GB2266912A - Door or door core using cement or gypsum - Google Patents

Abstract

A door, or core panel for a door, is made of a lightweight set and hardened material based on cement and/or gypsum. Lightweight characteristics can be achieved by having large voids in the panel (Fig 2), but are more preferably achieved by (a) suitable choice of lightweight, natural or synthetic, particulate or fibrous, fillers, additives and aggregates or (b) the intentional incorporation of a multiplicity of small air voids, as a set and hardened air-entrained or aerated material or (c) as both (a) and (b) together. The panel can also be configured with strengthened portions to accept hinge connections, door-closers, and like stress-applying fitments (Figs 5 and 6), and the faces and edges of the panel, as a core, can be suitably clad with wood (ply or veneer) decorative paper or metal sheets (Figs 3 and 4).

Description

IMPROVED DOOR CONSTRUCTION This invention relates to doors, and more especially to doors which give protection against the spread of fire.

Traditionally, doors are made of wooden framing and panels. Nowadays, doors are often made more cheaply, with wooden cladding over a structured cellulosic core.

Manufacture of doors is relatively labour intensive and does not lend itself to true mass production.

Wooden doors do not intrinsically possess the high thermal insulation properties required to stop the spread of fire, and must be laminated or clad for this purpose in various fire resistant materials, which adds to the labour costs.

Also, the sound insulation properties of wooden doors are not always adequate, and further sound insulating cladding may be required.

The cheaper types of door in particular can also change their shapes and dimensions, especially when clad with the various materials discussed or when subject to heat stresses or to moisture changes in the atmosphere.

Eventually, moreover, they will rot and any metal components will corrode.

The present invention is concerned with the fabrication of doors or the like from compositions containing cement and/or gypsum. Cement is a fine calcined powder typically containing silica, alumina, lime (i.e. calcium oxide) and often iron oxide(s) and magnesia. Gypsum is finely divided calcium sulphate usable as a calcined powder. In this specification the term cement/gypsum means either of the above defined materials, or a mixture of the two materials.

Cement/gypsum when mixed with water to a wet plastic mass undergoes a chemical hydration reaction, sets, and hardens. Aggregates (particulate and/or fibrous material) and/or air bubbles or voids can be incorporated into such wet materials to exert an effect on the set and hardened product.

It has already been proposed to make doors from a cement-bonded aggregate. However, such doors are typically used in shelters to be bombproof or radiation proof, and are made to a high specification. They are of considerable weight, and are fabricated accurately to the required size in the original moulding process.

They are completely unsuitable for use generally in residential property or in similar establishments.

The present invention sets out to provide a lightweight door structure composed of a set and hardened material based on cement/gypsum.

The invention consists in a door, or a core panel for a door, consisting essentially of a lightweight rectangular expanse of a set and hardened material based on cement/gypsum.

The invention may be embodied in many different forms and many optional variants may be introduced into the composition of the set and hardened material, into the internal configuration of the body of this material and into the structure of the total door assembly.

Preferably the door, or core panel thereof, is fabricated of a lightweight material. Usually this is achieved either (a) by the incorporation of a lightweight particulate or fibrous additives as aggregate into a settable mixture of water and cement and/or gypsum or (b) by the intentional incorporation of a multiplicity of small voids into such a mixture, usually with an aggregate additive as well e.g. a lightweight aggregate and often incorporating some stabilizing material to ensure that the air voids in the mix are retained in the hardened material. In this latter case the invention extends both to air entrained concrete, containing intermediate proportions of minor voids, and to aerated concretes, which are more foam-like and decorative and contain a high proportion of voids.

As aggregate additive material may be included naturally occurring additives such as hay, straw, cane, reeds or coconut husks, chopped to a suitable size for mixing. Industrially produced materials may also be used, such as areas or chopped fragments of wire mesh; like means or fragments of high-tensile strength polymeric mesh; wood shavings; chopped cardboard; paper fibre, fibreglass; rayon fibres; and polyolefin and like fibres from the petrochemical industry, especially polypropylene fibres.

The above materials tend to be of a fibrous nature.

However, lightweight particulate aggregates may be used, ..s and have the advantage of increasing the thermal insulation properties of the layer of set and hardened material. Examples of such lightweight aggregate materials are pearlite; exfoliated vermiculite; pumice; sintered pulverised fuel ash pellets; heat-expanded slate particles as produced in a rotary kiln; expanded clay particles as produced on a sinter strand; expanded slag particles; aerated sand materials produced by autoclaving; or foamed polystyrene beads.

Such materials as listed above are added to the wet plastic mix and are present in the hardened and set product. In the manufacture of the product it is also advantageous to add plasticizers or "superplasticizers", materials known per se to give a more workable and mouldable wet mass. It is also useful to incorporate foaming agents, aerating agents or air-entraining agents to provide stable air voids (to the extend required) in the wet mix. Moreover synthetic or natural additives known per se to reduce the risk of cracking and to increase the strength and structure flexibility may be added to the mix.

In addition, or instead of, the use of intrinsically lightweight materials, the actual internal configuration of the door or core panel can be modified to give an overall lightweight panel. This is especially useful where the panel is the core of a fabricated door structure. Such a modification may comprise major voids for elongate bores within the panel structure, or recesses e.g. elongate channels at one or both surfaces of the panel.

Further modification to the panel structure may comprise the incorporation of one or more areas of different composition and/or properties within the lightweight door or core. For example, one marginal long edge may be formed in a relatively more workable or drillable material, to improve retention of hinges for hanging the door. Additionally, or alternatively, a topmost edge may be so formed, to fix catches, door-closers, etc. Such incorporations of different material can be readily effected by pouring two different wet mixes successively into the same, temporarily partitioned, mould.

The invention provides a panel which can be used bare, optionally painted, as a door, for fitment with the usual hinges, catches, etc. More especially it can however constitute a central core panel for a door which is otherwise clad with surface layers. The surface cladding may be made of plywood, wood veneer, laminated materials, wall paper or other decorative paper or metal sheet such as steel, brass or aluminium sheet. Such layers of cladding may be glued, laminated in situ, or nailed (or similarly fixed) to the core panel.

Alternatively, they may be fixed in situ during moulding.

The invention will be further described with reference to the accompanying drawings, in which: Figure 1 shows the appearance of a typical door made in accordance with the invention, Figures 2a, 2b and 2c show diagrammaticially horizontal cross-sections of three door core panels of the present invention, each core being furnished with longitudinally extending major voids, Figures 3a to 3f show horizontal cross-sections of the respective vertical edges of six different embodiments of fabricated doors; Figure 4 shows a like horizontal cross-section of a further door, in accordance with the present invention, which door has been provided with a timber edge member; Figures 5a to 5d show successively a door and three embodiments of hinge connections, and means by which such connections may be anchored to a door in accordance with the invention; and Figures 6a and 6b show vertical cross-sections in the plane of the door of two doors which have been reinforced.

Figure 1 shows a door of generally conventional external appearance made in accordance with the invention. Such a door either consists of a lightweight panel of set and hardened material based on cement and/or gypsum, or comprises such a panel as a core, with suitable cladding on the front and back surfaces. Such a door will in practice be provided with suitable hinges, clasps and (optinally) door-closers, locks, etc. The lightweight panel may be a single integral casting, or may be a composite of two or more suitably united panels to aid transportation, handling and packaging.

As indicated above, such panels may be fabricated from a mixture of cement and/or gypsum, particulate and/or fibrous additives and aggregates, and/or air voids, to provide a lightweight set and hardened expanse. Such fabrication, utilising when desired plasticizer materials to assist working and moulding, and/or foaming agents, aerating agents and air-entraining agents to incorporate stable air voids is known per se in other contexts, but is novel when utilised for door construction.

Figures 2a and 2b show an additional or sometimes alternative expedient which may be used in accordance with the invention to achieve a lightweight panel. In these diagrammatic horizontal cross-sections through the panel are shown the uniform cross-sections of circular holes 4 extending through cast panel 21, surface recesses 5 of rectangular cross section extending along panel 22 or deep recesses 6 extending along panel 23.

These can readily be achieved by moulding techniques using removable pipes or other shaped removable units, and such panels as shown in Figs 2b and 2c at least will usually be core panels, i.e. will normally be clad with surface layers to form the door itself.

The cladding of such doors can either be achieved by casting in situ between two sheets (e.g. of plywood or steel) which subsequently adhere to the cast panel, or can be achieved by subsequently fixing separate sheets of such plywood, veneer, timber cladding, steel or other metal etc as may be desired.

Figs 3a to 3c show details of alternative edge finish of such composites. In each case the edge region 30 of the concrete panel is clad with a decorative plywood cladding 8 at the front and back faces. In Fig 3a the cladding 8 extends at 8a into an edge strip 7 of timber; in Fig 3b it extends over the edge strip 7 on both faces; and in Fig 3c it abuts the edge strip at 8b. In Fig 3d the cladding 8 extends over an inner strip 7b but abuts an outer strip 7a.

In Fig 3e there is shown a different finish, in which the cladding sheets 8 at their edges meet, and are covered by, a veneer layer 9. Finally Fig 3f shows a configuration in which the cladding 8 overlaps and conceals the edges of a steel end strip 10.

Fig 4 shows a more elaborate assembly. Cladding 8 again covers the edges of timber lipping 11 (similarly to Fig 3b) but the assembly also comprises wooded beading 12 to define surface panels (see Fig.1) and decorative brass attachment 13.

The door assembly may be conventionally completed with locks, closures, glazed transparent panels, eye-holes or other such features. Fig 5a shows a door core panel 51, in this instance consisting of a upper portion 51a and a lower portion 51b united at 51c.

Typical hinge positions are shown at 14. The nature of each hinge connection will in practice be the same at each position, but for brevity in depiction one example of each of the illustrated hinge connections (of Figs 5b, 5c and 5d) is shown at 14a, 14b, and 14c respectively.

Hinge connection 14a (Fig 5b) is shown in the form of a simple metal channel, with parallel side walls and a base carrying preformed screw holes 15. In practice this channel is located in the mould and thus arrives in situ at the desired location.

Hinge connection 14b (Fig. Sc) is generally T-shaped with a flat base carrying screw holes 16 and a central leg 18, bifurcated and splayed at 19 and welded at 20 to the base, which leg 18 is located in the mould in such a way as to become embedded in the hardened material and anchored by splayed non-coplanar end 19.

Hinge connection 14c (Fig. Sd) is similar but two parallel legs 21, welded at 22 and with bifurcated ends 23, are fixed to the base.

It has been found advantageous in some instances for the cast panel to be modified to accept hinges or like stress-bearing door fitments.

Fig 6d shows diagrammatically a core panel 62 for a door, fabricated of lightweight material. To improve the fixing of hinges the mould is such that, during the filling process, separate insets 621, 622 of differently constituted material, contiguous to the main body 620 and eventually becoming bonded thereto are poured into the mould. Such material may be somewhat higher density and strength, to improve fitment of hinges at 622 (or door-closers at 621) without significant weight increase overall.

Fig 6b shows an essentially similar door 64 with main body 640, three side inserts 642, 644, 646 and one top insert 648, being otherwise similar to Fig. 6a.

As an alternative (not shown) the hinge side edge of the door may be reinforced with metal plates or timber blocks.

It will of course be understood that doors can be fabricated in a variety of sizes. By way of example, the panel 62 can have overall dimensions of 2400mm x 1200 mm, with reinforcement member 621 300 mm x 100 mm and reinforcement member 622 2400 mm x 100 mm, in each case being 38 mm thick. Panel 64 was made up as 2135 mm x 915 mm overall; member 648 was 300 mm x 100 mm; and each member 642, 644, 646 was 200 mm x 100 mm, with all such members again being 38 mm thick.

The door may of course be cast within a range of thicknesses, depending on the desired end use and local building regulations.

Such panels may have a density between 600 - 1200 2 kg/m , and have wood-like properties whereby they may be screwed and drilled. They are incombustible, and do not rust or rot, or expand in wet weather.

A door or core panel for a door made up as described in either embodiment above, using the type of concrete mixtures for the panel and reinforcing units as described, has the advantage that the lightweight concrete may be cut, screwed, and planed with normal woodworking tools. Moreover, it has high thermal insulation and sound insulation even without additional cladding. Such a door (or core panel) can be made cheaply by mass production, and is very stable against distortion. Although it can be used as it stands, it may also be painted. Moreover, laminations or cladding in steel or aluminium or plywood by way of example can still be carried out since the core as shown will accept all the usual fixing members. Thus, a very wide range of finishes can be achieved using the basic core as shown. Also the door will remain operative for a long period of time, since in the core there are no wooden parts to rot and need be no metal parts to corrode.

Claims (14)

CLAIMS:

1. A door, or a core panel for a door, consisting essentially of a lightweight rectangular expanse of a set and hardened material based on cement and/or gypsum.

2. A door, or a core panel for a door, as claimed in claim 1 fabricated of lightweight material.

3. A door or core panel as claimed in claim 2 in which the set and hardened material comprises a lightweight naturally occurring or synthetically produced particulate or fibrous additive in addition to the cement and/or gypsum.

4. A door, or core panel, as claimed in claim 2 or 3 in which the set and hardened material comprises a multiplicity of intentionally incorporated small air voids.

5. A door, or core panel, as claimed in claim 4 in which the material is an air-entrained material.

6. A door, or core panel, as claimed in claim 4 in which the material is an aerated material.

7. A door, or core panel, as claimed in any one preceding claim comprising at least one major formed air void extending within or at the surface of the panel.

8. A door or core panel as claimed in claim 7 in which a plurality of major air voids are present as internal elongate bores extending along within the door, or core panel.

9. A door, or core panel, as claimed in claim 7 in which a plurality of major air voids are present as recesses extending along one or both panel surfaces.

10. A door, or core panel, as claimed in any one preceding claim comprising at least one area of different composition and/or properties from the remainder.

11. A door or core panel as claimed in claim 10 in which one long edge margin is formed in a relatively more drillable or workable material to improve connection and retention of a hinge fitment.

12. A door or core panel as claimed in claim 10 or 11 in which at least part or a top margin is formed in a relatively more drillable or workable material to improve connection and retention of a door closer fitment.

13. A door consisting in its major part of an unclad core panel as claimed in any one preceding claim, painted or unpainted.

14. A door consisting essentially of a core panel as claimed in any one of the preceding claims 1 to 12 clad on one or both faces with an attached layer of paper, wood or metal which is glued, attached with nails or like fixings or attached by moulding in situ.