FI92167B - Cement board with reinforced edges - Google Patents

Description

92167

This invention relates to the continuous manufacture of a reinforced cement board. More specifically, it relates to a method and apparatus for casting a cement mass into a thin, unlimited length sheet, the surfaces and longitudinal edges of which are reinforced with a fibrous mesh embedded immediately below the cement surface. However, the present invention relates specifically to a bare cement board having surfaces and longitudinal edges reinforced with a fiber mesh below the surface of the board.

Cement board, a thin reinforced concrete slab, has become increasingly popular over the last two decades as a durable substrate for ceramic tiles in bathrooms, 15 shower rooms, and other spaces where water often splashes into the walls and has a high moisture content. Interest in the use of cement boards in the external walls of buildings as a non-load-bearing surface structure is also constantly growing. In such applications, the concrete surface 20 is not required or desired to be coated. Because the panels are often attached at their edges to the building frame with needles or screws, it is highly desirable that the longitudinal edges of the panels be completely and uniformly filled and that they be reinforced at least as well as the end surfaces of the panels. The edge areas of the surfaces near the edges of the plate must not be thicker than their central areas so that the wall becomes smooth and not wavy.

Reinforced sheets, the inner part (core) of which is formed of a cement mixture, are already known. U.S. Pat. No. 1,439,954 relates to a building board having a gypsum or Portland cement interior, in which a mesh material, such as a cotton gauze, metal fabric, perforated paper or perforated fabric, is applied to both surfaces of the interior while the cement mass is still flowable.

U.S. Patent 3,284,980 (Dinkel) discloses a cast, lightweight concrete slab having a cellular interior, a thin, highly dense layer on each of its surfaces, and a fiber mesh layer embedded in each dense layer.

Each slab is individually cast in molds as a step process in which a thin layer of dense concrete is first formed, a mesh is placed on it, a lightweight concrete mixture is poured over the mesh to form an inner layer, a second mesh layer is placed on the inner mixture and a second layer of dense concrete is poured on the second mesh layer.

U.S. Patent 4,203,799 (Clear) describes a continuous process for making Dinkel absolute sheets. In said method, a continuous web of glass fiber-15 is fed through the cement mass, the net containing the cement mass is guided on several moving support sheets, the lightweight concrete mixture is placed on the net as it moves with the support sheets and another continuous web web is guided through the cement mass and placed on the lightweight concrete part. The elongate concrete slab then moves to the cutting station where it is cut into separate slabs.

U.S. Patent 4,159,361 (Schupack) discloses a cold-formable cement board in which fabric reinforcement layers are associated with a cementitious interior. The layers of reinforcement fabric and cementitious material for the board developed by Schupak come to the vibratory shaping table from a carriage that reciprocates longitudinally on top of it. The inner part of the cement is leveled with a laterally moving leveling board.

GB patent application 2,053,779 describes a continuous method of manufacturing building boards comprising placing a permeable fabric on a lower support surface, guiding a mass of binding material, e.g. gypsum plaster 35, onto said movable fabric, arranging the free surface of the mass 921 67 3 to contact the second fabric, guiding the pulp below the second support surface and advancing the pulp comprising the fabric surfaces between the two support surfaces by vibrating said surfaces. The vibration is said to cause the mass to penetrate through the fabric, forming a thin, continuous film on the outer surfaces of the fabric.

A common problem in all methods of making fiber mesh reinforced cement boards is the formation and reinforcement of smooth, uniform longitudinal edges. Schupack suggests using a denser woven reinforcing fabric at the edges of the board, but the fabric does not go around the vertical edges of the board. Said problem becomes particularly difficult when trying to make continuous production economical. The fiberglass mesh, which in most cases is chosen as the reinforcing material, does bend easily, but because it is flexible, it returns to its original shape when the bending force ceases.

In a method of continuous fabrication of a fiber-reinforced cement board, U.S. Patent 4,450,022 (Galer), the edges of the movable backing sheet are bent vertically as the concrete mix is directed into the fibrous web on top of the backing sheet. The trough-shaped sheet then forms 25 molds for a continuous concrete web. Once the mixture has been applied throughout the lower net and the second net is embedded in the upper surface of the mixture, the vertical edges of the backing sheet are turned over the upper surface. However, the fibrous nets have not been turned around the edges of the cement board. Indeed, even filling of the edge portions of the cement board has been a continuing problem prior to the invention disclosed and claimed in the present patent application, even when using the improved concrete mix distribution method described by Galer in U.S. Patent 4,504,335. Uneven edges have had to be cut to obtain a commercially acceptable product.

U.S. Pat. No. 4,504,533 (Altenhöfer) deals with the difficulties encountered in the manufacture of a gypsum board in which a first composite layer comprising an impermeable nonwoven fiberglass felt and a woven fiberglass nonwoven covers the lower surface of the gypsum interior and is inverted. around the longitudinal edges of the inner part so that the edge areas of the composite layer are on the upper surface of the inner part. The extension of both the nonwoven fiberglass felt and the fiberglass mat as a composite layer around the full edges of the long-10 causes difficulties in folding the composite layer, which is necessary for the turning and bending process. Further difficulties arise when a second composite layer superimposed on the top surface of the sheet and overlapping the edges of the first composite layer is attached to the first layer. According to Altenhöfer's patent, ridges and waves are then formed in the overlapping edge areas. However, they are not said to be desirable because they have poor gluing and make it difficult to form a smooth surface from gypsum board. To overcome these difficulties, Al-kontröfer proposes the use of composite layers in which the fiberglass mat component is not in the long-edge regions. When using such a combination, on the lower surface of the gypsum inner part of the board, only the non-woven felt layer has to be folded, bent and turned around the edge. When the carpet is cut from the edge areas of the upper composite layer, an improved adhesive adhesion is obtained between the upper and lower layers. The product is thus a gypsum board with a woven fiberglass mat embedded in the upper and lower surfaces of the inner part 30 and a non-woven fiberglass felt in the lower surface around the longitudinal edges and partly also in the area inwards from the edges, while the upper surface is covered with another nonwoven felt glued to the bent bottom.

35 Accordingly, there is still a need for a bare cement board reinforced with a completely embedded fiber bundle under both surfaces and both longitudinal edges, said edges being uniform and smooth in surface and said sheet being approximately uniform in strength.

It is therefore an object of the present invention to provide a flat, bare cement board with smooth, uniform longitudinal edges reinforced with a woven fiberglass mesh immediately below the edge surfaces.

It is a further object of the present invention to provide a bare cement board having a woven fiberglass mesh immediately below each of its surfaces, the mesh extending on one surface of the board below the surface of both longitudinal edges and alternatively the two meshes contacting or overlapping at opposite longitudinal edges.

Another object of the present invention is to provide a cement board having reinforcing, woven fiberglass embedded in its surfaces and longitudinal edges and whose edge areas at said edges do not extend above the plane of the central part of the board.

It is a further object of the present invention to provide a cement board having slightly tapered longitudinal edge regions on its second surface 25.

It is also an object of the present invention to provide a method for forming smooth, uniform and reinforced longitudinal edges in a cement board as a continuous function.

It is a further object of the present invention to provide an apparatus for forming such longitudinal edges in a cement board.

It is a further object of the present invention to provide a bare cement board having a longitudinal edge that is significantly more durable than a normal edge, so that the board does not break easily when nailed from the edges to the building frame.

It is also an object of the present invention to provide a cost-saving method for the continuous production of a cement board with intact, uniform edges.

These and other objects of the present invention, which will become apparent from the accompanying drawings and the following description, are achieved by a method for producing a cementitious building board having 10 reinforced longitudinal edges, in which a continuous belt conveyor conveys an unlimited length of non-stick support sheet in a continuous operation. on the upstream side of the belt conveyor, the sheet being wider than the cement sheet to be made; forming a continuous trough by bending the outer portions of the sheet vertically; a woven fiberglass mesh of unlimited length that is wider than the gutter is placed in the gutter as a continuous function; a hydrating cement mixture is fed onto the net 20 in a continuous operation and the mixture is distributed laterally so as to fill the trough to an approximately uniform depth, the method being mainly characterized by pulling the filled trough between two unlimited length-forming edge forming rails , wherein the rails are longitudinally on and in sliding contact with the belt conveyor; the vertical parts of the support sheet and the outer parts of the net are turned inwards and on top of the mixture; and the folded backing sheet is pressed down over the surface of the mixture and the woven web is pressed into the mixture.

The invention also relates to a device for making reinforced building boards of unlimited length from cement, which device 35 comprises a shaping table and a belt conveyor for conveying a support sheet over a shaping table and a predetermined path, forming a sheet of the device to place the hydrating cement mass of the device 5 on top of a moving, stationary net, and to distribute the mass of the device transversely and distribute it transversely to a web, the device being mainly characterized in that the device further comprises two parallel edge forming rails at a distance of 10 positioned longitudinally of the belt to define the path of the trough; and a device for bending the opposite edges of the trough and the stationary net inwards and for turning the edges 15 down on and into the moving mass. The cement board according to the invention, comprising mainly a core, a lower surface, a top surface and uniform longitudinal edge surfaces, is mainly characterized in that it further comprises a woven reinforcing fiber mesh embedded in the core immediately below said surfaces, the board being cut by a thin, substantially infinitely long board material.

The uncoated building board according to the invention, comprising a hydrated cement core, a lower surface, an upper surface and uniform longitudinal edge surfaces, is characterized in that it further comprises a woven reinforcing fiber mesh immediately below said surfaces, the board being made by cutting a thin, substantially infinitely long board material.

The aforementioned U.S. Patents 4,450,022 and 4,504,335 and also U.S. Patent 4,488,909 are incorporated herein by reference. U.S. Patent No. 4,450,022 discloses an apparatus and method for forming a gap between a support sheet and a bottom web as they move over a forming table so that a concrete-35 mixture can penetrate through mesh holes and form a concrete layer between the sheet and the net. U.S. Pat. No. 4,504,335 discloses a method of embedding a woven fiberglass mesh in the upper surface of a concrete mixture as the mixture moves over a forming table; the net is drawn into the gap between the movable mixture 5 and its cylindrical leveling roller which rotates in the opposite direction to the direction of movement of the mixture so that the roll presses the net onto the mixture surface and clears the adhering mixture as it sweeps the mixture onto the upper surface and holes. Patent 4,488,909 discloses a concrete mix recommended for the high speed, continuous production of a cement slab according to the present invention.

In order that the apparatus and method used in the manufacture of the cement board of the present invention may be more readily understood, they are shown in the accompanying drawings and described in connection with some portions of the production line described in Patents 4,450,022 and 4,504,335.

In the drawings Fig. 1 is a cut-away perspective view of the forming end of a cement slab production line using the apparatus 20 of the invention, Fig. 2 is a sectional view of the production line taken along line 2-2 of Fig. 1, Fig. 3 is a side view, partially cut away, of another structure of the device according to the invention; 5 along the line 4-4, Fig. 5 is a schematic plan view of the production line of Fig. 3, and Fig. 6 is a cross-sectional view of a cement board according to the present invention.

As shown in Fig. 1, the forming table 10 and the belt conveyor 12 form a support for the support sheet 14 and the woven fiberglass mesh 16. A mortar distribution belt 18 and a fixed plow li 9 9 2167 20 are mounted transversely on the forming table 10, the wings 20a, 20b, 20c and 20d of the contact belt scraping it to the surface. The guide flanges 22 are fixed to the table 10 immediately on the upstream side of the mortar leveling roller 24, said roller being adjustable upwards and downwards so that the gap between it and the support sheet 14 can be adjusted according to the desired strength of the plate to be manufactured. The roller 24 is mounted and operated by a conventional device not shown.

The support sheet 14 is wider than the cement-10 tile sheet to be formed, so that it can be made into a continuous trough. The deflection wheels 26 are optional; they can be used to form longitudinal folds on each side edge of the support sheet 14 to facilitate bending of the sheet so that vertical walls 28 can be formed as the sheet 15 moves between the guide flanges 22. The net 16 is also wider than the sheet to be made and therefore wider than the trough formed by the bent support sheet; it may be the same width or narrower than the smooth backing sheet, but not wider. The net 16 is fed into the trough under the holding roll 30 20, but because it is not folded and is quite flexible, it does not fully conform to the corners of the trough but curves from the bottom of the trough towards the walls 28, forming the spaces 32 shown in Fig. 2.

The longitudinal edge forming rails 34 extend downstream of the shaping table 10 and are in sliding contact with the belt conveyor 12. Pins 36 are attached to the rails 34 and rods 38 are slidably attached to the rings 40, as shown more clearly in Figure 4. The distance between the rails 34 is adjusted and maintained by moving the ring 40 along the rods 38 and tightening the set screws 42 to selected locations. As shown in Figure 3, a plurality of groups of pins 36 and rods 38 are spaced apart on rails 34 and prevent separate lateral movement of the rails, thus ensuring a constant width of the cement board. The rails can move 921 67 10 sideways together as the belt conveyor temporarily moves as it moves around the drive and receiving belt pulleys, but when the distance between them is constant, the vertical walls 28 of the support sheet cannot fall and the concrete mix 5 cannot spread randomly. The edge forming rails 34 are continuous parts made of a lightweight material, such as aluminum, and according to a preferred construction of the present invention, they are hollow, making them even lighter and can actually float on the belt conveyor, so that their wear is very low. The pins and rods are also made of light material for the same reason. The rails are preferably rectangular in cross-section, about 3.8 cm (1.5 ") wide and about 1.9 cm (0.75") strong, and their weight is distributed over a portion of their width as the belt conveyor moves below them.

Attached to the rods 38 are pairs of blades 44, shown in detail in Figure 4. In Figure 3, there are only three pairs of blades, but it should be noted that at least 20 pairs of eight blades can be spaced apart on the downstream side of the roll 24. The first pair of blades is preferably about 1.2 m to about 2.4 m (about 4 to about 8 feet) downstream of said roll, and the distance between successive pairs of blades is preferably about 1.5 m to about 25 m (about 5 to about 8 feet). 10 feet). Each child is pivotally secured to the bracket 46 by a screw 47. The bracket extends tangentially from a collar 48 which in turn is rotatably secured to the rod 38 inside the ring 40 and locked in place by an adjusting screw 50. as shown in Figure 5, so that each child can be tilted toward the respective rail 34 by pivoting it in the support 46, the tip 52 of the spatula being approximately at right angles to the respective rail. The outer edge of the tip is obtained I! 11 ii \ 67 then compress down more strongly than its inner edge over the bent portion 54 of the support sheet 14. In this way, the edges of the cement board are made to taper according to the desired amount. In this case, an angle of about 5 ° to about 20 ° is recommended, specifically an angle of 5 °. When using a spatula with a rectangular tip or additional tension if necessary, an elastic band 56 or other tensioning device connects the spatula blade pin 58 to the set screw 42, as shown, or to the ring 40. The spatula blade is made of a resilient material 10, such as chromium-plated spring steel. with a cement mixture containing The blade is thin, for example about 0.95 mm (about 20 gauge), and about 23 to 30 cm (about 9 "to 12") long. The bent strip 54 is preferably about 3.8 cm (about 1.5 ") wide, and the spatula blade may be as wide as the strip 54, but not wider, as scraping the concrete mix near the strip must be avoided.

An alternative device for attaching the spatulas to the rails 34 is a support member having a leg inserted into the hollow end 20 of the rail 34 and a vertical leg attached at a certain angle to the first leg and extending over its horizontal plane, and an arm attached at a vertical angle at a right angle thereto. with respect to a vertical plane passing through the first leg, 25 so that the arm remains inside when the leg is inserted into the rail. The first pair of spatula supports is attached to the upstream end of the hollow rails 34; the following pairs can be pushed into hollow rail segments placed on the rails 34. The separate support members may be right-handed or left-handed or may be made to be turned by forming the legs bidirectionally. The spatulas are attached to the support arms in the same way as to the bars 38.

Figures 1, 3 and 5 also show air nozzles 60 connected to valves 62 attached to a shaping table 10 and connected to a compressed air source 92167 12. The fingers 64 shown in Figures 3 and 5, which are used only when the edges of the lower net 16 are to be turned under the upper net 66, are attached to the table 10 and extend over the guide flanges 22 and force the vertical edges of the lower net 5 16 inwards and downwards. add down as they go under the roll 24.

The finished cement slab 70 is shown in cross-section in Figure 6, showing the inner part 72 of the slab, which engages the mouth-10 through the lower net 16 also as it bends upwards and overlaps the upper net 66 just below the upper surface of the slab. Thus, the concrete mix of the cement board is an autogenous binder for the overlapping nets 16 and 66 at the edges 76 of the top surface of the board. The edges 74 and 76 are smooth as shown due to the smoothing effect of the backing strips 54 as they press into the mix by rails 34 and spatulas 44. Smooth edges 76 are preferred when the cement boards are attached side by side to the septum and the sealing tape is glued to the edges 20 prior to placing the sealant. If the top surface of the slab is desired to be uneven, the strips 54 can be removed along the folds made by the spatulas before the concrete mix has finally hardened. The strips 54 then detach the thin layer of mixture from the edges and form a rough surface. When folding wheels 26 are used, the bottom of the support sheet 14 can be removed from the cement board before or after its final hardening.

Although Figure 6 shows a bent subnet 16 on the edges of the woven upper net 66, the sheet of the invention may also be made with the net 16 under the upper net 66 when fingers 64 are used to bend the vertical portions of the net 16 inward and downward before contacting them. roll 24.

Furthermore, although the continuous production of the cement board comprising the upper mesh 35 is described below, it should be noted that said mesh is not a feature essentially related to the invention.

92167 13

The folded backing sheet 14 and the woven mesh 16 are manually guided under the timing belt 18 between the flanges 22 under the leveling roller 24 and over the belt conveyor 12 so that when the conveyor drive (conventional, not shown) 5 operates, the trough covered by the net 16 with vertical walls 28 moves in the direction of the machine indicated by the arrow MD. The concrete mixture is fed to the belt 18 from a continuously operating mixer, shown as a box CM, and applied to the net 16 by plow blades 20a, b, c 10 and d. The concrete mix streams thus formed spread and coalesce as the roll 24 dampens their movement. The spreading mixture protrudes into the curved net 16 and moves into the spaces 32. The upper net 66 moves between the roll 24 and the damped mixture as the roll rotates in the opposite direction to the MD. 15 The roll continuously takes with it a layer of concrete mix which is pressed through the holes in the woven upper mesh 66 in the gap, and then wipes the mixture on the opposite surface of the upper mesh 66, which promotes its impregnation. If the upper mesh is slightly narrower than the cylindrical roller 24, the concrete mix ring wraps around the edges of the te-20 that have not been wiped. Said mixture comes under the effect of centrifugal force to the vertical wall 28 of the paper chute. If the walls 28 tend to bend too early, they can be kept upright by air directed at them by air nozzles 60. Splashes of concrete mixture in the walls which are undesirable can also be removed with the same air.

As the concrete mix gutter approaches the first bent pair of spatulas 44a, the edges of the net 16 and the gutter walls 28 fold under the splints 44a, whereby the folding of the continuously approaching support sheet 14 and the net 16 begins. It is preferred that the lower mesh be folded over the concrete mix that already covers the upper mesh 66 and that compression of the bent spatula blades be used to press the strips 54 onto the folded mesh 16 to push the woven glass fibers into the mix. Folding the edges of the mesh 16 over the mixture 921 67 14 before placing the upper mesh 66 is another way to provide an edge-reinforced cement board according to the present invention. To this end, the fingers 64 shown in Figures 3 and 5 are positioned so as to compress the edges of the net 16 inwards and downwards and the concrete mixture around the edges of the roll 24 moves over the bent edges. The weight of the mixture bends the edges further downwards before feeding the upper net 66. The folded net 16 is thus embedded near the top surface of the plate with the net 66 as they come under the roll 24, but the net 16 tends to rise due to its flexibility; the spatulas 44 are still needed to press the edges of the net 16 down as the concrete mix hardens.

The compression of the blades of the bent spatulas into the strip! -15 to 54 is adjusted according to the composition of the concrete mix and the stiffness of the net. The recommended pressure is about 0.07 to 0.28 kg / cm2 (about 1-4 psi). The minimum compression occurs with the first pair of blades 44a, and the compression gradually increases by the strips 54 below the next flexible pairs of blades 20 44b, 44c, and so on.

The placement of the blades 44 downstream of the mixer CM is determined by the speed of the slab production line and the amount of cement hydration, which in turn is a function of the cement composition and the temperature of the concrete mix. The fast-curing and high-early-strength cement described in the aforementioned U.S. Patent 4,488,909 is recommended for the manufacture of the cement board of the present invention. Also preferred is the high temperature concrete mix described in U.S. Patent No. 4,488,909. Although U.S. Pat. No. 4,504,335 mentions a mixture as a relatively rigid, solid mortar, for the purposes of the invention, a mixture having a composition such that the well 35 pressed into the mixture immediately after feeding it to the belt 12 disappears by the time the mixture reaches roll 24 is preferred. 67 15 in other words in about 4 seconds. It has been found that when such a self-leveling mortar is used, the subnetwork 16 sinks well into it, even if the device described in U.S. Patent 4,450,022 is used to form a gap between the support sheet and the subnetwork.

An example of such a mortar is a mortar whose cement powder comprises 68.1% Portland cement type III, 17.79% alumina-rich cement, 5.69% gypsum, 0.57% slaked lime and 7.84% fly-10 ash. A cheaper cement powder can be used if fine, high alumina-containing cement (about 6000 cm2 / g Blaine) is used at about 12.5% and corresponding changes are made to the amounts of other cement solids to obtain the best possible composition. Mortar si-15 also contains blast furnace slag in an amount corresponding to the weight of the cement powder when dried. The self-leveling property of the mortar is increased and extended by using one part Lomar D super softener and about 0.5 parts of 8% citric acid solution per 20 parts by weight of the cement powder. The ratio of water to cement powder is about 0.35 by weight, it comprising wet slag, a super plasticizer and the water supplied with the citric acid solution. Foam and expanded polystyrene spheres are also fed continuously to the mixer with other solids and liquids to provide a cement slab having a density of about 1184 kg / m 3 to about 1280 kg / m 3 (about 74 to about 80 pounds per cubic foot).

The immersion of the folded net 16 must, of course, take place before the concrete has first hardened, but the mixture 30 must also not be so fluid at the first pair of spatulas that the net rises again after passing under the spatula. A convenient and satisfactory way to measure the amount of cement hydration at various points on the production line is to place a sample from the mixer in a calorimeter connected to a registration card so as to see an increase in temperature relative to the elapsed time. In this case, the total temperature rise to equilibrium temperature is taken into account. The distance between the roll 24 and the selected blade location is measured and this distance is divided by the speed of the production line, giving the time used by the concrete mix as it moves from the roll 24 to the selected location. The time factor for the transfer of the mixture from the mixer CM to the roll 24 must then be added. This factor can be determined by measuring the travel time of a particular pigment point, for example, iron oxide placed in the mouth of the mixer 10 in the mixture. The notation on the time-temperature curve showing the curing time of the concrete mix indicates the temperature rise at the selected spatula point. The ratio of the increasing temperature increase to the total temperature increase indicates the amount of hydration at the selected site. For example, the concrete mixture prepared according to patent 4,488,909 reached the equilibrium temperature in 12.5 minutes, which corresponds to the curing time range disclosed in said patent, and the total temperature rise was 15 ° C (from 39 ° C to 54 ° C). At a production line speed of about 9.6 m / min (32 ft per minute), the amount of hydration, expressed as a percentage of hydration at equilibrium temperature, was 2.1 m (7 ft), 5.1 m (17 ft) at 44 locations for the four pairs of blades, 7.8 m (26 ft) and 10.5 m (35 ft) from the roll 24 counterparts, 25 counterparts 15%, 22%, 26% and 32%, respectively. The travel time of the concrete mix from the mixer to the roll 24 was estimated to be about 12 seconds. The spatulas can be used to press the mesh 16 onto the upper longitudinal edges of the concrete web and form flat, reinforced edges with the edge forming rails 34 on the concrete web 30 with a hydration rate of about 10 to about 35%, as indicated. It is preferred that the spatulas 44a be positioned to lightly press into the strips 54 upon hydration to a degree of about 10 to about 18% of the hydration at 35 equilibrium.

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The woven mesh is preferably composed of glass fibers, but nylon, metal and aramid resin fibers can also be used. The mesh size of the net and the diameter of the fiber are selected according to the required strength of the board and the size of the filler in the concrete mix 5. For most purposes, a mesh with a number of threads of 2.54 cm (inches) of 4 x 4 to 18 x 14 or 10 x 20 can be used. A mesh with denser fabric at the edges can be used to further reinforce the edges and edge areas of the board.

In making a cement board about 91.5 cm (36 ") wide and about 1.27 cm (1/2") strong in accordance with this invention, the mesh 16 was about 98 cm (38.5 ") wide, the mesh 66 was about 91 cm ( 35.75 ") wide, the number of yarns in each net per 2.54 cm (inch) was 10 x 10 and the backing sheet 15 14 was about 101.6 cm (40") wide. The edge of the net 66 was about 0.3 cm (1 / 8 ") inward from each longitudinal edge of the plate and on top of the net 66 at each longitudinal edge of the plate there was an overlap of the folded portion of the net 16 of about 2.2 cm (7/8").

The cement board according to the present invention is an improved ceramic tile base plate for bathrooms, in particular shower rooms, changing rooms, swimming pool rooms and other such units with a high moisture content or where a lot of water is sprayed. Reinforcing the edges and 25 edge areas of the plate makes it more secure to secure the plate to the frame structure of the space in question with nails or screws. Edge-reinforced panels can also be considered for use in the construction of non-load-bearing external walls.

Ten 1.27 cm (1/2 ") strength cement slab samples made in accordance with the present invention were tested to determine how much force was required to pull the nail sideways through the reinforced edge of the slab. A 0.3 cm (1/8") hole was drilled for this purpose. 0.95 cm (3/8 ") 35 miles from the edge of the plate to the edge area of the plate and the plate was secured in place. A pin simulating a nail and about 0.3 cm (1/8 ") in diameter was inserted through the hole and pulled out with a Tinius-Olsen machine attached to both ends of the pin and the force required to pull the pin sideways through the edge of the plate. The force required in the tenth test averaged 427 Newtons (96 lbs.) When the same test was performed on glass fiber reinforced cement boards with approximately the same cure time but no reinforced 10 edges, the force required to pull the pin laterally through the board was generally about 178 Newtons (40 pounds).

The invention has been described above with reference to a building board comprising a hydraulic cement core. A building board that does not have a hydraulic cement core but a hydrated core is also considered to be part of the scope of this invention. Thus, a gypsum building board that does not have a conventional paper coating but is reinforced with a reinforced fiber woven mesh embedded in the top, bottom, and longitudinal edge surfaces of the board core can be made using calcium sulfate hemihydrate in place of a concrete mix in the process described above.

Claims (14)

A method of producing a cement building plate with reinforced longitudinal edges, wherein - an indefinite length non-adhesive carrier sheet (14) is continuously measured on an endless conveyor belt (12) over a forming table (10) upstream from the conveyor belt (12), the sheet (14) being wider than the cement disk produced; - a continuous sluice is formed by bending the outer portions (28) of the sheet upright; - a first glass fiber fabric (16) of indefinite length is continuously laid in the trough, which fabric is wider than the trough; - a hydrating cement mixture is continuously measured on the tissue (16) and the mixture is distributed laterally to fill the wood to an approximately uniform depth; Characterized in that - the filled trough is driven in abutment to and between a pair of spaced-apart edge rails (34) of indefinite length, the edge rails resting longitudinally on the conveyor belt (12) in sliding contact therewith; the upright portions (28) of the carrier sheet (14) and the outer portions of the tissue (16) are folded inwards and over the mixture; and - the folded carrier sheet (14) is pressed down onto the surface of the mixture and the tissue (16) is pressed into the mixture. 2. A method according to claim 1, characterized in that a second glass fiber web (66) of indefinite length is submerged below the surface of the mixture and the edges of the first and second veins (16, 66) are overlapped with one another. 92167 3. A method according to claim 2, characterized in that the outer portions of the first tissue (16) are pressed into the mixture after the second tissue (66) has been immersed in the mixture. 5 4. A method according to claim 1, characterized in that the folded carrier sheet (14) and the tissue (16) are pressed down-tight by a pressure which increases as the filled trough moves downstream. 5. A process according to claim 1, characterized in that the mixture is concrete and that the degree of hydration of the mixture during the pressing step is about 10% - about 35% of the hydration that occurs at the maximum temperature of the hydrating mixture. 6. A method according to claim 1, characterized in that the mixture is concrete and that the pressing begins on the degree of hydration of the mixture about 10% - about 18% of the hydration that occurs at the maximum temperature of the hydrating mixture. Apparatus for continuous production of a reinforced cement board of indefinite length, comprising a forming table (10) and a conveyor belt (12) for transporting a carrier sheet (14) over the forming table (10) and along a predetermined length web, a device (22) for forming the sheet (14) into a trough, a device (30) for continuous insertion of a 4 tissue (16) of reinforcing fibers into the trough, a device (20) for applying a hydrating cement pulp on the movable, inserted tissue (16), and a device (24) for smoothing the pulp and for distributing it in the transverse direction of the web, characterized in that the device further comprises - two at a certain mutual distance from one another parallel edge forming rails. (34) in sliding contact with the conveyor belt (12) and positioned in the longitudinal direction of the belt 35 for defining the tread path; and II 92167 - a device (44) for folding the opposite edges of the trough and the inserted tissue (16) into the web and for folding the edges down on and into the moving mass. 8. Apparatus according to claim 7, characterized in that the folding and pressing device is a pair of spatulas (44) which are connected to the edge forming rails (34) and placed on the opposite longitudinal edges of the web. Device according to claim 8, characterized in that it further comprises a top (36) mounted on each rail (34), a ring (40) on each top (36), a closure (38), which runs transversely over the web and is slidably attached to each ring (40), a device (42) for reading the rod (38) to the rings 15 (40), and a device for coupling the grooves (41) to the rod (38) on the inside of the rings (40). A cement slab mainly comprising a core, a bottom surface, an upper surface and uniform longitudinal edges, characterized in that it further comprises a tissue (16, 66) of reinforcing fibers embedded in the core immediately below said surfaces, the slab being formed by cutting from a thin, substantially infinitely long sheet material. Cement sheet according to claim 10, characterized in that a first tissue (16) is embedded in the core at the bottom surface, at the edge surfaces and at the longitudinal edges of the top surface. Cement sheet according to claim 11, characterized in that a second tissue (66) is embedded in the core at the top surface layer-like in relation to the first tissue. Cement sheet according to claim 10, characterized in that the longitudinal edges at the top surface and the edge surfaces are smooth. 92167 Uncoated structural sheet comprising a hydrated cement core, a bottom surface, an upper surface and uniform longitudinal surfaces, characterized in that it further comprises a fabric of reinforcing fibers immediately below said surfaces, the panel being formed by cutting out a thin, woven fabric. infinitely long disc material.