Note: Descriptions are shown in the official language in which they were submitted.
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603g2~1283
FIELD OF THE INVENTION
This invention relates to an improved structural
component for use in fire-resistant applications~ for example, in
hollow shaft wall assemblies of the type used in constructing
elevator shafts and stairwells in buildings. More particularly,
this invention relates to fibrous mat-faced gypsum board having
improved fire-resistant properties and to its use in various
structural applications.
The invention of this application relates to glass mat-
faced gypsum board having a core which includes glass fibers in an
amount sufficient to improve the fire-resistant properties of the
board said core comprising the set product of a mixture comprising
calcium sulfate and at least about 0.03 wt.% of glass fibers, said
core having a density ranging from about 41 to about 47
lbs~cu.ft., and the amounts and proportions of ingredients
comprising the core being such that when said board has a ?
thickness of about 1 inch, a shaft wall test section including
said one-inch board has a fire endurance rating of at least about
three hours.
The invention of a divisional applicatlon relates to a
glass mat-faced gypsum board comprising a set core containing
gypsum dihydrate and at least a minimum amount of chopped glass
fibers sufficient to improve the fire resistance properties of
said gypsum board, wherein the fire resistance properties of said
board are significantly better than those of a conventional paper-
faced board of llke thickness that has a like amount of chopped
glass fibers ln its core.
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la 60382-1283
The invention of the divisional application also rela~es
to a glass mat-faced gypsum ~oard comprising a set core containing
gypsum dihydrate and a-t least a minimum amount of: chopped glass
fibers, water-resistant additive, and paper fibers sufficient to
improve the fire resistance properties of said gypsum board, such
that the board in 5/8 inch thickness achieves at least a one hour
fire rating in accordance with ASTM E-119.
The invention of the divisional application further
relates to a gypsum board including a set gypsum core having at
least one porous, glass mat adhered to one face surface thereof,
said gypsum board characterized by said mat consisting essentially
of randomly distributed glass fibers bonded by an adhesive
material and including an outer surface and an inner surface, said
mat being of substantially uniform density throughout its
thickness between said outer and inner surfaces, said outer
surface being substantially free of set gypsum and said inner
surface being adhered substantially continuously to said gypsum
core by a portion of said set gypsum.
The invention of the divisional application also relates
2~ to a gypsum board includlng a set gypsum core having at least one
porous, glass mat adhered to one face surface thereof, said gypsum
board characterized by said mat including an outer surface and an
inner surface, said gypsum core comprising a viscosity control
agent for thickening a gypsum slurry precursor of said set gypsum
to substantially prevent full penetration of said slurry through
said glass mat, whereby said ou~er surface of said mat is
substantially free of set gypsum.
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lb 60382~-1283
The invention of the divisional applicakion further
relates to a process for manufacturing in continuous fashion faced
gypsum board of indefinite length comprising:
(a) forming an aqueous slurry of calcined gypsum;
(b) continuously feeding the aqueous slurry onto an
underlying, moving, and supporting mat;
(c) forming the deposited slurry into a panel-like shape as
it is carried on the moving mat;
(d) applying to the top surface of the panel-like shape of
slurry an overlying porous glass fiber mat having a predetermined
thickness; and
(e) maintaining the panel-like shape whilst the calcined
gypsum sets to form a set gypsum core having the overlying mat
adhered to one surface thereof; characterized by the step of
~ f) maintaining the viscosity of the slurry at a value such
that said slurry penetrates but part-way into the thickness of the
overlying mat so that, upon the setting of the calcinecl gypsum,
the outer surface of the overlying mat is substantially free of
set gypsum.
This invention will be described initially in connection
wikh its use in a shaft wall assembly, but, as will be explained
hereinafter, its use has wider applicability.
A shaft wall assembly is used typically to line shafts
which commonly extend through a plurality of floors in a building.
Examples of such shafts are elevator shafts, air shafts, and
stairwells. A popularly used shaft wall assembly ls constructed
from panels of paper~faced gypsum board which are supported in
place by metal framework. The design of ~he assembly is such that
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lc ~03~2-12~33
the gypsum board panels, including the panels which line and face
the shaft~ can be installed from one side, that is, away from the
shaft being enclosed. Such assemblies are constructed in place by
workmen who are supported by the floor through which
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the shaft extends. ~his eliminates the necessity Eor
construction of internal scaffolding or other supports for
workmen within the shaft.
It is mandatory that shaft wall assemblies possess certain
characteristics for commercial acceptabi]ity. For example, i-t is
particularly important that gypsum board used in the shaft wall
assemblies possess fire-resistant qualities that enable the
assemblies utilizing them to meet the strict fire regulations of
most municiple codes. Still further, it should be kept in mind
that in an elevator, the gypsum board panels used in lining an
elevator shaft must be able to withstand signiicant orces tha-t
are imposed on them by compressed air which is generated by
ascending and descending elevator cars. Such Eorces can involve
air pressure loads as high as 15 pounds per square foot. Acous-
tical insulating characteristics are also desirable in shaft
walls.
The present invention relates to improved shaft wall
assemblies and also improved fire-resistant fibrous mat-faced
gypsum board which can be used in such assemblies, as well as
other types of structural applications.
Currently used shat wall assemblies include also in their
structure gypsum board comprising a core oE set gypsum sandwiched
between paper cover sheets. A shaft wall assembly that is used
widely at the present time consists of a metal framework which
supports a plurality of plies of panels of gypsum board. Such
assemblies are described in detail hereinbelow. In brief, one
wall of the assembly, which itself surrounds the open shaft,
comprises a pair of horizontally disposed metal J-tracks (one of
the pair of tracks being fastened to the ceiling and the other of
the pair being fastened to the floor) and a plurality o spaced
vertically disposed metal "I-studs" which are rictionally held
within the J~-tracks. Panels o gypsum board which line -the shaft
being enclosed are supported by the J-tracks and the I-studs.
1 3~2~
~ne or more facing layers of gypsum board panels are fastened to
the J-tracks and I-studs on the side of the metal assembly
opposite the shaft being enclosed. sy lncreasing the number of
facing layers and/or the thickness of the gypsum boards, the fire
resistance oE the assembly can be improved.
The core of gypsum board used in such commercial shaft
wall assemblies usually contain chopped glass fibers as an
additive to improve the fire-resistan-t properties of the board.
However, to achieve the necessary fire rating for the assembly,
such boards have a relatively high density. This adds to
shipping costs and makes installation more difEicult. In
addition, the amount of chopped glass fibers added to the core is
not insignifican-t and adds to the boards' cost. In addition, the
paper facing sheets smoke when exposed to the heat of Eire and
`eventually burn.
Gypsum boards suggested for use in shaft wall assemblies,
in which the flammable paper facing sheets have been eliminated
in favor of glass fibert mat or chopped glass fibers embedded in
and covered by set gypsum of the surface layers of the gypsum
board are described in U.S. Patent Nos. 4,195,110 and 4,2~5,979.
It is believed that the boards described in these pa-tents have
never been commercially used for a variety of reasons.
The '110 patent discloses a gypsum board formed from the
set product of a gypsum slurry sandwiched between two surface
layers of glass fiber-containing set gypsum composition. The
glass fibers may be in the form of rovings, continuous strand mat
or chopped glass. The single example of gypsum board which is
the subject of the paten-t shows a board of relatively high
density, namely, about 52 lbs/cu. ft. This is about 1 to 2
pounds higher than the conventional paper-faced boards which are
referred to in the '110 patent. The patent discloses also that
the board which is the subject of the paten-t has improved
flexural strength and does not smoke when exposed to the heat of
fire.
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~ 60382-1283
The '979 patent discloses a gypsum bo~rd that has chopped
glass fibers concentrated in the surface portions of the core of
the board. In the manufacture oE these boards, a mi~ture oE
chopped glass fibers and gypsum is hydrated and formed into
sheets. Before the sheets set, a "conventional" gypsum slurry is
sandwiched between the unset sheets, and the resulting three
layered composite is compress~d and allowed to dry. The patent
also discloses that such boards, in addition to being "llighly
fire resistant and smoke resistant" and "relatively light", have
improved flexural strength over conventional paper Eaced boards.
It is apparent from the disclosure that the patentees contemplate
a relatively dense gypsum board, the density of ~he ~urface sheet
being reported as 81 lbs/cu.ft.
Manufacture of each of the gypsum boards which are ~he
subjects of the aforementioned patents necessitates special
handling of the glass-containing surEace layers between which the
core is sandwiched, foreclosing manufacture of the boards on a
conventional gypsum board-making apparatus.
In accordance with the present invention, there are
provided an improved shaEt wall assembly including a gypsum-based
structural component and also gypsum board having improved fire-
resistant properties.
S~MMARY OF T~E INVENTION
In accordance with the invention described and claimed in
the present application, there is provided a shaft wall assembly
comp~ising fire-resistant framework and, supported by said
framework, fibrous mat-faced gypsum board. In preferred form,
the assembly comprises glass mat-faced gypsum board supported by
metal framework. As is described in detail hereinbelow, said
glass mat-faced gypsum board comprises a core which includes
glass Eibers in an am~unt sufficient to improve the Eire-
resis-tant properties of the board.
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60382-1283
In preferred form, the inven-tion includes glass ma-t-Eaced
gypsum board having a core which includes glass Eibers in a Eire-
resis-tant improving amount of, Eor example, abou-t 0.07 -to about
0.2 wt.%, based on the dry mixture Erom which the core is made.
A further aspect of the present invention includes the
provision of a glass mat-faced gypsum board which has signifi-
cantly improved fire-resistant properties notwithstanding the
presence in the board core oE a relatively small amount of fire-
resistant additives such as glass fibers and the use of a core
which has a relatively low density.
As will be described hereinbelow, the improved
fire-resistant board of the present invention can be used to
excellent advantage in shaft wall assemblies, as mentioned above,
and, in addition, the board can be used to excellent advantage in
the numerous and varied applications in which conventional paper-
faced gypsum board is used. Such applications include, for
example, the use of the board as structural components of walls,
ceilings, partitions, and the like.
The advantages which flow from the l~rovision of the
improved fire-resistant board of the present invention are
numerous and important. For example, the invention affords the
manufacture oE a gypsum-based product which has fire-resistant
properties not heretofore available in gypsum board of popularly
used thicknesses and having a relatively low weiyht.
Furthermore, such advantages can be achieved by manufacturing the
board o~ the present invention by the use of existing gypsum-
manufacturing equipment.
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~RIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a somewhat diagrammatic, fragmentary side
elevational view illustrating portions of a manufacturing line
for producing gypsum board of a type suitable for use in the
manufacture of gypsum board.prepared for use in accordance with
the present invention;
Figure 2 is an enlarged fragmentary sectional view, taken
as indicated toward the left of Figure 1, of an underlying fiber
glass mat used in the manufacture of the gypsum board;
Figure 3 is a fragmentary plan view taken as indicated by
the line 3-3 on Figure 2;
Figure 4 is an enlarged sectional view taken as indicated
toward the right on Figure 1 and illustrating both underlying and
overlying Eiber glass mats, with intervening gypsum composition,
used in the manufacture oE the board;
Figure 5 is a fragmentary plan view taken as indicated by
line 5-5 on Figure 4;
Figure 6 is a fragmen-tary bottom view taken as indicated
by the line 6-6 on Figure 4 and illustrating the bottom surface
of the underlying mat of the board;
Figure 7is a transverse sectional view of an edge portion
of the completed board, this view being taken as indicated by the
line 7-7 on Figure 4;
Figure 8 is a further enlarged fragmentary sectional view
taken as indicated toward the top of Figure 4;
Figure 9 is a further enlarged fragmentary sectional view
taken as indicated toward the bottom of Figure 4;
Figure 10 is an elevated view illustrating installation of
a typical shaft wall assembly enclosing a shaft between floors of
a building;
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Figure 11 is a diagramatic vertical sectional view ta~en
along line 11-11 t'nrough the shaft wall assembly illustrated in
Figure 10; and
Figure 12 is a diagramatic horizontal sectional view taken
along line 12-12 through the shaft wall assembly illustra-ted in
Figure 11.
~ETAILED DESCRIPTION OF THE INVENTION
Turning now to a description oE -the improved gypsum board
that can be used in improved shaft wall assemblies oE the present
invention, it comprises a set gypsum core faced with a fibrous
mat. The gypsum core is basically of the type used in those
gypsum structural products which are known as gypsum wallboard,
dry wall, gypsum board and gypsum sheathing. The core of such a
product is formed by mixing water with powdered anhydrous calcium
sulfate or calcium sulfate hemihydrate (CaS04 1/2H20), also known
as calcined gypsum; and thereaEter allowing the mixture to
hydrate or set into calcium sulfate dihydrate (~aSO4 2H20), a
relatively hard material. The core of the product will in
general comprise a-t least about 85 wt.~ of set gypsum.
The composition from which the set gypsum core is made can
include optional constituents, including, Eor example, those
included conventionally in gypsum sheathing. Examples oE such
constituents include set accelerators, re-tarders, foaming agents,
and dispersing agents.
The set gypsum core is faced with a fibrous mat. The
fibrous mat should be sufficiently porous to permit water in the
aqueous gypsum slurry from which the gypsum core is made to
e~aporate therethrough. As described in detail below, the
fibrous mat-faced gypsum board can be made eEficiently by Eorming
an aqueous gypsum slurry which contains excess water and placing
thereon ~he fibrous mat. Aided by heating, excess water evapo-
rates through the porous mat af-ter the calcined gypsum sets.
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The fibrous mat comprises material whlch is capable of
forming a strong bond with the set gypsum comprising -the core of
the gypsum board. Examples of such materials include a mineral-
type material such as glass fibers and synthetic resin fibers.
The mat can comprise continuous or discrete strands or fibers and
be woven or nonwoven in form. Nonwoven mats such as chopped
strand mat and continuous strand mat can be used satisfactorily
and are less costly than woven materials. The strands of such
mats are bonded together by suitable adhesive. The mat can range
in thickness, for example, from about 15 to about 40 mils, with a
thickness of about 25 to about 35 mils being preferred. The
aforementioned fibrous mats are known and are comrnercially
available in many forms.
The preferred fibrous mat is a fiber glass mat comprising
fiber glass filaments oriented in random pattern and bound
together with a resin binder. Fiber glass mats of this type are
commercially available, for example, those sold under the
trademark ~UR~-GLASS by Manville Building Materials Corporation
and those sold by Elk Corporation as BUR or shingle mat.
Although improvements can be realized by the use of a
gypsum core which has but one of its surfaces faced with fibrous
mat as described herein, it is preferred that bo-th surfaces of
the core be faced with substantially the same fibrous material.
If the surfaces of the core are faced with materials that have
diffe-rent coefficients o-f expansion, the core tends to warp.
Fibrous mat-faced gypsum board and methods for making the same
are known, for example, as described in Canadian Patent No.
993,779 and U.S. Patent No. 3,993,822.
In accordance with the present invention, gypsum board
comprising a set gypsum core faced with a fibrous mat, as
described hereinabove, and preferably gypsum board comprising a
set gypsum core sandwiched between -two sheets of porous glass
mat, is used as a component of a shaft wall assembly or similar
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assembly in the interior oE a building. In such application, the
fibrous mat-faced board can be used to particular advantage in
place of conventional paper-faced gypsum core board or sha~t
liner panels r the core of which generally includes Eire-resistant
additives. Shaft wall assemblies including the fibrous mat-faced
board have improved fire endurance relative to assemblies which
include paper-faced gypsum core board. As mentioned hereinabove,
assemblies of this type generally comprise metal framework or
studs for support of the gypsum panels which form the walls of
the shafts of elevators, stairwells, air shafts and the like.
Examples of such assemblies are shown in U.S. Patent Nos.
4,047,355; 4,324,082; and 4,364,212. Fibrous mat-faced board, as
described herein, can be used, for example, in the assemblies
described in the aforementioned patents and the shaft liner
panels and/or as facing panels.
In these types of applications where fire-resistant prop-
erties are considered important, the core of the fibrous
mat-faced gypsum board includes one or more additives which
improve the ability of the set gypsum composition to maintain its
integrity when subjected to the heat of fire. Examples of
materials which have been reported as being effective Eor
improving the fire-resistant properties of gypsum products
include mineral fibers such as, for example, glass fibers,
asbestos fibers, and calcium sulfate whisker fibers. A mixture
of one or more of such fibers can be used. Other exemplary
materials which are known for use in conventional fire-resistant
gypsum board are unexpanded vermiculite, clay, colloidal silica
and colloidal alumina. Typically, mineral fibers, and particu-
larly glass fibers, are used in admixture wi-th one or more of the
aforementioned exemplary materials. For example, see ~S. Patent
No. 3,616,173, assigned to the same assignees as the present
invention.
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60382-1283
A preEerred material for use in improving the fire-
resistant properties of the fibrous mat~faced gypsum board
comprises chopped glass fibers, for example, as described in
aforementioned U.S. Patent No. 3,616,173.
Briefly described, said glass fibers are of the drawn
textile glass fiber type, produced as continuous individual fila-
ments and having a diameter of from about 0.00~2 to about 0.001".
The individual filaments are usually grouped into strands, the
filaments having coated thereon a relatively weak, bonding type
material, such as, for example, starch or other water softenable
or soluble coatin~ material. The bonding material helps to
prevent abraiding between the several grouped filaments oE each
strand. Prior to the addition of the loosely bonded textile
glass fibers to the core composition, the strands are cut into
short lengths such as, for example, 1/8" to 1". Once added to
the aqueous slurry composition from ~hich the core is made, the
bonding or coating material dissolves, and the strands separate
into individual fibers which become uniformly distributed
throughout the slurry as the slurry is mixed.
The presence of mineral fibers in the core of fibrous
mat-faced gypsum board in accordance with the present invention
results in a product which has unusually hi~h fire-resistant
characteristics. For exqample, the presence of a predetermined
amount of chopped glass fibers in the core of glass mat-faced
gypsum board of predetermined thickness provides a product which
has fire-resistant characteristics that are significantly better
than those of conventional paper-faced gypsum board that has a
like amount of glass fibers in its core and a like thickness.
The effects which flow from this development are significantly
important and can desirably be taken advantage oF in several
different ways. For example, the development can ~e used to
produce a glass mat-faced ~ypsum board which has a lower density
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11
than that of conventional paper-faced, glass fiber-containing
gypsum board without sacrificing fire~resistant properties.
Similarly, significantly lower amounts of glass fibers can be
used in the glass mat-faced board without sacrificing fire-
resistant properties.
The amount of glass fibers in -the core should be at least
about 0.03 wt.% and can vary over a wide range, for example, from
about 0.03 to about 0.3 wt.% based on the total weight of the dry
ingredients comprising the core, that is, the total weight of the
ingredients before they are combined with water to make the
aqueous slurry from which the core is Eormed. In preferred form,
the amount of glass fibers comprises about 0.07 to about 0.2
wt.%.
The core of the fibrous mat-faced board for use in fire-
resistant applications can be fabricated according to available
techniques into a density of desired value. For a relatively
thick board, for example, a thickness in excess of one inch, the
density of the core can be as low as about 35 lb/cu.ft. In con-
ventional paper-faced board having a relatively low density, the
bond between the gypsum core and paper facings is generally
unsatisfactory due to the low density of the core. Preferably,
the density of the core should not exceed about 47 lbs/cu.ft. It
is believed that a density within the range of about 40 to about
47 lbs/cu. ft. will be used most widely. Board having a core
density of about 41 to about 45 lbs/cu. ft. has a particularly
good combination of properties, including good fire- resistant
characteristics and relatively low weight.
Another aspect of the present invention comprises a glass
mat~faced gypsum board having a core comprising the set product
of calcium sulfate and at least about 0.03 w-t.% of glass fîbers,
said core having a density ranging from about 41 to about 47
lbs./cu.ft., and the amounts and proportions of ingredients com-
prising the core being such that when said board has a thickness
---` 13~82~
of about 1 inch, a shaft wall -test section including said
one-inch board has a fire endurance rating oE at least about
three hours. The method for evaluating said fire endurance
rating is described in detail hereinbelow in the ~xample section.
It should also be understood that included within the
scope of this invention is glass mat-Eaced gypsum board which has
a thickness less than or greater t'nan one inch, so long as the
core density falls within the above range, so long as the core
includes the ingredients as set forth above, and so long as the
particular core formulation involved, when part of a one-inch
board having said density yields a board which reults in said
rating. It will be appreciated that a board having a thickness
less than one inch generally will not have as good Eire-resistant
properties as a one-inch board even if the densities of the cores
and the ingredients, and the amounts thereof, from which -the
cores are formed are the same. On the other hand, a board having
a thickness greater than one inch will generally have better
fire-resistant properties than a one-inch core, even though the
core densities and the ingredients, and amounts thereoE, from
which the cores are formed are the same.
For use as shaft liner panels in a shaEt wall assembly, it
is recommended that there be used glass mat-faced gypsum board
having a thickness of about 1", and core density oE about 41 -to
about 47 lbs./cu.ft., preferably no greater than about 45 lbs/cu.
ft., and prepared from a Eormulation containing about 0.03 to
about 0.3 wt.% of glass fibers. In such an assembly, it is
believed that the glass mat surface of the gypsum board assists
in conducting heat away from the framework which supports the
board, thus leading to improvements in the fire endurance of the
assembly.
Glass mat-faced gypsum board, as described herein, and
including also such board having a glass fiber-containing core,
can be used also as board panels in one or more of -the plies of
---` 130~82~
facing layers which comprise shaft wall assemblies. In addition,
the board can be used to advantage in any application oE the type
in which conventional fire-resistant gypsum board is generally
used. The board can be fabricated into thicknesses which are
popularly used, for example l/2", 5/8", 3/4" and l".
There are advantages to using that Eorm of the board in
which at least one of the surEaces of the board has se-t gypsum
over substantial area portions thereof. The set gypsum appears
to aid in dissipating heat as it is consumed in drivlng off the
water hydration of set gypsum.
In applications where both fire resistance and improved
weathering characteristics are desired, both Eire-resistant and
water-resistant additives can be included in the core.
The use of certain water-resistant additives may reduce
the fire resistance of the board. In the event this occurs, such
reduction in fire resistance can be offset by making the core
more dense. In this type of situation, it is recommended that
the core density be about 4~ to about 55 lbs/cu.ft. to provide a
5/8" board that achieves a one-hour fire rating according to ASTM
E-ll9.
The preferred means for imparting water-resistant proper-
ties to the gypsum core is to include in the gypsum composition
from which -the core is made one or more additives which improve
the ability of the set gypsum composition to resist being
degraded by water, for example, to resist dissolution. In
preferred form, the water resistance of the core is such that it
absorbs less than about 10%, preferably less than about 7.5% and
most preferably less than about 5~ water when tested in accor-
dance with ASTM metllod C-473 with only the edges exposed.
The fibrous mat for use in structural systems described
herein has substantially better water-resistant properties than
the conventional paper facing of gypsum wallboard or sheathing.
Nevertheless, evaluations have shown that the bond between the
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fibrous mat and gypsum core can deteriorate relatively quickly
under the influence of water. For example, samples exposed to
the weather showed loosening at the glass fiber facing within one
to two months. In contrast, evaluations of water-resistant
gypsum core faced with fibrous mat, as described herein, have
shown the bond between the mat and core resists being degraded by
water for indefinite periods oE time.
Examples of materials which have been reported as being
effective for improving the water-resistant properties of gypsum
products are the following: poly(vinyl alcohol), with or without
a minor amount of poly(vinyl acetate); metallic resinates; wax or
asphalt or mixtures thereof; a mixture of wax/or asphal-t and also
cornflower and potassium permanganate; water insoluble thermo-
plastic organic materials such as petroleum and natural asphalt,
coal tar, and thermoplastic synthetic resins such as poly(vinyl
acetate), poly(~inyl chloride) and a copolymer of vinyl acetate
and vinyl chloride and acrylic resins; a mixture of rosin soap, a
water soluble alkaline earth me-tal salt, and residual uel oil; a
mixture of petroleum wax in the form of-an emulsion and either
residual fuel oil, pine tar or coal tar; a mixture comprising
residual fuel oil and rosin; aromatic isocyanates and diisocya-
nates; organohydrogenpolysiloxanes; a wax-asphalt emulsion with
or without such materials as po-tassium sulfate, alkali and
alkaline earth aluminates, and Portland cement; a wax-asphalt
emulsion prepared by adding to a blend of molten wax and asphalt
an oil-soluble, water-dispersing emulsifying agent, and admixing
the aforementioned with a solution of casein which contains, as a
dispersing agent, an alkali sulfonate of a polyarylmethylene con-
densation product.
A preferred material for use in improving the
water-resistant properties of the gypsum core comprises
wax-asphalt emulsion, species of which are available commercially
The wax portion o the emulslon is preferably a paraffin or
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microcrystalline wax, but other waxes can be used also. The
asphalt in general should have a softening point of about 115F,
as determined by the ring and ball method. The total amount of
wax and asphalt in the aqueous emulsion will generally comprise
about 50 to 60 wt.% of the aqueous emulsion, with the weight
ratio of asphalt to wax varying from about 1 to 1 to about 10 to
1. Various methods are known for preparing the wa~-asphalt
emulsion, as reported in U.S. Patent No. 3,935,021 to D.R. Greve
and E.D. O'Neill, assigned to the same assignee as the present
invention. Commercially available wax asphalt emulsions that can
be used in the composition described herein are sold by United
States Gypsum Co. tWax ~mulsion), Monsey Products (No. 52
Emulsion) and Douglas Oil Co. (Docal No. 1034). The amount oE
wax-asphalt emulsion used can be within the range of about 3 to
about 10 wt.~, preEerably about 5 to about 7 wt.~, based on the
total weight of the ingredients of the composition from which the
set gypsum core is made, said ingredients including the water of
the wax-asphalt emulsion, but not including addi-tional amounts of
water that are added to the gypsum composition for forming an
aqueous slurry thereof.
A particularly preferred material for use in improving the
water-resistant properties of the gypsum core comprises a mixture
of materials, namely, poly(vinyl alcohol) and wa~-asphalt
emulsion of the aforementioned type. The use of such additives
to improve the water resistance of gypsum products is described
in aforementioned U.S. Patent No. 3,935,021.
The source of the poly(vinyl alcohol) is preferably a sub-
stantially completely hydrolyzed form of poly(vinyl acetate),
that is, about 97 to 100% hydrolyzed poly(vinyl acetate. The
poly(vinyl alcohol) should be cold-water insoluble and soluble in
water at elevated temperatures, for e~ample, at te~peratures of
about 140 to about 205F. In general, a 4 wt.% water solution of
poly(vinyl alcohol) at 20C will have a viscosity of about 25 to
~ rvt~rk
~3~9~
16
70 cp as determined by means of the Hoeppler Ealling ball method.
Commercially available poly(vinyl alcohols) Eor use in the com-
position of the present invention are available Erom E. I. du Pont
de Nemours and Company, sold under the trademark "Elvanol" and
from Monsanto Co., sold under the trademark "Gelvatol". Examples
of such products are Elvanol, Grades 71-30, 72-60, and 70-05, and
Gelvatol, Grades 1-90, 3-91, 1-60, and 3-60. Air Products Corp.
' also sells the product as WS-42.
~ The amounts of poly(vinyl alcohol) and wax-asphalt emulsion
used should be at least about 0.05 wt.% and about 2 wt.~ respec-
tively. The preferred amounts of poly(vinyl alcohol) and
wax-asphalt emulsion are about 0.15 to about 0.4 wt.% and about
3.0 to about 5.0 wt.~ respectively.
Unless stated otherwise, the term "wt.%" when used herein
and in the claims means weight percen-t based on the total weight
of the ingredients of the composition from which the set gypsum
core is made, said inyredients including the water of the wax-
asphalt emulsion or the water associated with other additives,
but not including additional amounts of water that are added to
the gypsum composition for forming an aqueous slurry thereof.
The fibrous mat of the gypsum board described herein is
also a significant factor in reducing transmission of sound, a
desirable characteristic, which can be taken advantage of in
elevator shaft wall assemblies, as well as other structural
assemblies where reduced sound transmission is desired. For
example, in partition assemblies wherein a Eibrous ma-t-faced
board provides a support surface for a facing layer of material
adhesively fastened thereto, the adhesive interface between the
board and facing layer provides a resilient connection which
tends to dissipate sound energy, thereby providing a sound resis-
tant assembly.
An attractive feature of the present invention is that the
fibrous mat-faced gypsum board can be made utilizing existing
~ ~ rL~ k
., , ' . , . ' . .
` . . ` -
~3~82~
17
wallboard manufacturing lines, for example, as s'nown somewhat
diagramatically in Figure 1. In conventional fashion, dry
ingredients (not shown) from which the gypsum core is formed are
pre-mixed and then fed to a mixer of the type commonly referred
to as a pin mixer 2. Water and other liquid constituents (not
shown) used in making the core are metered into the pin mixer 2
where they are combined with the dry ingredients to Eorm an
aqueous gypsum slurry. Foam is generally added to -the slurry in
the pin mixer to control -the density of the resul-ting core. The
slurry ~ is dispersed through one or more outlets at the bottom
of the mixer 2 onto a moving sheet of fibrous mat 6. The sheet
of fibrous ma-t 6 is indefinite in leng-th and is fed from a roll
(not shown) of the mat.
As is common practice in the manuEacture oE conventional
paper-~aced gypsum board, the two opposite edge portions of the
fibrous mat 6 are progressively flexed upwardly from the mean
plane of the mat 6 and then turned inwardly at the margins so as
to provide coverings for the edges of the resulting board 40. In
Figure 1, this progressive flexing and shaping of the edges of
the mat 6 are shown for only one side edge of the mat and the
conventional guiding devices which are ordinarily employed for
this purpose are omitted from the figure for the sake of clarity.
Figure 7 shows also score marks 10 and lOA of the mat 6, the
score marks permitting the formation of good edges and flat
surfaces. The score marks 10 and lOA are made by a conventional
scoring wheel 12. An advantage of using the preferred form of
glass ~iber mat is that it is capable of being scored and edged
like conventional paper facing.
Another sheet of fibrous mat 1~ is fed from a roll (not
shown) onto the top of slurry 4, thereby sandwiching the slurry
between the two moving fibrous mats which form -the slurry. The
mats 6 and 16 with the slurry 4 sandwiched therebetween enter the
nip between the upper and lower forming or shaping rolls 18 and
~ 3 ~
18
20, and are thereaEter received on a conveyor belt 22. Conven-
tional edge guiding devices, such AS indicated at 2~ shape and
maintain the edges oE the composi-te until the gypsum has set
sufficiently to retain its shape. In due coursel sequential
lengths of the board are cut and further processed by exposure to
heat which accelerates the drying of the board by increasing the
rate of evaporation of excess water in the gypsum slurry.
With reference to Figure 7, it has been observed that the
set gypsum of the core 42 is effective in forming sa-tisfactory
bonds with the mats and between the edge portions of the
overlying mat 16 and the overlapped edge portion 6A of the under-
lying mat 6, thus making it unnecessary -to use a bond improver in
the slurry or an edge paste to form the aforementioned bonds.
The preferred Eorm of mats 6 and 16, as shown in Figures 2
and 3, comprise glass fiber filaments 30 oriented in random
pattern and bound together with a resin binder (not shown).
A preferred Eorm of glass fiber mat-faced gypsum board 40
is shown in Figures 4 and 7. It comprises one in which the set
gypsum of the core 42 penetrates substantially through the
thickness of the mat 6 over substantial area portions thereof and
in which the set gypsum of the core 42 penetrates the mat lG
partially, with the surface being thus substantially free of set
gypsum. The gypsum-free surface of mat 16, as seen in Figure 8,
is highly textured, and provides an excellent substrate Eor
adhering thereto an overlying component inasmuch as it comprises
many interstices into which an adhesive composition can flow and
bond.
The phrase "substantially penetrated by set gypsum", as
used herein, means that the set gypsum of the core, extends from
the mat surface which is contiguous to the core to the outer mat
surface and coats glass fibers on the outer surEace with a thin
film or set gypsum to the extent that the outline of glass fibers
can be seen through the thin film of set gypsum. The phrase
, . . . .
~` ~3(~2~
19
"over substantial area portions of the outer surface", as used
herein, means that about 30 to 75% oE the outer sur~ace area of
the mat is substantially penetrated by set gypsum. Preferably,
about 45 to about 55% oE the outer surface area oE the mat is
substantially penetrated by set gypsum. Accordingly, the gypsum-
coated surface of this preferred embodiment oE the board
comprises a surface that has a roughened or patterned appearance;
it does not comprise a smooth con-tinuous coating of set gypsum.
This preferred form of board can be formed with relatively small
amounts of gypsum slurry being deposited on the underlying
support surface, thus minimizing the need to clean the surface of
the board-forming equipment.
The need for such cleaning can be substantially avoided by
adjusting the viscosity of the slurry so that it penetrates but
part-way through thë underlying fibrous mat, for example, up to
about 50~ of its thickness. Thus, this preferred form of board
has two gypsum-free fiber-faced surfaces.
The manufacture of the aforementioned preferred forms of
board can be accomplished by controlling the viscosity of the
aqueous slurry of the calcined gypsum in a manner such that the
slurry penetrates the underlying and overlying mats to the
desired degree. In manufacturing each of the aforementioned
preferred forms of board, the viscosity of the slurry should be
such that it penetrates about 10 to 50% of the thickness of the
overlying mat over the entire surface area thereoE.
The reco~mended means for controlling the viscosity of the
slurry is to add thereto a viscosity-control agent. Such
viscosity-control agents are known in the field of gypsum board
manufacture. A preferred viscosity-control agent is paper fiber.
Examples of other agents that can be used are cellulosic
thickeners, bentonite clays, starches, and gypsum whisker fibers.
The particular viscosity values that are used in the manu-
facturing operation can vary from one application to the next,
~309~28
depending on the porosity of the mat, the hydration rate of the
calcined gypsum and the desired penetration of the slurry.
Accordingly, for any particular application, the viscosity value
is best determined empirically.
In using the preferred form of glass fiber mat, as
described above, to manufacture the aforementioned preferred
forms of board, developmental work has shown that satisfactory
results can be achieved utilizing a gypsum slurry having a vis~
cosity within the range of about 5000 to 7000 cp. As used
herein, the viscosity value refers to srookfield viscosity
measured at a temperature of 70F at 10 rpm utilizing paddle No.
3. It should be appreciated that the amount of viscosity-
control agent added to the slurry to give the desired viscosity
will vary depending on the particular agent used and the speciEic
viscosity desired.
The manu~acture of cores of predetermined de~sities can be
efEected by using known techniques, for example, by introducing
an appropriate amount of foam into the aqueous gypsum slurry from
which the core is formed. There are weight advantages that can
be realized by the use of fibrous ma-t-faced gypsum board in fire-
resistant applications in that fibrous mats which are lighter in
weight than conventlonal paper facing are available. For
example, the weight of a widely used paper facing in the manu-
facture of conventional gypsum sheathing is in the range of abou-t
120 lbs/1000 sq.ft. of board, whereas the weight oE a preferred
Eorm of glass fiber mat for use in the present invention is about
40 lbs/1000 sq.ft. of board.
With reference to Figures 10, 11 and 12, -there is shown an
example of a typical commercial shaft wall assembly in which
ibrous mat-faced gypsum board as described herein can be used.
Shaft wall assembly 100 comprises metal framèwork consisting of
ceiling- and floor-mounted J-tracks 101 and I-studs 103 for
supporting gypsum board panels 110 and 112. J-tracks 101 are
~ .
~, ,
13~2~
21
fastened by bolts 104 to the ceiling C and to the floor F
adjacent to the shaft S to be enclosed. Each J-track has a short
leg 106 and a long leg 107, the long leg 107 lying in
substantially the same plane as the shaft side 120 of shaft wall
assembly 100. I-studs 103 are positioned vertically between the
ceiling and floor J-tracks 101. The terminal ends of I-studs 103
are friction-fit between the legs 106 and 107 of the ceiling and
floor J-tracks. Generally described, I-studs 103 comprise
flanges 109 and 109' extending perpendicularly from an interme-
diate body portion 114.
Tabs T are cut and folded out of the metal sheet from
which I-studs 103 are made. ~he forming oE such tabs results in
forming ho]es 140 in body portion 114 of the I-studs.
Gypsum board panels 110 comprising the shaEt liner panels
of the assembly, are positioned between legs 106 and 107 of
J-tracks 101, with the vertical edges of said panels being
friction-fit between the I-stud tabs T and flanges 109. Facing
layers of gypsum board panels 112 are fastened by screw fasteners
113 to the face side 130 of shaft wall assembly 130. Two Eacing
layers or plies of gypsum board panels 112 are illustrated,
although it should be understood that additional Eace layers of
gypsum board may be applied, as desired. Facing layers of gypsum
board may also be applied to the shaft side of the assernbly in
stairwell applications where a finished wall surface is desired.
In the embodiment shown in Figures 10 to 12, gypsum board
panels 110 ~shaft liner panels of the assembly) are intended to
be shown as comprising a gypsum core sandwiched between and ~aced
with glass mats, as described herein, and gypsum board panels 112
(the facing layers of the assembly) are intended to be shown as
comprising a gypsum core sandwiched between and faced with paper.
Exemplary alternative embodiments include the use of panels
comprising a gypsum core having but one side faced with a fibrous
mat and oriented in the assembly with the "mat" facing the shaft
.
13~g~2~
22
and the use of ~ibrous mat-faced gypsum board in one or more
plies of the ~acing layers.
EXAMPLES
In the e~amples which follow, glass fiber mat-faced gypsum
boards falling within the scope of the present invention were
installed and evaluated for fire endurance in test sections of
conventional shaft wall assemblies oE -the general type shown in
the drawings.
The metal components oE the shaft wall metal Eramework
were supplied by Georgia Paci~ic Corporation and were manuEac-
tured from 25 gauge hot dipped galvanized steel. The components
consisted of four J-tracks having a 2 1/2" wide base portion ~rom
which 2 1/4" and 1" legs extended and a single I-stud which was 1
1/2" wide and 2 1/2" deep. The J-tracks were Eastened by bolts
to horizontal and vertical edges of a masonry framing structure.
The ends of the I-stud were friction-fit between the legs of the
upper and lower horizontally positioned J-tracks. For
convenience, the side of the assembly defined by the mean plane
of the long legs of the J-tracks is referred to hereafter as the
"shaft side"; the side oE the assembly defined by mean plane of
the short legs of the J-tracks is hereafter referred to as the
"face side."
In each of the shaft wall assemblies that were -tested,
there were used two 1" thick gypsum boards having repsective
dimensions of 15" x 66" and 24" x 66". The boards were inserted
between the legs of the upper and lower horizontal J-tracks on
either side of the I-stud, and their longest dimensions
vertically oriented. ~ertical edges of the boards, positioned
adjacent the I-stud, were ~riction-fit between the I-stud tabs
and flanges, thereby sandwiching the I-stud between the edges oE
the boards. The opposite vertical edges of the boards were
._,
``` 13~9~2~
23
secured to the long legs of the vertically positioned J-tracks by
1 1/4" Type S screws 24" on center (O.C.) such that the long legs
overlapped the boards on their shaft side.
Each of the glass fiber mat-faced gypsum boards that were
tested had a substantially gypsum-free face and a face having
gypsurn over substantial area portions thereof. Each of the
boards was installed in its test assembly so that its gypsum-free
face was exposed to the shaft side of -the as~embly. Following
installation of the glass fiber mat-faced gypsum boards in the
metal assembly, facing layers of paper-faced gypsum board were
fastened to the face side of the metal Eramework. These facing
layers are described in more detail hereinbelow.
The resulting assembly positioned in the aEorementioned
masonry frame formed one wall of a test furnace. The furnace was
fired with multiple gas burners positioned such that the yellow
luminous flame ~rom each burner impinged on the face oE the
specimen thereby maintaining a uniform temperature thereover.
Furnace temperature was gradually increased according to the
standard time temperature curve of ASTM E-ll9, as shown below.
Time (minutes) Temp. (F)Time (minutes)Temp. (F)
1000 120 1850
1300 180 1925
155Q 240 2000
1700
Temperature measurements of the test assembly were made by eight
Chromel-Alumel ~Type K) thermocouples, four of which were
positioned on the furnace exposed side and the remaining four of
which were positioned on the unexposed side of the assembly.
Fire endurance of each assembly tested was measured as
time taken for either (1) the average -temperature of the
unexposed side, as measured by the four thermocouples~ to reach
4~/<
` ~ .
,- ~
13~2~
24
250~F above ambient temperature or (2) any indivi~ual thermo-
couple temperature measurement to reach 325F above ambient -tem-
perature. Once either of these -two temperatures was reached, the
test was concluded and the time measured Erom the start oE the
test was recorded. During each test, observations were made of
each assembly respecting board deterioration, cracking,
distortion and metal component failure.
The evaluations involved two~hour fire endurance tests and
three-hour fire endurance tests, as described below.
Two-Hour Tests
Five two-hour fire endurance tests were conducted as
described below. In three oE the tests, 1" thick glass Eiber
mat-faced gypsum board was installed in a test section of a
conventional shaf-t wall assembly as described above. For
comparative purposes, the other two tests were conducted using
conventional 1" thick paper-faced gypsum board sold under the
trademark SHAFTLINER by Georgia-Pacific Corporation.
In each shaft wall assembly tested, two Eacing layers (an
inner layer and an outer layer) of gypsum board were fastened to
the face of the metal framework. These two layers consisted of
1/2" fire-resistant gypsym boards, the core composl-tion of which
is set forth below. Two such boards, each having dimensions of
33" x 39", their longest dimensions oriented horizontally, were
fastened to the face side of the framework using 1" Type S
screws, 24" O.C. to form an inner facing layer. The joint formed
between the edges of these two boards extended horizontally and
was not finished. The outer facing layer consisted of a single
gypsum board having dimensions of 39" x 66", the longest board
dimension being vertically oriented. The board was fastened over
the boards of the inner facing layer using 1 5/8" Type S screws,
16" O.C.
,
.. . , ~ . , .
~3~82~
The aforementioned 1/2" fire-resistant gypsuM boards that
were used in the tests are sold by Georgia-Pacific Corporation
under the trademark FIRESTOP, Type "~XX". Such boards have a
density of about 48 lbs./cu.ft. and comprise a set core Erom the
following composition.
Wt.% based on -total
weigh-t of ingredients
prior to addi-tion of
Ingredients mixing water
finely ground calcium
sulfate hemihydrate 9~.67
clay (aluminum silicate) 2.59
unexpanded vermiculite 1.10
glass fiber roving,
1/2" chopped glass fiber roving 0.4~
core adhesive 0.52
dispersing aJent 0.10
foaming agent 0.06
accelerator 0.52
100 . 00
In three of the two-hour tests that were conclucted, the
shaft side of each assembly was exposed to the gas flame inside
the furnace. The face side of the tested assembly Eaced outside
the furnace and was not exposed to flame. Table 1 below includes
a description of the 1" boards that were used in the shaEt wall
assemblies that were tested and the fire endurance rating for
each of the tested assemblies.
The glass fiber mat-faced gypsum boards reEerred to in
Table 1 below, that is, those boards falling within the scope of
the present invention, were made utilizing nonwoven mat composed
of glass fiber filaments oriented in a random pattern bonded
13~2~
26
together by an adhesive referred to by the manufacturer as a
"modified urea-formaldehyde resin". The mat had a thickness o-E
33 mils, and was more porous than paper oE the type used as the
cover sheet of gypsum wallboard. The air permeability oE the mat
was 700 CFM/sq.ft. (test method FG 436-910). The mat is
available commercially as DUR~-GLASS 7502-2 lbs and is an example
of a preferred fibrous mat for use in the prac-tice oE the present
invention. Continuous length board was made from an aqueous
slurry of the gypsum formulations described in Table 1 below on a
conventional wallboard machine. The slurry was fed onto a moving
sheet of the mat as it was unrolled from a roll onto a moving
support surface. The mat had a width of about 51 inches and was
scored continuously by conventional scoring blades prior to the
deposition of the slurry thereon~ Each edge of the mat was
scored with two score marks, with each of the outer scores being
about 1 inch from its respective edge of the mat and each oE the
inner scores being about 1 1/2" from its respective edge. After,
the slurry was deposited on the mat, the edges were folded at the
score marks and overlapped on top of the slurry. (The gypsum
core formed from this operation had a width of 47 7/8" and a
thickness of 1/2".) Mat from another roll thereof and having a
width of 47 1/2" was fed onto the top of the gypsum,slurry and
the overlapped edge portions of the underlying mat. The gypsum
slurry penetrated the overlapped edge portions and served to bond
the edge portions of the overlying mat to the overlapped edge
portions of the underlying mat. The viscosity oE the gypsum
slurry was about 5900 cp at 70F. At this viscosity, the slurry
penetrated substantially through some portions of the underlying
mat to form a thin film thereof on about 40 to 50% of the area oE
the outer surface of the mat. As the gypsum in the Eilm set,
substantial portions of the outer surface oE the mat were covered
with a thin film of set gypsum. The surface had a roughened
appearance with outlines of the glass filaments being observable
~ 3 ~
27
underneath the thin coatings of gypsum which covered them. How-
ever, at the aforementioned viscosity, the slurry penetrated but
a portion (about 5 mils) of the thickness oE the overlying mat
over the entire area thereof, with no slurry being observed on
the outer surface of the mat. As the gypsum set in the inter-
mediate portions of -the mat that were penetrated by the slurry,
it formed a bond that included a mechanical interlock with the
set gypsum core. The continuous length board is cut into lengths
of about ~ feet. Drying of the gypsum boarcd is accelera-ted by
heating in an oven at 350F for about 2 hours and until -the board
is almost dry and then at 200F for about 1 hour until it is
dried completely.
''' ''
13~82~
28
T~BLE 1
TEST 1 TEST 2
glass fiber glass f;.ber TESi.r 3
mat-faced mat-Eaced p~per-~aced
gypsum board, gypsum board, gypsum board,
Board G-l _ Board G-2 _ _oard P _
calcium sulfate
dihydrate
glass fiber 2.18 2.18 5.9
(lbs/1000 ft.2) (0.056 wt%)(0.065 wt%) (0.15 wt~)
paper fiber
(lbs/1000 ft.2) 19.45* 19.45* 1.0*
board thickness
(inches) 1. 023 1. 081 0 . 9 63
density
(lbs/ft.) 45 37 50
board weight
(lbs/1000 ft.2) 3875 3348 4015
fire endurance
(hours) 2.0 1.92 1.82
*The difference in paper fiber content is primarily due to the
slurry viscosity control function which the fibers per:Eorm in
regulating the degree of slurry penetration into the g].ass Eiber
mats.
Calculations show that the cores of glass fiber mat--faced gypsum
Boards G-l and G-2 contain 63~ less glass fiber than the core o:E
Board P, that is, the conventional paper-faced board. Although
Board G-l is 10~ less dense than the conventional board, the
shaft wall assembly containing Board G-l showed a 9~ improvement
in fire endurance over the assembly which included Board P.
Although Board G-2 is 17.5% lighter in weight and 26% less dense
than Board P, the shaft wall assembly including Board G-2 showed
a 5~ improvement in fire endurance over the assembly including
~ .
-
~3~82~
29
the conventional board. Thus, even though soalds G-l and G-2
contained less glass fibers in their cores and were less dense
than the conventional paper-faced board, test assemblies
including the Eormer boards showed an average 7~ improvement in
fire endurance over the assembly which included Board P.
In contrast to the previous three tests, the ,Eollowing two
tests were conducted on shaEt assemblies in which the face side
of the assembly was exposed to the gas Elame inside -the furnace;
the shaft side faced outside the Eurnace and was not exposed to
flame. Table 2 below includes a description of the 1" boards
that were used in the shaEt wall assemblies that were tested and
the fire endurance rating for each of the tes-ted assemblles.
TAsLF. 2
TEST 4
glass fiher TEST 5
mat-faced paper-faced
gypsum board,yypsum board,
Board G-3 Board P-l
calcium sulfate
dihydrate
glass fiber 22.18- 5.9
(lbs/1000 ft. ) (0.06 wt%) (0.15 wt~
paper fiber 2
(lbs/1000 ft. ) 19.~5 1.0
board -thickness
(inches) 1.086 0.977
density
~lbs/ft.3) 39 48
board weiyht 2
(lbs/1000 ft. ) 353~ 3931
fire endurance
(hours) 2.32 2.0
. . .
`` ~ 30982~
Calculations show that the core of soard G-3 contains 63~ less
glass fiber than the core of sOard P-l, that soard G-3 is 11%
ligh-ter in weight than soard P-l and is 20~ less dense than soard
P-l. Nevertheless, -the shaft wall assembly includiny Board G-3
showed a 14% improvement in fire endurance over the assembly
including Board P-l.
Three-Hour Test
~ three-hour fire endurance test was conducted as
described below. A 1" thick glass Eiber rnat-faced board having a
density of 42 lbs/f-t.3 was installed in a test section of a
conventional shaft wall assembly as described earlier. The core
composition of the board, referred to herein as G-~, is set forth
below.
I~t.% of Set & lbs/1000 ft.2 of set
Constituents dried Composition & dried Composition
. ~
calcium sulfate
dihydrate 99.081 3388.6
glass fiber (1/2"
glass fiber roving) 0.063 2.2
paper fiber
(sulfite) 0.561 19.2
dispersing agent
(lignosite) 0.226 7-7
commercial retarder 0.021 0.7
foaming agent
(ammonium lauryl
sulfonate, "Micro
Foam CP")~ 0.0~8 1.6
The face side of the assembly which was tested included
three facing layers oE conventional yypsum board having a thick-
~ l r~ 6~
i
" 13~9~28
ness of 5/8" and a core composition as set forth below. T'neinnermost facing layer was formed from two such boards having
respective dimensions of 15" x 66" and 24" x 66", -their longest
dimensions orien-ted vertically. These boards were fastened to
the short legs oE the J-tracks and I-stud flanges using 1" Type S
screws, 2~" O.C. The joint Eormed between the edges of these
boards was centered over the I-stud. The joint was not finished.
The boards forming th eintermediate and outer facing layers had
the same length and width dimensions and were positioned in the
same orientation as the inner and outer facing layers of the
assembly described above for the two-hour tests. The outermost
facing layer was fastened in place using 2 1/4" Type S screws.
The face side oE the test assembly was exposed to the gas Elames
of the ~urnace, the shaft side remaining unexposed to Elames.
The paper-faced gypsum boards were Type "X" board sold by
Georgia-Pacific Corporation under the trademark FIRESr~OP. These
facing boards have an average weight of 2350 lbs/1000 ft.2 and a
core composition as set forth below.
Component lbs/1000 ft2 wt.
glass fiber
(chopped glass roving) 5.0 (minimum) 0.2
core adhesive 13.0 (maximum) 0.53
dispersant 12.0 (maximum) 0.5
foaming agent as necessary to
achieve minimum
dry weight.
accelerator as necessary to
achieve a slurry
setting time of
4 to 5 minutes.
gypsum board weight less
the total weight
of additives and
a paper cover
sheet weight of 2
120 lbs/1000 ft.
. ... . .... . .
13~g~2~
During -the test, the temperature of the flame-exposed face
of the assembly rose at a rate oE approximately ~8F/minute in
the first 15 minutes of the -tes~, 9~F/minute in the second 15
minutes, and 1.8F/minute for the remaining two hours and Eorty-
five minutes of the test, and reached an average temperature
after three hours and Eifteen minutes of about 1,910F. The
average temperature measured on the une~posed face side oE -the
assembly rose from approximately 77F (ambient temperature) to
327F over a period of time of three hours, thirteen minutes.
The maximum temperature measured on the une~posed Eace side wa~s
402~F. It was reached in three hours and twelve minutes. Thusr
a fire endurance of 3.2 hours was achieved by the test assembly.
There was no indication at any time during the test of pending
integrity failure, as would have been maniEested by the develop-
ment oE cracks or distortion, of either the Eurnace-exposed glass
fiber mat-faced board or facing boards. The I-stud showed some
evidence of buckling after three hours.
It is noted that, in conventional thxee-hour rated shaft
wall assemblies, a 3/4" Type "X" gypsum board is positioned in
the assembly in the same manner as -the 1" glass fiber mat-faced
board described herein, and four layers of 5/8" Type "X" FIRESTOP
board are applied to the face of the assembly, there being a
space maintained between the third and outermost Eourth layer of
board. Thus, even though the glass mat-faced gypsum boaxd
described herein was but 1/4" thickex than the conventional
paper-faced board, the shaft assembly with soard G-4 included
only three facing layers (instexad of 4) of 5/8" Type "X"
FIRESTOP board to achieve a fire endurance oE better than three
hours.
It will be appreciated from the above described tests -tha-t
glass fiber mat-faced gypsum boards as described herein, when
tested in shaft wall assemblies, show significant improvements in
fire endurance over their conventional paper-faced counterparts
,,, ,,, ,, , , :
,
13~9~28
33
despite tile Eact that their cores are signiEicantly less dense
and contain a significantly smaller quantity oE Eire-resistant
additives, namely glass Eibers.
The next example involves the evaluation in a Eire test of
a 5/8" thick glass fiber mat-Eaced gypsum board having a core
composition as set Eorth below and prepared according to the
techniques described for glass fiber mat-Eaced gypsum boards of
the earlier examples herein.
Components Wt.~, set & dried board
glass fiber mat facing 1.58
calcium sulfate dihydrate94.06
glass fiber ~]./2" chopped0.08
glass roving)
paper fiber 0-74
potash (accelerator) 0.15
wa~-asphalt emulsion 2.96
poly(vinyl alcohol) 0.28
calcium lingosulfonate 0.11
(dispersing agent)
ammonium lauryl sulfonate0.04
(foaming agent)
The density of the core oE the board was 53 lbs/cu.ft. A fire
rating o~ 1 hour and 30 seconds was achieved when the board was
evaluated Eor fire resistance and hose stream resistance accord-
ing to ASTM E-119. I-t is noted that the board has excellent
water-resistant properties due to the use of water-resis-tant
additives in its core, those addi-tives being wax-asphalt emulsion
and poly(vinyl alcohol).
The aforementioned examples well illustrate the excellent
fire-resistant characteristics possessed by the clevelopment of
the present invention. In the examples and other portions o:E the
description of the invention, reEerence has been made specifi-
cally to a shaft wall assembly including metal framework of
particular design. I-t should be understood that fibrous mat-
.. ... . .............................. . . .
. ~
~3~9~28
3~
faced gypsum board as described herein can be used in other typesof shaft wall assemblies, including assemblies made from other
types of fire-resistant materials, for example, fire-resistant
plastics. It is noted also that the compositions oE the e~amples
included the use of calcium sulfate hemihydrate to form the set
gypsum product. ~lternatively, there can be used calcium
sulfate, the term used in the claims to cover generically both
calcium sulfate and calcium sulfate hemihydrate.
In summary, it can be said that the present inven-tion
provides ina practical way important functional improvements in
structural assernblies which are intended to have fire-resistant
properties designed to ensure the safety of life and property.
~O
