CA2060060A1 - Method and apparatus for production of reinforced cementitious panels - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A method and an apparatus are described for pro-ducing light-weight construction panels having a cemen-titious core surfaced with a layer of reinforcing fabric bonded to the two faces of the core. The edges of the panel also are covered with the fabric. Cementitious slurry, for example, portland cement slurry, is applied to the fabric by means of a supporting plate over which the fabric is drawn and a doctor blade adjustably mount-ed above the plate. The supporting plate is of a non-base-reactive material such as polypropylene; the use of such a plate permits better application of the slurry to the fabric.

Description

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Method ~na Apparatus for I'roduction of Reinforced Cementitious Panels Background This application is a continuation-in-part of my copend-ing patent application, Serial No. 649,468, filed February 1, 1991. '' This invention relates to ~he production of fabric-rein-forced cementitious panels including gypsu~ w~llboard, 10 light-weight concrete panels, ~ile backerboards, and -the like. In generàl, such cementitious panels ar~ fastene'a to the framing of a wall or building exterior or over a sub-floor, to serve as a backerboard for the installation of a facing material such as ceramic tile, thin brick, -thin 15 marble panels and stucco. However, they also are used with-out a hard facing material as with the application of a layer of paint or wallpaper.
More particularly, this invention relates to a novel meth-od and apparatus for producing cementitious backerboards 20comprising a panel having a core of lightweight concrete with the faces being reinforced with a layer of fabric bonded thereto. Such cementitious panels are described in U. S. Patent No. 3,284,980 (1966) P. E. Dinkel, U. S. Patent No. 4,450,022 (1984~ R. E. Galer et al and U. S. Patent No-254,916,004 (1990~, R. P. Ensminger et al. These panels arenailable and are readily fastened to framing members and the like with nails, screws or other ~asteners. Since the panels are of concrete they are substantially unaffected by water a~d consequently find ex-tensive use in wet areas such 30as shower enclosures, bathtub surrounds, kitchen areas and entryways as well as on building exteriors.
However, my invention is not limited to the production of cementitious backerboards having a core of lightweight con-crete. Included within the class of cementitious panels to 3swhich my invention pertains are panels having a gypsum core such as the gypsum boards with a fibrous mat face as described in U. S. Pa-tent No. 4,810,569 (1989), 3. G.
Randall~ Other examples of gypsum wallboards are des-cribed in U. S. Patent No. 4,518,652 (1985), M. D. Will-5 oughby, and u. S. Paten-t No. 3,993,822 (1973), A. Knauf.
Cementitious panels are yenerally produced ernploying a core mix of water, a cementitious material (e.g., portland cement, magnesia cement, alumina cement, gypsum and blends thereof) and a lightweight aggregate (e.g., expanded clay, 10 expanded slag, expanded shale, perlite, pumice, expanded glass beads and polystyrene beads). The core may also contain foamed gypsum or oamed portland cement composi-tions, and may contain no aggregate.
~he reinforci~g fabric most generally employed is a 15 fiber-glass scrim, in particular, a woven mesh of pol~-vinylchloride coated glass-fiber yarns. The fabric is bonded to the core by a cementitious slurry, for example, a portland cement slurry, or is bonded by the core mix composition itself extending through the openings in the 20 fabric.
In the present invention the reinforcing fabric is per-vious; the openings in the mesh, scri~ or other fabric are sufficiently large to permit passage of the fabric ~onding material such as a portland ce~ent slurry with or `I 25 without an aggregate added. Fabrics other than glass--fiber meshes, such as fabrics of synthetic resin fibers, for example, nylon fibers, polyvinylidene chloride fibers and polyester fiber yarns coated with PvC, can be used.
Recently fabric reinforced panels with fabric-wrapped edges have been introduced. U. S. Patent No. 4,916,004 (1990) R. P Ensminger et al describes such a cement board with longitudinal edges (as well as the top and bottom surfaces) reinforced with fiber-glass mesh; in this patent the reinforcing mesh is completely embedded in the core material on all surfaces.
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Another development has been that of a fabric reinEor-ced cementitious panel with the longitudinal edges wrap-ped with the fabric, but with the fabric left open 5along the edges, as described in U. S. Patent No .
5,030,502 (l99l) J. W. Teare.
In each of these two developments the fabric reinfor-ces the longitudinal edges to provide better edge strength. Where a nail or screw is inserted close to the 10edge of a panel in fastening to the narrow face of a stud or other framing member the fabric minimizes break out of edge and provides more secure attachment of the panel to the framing.
Description of the Invention My invention relates to a novel means for applying a cementitious slurry to a moving web of a pe~vious rein-forcing fabric and furthermore for applying slurrY in a selected longitudinal section. It has particular appli-cation in the production of the wrapped-edge type fabric 20reinforced panel.
In my invention the web of fabric is passed over a sup-porting member such as a plate, a cementitious slurry is fed to the upper surface of the web and then is spread uniformly over the web in controlled amo~mt by means of 25a doctor (blade, bar or roller) adjustably spaced from the supporting member or by other means as described herein.
~he web is drawn out of the slot formed by the doctor and supporting pla~e,t~ereby applying the desired coating of slurry; the web is then deposited upon the appropriate 30surface. If it is the first web it is deposited upon the carrier (e.g., a plastic coated paper web or plastic carrier sheet) on which the panels are formed. If it is the second web it is deposited upon the upper face of the core layer.
In the manufacture of these fabric-reinforced panels it is essential that the web of pervlous fabric must be adequately coated with the slurry on both the lower and upper surfaces and that the openings in the pervious fabric be filled with the slurry. This is necessary in 5order to secure adequate bonding of the web to the core layer. Even where the web is properly coated and the openings filled, the amount of s:Lurry carried by the web is very small. In general, all of this light layer of slurry is needed in order to obtain good bonding of the 10 web to the core layer. A heavier layer of slurry on the mesh might be required for some purposes but a heavy layer tends to make the panel surface too hard, impairing the nailability of the panel, or makes the panel unduly heavy.
I have discovered that with a supporting plate having a non-base-reactive surface, the web of fabric, as it is drawn over the plate, is suitably coated with a layer of the slurry in the desired amount on the bottom surface as well as on the top surface and openings in the web are 20filled. There is little or no tendency for the slurry to cling to such a supporting plate and consequently this eliminates the tendency to drag the slurry off the bottom surface of the web. As can be appreciated, where the slurry is wiped off of the surface of the web there will 25be an inadequate amount of material to effect bonding to the core layer. This is especially true in the case of the top or second web which must be laid down on the core layer.
Cementitious slurries, such as a portland slurry, are 30strongly basic; a portland cement slurry is very alkaline with a pH of at least 11-12, due to the presence of cal-cium hydroxide. These slurries tend to react with,or have an affinity for, base-reactive surfaces and conse-quently have a decided tendency to c~ing to these sur-35faces. With a supporting plate of a base-reactive mater--ial the slurry in a large measure is wiped off the bottom .. . .. .... . .. . ...

5~3 face of the fabric web. Examples of base-reactive (or acidic) materials are certain metals such as aluminum, tin and zinc and polymers such as acetals, polyesters, 5 polycarbonates and silicones, and phenolic and urea-formaldehyde resins.
Non-base-reactive materials which I have found to be suitable as the surface of the supporting plate include various polymers; polyethylene, polypropylene, poly-10styrene, fluorocarbon polymers ("Teflons") such as poly-tetrafluoroethylene and perfluoro(ethylene/propylene copolymers), methyl methacrylate polymer ("Ple~iglas"), various nylon resins such as nylon 612 ~r a"Nylotron GX"
sheet:, polypheny~ene oxide, polyphenylene sulfide and 15polysulfones. These are by way of example and are not intended to be exclusive of other non-base-reactive poly-mers.Because..~. the very large nu~b,e.~ of polymers that have been developed and are continuing to be developed, and with many different properties being imparted by 20copolymerizat.ion, chemical group substitution, different degrees of polymerization, and the like, it is not pos-sible to specify all of the non-base-reactive polymers.
One skilled in the art will be able to select a non-base-reactive material that would be most suitable, 25functionally and economically, for the intended panel production process. The supporting plate can be entirely non-base-reactive.material or only the surface of the plate can be o~ a non-base-reactive material.
A polymer which in one form may function properly as a 30non-base-reactive surface may fail if used in a modified form or may fail due to the operating environment. An example is a rigid polyvinylchloride plate which can be-come base-reactive due to the tendency of PVC to dehalo-genate under certain conditions resulting in an acidic 35surface.

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Good smoothness of the surface of the supporting member is ~ factor. Normally the surface of the supporting mem-ber, such as a new polypropylene plate, nylon plate or 5stai.nless steel plate will be smooth as installed. wear of the plate surface due to the abrasiveness of the port-land cement particles in the slurry and of an~ aggregate added to the sluxry, as well as of the sliding action of the web of fiber-glass mesh, can cause the plate surface 10to become roughened. When weax occurs even a non-base-reactive surface will not function properly and will tend to drag the slurry off the face of the web of mesh. For example, I have found that a methyl methacrvlate plate ~ lexiglas from Rohm and Haas) will function properly 15for several days until the surface becomes roughened by wear. It then tends to exert a dragging action, wiping the slurry off of the mesh surface in some longitudinal areas and eventually across the width of the mesh. Con-sequently the sup~orting member will need to be removed 20and replaced with a new plate or a re~surfaced plate.
For long, continuous operation of the panel production machine good abrasion resistance of the plate surface is needed so as to retain a relatively smooth, non-dragging surface. Thus, while the plate that is employed has a 25l~o~ C~o~ c~ive s.l1r~ce, iF i~ is not wear resistant the plate w:il.l need to l~c rel~1aced ~requently with re-sulting interruption of the machine. I have found that the filled polymers such as filled epoxies and compo-sites such as the polypropylene/fiber-glass sheet sold 30by Azdel, Inc., Shelby, NC, under -the name "Azdel"
function reasonably well as wear resistant non-base-re-active surfaces. An "Azdel" plate can be used for as long as two weeks before the surface becomes so abraded that it will need to be replaced. Furthermore, I have 3sfound that stainless steels provide not only a non-base-reactive surface but also good abrasion resistance and 2~a,n~ S~"~

permit longer running time. Stainless steels such as SS 304 and ss 316L work well, providing a surface life substantially in excess of two weeks. The chi~omium used 5 in the stainless steels lencls p~ssivity to~provi~e a strong non-base-reactive surface. A chromium plated steel plate also provides a very good non-base-reactive abrasion-resistant surface as -the supporting member. The surface of the s-tainless steel or chromium plated member should be 10 ground and/or polished to provide a smooth and true face.
Although various carbon steels behave as non-base-reactive materials the abrasion res~stance m~y nO~ be adequate.
As is apparent the supporting member must present a true plane in the transverse direction, at least at the 15 point where the web of mesh passes under the doctor blade, or if no doctor is employed, then at the point at which the mesh leaves the memher. Otherwise the coating of slurry deposited upon the mesh will be non-uniform. If the surface is out as little as 0.005" from the true plane the result 20can be unwanted heavily coated areas, for example, a bead along the edge.
The choice of non-base-reactive material thus de-pends upon the use to be made and the operating conditions and economics. I'hus, if it is practical to change the plate 2sfrequently, then the "Azdel" polypropylene composite sheet can be employed. The "Teflon" polymers afford good alkali resistance (non base~reactive) but are not abrasion resis-tant. While the UHM~1 polyolefins are not only non-base-reactive but also abrasion resistant, a plate of the mater-30ial is difficult to hold in a true plane. Certain rubber-ized coatings or elastomeric coatin~s which~provide a non-base-reactive ~rface having desirable abrasion resistance can be-used if bonded to a substr~te in a true plane.
Where a doctor is employed, for best results, the 35surface of the doctor also should be of a non--base-reactive material, such as a polymeric material,to minimize clinging ~., , . ~:: . . ,: : , , . . ........ ~, :

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of the slurry to the doctor, thus reducing any tendency of the doctor -to wipe bare the top surface of the web.
It is necessary that the working edge of the doctor and 5 the face of the supporting member be ma-tched to provide a uniform slot.
My invention includes means for produciny fabric reinforced cementi-tious panels having fabric-wrapped lon-gitudinal edges and in par-ticular it includes means for 10 producing such panel.s with ~e fabric on the edges ~eing substantially open and free of slurry or the like. Such panels, having open fabric along the longitudinal edges, offer the advantage of improved edge-to-edge bonding of the panels when they are installed abutting each other 15 as in the construction of a wall.
In order to produce such wrapped-edge cementitious panels the first web of reinforcing fabric (which forms the bottom layer of the panel) is wider than the panel width; the center section of the web reCeiveS the core 2Qlayer and a margin section of the web on each side of the center is folded over to wrap each of the two edges of the core layer and also to extend over on to the -top face of the core layer. The slurry is applied only in the longitudinally extending center section of this web where 25it is to be bonded to the bottom face of the core layer.
Subsequently a second web of fabric with slurry applied is deposited upon the top surface of the core layer to cover the top surface and to overlay the margin strips of the hottom web that ha~e been folded over the edges.
30Bonding material such as a portland cement slurry is ap-plied to t~e second web either before or after it is laid down on the core layer.
Description of the Drawings Fig. l is a diagram of the sequence of steps em 35ployed in producing fabric-reinforced cementitious panels.

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Figs. 2A-2D illustrate, in cross~sectional views, the steps of placing the fabric web, in the for~nation of wrapped-edge cementitious panels having open-mesh edges.
Fig. 3 is a par-tial cross-~sectional view of a 5 fabric-reinforced cementitious panel with an open-mesh wrapped edge.
Fig. 4 is a side view of the slurry applicator Fig. 5 is a side view of a modified slurry appli-cator with guides.
Fig. 6 is a top view of a web of reinforcing fabric at the slurry application station showing applicatlon o the slur~y to a ;selected longitudinal section oE the web.
~ig. 7 is a side view of a second embodiment of my slurry applicator which re~uires no doctor.
Fig. 8 is a side view of n~y slurry applicator which employs an air knife doctor.
Detailed Description of the Drawings Fig. 1 illustrates, diagramatically, a conventional 20 process for producing fabric-reinforced cementitious panels. In the process aescribed in U.S.Patent No. Re 32,038 tl980), T.E.Clear et al, the panels are formed on abutting carrier sheets on a moving conveyor belt.
Methods and apparatus for forming such panels on a web of 2 plastic coated paper deposited on a aonveyor belt are di~-closed in U.S.Patent No. 4,298,413 (1981) Teare, and in U.S.Patent No. 4,450,022 (1984), Galer.
Figs. 2A-2D illustrate in cross-sectional views the sequence of steps in the folding of the fabric web to form a wrapped-edge, fabric-reinforced cementitious panel with the section of fabric on each of the longit-udinal edges of the panel being open and unbonded.
Numeral 2 indicates one of several abutting plastic carrier sheets supported on a moving conveyor belt 1. In 35 Fig. 2A a web of woven fiber-glass mesh 4 (first mesh), 2r~ r~

coated in center section 9 with a portland cement slurry 5, is deposited on carrier sheet 2; the two margin sec--tions 10 and 10' of the mesh. are left uns].urried. Numer-5 al 4a indicates the slu.~ried web.
In Fig. 2B the two margin sections 10 and 10' are folded upward by suitable guides into a more or less ver-tical position after the core mix is deposited upon the slurried center sectiOn 9 and shaped to form the core 10 layer 12. The bottom of Core layer 12 becomes bonded to :~he center section 9 of mesh 4 by slurry 5.
In Fig. 2C the margin sections 10 and 10' of mesh 4 are folded over onto the top face 11 of core layer 12.
In Fig. 2D a second web of woven fiber-glass mesh 14 (second mesh),.coated with a portland cement slurry 13 is laid on top face 11 of core layer 12, covering the portions of the margin sections 10 and 10' of mesh 4 which are folded over on the top face of the core layer. The tap we~ 14 can be coated with slurry before or after it is 20laid down upon the core. The edges o~ the mesh 4 thus become bonded to the top face o~ the core laye.r 12 at 15 and 16' and to the web of mesh 14 by virtue of the sl.urry 13 applied to the mesh 1~. A fabric-reinforced cementi~

tious panel web ~,as a wet ribbon) sui.table for cutting , ' ;
2sinto individual panels is thus formed. The subsequent steps in the process, that of cutting the panel web into panel lengths, stac~ing and curing, are not shown as such : are old in the art.
Fig. .3 shows a partial cross-sectional view of a wrapped-edge fiber~reinforced cementitious panel as:form~ '~r?
ed by the foregoing steps. Specifically, it shows the ~esh on the wrapped edge of the panel as bei.ng open, num-eral 16, that is, s~stantially ~ree of slurry and core material, in a condition to receive the edge bonding 3smaterlal (mortar, etc.) ... .. ..

In order to provide the means Eor applying slurry to a selected section of the reinforcing fabri.c web I
have developed a novel slurry applicator. This is des-5 cribed with reference to Fig. 4. It is described in thispart of the specification as the applicator for the first mesh as discussed under Fig. 2A. The web of reinforcin~
fabric 4, as it is advanced, passes over supporting pla~e 3 and under doctor 6 (a blade, roller or bar) which 10 spreads cementitious slurry 5 (in this example a portland slurry), fed from tube 5a, uniformly on the web, coating both faces thereof and filling substantially all of the openings in the mesh web. The slurried web 4a is then laid down on carrier sheets 2 moving on conveyor belt l.
The doctor 6 is adjustably spaced from the supporting plate ~ to permit control of the amount of S]Urry applied to the web 4 . End dams 8, separately mounted but co-acting with doctor 6, ~onf ine the slurry .
As discussed elsewhere in the specification, the 20surface of the supporting plate must be a non-base-reac-tive material, for exarnple, nylon, UHMW polyethylene or stainless steel.Preferably the entire plate is of a non-base-reactive material although it is sufficient that the surface of the plate is a non-base-reactive material.
25I have found that by using such a non-base-reactive sup-porting plate, the web can be fully coated on both sur-faces with su~ficient layer of slurry, on the bottom face, as well as the top face, in one simple operation. Fur-thermore, with this applicator, even with a 9 x 9 mesh 30which has relatively wide spacing of the yarns and there-fore relatively large openings, virtually all of the mesh openings are filled. The result is that the mesh carries sufficient slurry for a substantially complete coverage of the face of the panel.
Fig. 5 shows a modi~ication o~ the slurry applica-tor. Guide 7a serves to hold the mesh 4 down on support-~ 5,~ r~

ing plate 3 with slight tension thereby eliminating wrinkles and puckers in the mesh. As a result a more uniform coating of the web is obtained as the web is 5 held flat as it slides off of -the plate. Guide 7 lifts the mesh 4 off of the plate slightly to facilitate pen-etration of the slurry -through the mesh.
In Fig . 6 the application of slurry to a selected longitudinal section of the web (in this example, the 10 central section) is shown. A web of reinforcing fabric 4 is advanced over supporting plate 3 which is of a suit-able length to span the width of the web 4. DOctor blade 6 is sui-tably mounted above plate 3 and adjustably spaced therefrom. Adjustable end-dams 8' a~d 8", independently 15 mounted but in co-a~tlng relationship with doctor 6, are spaced to the desired width 9 of application of slurry 5, The slurry 5 is fed to the doctor area by means of hose - 5a. As the web leaves the slurry applicator, that is as it leaves doctor 6, the selected section 9 of the web will 20be properly coated with slurry 5, top and bottom faces and - the openings in the mesh filled, while the margin sections 10 and 10' will be free of slurry, ~i!e. for the open-mesh edges).
In a second embodiment o~ my invention, the use of 2sa doctor to spread the slurry uniformly Over the mesh is eliminated. This slurry coater is shown in Fig. 7. The supporting member, plate 3,is inclined upward in the direction of travel of the mesh web 4. Slurry 5 is spray~
ed across the desired width of the web by spray nozzles 305b, in controlled amount to provide the desired coating of slurry on the mesh. Adjustable side dams (not shown) define the width of the longitudinal area of the mesh web being coated. The length of plate 3 and its angle of in-clination are regulated to permit the slurry to level 3sout before -the mesh 4a leaves plate 3. The non-base-.

r~nctlv~ natur~ o~ th0 ~urfac~ o~ pl~to 3 ~nak~ thl~
~thod ~e~lbl~ .
~n Fl~ lr knl~, hown at 17, 1~ ~mployed 8 to pr~ad thd lurry unlformly over the mellh ~n~ to roll b~lck t~a ~xce~ lurry. A~ th~ h web ~ a~ro~
plate 3 ~lurry 5 11l f~a ~o~ plpo 5a. P~osaurlzo~ ~lr 1~ od to th~ knlfo 1~ f~ air llno la. A tbln hl~d~ o~ ~lr ~ltted fro~ nozzle 19 r~moYes th3 oxc~
10 slurry 5c l-avlnq a unlform co~tlng o~ ~lurry on thss ~ h.
Ad~u~tabl~ ol~ dam~, not ~hown, control tho ~idtb o2!
tho longltud~nAl ~roa o ths ~nesh th~t 10 b~lng co~ted.
Exc~3~ Dlu~y 5C flowo o~ the end o~ plat~ 3 ~nd is ~ught ln pan 20 ~or r~cyeltng. Tbo omDunt of ~lur~y 16r~tained on ~e~h at 4a 1~ xegulat~d by ~h8 ~lr pr~6ure and ~nql~ ol! lnc~derlc~ 9~! th~ ~lr knlfe.
My slurry appllc~tor, Fig. 4 or Plg. 5, i~ adapted to apply ~lurry to tl~ ~11 wide~ o~ ~ wo~ of abrlc, a~
~all ~ to ~ele~ted longitudlnal sect~on~, by UBO 0 20 ~uf~lclently long dootor and by sult~ble place~ent o~
tho end-dh~3. ~h~ web o~ me~h 14 in Plg. 2D for ~xample, can b~ co~t~d wi~h ~lurry a~ro~s ~t8 ~ull w~dth.
Thu~ y invent~c!n i~ ~lso u~e~ul in producina wrap p~d-edge Sab~ reil3forced p~nclA of tho type h~v~ng ce-25 ~cntitlous ~onding materi~l covering and em~edding th~~ei~orcing ~z~ric on all o~ tho ~urfaces, tha. i~ on the top asld bottom ~ac~s of tho core ~g well a~ along ~ç~
longitudin~l e~ge~ . Sue~ pan~l~ a~ descri~d ~ n U . S .
P~eer~t 2to. 4,916,00~ ~Ensmingerl. ~r~a end~ o~ my 30qlurry ~pplicator ~xo set to the full wld~ of ~a web ~e~h) ~o ~ to apply ~h~ 31~ry or othor cemeneitious m~tesi~l to the ~ull w$dtb, and th~ me~h ~ then folded around th~ edges o~ a~r~ l~yer in tha manner ~how~
~n ~ig~. 2A-2D. Howevor, it~ casa th~ m~rgin sec-35eiOn~ o~ tho ~esh folded arc~und th~ core edge~ are ~lurrycoated, embedding th0 mo~h on the edges.

~ , ,, Whlle I have described my invention wlth re~erence to the supporting member in the slurry applicator as being a "plate" and in the drawings have shown the sup-5 porting member 3 as a flat plate my invention is notlimited to such. The supporting member can a~so be a somewhat curved plate or arcuate surface or a non-rotat-ing roll. A roll having a non-base-reactive surface offers the advantage that at such time as a given axial 10 area o~ its surface becomes worn the roll can be rota~
ted a few degrees to present a non-worn surface area.
This would reduce or eliminate the time required to re-place the supporting member.

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Claims (15)

1. A method of applying a cementitious slurry to a pervious reinforcing fabric web to coat both faces thereof and to fill the openings in said web, which comprises advancing said web over a supporting member having a non-base-reactive surface, depositing cem-entitious slurry upon said web and spreading said slurry over said web while supported by said member.

2. The method as claimed in claim 1 wherein said slurry is spread by a doctor having a non-base-reactive surface.

3. A method of producing a fabric reinforced cementi-tious panel web suitable for cutting into individual panels, which comprises advancing a first pervious re-inforcing web over a supporting member having a non-base-reactive surface, depositing cementitious slurry upon said first web and spreading said slurry on said first web while said first web is supported by said mem-ber to thereby coat both faces of said first web and fill the openings thereof with said slurry, depositing a cementitious core mix upon said first web, shaping said core mix to form a core layer, advancing and laying a second pervious reinforcing fabric web on the upper surface of said core layer, and bonding said second web to said core layer, thereby forming a panel web.

4. A method of applying a cementitious slurry to a per-vious reinforcing fabric web to impregnate and to coat both faces thereof in a selected longitudinal area which comprises advancing a pervious reinforcing fabric web between a supporting member having a non-base-reactive surface and a doctor with adjustable end dams spaced apart to the width of said selected longitudinal area, depositing a cementitious slurry upon said web between said end dams thereby coating both faces of said web said web and filling the openings in said web with slurry in said longitudinal section as said web advances across said member and under said doctoring means.

5. A method of producing a fabric reinforced cementitious panel web suitable for cutting into individual panels, which comprises advancing a first pervious reinforcing web over a supporting member having a non-base-reactive sur-face, depositing cementitious slurry upon said first web and spreading said slurry on said first web while support-ed by said member, thereby coating both faces of said web, depositing a cementitious core mix upon said first web in a selected central longitudinal section thereof of panel width and shaping said core mix to form a core layer in said central longitudinal section, folding each of the two margin sections, one on each side of said central section, of said first web around a longitudinal edge of said core layer and over and onto the upper face of said core layer, depositing a second pervious reinforcing web upon said upper face of said core layer to cover said upper face and to overlay said folded-over margin sections, and bonding said second web to said upper face of said core layer and to said folded-over margin sections.

6. A method of producing a fabric reinforced cementitious panel web suitable for cutting into individual panels, which comprises advancing a first pervious reinforcing web over a supporting member having a non-base-reactive sur-face, depositing and spreading cementitious slurry upon said first web in a selected central longitudinal section of said first web while leaving the two longitudinal mar-gin sections, one on each side of said central section of said first web, free of said slurry, said central section being of panel width, depositing a cementitious core mix upon said central section of first web, shaping said core mix to form a core layer, folding each of said two longi-tudinal margin sections around a longitudinal edge of said core layer and over onto the face of said core layer, depositing a second pervious re-inforcing web upon said upper face of said core layer to cover said upper face and to overlap said folded-over margin sections, bonding said second web to said core layer and said folded-over margin sections, while leaving those por-tions of said first web which wrap and are along said long-itudinal edges of said core layer substantially free of said slurry.

7. The method as claimed in claim 3, 5 or 6, wherein said second web is advanced over a supporting member having a non-base-reactive surface, cementitious slurry is deposited and spread on said second web while supported by said mem-ber to thereby coat both faces of said second web and fill the openings thereof.

8. The method as claimed in claim 1 or 4, wherein said surface of said supporting member is a metal selected from the group consisting of stainless steels and chromium-plated steel.

9. The method as claimed in claim 1 or 4, wherein said surface of said supporting member is a polymeric material selected from the group consisting of polyolefins and poly-olefin-glass-fiber composites.

10. Apparatus for simultaneously applying cementitious slurry to both faces of a web of pervious reinforcing fabric which comprises:
- a fabric web supporting member having a non-base-reactive surface, - means for advancing a web of pervious reinforcing fabric across said member surface, - means for feeding cementitious slurry onto said web while advancing across said supporting member, and means for spreading and metering said slurry thereby coating both faces of said web and filling the openings thereof.

11. Apparatus for producing a fabric reinforced cementi-tious panel web suitable for cutting into fabric rein-forced cementitious panels which comprises:
- conveyor means, - a fabric web supporting member having a non-base-reactive surface, - means for advancing a first web of pervious rein-forcing fabric across said member, - means for depositing and spreading cementitious slurry upon said first web as it is advanced across said member to coat both faces thereof and to fill the openings thereof, - means for depositing a core layer on said first web, - means for advancing a second web of pervious rein-forcing fabric, - means for applying cementitious slurry to said second web, and - means for depositing said second web on the upper face of said core layer in bonding contact therewith thereby forming a fabric-reinforced panel web.

12. Apparatus for producing a fabric reinforced cementi-tious panel web suitable for cutting into fabric reinforc-ed cementitious panels having fabric-wrapped longitudinal edges with the fabric along said edges being open and sub-stantially free of slurry, which comprises:
- conveyor means, - a fabric supporting member having a non-base-reactive usrface, - means for advancing a first web of pervious rein-forcing fabric across said member, - means for depositing and spreading cementitious slurry upon said first web as it is advanced across said member, - doctor means adjustable spaced from member, - spaced end-dams co-acting with said doctor to confine said cementitious slurry to a longi-tudinal section central of said web, said section being of panel width, said doctor means serving to spread said slurry over said section central of said web to coat in controlled amount both faces thereof and to fill the openings thereof while leaving the two margin sections of said web substantially free of said slurry, - means for depositing a core layer on said web in said central area, - means for folding each of the two said margin sections of said web around a longitudinal edge of said core layer and onto the upper face of said core layer, - means for advancing a second web of pervious re-inforcing fabric, - means for applying cementitious slurry to said second web to coat both faces thereof and to fill the openings thereof, and - means for depositing said second web on the upper face of said core layer to overlap and bond said folded-over margin sections of said first web to said upper face of said core layer, thereby forming a fabric-wrapped-edge panel web.

13. The apparatus as claimed in claim 12, wherein the means for applying cementitious slurry onto said second web comprises:
- a fabric web supporting member having a non-base-reactive surface, - means for depositing cementitious slurry upon said second web as it is advanced across said supporting member, and - means adjustably spaced from said supporting member to spread said slurry to coat both faces of said second web in controlled amount and to fill the openings thereof.

14. Apparatus for producing a fabric reinforced cemen-titious panel web suitable for cutting into fabric re-inforced panels having fabric-wrapped longitudinal edges which comprises:
- conveyor means - a fabric web supporting member having a non-base-reactive surface, - means for advancing a first web of pervious rein-forcing fabric across said member, - means for depositing and spreading cementitious slurry upon said first web as it is advanced across said member, - means for depositing a core layer on said first web in a longitudinal central section thereof, leaving a margin section on each side of the center section substantially free of core layer material, - means for folding each of the two margin sections of said first web around a longitudinal edge of said core layer and onto the upper face of said core layer, - means for advancing a second web of pervious reinforcing fabric, - means for applying cementitious slurry to said second web, and - means for depositing said second web on the upper face of said core layer to overlap and bond said folded-over margin sections of said first web to said upper face of said core layer, thereby forming a wrapped-edge fabric-reinforced panel web.

15. The apparatus as claimed in claim 11 or 14 wherein the means for applying cementitious slurry onto said second web comprises:
- a fabric web supporting member having a non-base-reactive surface, and - means for depositing and spreading cementitious slurry upon said second web as it is advanced across said supporting member.