Stock material or miscellaneous articles – Sheet including cover or casing – Encased layer derived from inorganic settable ingredient
Reexamination Certificate
1998-03-30
2001-02-13
Maki, Steven D. (Department: 1733)
Stock material or miscellaneous articles
Sheet including cover or casing
Encased layer derived from inorganic settable ingredient
C052S601000, C052S800120, C428S119000, C428S122000, C428S192000, C428S703000, C442S386000
Reexamination Certificate
active
06187409
ABSTRACT:
The present invention relates to reinforced cementitious panels or boards comprising a cementitious core, the boards or panels being fabric-reinforced at the surface thereof. More particularly, it relates to panels or boards whose opposed broad faces are reinforced by a network of fibers which may be adhered at a surface thereof e.g. be adhered to or embedded at or just below the cementitious surfaces thereof. Still more particularly, the present invention relates to a cementitious board whose longitudinal edges are reinforced by a network of fibers. Such a cementitious panel or board may, for example, be a light-weight concrete panel, a tile backerboard panel, or the like.
The word “cementitious” as used herein is to be understood as referring to any material, substance or composition containing or derived from a hydraulic cement such as for example, portland cement (see below). The term “slurry” is to be understood as referring to a flowable mixture, e.g. a flowable mixture of water and a hydraulic cement. The term “core” is to be understood as referring to a mixture of a hydraulic cement, water and aggregate (such as sand, expanded shale or clay, expanded polystyrene beads, slag and similar materials—see below), as well as, if desired or necessary, additional additives such as foaming agents, modifiers and the like.
The term “slurry pervious reinforcing mesh” is to be understood as characterizing a mesh as being suitable for use in the preparation of a concrete panel by having openings sufficiently large to permit penetration of a cementitious slurry or a slurry component of a core mix into and through the openings so as to permit (mechanical) bonding of the mesh to the core either by for example by being cemented to the core or by being embedded in a face or surface of the core of a panel.
The expression “slurry impervious mesh” is to be understood as characterizing a mesh as being water impervious or as being able to filter out or inhibit the penetration of slurry solids therein so as to inhibit (mechanical) bonding of the mesh to the core by the cementitious material.
It is to be understood herein that the expression “adhered to” in relation to a reinforcing mesh component (e.g. mesh, mat, fabric, tissue, etc.) means that the mesh component may be adhered for example to a face or surface by any suitable means such as by an adhesive, by a cement, or by being embedded in, at or immediately beneath the surface of a respective face or surface such that the mesh component is effectively bonded to the core, i.e. a hardened or set cementitious material extends through the interstices of the fibrous layers.
Keeping the above immediate definition in mind, it is to be understood herein that the expression “adhered to said core at” in relation to a reinforcing mesh component (e.g. mesh, mat, fabric, tissue, etc.) means that the mesh component does not extend beyond the specified face, area, region, or the like, i.e. it is restricted to the specified face region etc.. Thus for example in relation to a broad face reinforcing mesh indicated as being adhered to a core at a broad face means that the mesh is restricted to being adhered to the broad face.
The word “woven” as used herein is to be understood as characterizing a material such as a reinforcing mesh (e.g. mat, fabric, tissue or the like) as comprising fibers or filaments which are oriented; oriented fibers or filaments being disposed in an organized fashion.
The word “non-woven” as used herein is to be understood as characterizing a material such as a reinforcing mesh (e.g. mat, fabric, tissue or the like) as comprising fibers or filaments which are oriented (as described above) or which are non-oriented; non-oriented fibers or filaments being disposed in random fashion.
In general, a reinforced cementitious panel or board may be fastened to a wall frame for the construction of a wall and particularly for the construction of a wall where high moisture conditions are to be encountered. Such a wall panel may provide a long lasting substrate for humid or wet areas such as shower rooms and bath rooms and provide high impact resistance where there is high number of people circulating. For example, such a reinforced cementitious panel or board may be used as a substrate for ceramic tile in bath rooms, shower rooms, locker rooms, swimming pool rooms and other areas where the wall are subject to frequent splashing of water and high humidity. Once the panel is affixed to a wall frame a wall facing material may, as desired or necessary, in turn be affixed thereto such as, for example, ceramic tile, thin brick, thin marble panels, stucco or the like. Reinforced cementitious panels or boards having cores formed of a cementitious composition with the faces being reinforced with a layer of fabric bonded thereto are known; see for example U.S. Pat. No. 1,439,954, U.S. Pat. No. 3,284,980, U.S. Pat. No. 4,450,022, U.S. Pat. No. 4,916,604, etc.
Various processes for the preparation of such cementitious boards or panels are also known. British Patent application No. 2,053,779 for example discloses a method for the continuous production of a building board which comprises advancing a pervious fabric on a lower support surface, depositing a slurry of cementitious material onto the advancing fabric, contacting the exposed face of the slurry with a second fabric such that the slurry penetrates through the fabric to form a thin, continuous film on the outer faces of the fabric.
Because of its cementitious nature, a cement board may have a tendency to be relatively brittle.
Cementitious wall board or panels are often attached at their marginal edges to the building framework with for example fasteners such as nails, screws and the like. When fasteners for example such as screws or nails are installed near the edge (less than ½), it is highly desirable that the edge be able to retain sufficient structural integrity such that the panel remains attached to a wall member, i.e. that the panel have a relatively high fastener pull resistance such that the fastener will not laterally pull through or break through the board edge.
It is known to augment the strength of the border edge regions by wrapping the fabric covering one broad face of the board around the edge so as to overlay the fabric on the other opposite broad side thereof.
U.S. Pat. No. 4,916,004, for example, discloses a cement board having a woven mesh of glass fibers immediately below each face thereof, the mesh in one broad face continuing under the surface of both longitudinal edge faces, with the two meshes in an abutting or an overlapping relation along the longitudinal margins of the opposite face. Please also see U.S. Pat. Nos. 5,221,386 and 5,350,554.
U.S. Pat. No. 4,504,533, for example, discloses a gypsum board in which a composite web of a non-woven fiberglass felt and a woven fiberglass mat covers the upper and lower faces of a gypsum core while only the lower non-woven fiberglass felt is wrapped around the longitudinal edges of the gypsum core so that the non-woven fiberglass felt extends partially inward on the upper face of the core such that the border edge regions are covered only by non-woven fiberglass felt.
U.S. Pat. No. 1,787,163 on the other hand discloses a gypsum board in which side edge portions include a separate strip of U-shaped fabric extending from one broad face across the edge to the other broad face; the fabric legs of this separate strip each extend into the plaster core body beneath a respective sheet of fibrous material covering a respective broad face, i.e. the legs are submerged below the broad face and in particular below the broad face reinforcement means.
The problem common to all methods of production of fiber mesh reinforced cementitious panels still remains as to how to effectively reinforce longitudinal edges of cementitious panels. The problem is particularly difficult when the economics of continuous production are desired. Glass fiber mesh, is a common reinforcing fabric and is used in the form of a fibreglass scrim. The open fibreglass scri
Maki Steven D.
Marshall O'Toole Gerstein Murray & Borun
National Gypsum Company
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