer provides a suitable bond.
It is necessary, however, that the bituminous material
does not have a temperature sufficiently high to destroy a
large portion or proportion of such cellular material.
For example, when foamed polystyrene sheets are utilized
as the insulating layer, it is generally desirable that
the bi~uminous material have a temperature not greatly in
excess of about 100 Centigrade, to prevent distortion or
melting of such polystyrene foam material. It is essential
to the practice of the present invention, that the insulating
layer be of a closed cell configuration. The particular
density or physical strength of such insulating material
need only be sufficient to meet the mechanical demands of
the particular installation. Generally, foamed polystyrene
sheets having a density of about 1.5 pounds per cubic foot
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are adequate providing the protective layer is of
sufficient thickness to resist mechanical damage. Thus,
in a region where little or no foot traffic is expected on
a roof, a protective layer having a thickness of about 1/8
of an inch provides adequate protection. However, in
regions where frequent or heavy foot traffic occurs, it is
often desirable to employ a layer of cementitious material
of from about 1/4 to about 3/8 of an inch or more.
It is not essential that the protective layer
be resistant to the passage of moisture, nor is it essential
the insulating layer have a surface which prevents moisture
from contacting the water resistant membrane.
In another embodiment of the present invention,
bonding of the foam insulating layer to the latex modified
cementitious layer can be further enhanced by applying
a substantially continuous coating of the styrene-butadiene
latex described herein (but absent the polyorganosiloxane
foam depressant), to the foam insulation, followed by
application thereto of the protective layer prior to
substantial dehydration of such latex coating.
Roof structures, in accordance with the invention,
do not appear subject to damage by freezing of water in
spaces between adjacent foam insulating elements. The foam
insulating elements appear to have sufficient resilience
to resist rupturing by the expansion of freezing water in
crevices. Furthermore, in installations on a heated building
the temperature adjacent the water resistant membrane usually
does not reach freezing temperatures. In buildings having a
roof applied in accordance with the present invention, little
or no tendency is observed for moisture to condense on the
inner surface of the roof deck.
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By way of further illustration, a plurality of
blocks of closed cell, generally smooth skinned poly-
styrene foam measuring about 1 1/4 inches in thickness,
2 feet in width and about 4 feet long, were forwarded
along a roll having individual projections thereon, which
projections were about 1/2" apart in both directions and
about 1/8" by 1/8" in cross sectional area and 3/16" in
height. Such projections produced a plurality of inden-
tations in the foam which indentations were in the shape
of a trapezoid with the short parallel side of the hole
opening at the surface of the foam. Thereafter, the
surface of the foam having such indentations was coated
with a substantially continuous coating of a styrene-butadiene
latex composed essentially of an aqueous emulsion of about
48 weight percent of a solid copolymer of about 66 per
cent by weight styrene and 34 percent by weight butadiene-
-1,3; and based on the copolymer weight, about 4.65
percent of the non-ionic surfactant di-t-butylphenoxy-
nonaethylene-ethanol; and about 0.78 percent of a mixture
of anionic surfactants comprising predominant amounts of
sodium lauryl sulfate and correspondingly lesser amounts
of dodecyl-benzene sulfonate.
A 1/2 inch coating of a cementitious protective
layer was then cast on the coated surface of the foam, prior
to significant dehydration of the latex coating. The cemen-
titious protective material used was prepared by admixing
a Type K shrinkage compensating cement with sufficient
water to form water to cement ratios of 0.29 to 0.635, a
sharp mason sand in amount to provide a sand to cement
ratio of about 2.75-1, to 3-1, the styrene-butadiene latex
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previously described in amount to provide about 15 percent
latex solids based on the weight of cement, a polymethyl-
siloxane foam depressant in amount to provide about 0.4
percent by weight active silicon based on the weight of
latex solids, and with about 4 pounds of 1/2" long alkali-
-resistant glass fibers per 94 pounds of cement, to
furnish restraint. The Type K compensating cement was a
mixture of portland cement compounds, anhydrous calcium
sulfoaluminate tCaO)4(A12O3)3(SO3), calcium sulfate
(CaSO4), and lime (CaO).
The cementitious protective layer was then vibrated
to remove entrapped air and to seat a portion of such cementi-
tious layer in the indentations present in the foam.
The so-formed panels were then cured under ambient
temperatures.
The cured panels were characterized by being
exceptionally resistant to delamination. More particularly,
delamination did not occur following 300 temperature
cycles of from 15F to 85F or following 500 temperature
cycles of from 50F to 140F.
Further, the cured panels were characterized
by a freeze-thaw value of greater than 300 cycles, as
determined by ASTM Test No. C-666, i.e. such panels were
not significantly deteriorated following such temperature
cycling.
By way of further illustration of the exceptional
binding produced by the use of Latex A as prescribed by the
invention, in each of a series of experiments one of a series
of latex materials were cast as the substantially continu-
ous coating on a block of a closed cell, generally smooth
skinned polystyrene foam. The latex materials used were as
follows:
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Latex A -- (as described supra)
Latex B -- As per Latex A but additionally
containing a polymethylsiloxane foam depressant in amount to
provide about 0.4 percent by weight active silicone, based
on the weight of latex solids.
Latex C (For Comparison)
A blend of (1) about 25 percent by weight of Latex
A above with (2) about 75 percent by weight of a latex com-
posed of an aqueous emulsion of about 75 percent by weight
vinylidene chloride, about 20 percent by weight vinyl
chloride, about 3 percent by weight ethyl acrylate and about
2 percent by weight methyl methacrylate.
Latex D (For Comparison)
As per Latex C but additionally containing small
amounts of a polymethylsiloxane foam depressant.
Each coated foam sample was tested for tensile
bond strength by adhering the coated foam sample between
opposed wooden blocks via an epoxy adhesive. The tensile
bond strength was obtained by drawing the wooden blocks apart
and moving the point of separation. The following Table
illustrates the samples used and the results obtained.
TAsLE
Latex Coating Tensile Type of
Used Strength (PSI) Fracture
A 73-76 Wood to Foam
B 69-70 Film to Foam
C 24-28 Film to Foam
D 25-32 Film to Foam
The above data illustrate the unexpectedly greater
bond strength achieved using Latex A. Panels prepared as
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described herein are particularly useful in building
construction, e.g., as roofing panels or panels used for
sidewall construction. By way of comparison, panels
prepared as described herein but utilizing (a) a non-latex
modified, non-reinforced conventional portland cement
or (b) a non-latex modified, fiber reinforced shrinkage
compensating cement of the type as specifically disclosed
herein; were both characterized by significant deter-
ioration following about 200 temperature cycles.
A roof structure was prepared using the panels as
prescribed by the present invention by mopping a wooden
roof deck with a roofing grade asphalt followed by the
application of a roofing felt thereto. The procedure
was repeated until a water resistant membrane was formed.
A plurality of the cement coated foam panels were then
adhered (with the cementitious layer on top) to the
upper surface of the waterproof membrane by means of
hot bitumen having a temperature of about 100 Centigrade.
The resulting roof structure was characterized
by having a weight of less than about 5 pounds per
square foot and was free from delamination of the cementi-
tious layer from the foam even when exposed to repeated
temperature cycles of about 100F and total temperature
differences of up to 200F. Such roof structure was fur-
ther characterized by having a Class A fire rating, the
capability of sustaining foot traffic and normal loads
or impacts without cracking and of being light in color
and thus capable of reflecting sunlight to prevent
excessive temperature rise in the insulation.
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Further, after an extended period of exposure,
portions of the membrane were removed and evaluated for
resiliency. The membrane disposed underneath the cement
latex modified cement coated foam polystyrene installation
was in excellent condition and exhibited no indication of
undue hardening. By way of comparison, a similar membrane
covered with gravel and having a 2 inch layer of cellular
styrene disposed beneath the roof deck showed marked
deterioration.
By way of further illustration, the following
comparative examples serve to emphasize the exceptional
bonding properties obtained with a styrene-butadiene-1,3
copolymer when used as a modifying agent in the cement
and when used as a primer coating on a perforated or
indented generally closed cell styrene polymer foam in-
sulating layer.
Example 1
A cementitious composition was prepared from a
mixture of the following:
3000 grams of mason sand (ASTM C-144)
1000 grams of Type 1 cement (ASTM C-150) and
231 grams of water.
The cement composition was mixed and poured into
a plurality of cup shaped molds, each having a diameter of
3.92 inches or an equivalent surface area of 12.07 square
inches. The cup shaped molds, with the cement mixture
therein, were inverted onto a closed cell, generally smooth-
-skinned polystyrene foam backing and the cement was
allowed to set and cure thereon. After 24 hours, the
cement was sufficiently cured so that the molds could be
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removed leaving a disc-shaped cement block adhered to
the foam backing. The cement was then allowed to cure
for another 6 days. A load was applied to the composite
disc-shaped block and gradually increased until a separation
of the cement block from the foam backing was obtained.
The load obtained at separation of the cement block from
the foam backing was recorded and readily converted into
pounds per square inch. The following results were
obtained:
TABLE I
Total LoadLoad (in pounds
Test No. (in pounds)per square inch)
1 32 2.65
2 28 2.31
3 31.5 2.61
4 31 2.54
An average load of 2.54 pounds per square
inch was obtained in this test series attesting to the low
bonding strength between the cement blocks and their foam
backings.
Example la
A series of tests, similar to the tests in Example 1
were conducted with a cement composition comprising a mixture
of the following:
30 pounds of mason cement (ASTM C-144)
10 pounds of Peereless Type I cement ~ASTM C-150)
and 5.1 pounds of water.
A load was applied to each of a plurality of cement
blocks of this composition adhered to their respective
foam backing. The following results were obtained:
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TABLE Ia
Total Load Load (in pounds
Test No. (in pounds)per square inch)
1 27 2.24
2 29.5 2.44
3 20.5 1.70
An average load of only 2.13 pounds per square
inch was obtained in this test series again attesting to
the low bonding strength of a cement block when adhered to
a smooth-skinned STYROFOAM backing without the benefit
of a styrene-butadiene copolymer latex as a cement modifier
or primer coating on the foam board.
Example 2
The tests conducted with the cement composition
of Example la were repeated except that the smooth-skinned
closed cell plastic foam board was first provided with
a substantially continuous primer coating of the styrene-
-butadiene-1,3 copolymer latex described herein (but absent
the polyorganosiloxane foam depressant). The cement com-
position was allowed to cure on the primer coated foam
board for 7 days. The following load test results were
recorded:
TABLE II
Total Load Load (in pounds
Test No. (in pounds)per square inch)
1 153 12.7
2 100 8.3
3 253 21.0
4 163 13.5
250 20.7
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An average load of 15.2 pounds per square inch
was obtained in this test series indicating a substantial
improvement in the load capacity obtained with the specified
latex primer coating between a foam backing and a cement
molding.
Example 3
A series of tests with the cement composition
of Example la were conducted except that the cement composition
was modified with a 15%, by weight, styrene-butadiene-1,3
copolymer latex of the composition described herein (including
the polyorganosiloxane foam depressant). The latex composi-
tion being calculated on a latex solids content of 48% with
respect to the cement. The latex modified cement composition
contained the following amounts:
30 pounds mason sand
10 pounds Peereless Type I cement
3,19 pounds of the styrene-butadiene-1,3 copolymer
latex (48% solids)
2.13 pounds of water.
The following load test results were recorded:
TABLE III
Total Load Load (in pounds
Test No. (in pounds)per square inch)
1 305 25.26
2 110 9.11
3 213 17.65
4 240 19.88
220 18.22
An average load of 18.0 pounds per square inch
was obtained in this test series attesting to a further
improvement in bonding strength obtained with the latex
modified cement as compared to the test series conducted
in Example 2.
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Example 4
A series of tests were conducted with the same
latex modified cement mixture of Example 3 with the further
proviso that the foam board was first provided with a sub-
stantially continuous coating of the styrene-butadiene-1,3
copolymer latex binder (without the polyorganosiloxane foam
depressant). The cement composition was allowed to cure
simultaneously with the primer coating for 7 days. The
following results were recorded.
TABLE IV
Total Load Load (in pounds
Test No. (in pounds) per square inch)
1 340 28.2
2 340 28.2
3 358 29.7
4 357 29.6
340 28.2
An average load of 28.8 pounds per square inch
was obtained before separation of the foam board from the
cement blocks occurred. The load results are much superior
to the test results of Examples 2 and 3 and also indicate
a high degree of consistency. This consistency is ascribed
to the fact that the load figures approach the tensile
strength of the foam backing itself. Separation between
each concrete block and foam backing was not always observed
to be a clean separation between the two members but often
resulted in breakage of the foam backing rather than
separation at the interface between the concrete block and
backing.
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Example 5
A further test series was conducted using a
7 1/2~, by weight, of the styrene-butadiene latex binder
`~ in the cement mixture of Example 3. Thus, the cement
mixture contained the following amounts:
30 pounds mason sand
10 pounds Peereless Type I cement
723.5 grams of the styrene-butadiene-1,3 copolymer
latex (48~ solids) and
1650 grams of water.
The following results were recorded:
TABLE V
Total LoadLoad (in pounds
Test No. (in pounds)per s~uare inch)
1 43 3.56
2 80 6.62
3 13 1.07
4 25 2.07
48 3.98
An average load of 3.46 pounds per square inch
was obtained which indicated that the use of about 1/2
of the amount of the latex binder in the cement composition
was substantially less effective than the results obtained
with the 15~, by weight, latex modified cement composition
of Example 3.
Example 6
The test series of Example 5 was repeated except that
the foam board was first provided with a substantially con-
tinuous coating of the styrene-butadiene-1,3 copolymer latex
binder and allowed to cure with the cement composition for
7 days. The following results were recorded:
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TABLE VI
Total LoadLoad (in pounds
Test No. (in pounds)per square inch)
1 180 14.9
2 165 13.7
3 215 17.8
4 175 14.5
213 17.6
An average load of 15.7 pounds per square inch
was obtained which indicates a substantial improvement over
the unprimed foam board of Example 5. The results also
indicate that substantially better results are obtained with
the 15%, by weight, latex modified cement of Example 4.
Example 7
Molded cement blocks were prepared in accordance
with the procedure of Example 1. The cement blocks were
prepared from an admixture of the following:
3000 grams of mason sand
1000 grams of Type I cement and
510 grams of water.
The foam board was provided with a plurality of
indentations by means of a plurality of 1/8 inch diameter
brass pins mounted in a staggered relationship on a plate
having a surface area of 64 square inches. With 98 pins
being provided on the plate, a total pin area of 1.2
square inches was calculated. With this arrangement
21 impressions or indentations were made in a 12.07 square
inch surface area of the foam backing covered by the
circular cement block. The depth of the indentations
into the foam board was held to 0.085 inches. The following
results were recorded:
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TABLE VII
Total LoadLoad (in pounds
Test No. (in pounds)per square inch)
1 19.8 1.6
2 ` 45 3.7
3 16 1.3
4 8 0.6
An average of only 1.8 pounds per square inch
was obtained in this test series with a perforated indented
foam board. The test did not show any improvement over the
results obtained in the test of Example 1, even though an
increase in the bonding of the cement block to the foam
board could reasonably have been expected due to the
provisions of the indentations in the foam board.
Example 8
A series of tests similar to the test of Example
7 were conducted except that the foam board was first provided
with a substantially continuous coating of the styrene-
-butadiene-1,3 copolymer latex binder (without the foam
depressant). The same number of indentations having
first been applied to the foam board to an average depth of
about 0.085 in. The following results were recorded:
TABLE VIII
Total Load Load (in pounds
Test No. (in pounds)per square inch)
1 112 9.3
2 99 8.2
3 131 10.8
4 97 8.0
107 8.9
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An average load of 9.1 pounds per square inch
was obtained which indicated a substantial improvement in
the load capacity over the tests conducted in Example 7.
Surprisingly, the primed perforated foam board did not
show any improvement over the primed but unperforated
foam board of Example 2.
Example 9
A latex modified cement mixture was prepared in
accordance with Example 5. The foam board was provided with
indentations as in Example 7. However, the indentations were
only applied to an average depth of 0.034 inch. The following
test results were recorded.
TABLE IX
Total Load Load (in pounds
Test No. (in pounds) per square inch)
1 70 5.80
2 55 4.56
3 63 5.22
4 50 4.14
4.14
An average load of 4.77 pounds per square inch
was obtained which indicated a slight improvement over the
unperforated board of Example 5.
Example 10
Example 9 was repeated'except that the foam
board was first provided with a substantially continuous
coating of the styrene-butadiene-1,3 copolymer latex binder
(without the foam depressant). The following results
were recorded:
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TABLE X
Total Load Load (in pounds
Test No. (in pounds) per square inch)
1 170 14.1
2 248 20.5
3 225 18.6
4 178 14.7
165 13.7
An average load of 16.3 pounds per square inch
was obtained which indicates a substantial improvement in
the load capacity over the unprimed foam board of Example 9.
Example 11
A series of tests were conducted in which latex
modified cement moldings were prepared from the following
admixture:
3000 grams of mason sand
1000 grams of Type I cement
319 grams of the styrene-butadiene-1,3 copolymer
latex (48% solids) and
287 grams of water.
The admixture contained 15%, by weight latex
solids in the cement. A closed cell generally smooth-skinned
polystyrene foam board was provided with indentations to
a depth of 0.85 in. substantially by the same procedure
as in Example 7. The foam backing was not provided, however,
with a latex primer coating. The following test results
were recorded:
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TABLE XI
Total Load Load (in pounds
Test No. (in pounds) per square inch)
1 293 24.3
2 390 32.3
3 237 19.6
4 293 24.3
267 22.1
An average load of 24.5 pounds per square inch
was obtained, indicating a substantial improvement over the
tests conducted with the unperforated foam board of Example 3.
Example 12
A final series of tests were conducted similar
to the tests of Example 11 except that the foam board was also
provided with a substantially continuous coating of the
styrene-butadiene-1,3 copolymer latex binder. The following
results were recorded:
TABLE XII
Total Load Load (in pounds
Test No. (in pounds) per square inch)
1 365 30.2
2 317 26.3
3 332 27.5
4 372 30.8
370 30.6
An average load of 29.1 pounds per square inch
was obtained indicating a slightly better performance
over the 15%, by weight, latex modified cement moldings
and primer coated foam board (but unperforated foam board)
given in Example 4.
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All of the foregoing tests were conducted at
a temperature of 73F and 50% relative humidity in a con-
stant temperature room. In each instance, the mold was
removed after 24 hours and after the cement had set to
allow for an even curing of the cement blocks for an
additional 6 days.
Although slight improvements only are obtained
with the tests of Example 12 over the tests conducted in
Example 4, they do not in any way detract from the desira-
bility of providing the foam boards with indentations
since they provide substantial lateral support for the
cement layer.
As is apparent from the foregoing specification,
the present invention is susceptible of being embodied
with various alterations and modification which may differ
particularly from those that have been described in the
preceding specification and description. For this reason,
it is to be fully understood that all of the foregoing is
intended to be merely illustrative and is not to be
construed or interpreted as being restrictive or otherwise
limiting of the present invention, excepting as it is set
forth and defined in the hereto appended claims.
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