CA1326625C - Use of fibrous mat-faced gypsum board in shaft wall assemblies and improved fire-resistant board - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
In a shaft wall assembly comprising fire-resistant framework and gypsum board supported by said framework, the improvement comprising gypsum board which is faced with fibrous mat.

Description

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This appl$cation i5 a divisional applica$ion of Canadian Paten~ Applica~ion No. 516,60? ~iled on Auguæt 22nd, 1~86.
The inven~ion of the parent applica$ion relates to glass mat-faced gypsum board having a core which includes glass fibers in an amount sufficient to improve the fire-reslstant properties of the board said core comprising the set produc~ of a mixture comprising calcium æulfa~e and at least about 0.03 w~.% o~ glass -~
fibers, said core having a density ranging from about 41 to about 47 lbs~cu.ft., and the amounts and proportion~ of ingredients comprising ~he core bein~ such that when said board has a thickness of ahout 1 inch, a shaft wall test sec~ion including sald one~inch board has a fir~ endu~ance raking of at leaæt about ~
three hours. ~:
The invention o~ this divisional application relates to a ~lass mat-faced gypsum board compri~lng a se~ core con~aining ~ ~ypæum dihydrate and at least a mlnlmu~ amount of chopped glass $ fibers sufficient to improve the flre-re~istant properkies of said i : gypsum board, wherein the fire resistance properties o~ said board ~- -are signiflcantly better than tho~e of a conYentlonal paper-faced board of llke thickness that ha6 a like amount of chopped glass ~, flbers ln its core, sald board charaaterized by the glass mat containing a plurality of interstices which are free of set gypsum.
The inventlon of this divislonal application also :
relates to a glass mat-faced gypsu~ ~oard comprlsing a set core con~aining gypsum dlhydrate and at least a minimum amount of:

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; chopped glass fibers, water-resistant additive, and paper fibers sufficient to improve the fire resistance properties o~ said gypsum board, such that the board in 5~8 inch thickness achleves at least a one hour fire rating in accordance with ASTM ~
~ he invention of this divisional application al50 concerns a ylass mat-faced gypsum board comprising a set core containlng gypsum dihydrate and uniformly distributed chopped glass fibers, said ooard having a fire rating of at least about one hour when tested in accordance with ASTM ~-119, said board ;l 10 characterized by the glass mat containing a plurality of interstices which ar~ free of set gyp~um.

, The lnvention of this dlvisional application fur~her :i .
relate~ to a gypsum board includin~ a set gypsum core having at least one porous, gla~s ma~ adheredl to one face surface ~hereo~, 'j said gypsu~ board characterizad by said mat co~si~ing essentially o~ randomly di~tributed glas3 ~ibers bonded by an adheslve material and including an outer surface and an inner surface, said ~at being of substantially uni~orm denslty throughiout l~s ~hickness between said outex and inner æurfaces, said outer surface being substantially free of iet gypsum and sald inner surface bein~ adhered substantially continuously to said gypsum core by a portlon of said ~et gypsum.
The invention o~ this divisional application also relates to a gypsum board including a æet gypsum core having at least one porous, glass mat adhere~ to one fair-e surface thereof, : sald gypsum board characterized by said mat including an outer sur$ace and an inner surface, said gypsum core comprising a ~,. '~'.

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viscosity control agent for thickening a gypsum slurry precursor :~
of said set gypsum to substan~ially prevent full penetration of said slurry through said glass mat, whereby sald outer surface of said mat is substantially free of set gypsum.
The invention of this divisional application further ~-relates ~o a process for manufacturing in continuous fashion face gypsum board of inde~inite length compri~ing: -, ~.
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(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;
J (d) applying to the top surface of the panel-like s shape o~ slurry an overlying porous glass fiber mat having a ~ predetermined thickness; and ! (e) maintaining the panel-like shape whils~ the cal- ~
- 10 cined gypsum sets to form a set gypsum core having the overlying :
.il mat adhered to one surface thereof; characterized by the step of , (f) maintaining the viscosity of the slurry at a f value such that said slurry penetrates but part-way into the ¦ thickness of the overlying mat so that, upon the setting of the 1 calcined gypsum, the outer surface of the overlying mat is substantially free of set gypsum.
FIELD:OF THE INV:ENTION
This invention relates to an improved structural component for use in fire-resistant applic~tions, ~or example, in ~hollow shaft wall assemblIes of the type used in constxucting elevator shafts and stairwells in buildings. More particularly, this lnventiGn relates to fibrous mat-faced gypsum board having 1~ ~ improved~fire-resistant properties and to its use in various s~tructural applications. ~:
This invention will be described initially in connec-tlon with its use in a shaft wall assembly, buk, as will be ~f~

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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 is constructed -from panels of paper-faced gypsum board which are supported in '~ place by metal framework. The design of the assembly is such il that the gypsum board panels r including the panels which line and face the shaft, can be installed from one side, that is, away lCi from the shaft being enclosed. Such assemblies are constructed in place by workmen who aria supported by the floor through which .', ;','''.~

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the shaft extends. This eliminates the necessity for construction of internal scaffolding or other supports for workmen within the shaft.
It is mandatory that shaft wall assemblies possess certain ch~racteristics for commercial acceptability. For example, it 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 significant forces that are imposed on them by compressed air which is generated by ascending and descending elevator cars. Such forces 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-lesistant fibrous mat-faced gypsum board which can be used in ~;uch assemblies, as well as other types of structural applications.
Currently used shaft wall assemblies include also in their structure gypsum board comprising a core of set gypsum sandwiched between paper cover sh~ets. A shaft wall assembly that is used widely at the present time consists of a metal framework which support~ a plurality of plies of panels of gypsum board. Such ~.
assemblies are describ~ed 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 thf~ pair of tracks being fastened to the ceiling and the other of the pair being fastened to the floor) and a plurality of spaced vertically disposed metal "I-studs" which are frictionally held within the ~-tracks. Panels of gypsum board which line the shaft --being enclocied are supporte~ by the J-tracks and the I-studs.

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One 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. By increasing the number of facing layers and/or the thickness of the gypsum boards, the fire resistance of 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-resistant properties of the board.
However, to achieve the necessary fire rating for the assembly, such boards have a relatively high densityO This adds to shipping costs and makes installation more difficult. In addition, the amount of chopped glass fibers added to the core is not insignificant and adds to the boards' cost. In addition, the paper facing sheets smoke when exposed to the heat of fire 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 4,265,97g.
It is believed that the boards described in these patents have never been commercially used for a variety of reasons.
The '110 patent discloses a gypsum board formed from the set product o~ a gypsum slurry sandwiched between two surface i ~layers of glass fiber-containing set gypsum composition. The glass fibers may be in the form of rovings, continuous strand mat or chopped glassO The single example of gypsum board which is the subject of the patPnt shows a board of relatively high ~-density, namely, about 52 lbs/cu. ft. Thiisi 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 patent has improved flexural strenJth and does not smoke when exposed to the heat of fire.
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The '979 patent discloses a gypsum board that has c~opped glass fibers concentrated in the surface portions of the core of the board. In the manufacture of these boards 9 a mixture of 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, a~d the resulting three layered composite is compressed and allowed to dry. The pa~ent also discloses th~ such boards, in addition to being "highly fire resistant and smoke resistant" and "rel~tively light", have improved flexural strength over conventional paper faced boards.
It is apparent from the disclosure that th~ patentees contempla~e a relatively dense gypsum board~ the density of the surface sheet being reported as 81 lbs/cu.ft.
Manufacture of each of the gypsum boards which are the c:ubject5 of the aforementioned patents necessi~ates special -:
handling of the glass-containing surface layers between which the core is sandwiched, foreclosing manufacture of th~ boards on a conventional gypsum board-making apparatus.
In accordance with the present invention~ there are provided an improved shaft wall a~sembly including a gypsum-based structural component and also gyp~um bsard having improve~ fire r~sistant properties.

SUMMARY OF THE INVENTION
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In accordance with the invention described and claimed in :~ -the pre~ent application, there is provided a shaft wall assembly ::
comp~ising fire-re-~istant framework and, supported by said framework, fibrous mat-aced gypsum board. In preferred form, the assembly compris~s gla ~ mat-faced gypsum board supported by metal framework. As is described in detail hereinbelow, c~aid ~:
glass mat-faced gypsum board comprise~ a core which includes . ~-glass fibers in an amoun1t sufficient to imprnve the fire-resistant propexties of the board.

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~U3~2-12~3 In preferred form, the invention include~i glass mat-faced gyp~um board having a core whi~h includes glass fib~rii in a fire-resistant improving ~mount of, for example, about 0~07 to abou~ :
O.2 ~t.~i, ba~ed on the dry mixture fr~m which the core is made.
A further aspect of the presant invention includes theprovisi~n of a glas~ mat-fac~d gypsum board which has signifi-cantly improved fire-r~sistant properties notwithstanding the preeence in the board core of a relatively small amount of fire-re~istant addltives 3uch as glass fiberis and the use of a core which has a relatively low density.
A~ will be described hereinbelow, the improved fire-re~istant board o~ the present invention can be used to excellent advantage in shaft wall ai~sembli~3, as ~entioned above, and, in addition, the board can be u~ed to excellent advantage in the numerous and varied application~ in which conventional paper-faced gypsum board i9 u~ed. Such alpplications include, for example, the use of the board as structural components of walls, ceilings, partitions, and th~ like.
The advantages whi h flow from the provi3io~ of the improved fire-re~istant board of the present invention are numerous and important. For example, the invention affords the manufacture of a gypsum-based product which has fire-resiitant ~ :
prop~rtie~ not h~retofore available in gypsum board of popularly ;~-used thicknes~es and having a relativ~ly low weight.
Furthermore, such advantages can be achieved by manufacturing the board o~ the pres~nt invention by the use of existing gypsum-manufi~cturing equipm~nt.
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BRIEE` _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 l the present invention;
., Figure 2 is an enlarged fragmentary sectional view, taken as indicated toward the left of Figure 1, of an underlying iber . 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; :
.1 Figure 4 is an enlarged sectional view taken as indicated toward the right on Figure 1 and illustrating both underlying and :
1 overlying fiber glass mats, with intervening gypsum composition, :1 used in the manuacture oE the board; :`
Figure 5 is a fragmentary plan view taken as indicated by line 5-5 on Figure 4; ~ :
I Figure 6 is a fragmentary bottom view taken as indicated ~-1~ by the line 6-6 on Figure 4 and illustrating the bottom surface of the underlying mat of the board;
Flgure 7is a transverse~sectional view of an edge portion - -of the completed board,~this Yiew being taken as indicated by the : line 7-7 on Figure 4;
Figure ~ 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 lO 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 taken ; along line 11-11 through 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 illustrated in FLgure ll.
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~ETAILED DESCRIPTION OF THE INVENTION
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Turning now to a description of the impxoved gypsum board that can be used in improved shaft wall assemblies of the present invention, it comprises a set gypsum core faced with a fibrous , mat. The gypsum core is basically o~ 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 I sulfate ox calcium sulfate hemihydrate (CaSO4 l/2H20), also known I as calcined gypsum; and thereafter allowing the mix~ure to hydrate or set into calcium sulfate dihydrate (CaSO~ 2H20), a ~, relatively hard material. The core of the product will in general comprise at least about 85 wt.% o~ set gypsum.
', The composition from which the set gypsum core is made can l~ include optional constituents, including, for example, those included convent-ionally in gypsum sheathing. Examples of such constituents include set accelerators~ retarders, foaming agents, and dispersing agentsO
¦ 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 evaporate therethrough. As described in detail below, the !~ fibrous mat-faced gyp um board can be made efficiently by forming i~
j an aqueous gypsum slurry which contains excess water and placing ,~ t~hereon the fibrous mat. Aided by heating, excess water evapo-~,- rates through the porou~ mat after the calcined gypsum sets.
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8 ~L~26~25 The fibrous mat comprises material which 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 stra~ds 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 c05tly 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 commercially 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 DURA-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 it:s surfaces faced with fibrous mat as described herein, it is pref.erred that both surfaces of the core be faced wi~h substantially th~ same fibrous material.
If the surfaces of the core are faced with materials that have different coefficients of 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 ~etween 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 of 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 shaft liner panels, the core of which generally includes fire-resistant ~ -additives. Shaft wall assemblies including the fibrous mat-faced boa~d have improved fire endurance relative to assemblies which 1 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 o~ such assemblies are shown in U.S. Patent Nos~ ;
4,047,355; 4,324,082; and 4,~64,212. Fibrous rnat~faced board, as described herein, can be used, for example, in the assemblies f described in the aforementioned patents and the shaft liner panels and/or as facing panels.
In these types of applications where fire-resistant prop-i erties are con~idered important, the core of the fibrous mat-faced yypsum 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 for '; improving the fire-resistant properties of gypsum products include mineral fibers such as, fo~ example, glass fibers, asbe~to5 Pibers~ and calcium ~ulfate whisker fibers. A mixture o~ one or more of ~uch fibers can be used. Other exemplary ' ~ materials which are known for use in conventional fire resistant gypsum board are unexpanded vexmiculite, clay, colloidal silica and colloidal alumina. Typically, mineral fibers, and particu-larly glass fibers, are used in admixture with one or more of the ~ ~aforementioned exemplary materials. For example, see U.S. Patent f,: ' No. 3,616,173, assigned to the same assignees as the present i inventiOn.
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A preferred material for U5~ in improving the fire-resistant properties of the fibrous mat-faced gypsum board comprises chopped glass fib~rs~ for example, as described in aforemention~d U.5. Patent No. 3,616,173.

Briefly de~cribed, said glass fibers ar~ of the drawn textile glass fiber type, produc d aq continuou~ individual fila~
ments and having a diameter of from about o~oao2 to about O~OOl".
~he individual filaments are usually grouped into strand~, the ilamPn~s having coated ther~on a r~ldtively weak, bonding ~ype material, such as, for example, ~tarch or other water softenable or -~oluble coating mats~rial. The bonding ma erial help~ to prevent abraiding between the ~everal group~d filaments of ~ach strand. Prior to th~ ~ddition o~ th0 loosely bonded textile gla~s fibers to ~he cor~ compo5ition, the strand~ ar~ cut in~o shsrt length~ such a~, for example~ 1/8" to 1". Once added t4 the aqueous slurry com~o~ition from which the cor@ is made, the bonding or coating material di~solve~, and the strands separate into individual fibers which b~comle uniformly distributed throughout tha ~lurry as the slurr~y is mix~d.
~ h~ pr~sence o~ mineral fib~rs in the cor~ of fibrous mat-faced gyp~um board i~ accordance with the pres~nt inYen~ion results in a product which ha~ unu.~ually high f ire-resistant charact~ris ic~. For ex~am~l~, th~ pxe~ence o a predet2rmined :
amount of chopped glass ~ibers in the core of glass mat-faced gypsum board of p~edetermined thickness provides a product which has fire-r~si~ta~t charact~ristics that ar~ significantly better than those o conventional paper-faced gypsum board ~hat has a like amount of glass fibers in its core and a like thickness. ~-The effects which flow ~om this development are significan~ly important and ca~ desirably be taken advantage o in several different way For example, th~ development can be u-Qed to produce a glass mat-~aced gy~um board which has a lower density ~ ':
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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 snould be at least about 0.03 wt.~ and can vary over a widff~ 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 wei~ht of the ingredients before they are combined with water to make the aqueous slurry from which the core is formed. In preferred form, the amount of glass fibers comprises about 0.07 to about 0.2 wt.%.
f~fhe core of the fibrous mat-faced board for use in fire- -resistant applications can be fabricated according to available f techniques into a density of desired value. For a relatively f thick board, for example, a thickness in excess of one inch, the I denfsiity 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 f 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 ~f~ 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 -~
l ~ - characteristics a~d relatively low weight. i `I Another aspect of the present invention comprises a glass ~ mat-faced gypsum board having a core comprising the set product j of calcium sulfate and at least about 0.03 wt.~ of glass fibers, said core having a density ranging from about 41 to about 47 f~ ~ lbff~i./cu.ft., and the amounts and proportions of ingredients com~
prising the core being such that when said board has a thickness f , ~ .

12 ~ 5 of about l inch, a shaft wall test section including said one-inch board has a fire endurance rating of at least about three hours. The method for evaluating said fire endurance rating is described in detail hereinbelow in the Example section.
It should also be understood that included within the scope of this inven-tion is glass mat-faced gypsum board which has a thickness less than or greater than 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 paxticular 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 1~5s than one inch generally will not have as good fire-resistant properties as a one-inch board even if the densities of the cores and the ingredients, and the amount:s thereof, from which the cores are formed are the same. On the other hand, a board ~aving a thickness greater than one inch will generally have better fire-resistant properties than a one-inch core, even though the core densitles and the ingredients, and amounts thereof, from which the cores are formed are the same. ;~
For use as shaft liner panels in a shat wall assembly, it i~ recommended that there be u~ed glass mat-faced gypsum board having ~ thicknes~ o~ about 1", and core density of about 41 to about 47 lbs./cu.ft., preferably no greater than about 45 lbs/cu.
ft., and prepared from a formulation containing about 0.03 to about 0.3 wt.~ o~ glass fibers. In such an assembly, it is believed th~t the glass mat surface of the gypsum board assists in conducting heat away from the framework which supports the board, tkus 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 ;-13 13~662~ ~
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facing layers which comprise shaft wall assemblies. In addition, the board can be used to advantage in any application of 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 1/2", 5/8", 3/4" and 1".
There are advantages to using that form of the board in which at least one of the surfaces of the board has set gypsum over substantial area portions thereof. The set gypsum appears to aid in dissipating heat as it is consumed in driving off the water hydration of set gypsum.
In applications where bvth fire resistance and improved weathering characteristics are desired, both fire-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 recommtended that the core density be about 48 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 preerred 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 method 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 of time.
Examples of materials which have been reported as being effective fox 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 asphalt and also cornflower and potasisium permanganate; water insoluble thermo-plastic organic materials such as petroleum and na~ural asphalt, coal tar, and thermoplastic synthetic resins such as poly(vinyl acetate), poly(vinyl chloride) and a copolymer of vinyl acetate and vinyl chloride and acrylic resins; a mixture of rosin soap, a water soluble alkaline earth metal salt, and residual fuel 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 potassium sulfate, alkali an~
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 of the emulsion 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 wax-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 tnat can be used in the composition described herein are sold by United States Gypsum Co. (Wax Emulsion), Monsey Products (No~ 52 Emulsion) and Douglas Oil Co. (Doca ~ o~ 1034). The amount of wax-asphalt emulsion used can be within the range of about 3 to about 10 wt.%, preferably about 5 to about 7 wto~ 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 additional amounts of water that are added to the gypsum composition for forming an aqueous slurry thereof.
particularly preferred material for use in improving the water-resistant properties of the gypsum core comprises a mixture of materials, namely, polytvinyl 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 V.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 polytvinyl acetate. The poly(vinyl alcohol) should be cold-water insoluble and soluble in water at elevated temperatures, for example, at temperatures of about 140 to about 205F. In general, a 4 wto% water solution of polytvinyl alcohol) at 20C will have a viscosity of about 25 to .1 ,,.-. .:
~r~.~

16 ~L32~62~ ~

70 cp as determined by means of the Hoeppler falling ball method.
Commercially available poly~vinyl alcohols) for use in the com-position of the present invention are available from 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-4 ~
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 percent 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 or the water assoriated with other additives, but not including additional amounts of water that are added to i the gypsum composition for forming an aqueous slurry thereof.
I The fibrous mat of the gypsum board described herein is also a significant factor in reduc:ing 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 fibrous mat-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 J~ tends to dissipate sound energy, thereby providing a sound resis- ~
tant assembly.
An attractive feature of the pr~sent invention is that the fibrous mat-faced gypsum board can be made utilizing existing ~! z 1~ ~r~ ~ :
: :~

17 ~L~2~2~
, ~, wallboard manufacturing lines, for example, as shown somewhat diagramatically in Figure l. 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 form an aqueous gypsum slurry. Foam is generally add~d to the slurry in the pin mixer to control the density of the resulting core. The slurry 4 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 mat 6 is indefinitP in length and is fed from a roll (not shown~ o the mat.
As is common practice in the manufacture of conventional paper-faced 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 l, 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.
i ~ Figure 7 shows also score marks 10 and lOA of the mat 6, the score mark~ permitting the formation of good edges and flat ~-surfaces. The score marks 10 and 10A are made by a conventional ;~ scoring wheel 12. An advantage of using the preferred form of -~
glass fiber mat is that it is capable of being scored and edged like conventional paper facin~.
~ Another sheet of fibrous mat 16 is fed from a roll (not shown) onto the top of slurry 4, thereby sandwiching the slurry ~I between the two moving fibrous mats which form the slurry. The mats~6 and 16 with the slurry 4 sandwiched therebetween enter the n1p between the upper and lower forming or shaping rolls 18 and .:
, ,: ' ':, 1~ ~.3~6~ ~

20, and are thereafter received on a conveyor belt 22. Conven-tional edge guiding devices, such as indicated at 24 shape and maintain the edges of the composite until t'ne gypsum has set sufficiently to retain its shape. In due course, 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 th2 gypsum slurry. --With reference to Figure 7, it has been observed that the set gypsum of the core 42 is effective in forming satisfactory 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 bo~ds~
The preferred form of mats 6 and 16, as shown in Figures 2 and 3, comprise glass fiber filaments 30 oriented in random pattern and bound to~ether with a resin binder (not shown). ;;
A preferred foxm 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 ~2 penetrates substantially through the thickness of the mat 6 over substantial area portions thereof and in which the set gypsu~ of the core 42 penetrates the mat 16 partially, with the surface being t:hus 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 for adhering thereto an overlying component inasmuch as it comprises many interstice~ 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 surace and coats glass fibers on the outer surface with a thin film of set gypsum to the exte~t that the outline of glass fibers can be seen through the thin film of set gypsum. The phrase 19 ~ 3 2 6 ~ % ~

"over substantial area portions of the outer surface", as used herein, means that about 30 to 75% of the outer surface area of the ~at is substantially penetrated by set gypsum. Preferably, about 45 to about 55% of the outer surface area of the mat is substantially penetrated by set gypsum. Accordingly, the gypsum-coated surface of this preferred embodiment of the board comprises a surface that has a roughened or patterned appearance;
it does not comprise a smooth continuous 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 s~rface of the board-forming equipment.
; The need for such cleaning can be substantially avoided by adjusting the viscosity of the slurry so that lt penetrates but part-way through the 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 afore~mentioned preferred forms of board can be accomplished by controlling the viscosity of the I 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 thereo~
The recommended means for controlling the viscosity of the slurry is to add thereto a viscosity~control agent. Such viscosity~ccntrol 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-,1 facturing operation can vary from one application to the next, , ~ :
-:
....
'':
: . .

~ 32~2~

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 Brookfield 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 specific viscosity desired.
, The manufacture of cores of predetermined densities can be i effected 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 mat-faced gypsum board in fire-resistan~ applications in that fibrous mats which are lighter in weight than conventional paper facing ~re available. For example, the weight of a widely used paper facing in the manu- -~
¦ facture of conventional gypsum sheathing is in the range of about ¦ 120 lb~/1000 sq.ft. of board, whereas the weight of a preferred form of glass fiber mat for use in the present invention is about 40 lbs~1000 ~q.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 l fibrous mat-faced gypsum board as described herein can be used.
Shaft wall assembly 100 compxises metal framework consisting of ceiling- and floor-mounted J-tracks 101 and I-studs 103 for supportin~ gypsum board panels 110 and 112. J-tracks 101 are .. :

21 ~32662~

.
, 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 la7 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 bet~"een 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. -~
~ abs T are cut and folded out of the metal sheet from which I-studs 103 are made. The forming of such tabs results in forming holes 140 in body portion 114 of the I-studs.
Gypsum board panels 110 comprising the shaft liner panels of the assembly, are positioned between legs 106 and 107 of J-tracks 101, with the vertical edges of said panels being l friction-fit between the I-stud tabs T and flanges 109. Facing JI layers of gypsum board panels 112 are fastened by screw fasteners 113 to th~ face side 130 of shaft wall assembly 130. Two facing layers or plie~ of gypsum board panel~ 112 are illustrated, 1though it should ke understood that additional face layers of gypsum board may be applied, a~ desired. Facing layers of gypsum -l~ board may al~o be applied to the shaft side of the assembly in ;l 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 faced with glass mats, as described herein, and gypsum board panels 112 l~ (the facing layer-s 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 :i. ' ' . .
.

1 3 2 ~

:

and the use of fibrous mat-faced gypsum board in one or more ~-~
plies of the facing layers.

EXAMPLES

In the examples which follow, glass fiber mat-faced gypsum boards falling within the scope of the present invention were ~ --inst~lled and evaluated for fire endurance in test sections of ~-conventional shaft wall assemblies of khe general type shown in ;~
the drawings. -The metal compsnents of the shaft wall metal framework were supplied by Georgia Pacif ic Corporation and were manufac-tured from 25 gauge hot dipped galvanized steel. The components con~isted of four J-tracks having a 2 1/2" wide base portion from which 2 1/4" and 1" leg~ extended and a single I-stud which was 1 :~
1/2" wide and 2 1/2~ deep. The J~tracks were fastened by bolts to hori20ntal and vertical edges o.E a masonry framing structure. ~.
The end~ of the I-stud were friction-fit between the legs of the upper and lower horizvntally posit:ioned J-tracks. For conveni~nce, 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 of the assembly defined by mean plane of th~ ~hort 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 dimension.~ 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. Vertical edges of the boards, positioned ~i adjacent the I-stud, were friction-fit between the I-stud tabs -~
i~ and ~lange~, thereby sandwiching the I-stud between the edges of : .
,~ the boards. The oppo~ite vertical edges of the boards were i~: ' ' '' 1: . . .
.' .,~
,. :.
~ . . ~, .

secured to the long legs of the vertically positioned J-tracks by 1 1/4" Type S screws 24" on center (O.C.1 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 .I gypsurn over substantial area portions thereof. Each of the f boards was installed in its test assembly so that its gypsum-free face was exposed to the shaft side of the assembly. 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 o the metal framework. These facing layers are described in more detail hereinbelow.
i The resulting assembly positioned in the a~orementioned masonry frame formed one wall of a test furnace. The furnace was i f irff~d with multiple gas burners po~itioned such that the yellow luminous flame from each burner impinged on the face of the ¦ specimen thereby maintaining a uni~form temperature thereover.
¦ Furnace temperature was gradually increased according to the standard time temperature curve of ASTM E-ll9~ as shown below.

Timff (minutes) Temp. ~F)Time (minutes) Tem~. (F) 3 ~ 1000 120 18~fO `

Tf~mperaturf~ measurement~ of the test assembly were made by eight Chromel-Alumel~$ype K) thermocouples, four of which were ~ positioned on the furnace exposed side and the remaining four of f~ ; whifch were positioned on the unexposed side of the assembly.
: Fire endurance of each assf~mbly tested was measured as time taken for either ~1) the average temperature of the unexposed side, as measured by the four thermocouples, to reach f ~
,:~ . . .

~.

2S0F above ambient temperature or (2) an~ individual 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 from the start of 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.
'7 Two-Hour Tests , Five two-hQur fire endurance tests were conducted as j described below. In three of the tests, 1" thick glass fiber mat-faced gypsum board was installed in a test section of a conventional shaft wall assembly as described above. For comparative purposes, th~ other two tests were conducted using , conventional 1" thick paper-faced gypsum board sold undex the i trademark SHAFTLINER by Georgia-Pacific Corporation.
¦ In each shaft wall assembly tested, two facing layers (an inner layer and an outer layer i of gypsum board were Eastened to the face of the metal framework. These two layers consisted of 1/2" fire-r~sista~t gypsym board~ the core composition of which is set forth belowO Two such boards, each having dimensions of ;-~ 33" x 39'~, their longest dimensions oriented horizontally, were J fa~stened to the face side of the framework using 1" Type S
screws, 24" O.C. to form an inner facing layer. The ~oint 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 d~mension 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. ;
} - ~ . ,' ',~ ' '',":
} ~

7~

~32~6~

The aforementioned l/2" fire-resistant gypsum ~oards that were used in the tests are sold by Georgia-Pacific Corporation i under the trademark FIRESTOP, Type "XXX". Such boards have a density of about 48 lbs./cu.ft. and comprise a set core from the following composition. -Wt.% based on total , weight of ingredients I prior to addition of Inqredients mixin~water _ q finely ground calcium sulfate hemihydrate 94.67 clay (aluminum silicate) 2.59 , unexpanded vermiculite 1.10 '~ glass fiber roving, l/2" chopped glass fiber roving 0.44 core adhe~ive 0.52 dispersing agent 0.10 foaming agent 0.06 accelerator 0 52 --In three of the two-hour tests that were conducted, the shaft side of each assembly was exposed to the gas flame inside -~the furnace. The face side of the tested assembly faced outside the furnace and was not exposed to flame. Table 1 below includes a description of the l" boards that were used in the shaft wall --assemblies that were tested and the fire endurance rating for '~ each of the tested assemblies.
The glass fiber mat-faced gypsum boards referred to in Table 1 below, that is,~ those boards falling within the scope of t~he prese~t invention, were made utilizing nonwoven mat composed of glass fiber filaments oriented in a random pattern bonded ':;: ' : , ,; ~
: ,:

r ;' ~ " ~ !.

', ~6 132~2~

together by an adhesive referred to by the manufacturer as a "modified urea-formaldehyde resin". The ~at had a thickness of ~, 33 mils, and was more porous than paper oE the type used as the cover sheet of gypsum wallboard. The air permeability of the ~nat was 700 CFM/sq.ft. (test method FG 436-910). The mat is J, available commerciaLly as DURA-GLASS 7502-2 lbs and is an example 1 of a preferred fibrous mat for use in the practice of the present ~, invention. Continuous length board was made from an aqueous ,~ slurry of the gypsum formulations described in Table 1 below on a 1, ,~ conventional wallboard machine~ The slurry was fed onto a moving j 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 j 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 eclge of the mat and each of 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 I score marks and overlapped on top of the slurry. (The gypsum core formed from this operation hadl 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" wa~ fed onto the top of the gypsum slurry and the overlapped edge portions of the underlying mat. The gypsum ~1~ slurry penetrated the overlapped edge portions and served to bond I the edge portions of the overlying mat to the overlapped edge ¦ portions of the underlying mat. The viscosity of the gypsum slurry was about 5900 cp at 70~F. At this viscosity, the slurry penetrated substa~tially through some portions of the underlying mat to form a thln film thereof on about 40 to 50% of the area of 1 the outer surface of the mat. As the gypsum in the film set, ¦ substantial portions o the outer surface o the ~at were covered with a thin film of set gypsum. The surface had a roughened appearance with outlines of the glass filaments being observable '1 .1 ..
.1 . .. . .

27 ~ 32662~
"` .

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 of 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 8 feet. Drying of the gypsum board is accelerated 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.

-',:
;.~'.

.
:. : : - .
~ ~ , .
. . ~

.~ . . .

:, 1 , - , ' ' :l :

:
2~ ~3~2~

TABLE l ~
1 ., :.
I TEST l TEST 2 -~, glass fiber glas~s fiber TEST 3 mat-faced mat-faced paper-faced gypsum board, gypsum board, gypsum board, Board G-l Board G-2 Board P
calcium sulfate dihydrate ¦ glass fiber Z 18 2 18 (lbs/1000 ft.2)(0.056 wt%~(0.065 wt%) (0.15 wt%) paper fiber .
l (lbs/1000 ft.2)19.45* 19.45* l.0*
j board thickness 3 (inches) 1.023 1.081 0.963 density (lbs/ft.) 45 37 50 ~-~
j board weight (lbs/lO00 ft.2)3875 3348 4015 fire endurance (hours) 2.0 1.92 1.82 *The difference in paper fiber cont:ent is primarily due to the slurry VlSCosity control function which the fibers perform in regulating the degree of slurry penetration into the glass fiber a s.

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 of Board P, that is~ the conventional paper-faced board. Although Board G-l i9 10% less dense;than the conventional board, the shaft wall assembly containing Board G-l showed a 9% improvement ~n~;~fire endurance over the assembly which included Board P.
Although Board G-2 is 17.5~ 1ightex in weight and 26~ less dense than B~ard P, the shaft wall assembly including Board 5-2 showed ~ a 5% improvement in fire endurance over the assem~ly lncluding 3 ~ -'i~ , ~ .. :

~ 3 ~

., .
the conventional board. Thus, even though Boards 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 former boards showed an average 7% improvement in fire endurance over the assembly which included Board P.
¦ In contrast to t'ne previous three tests, the following two i tests were conducted on shaft assemblies in which the face side :
of the assembly was exposed to the gas flame inside the furnace; :
- the shaft side faced outside the furnace and was not exposed to flame. Table 2 below includes a description of the 1" boards `.
that were used in the shaft wall assemblies that were tested and the fire endurance rating for each of the tested assemblies.
.' .:

~ glass fiber TEST 5 :~ ~at-faced paper-faced .
I gypsum boa:rd,gypsum board, l Board G-3 Board P-l ..
l calcium sulfate -~ dihydrate glass fiber 2 2.18 5.9 :~ (lbs/1000 f~. )(0.06 wt%)(0.15 wt%) ~:
paper f`iber 2 (lbs/1000 ft. )19.45 1.0 : board thickness ~ : (inches) 1.086 0.977 density 3 (lbs/ft. ) 39 48 :~ :
: board weight 2 $:~ (lbs/1000 ft. ) 3534 3981 .,. ~ ..
fire endurance ;-(hours) 2.32 2.0 3 ..
t~, ~
, . ` .

:.

30 ~3~66~ ;
:
Calculations show that the core of Board G-3 contains 63% less glass fiber than the core of ~oard P-l, that Board G-3 is 11%
lighter in weight than Board P-l and is 20% less dense than Board P-l. Nevertheless, the shaft wall assembly including Board G-3 showed a 14% improvement in fire endurance over the assembly I including Board P~

Three-Hour Test ., ' '. ~
A three-hour fire endurance test was conducted as described below. A 1'1 thick glas.s fiber mat-faced board having a density of 42 lbs/ft.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-4, is set forth below.
Wt.% of Set & lbs/1000 ft 2 of set Constituents dried_Composition & dried Composition calcium sulfate dihydrate 99.081 3388.6 J 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 sulfona~te, "Micro Foam CF~) O.048 1.6 The face side of the assembly which was tested included ,~ three facing layers of conventlonal gypsum board having a thick- -,f : :

31 ~3~

ness of 5/8" and a core composition as set forth below. The innermost facing layer was formed from two such boards having respective dimensions of 15" x 66" and 24" x 65", their longest dimensions oriented vertically. These boards were fastened to the short legs of the J-tracks and I-stud flanges using 1" Type S
screws, 24" O.C. The joint formed between the edges of these boards was centered over the I-stud. T~e 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 of the test assembly was exposed to the gas flames of the furnace, the shaft side remaining unexposed to flames.
The paper-faced gypsum boards were Type "X" board sold by Georgia-Pacific Corporation under the trademark FIRESTOP. These facing boards have an average weight of 2350 lbs/1000 ft,2 and a core composition as set forth below.

... :1 . .
' Component lbs/1000 ft wt.%

l - .
- glass ~iber (chopped glass roving) 5.0 ~minimum) 0.2 core adhesive 13.0 (maximum) 0.53 dispersant 12.0 (maximum) 0.54 ..
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 120 l~s/1000 ft.2 ::.:
, i .. . .
. .' :.
., " ~ .
~, ''., ',-32 ~32~2~

During the test, the temperature of the flame-exposed face -of the assembly rose at a rate of approximately 88F/minute in the first 15 minutes of the test~ 9F/minute in the second 15 minutes, and 1.8F/minute for the remaining two hours and forty- -~
five minutes of the test, and reached an average temperature after three hours and fifteen minutes of about 1,910F. The average temperature measured on the unexposed face side of 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 unexposed ace side was 402F. It was reached in three hours and twelve minutes. Thus, 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 manifested by the develop-ment of crack~ or distortion, of either the furnace-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 three-hour rated shaft wall assemblies~ a 3/4i. Type "X" gypsum board is positioned in the assembly in the same manner as the 1'l 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, ~here being a space maintained between the third and outermost fourth layer of board. Thus, even though the glass mat-faced gypsum board described herein was but 1/4" thicker than the conventional paper-faced board, the shaft assembly with Board G-4 included only three facing layers (insterad of 4) of 5/8" Type "X"
FIRESTOP board to achieve a fire endurance of better than three hours.
It will be appreciated from the above described tests that 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 ' ", ~, .
...

~32~2~
, despite the fact that their cores are significantly less dense and contain a significantly smaller quantity of fire-resistant additives, namely glass fibers.
The next example involves the evaluation in a fire test of a 5/8" thick glass fiber mat-faced gypsum board having a core composition as set forth below and prepared according to the techniques described for glass fiber mat-faced gypsum boards of the earlier examples hexein.
Components Wt.%, set ~ dried board glass flber mat facing 1.58 calcium sulfate dihydrate 9~.. 06 glass fiber (1/2" chopped 0.08 glass roving) paper fiber 0.74 potash (accelerator) 0.15 wax-asphalt emulsion 2.96 poly(vinyl alcohol) 0.
calcium lingosulfonate - 0.11 (dispersing agent~
ammonium lauryl sulfonate O.04 (foaming agent) The density of the core of the board was 53 lbs/cu.ft. A fire -~
rating of 1 hour and 30 seconds was achie~ed when the board wa~
evaluated for flre resistance and hose stream resistance accord-ing to ASTM E-ll9. It is noted that the board has excellent water-resistant properties due to the use of watèr-resistant additives in its core, those additives being wax-asphalt emulsion --and poly(vinyl aLcohol).
The aforementioned examples well illustrate the excellent fire-resistant characteristics possessed by the development of ~j the present invention. In the examples and other portions oE the des~ription of the invention, reEerence has been made specifi-cally to~a shaft wall assembly including metal framework of particular design. It should be understood that fibrous mat-. : .

34 132~

faced gypsum board as described herein can be used in other types of 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 of the examples 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 invention provides ina practical way important functional improvements in structural assemblies which are intended to have fire-resistant properties designed to en=ure the safety of l1fe and property.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. 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 like thickness that has a like amount of chopped glass fibers in its core, said board characterized by the glass mat containing a plurality of interstices which are free of set gypsum.

2. The gypsum board of claim 1, wherein the core comprises at least about 0.03 wk.% chopped glass fibers.

3. The gypsum board of claim 1, wherein said core comprises about 0.03 to about 0.3 wt.% chopped glass fibers.

4. The gypsum board of claim 3, wherein said core has a density of less than about 47 lbs/cu.ft3.

5. The gypsum board of claim 1 wherein said core is sandwiched between two sheets of porous glass mat.

6. The gypsum board of claim 5, wherein said sheet of porous glass mat comprise randomly distributed glass fibers bonded by an adhesive material, said sheets of porous glass mat adhered to said gypsum core by a portion of said gypsum dihydrate.

7. The gypsum board of claim 1 further comprising a water-resistant additive in at least a minimum amount sufficient to further improve the fire resistance properties of said gypsum board.

8. The gypsum board of claim 1, wherein said core further comprises paper fiber in at least a minimum amount sufficient to further improve the fire resistance properties of said gypsum board.

9. The gypsum board of claim 1 incorporated into a shaft wall assembly comprising a fire-resistant frame work.

10. A glass mat-faced gypsum board comprising a set core containing gypsum dihydrate and at 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.

11. The gypsum board of claim 10 having a density of less than about 47 lbs./cu.ft.3 and at least about 0.03 wt.% of chopped glass fibers in its core.

36a 12. The gypsum board of claim 10, wherein said glass mat comprises a plurality of interstices which are free of set gypsum.

13. A glass mat-faced gypsum board comprising a set core containing gypsum dihydrate and uniformly distributed chopped glass fibers, aid board having a fire rating of at least about one hour when tested in accordance with ASTM E-119, said board characterized by the glass mat containing a plurality of interstices which are free of set gypsum.

14. A gypsum board including a set gypsum core having at least one porous, glass mat adhered to one face surface there-of, 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 through-out 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.

15. The gypsum board of claim 14 further characterized by a second porous, glass mat adhered to an oppositely facing surface of said set gypsum core from said first porous, glass mat.

16. The gypsum board of claim 15 further characterized by said second of said mats having an outer surface containing set gypsum permeating over substantial area portions thereof.

17. The gypsum board of claim 15 further characterized by said second of said mats comprising an outer surface which is substantially free of set gypsum.

18. The gypsum board of claim 14, wherein said mat is further characterized by containing non-woven chopped or continu-ous glass strand.

19. The gypsum board of claim 15, wherein said set gypsum core is further characterized by including a water-resistant additive.

20. The gypsum board of claim 15, wherein said core is further characterized by including a fire-resistant additive.

21. The gypsum board of claim 15 further characterized by said mats being adhered to said core during the fabrication of said core, said fabrication including disposing a gypsum slurry having a viscosity sufficient to prevent full saturation of at least one of said mats.

22. The gypsum board of claim 15 further characterized by said mats being adhered to said core during the fabrication of said core, said fabrication being without the application of any paper facings to said core or said mats and including disposing a gypsum slurry having a viscosity sufficient to prevent full saturation of at least one of said mats.

23. The gypsum board of claim 21, wherein said core is further characterized by including a viscosity control agent.

24. The gypsum board of claim 14 further characterized by a mechanical interlocking bond consisting essentially of a por-tion of said randomly distributed glass fibers and a portion of said set gypsum.

25. An exterior insulation system for a building, in-cluding a support surface, insulating material having an inner surface and an outer surface, the inner surface of Which is adhered to the support surface by an adhesive material, and an exterior finishing material overlying the outer surface of the insulating material, characterized in that the support surface comprises gypsum board according to claim 14.

26. An exterior insulation system according to claim 25, characterized in that the insulating material is substantially free of channels penetrating therethrough and between the inner and outer surfaces.

27. An exterior insulation system according to claim 25 further characterized in that the support surface comprises a plurality of the gypsum boards as panels in abutting relationship, with panels of the insulating material in abutting relationship adhered to the gypsum-free outer surfaces of the gypsum board panels, and exterior finishing material having weathering and aesthetic characteristics overlying the panels of insulating material.

28. An exterior insulation system according to claim 25 further characterized in that a reinforcing member is sandwiched between the insulating material and the finishing material.

29. An exterior finishing system for a building comprising an underlying structural support element which is covered with an overlying finishing material, characterized in that the support element includes gypsum board according to claim 14.

30. A shaft wall assembly comprising metal framework and gypsum board supported by said framework, characterized in that the gypsum board is gypsum board according to claim 14.

31. A method for installing an exterior insulation system in a building comprising affixing thereto a gypsum board, affixing insulating material having an inner surface and an outer surface to the gypsum board with an adhesive material, and affixing an exterior finishing material to the insulating material outer surface, characterized in that the gypsum board is gypsum board according to claim 14 and is affixed such that its substantially gypsum-free outer surface faces away from the building, and the insulating material inner surface is adhered to the gypsum-free outer surface of the gypsum board.

32. An exterior finishing system for a building character-ized by a support surface containing a gypsum board according to claim 14, 15, 16, 17, 18, 19, 20, 21, 22 or 23 having an inner and outer surface and an exterior finishing material overlying the outer surface of said board.

33. 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 he moving mat;
(d) applying to the top surface of the panel-like shape of slurry an overlying porous glass fiber mat having a pre-determined 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 calcined gypsum, the outer surface of the overlying mat is substantially free of set gypsum.

34. A process according to claim 33, wherein the under-lying mat comprises a porous glass fiber mat having an outer sur-face and a predetermined thickness, characterized in that the viscosity of the slurry is maintained at a value such that the slurry penetrates but part-way into the thickness of the under-lying mat so that, without the application of any paper facing to the outer surface of the underlying mat, upon the setting of the calcined gypsum, the outer surface of the underlying mat is substantially free of set gypsum.

35. 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 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 outer surface of said mat is substantially free of set gypsum.