GB2448921A - Construction Unit - Google Patents

Abstract

A construction unit used in the construction of walls, buildings and other structures and is particularly applicable to a construction unit in the form of a brick. The construction unit comprises a metal shell in the form of an open-topped waste steel can 3 having a glass core 5. The glass core 5 is a solid glass core provided by a quantity of waste glass cullet which has been heated in the can to fuse the cullet, before being allowed to cool. The construction unit 1 may have a plurality of linking members in the form of metal wires 7 extending from one end to the other through the entire length of the glass core and projecting from its ends 4, 8. The wires may facilitate joining of the construction unit to other construction units in use. Later embodiments relate to a method of producing said construction unit; a construction unit comprising a glass insert and a non-glass outer shell; and a construction unit comprising a metal outer shell (32 figure 5), a metal inner insert (34 figure 5) and a glass sleeve insert (36 figure 5) located in a cavity defined between the metal shell and the metal inner insert.

Description

Construction Unit The present invention relates to a construction unit,

and more particularly to a metal-glass composite construction unit, and to methods for producing such construction units.

The present invention is directed to a construction unit which may he used e g. in the construction of walls, buildings and other structures. The present invention is particularly applicable to a construction unit in the form of a brick, and preferably a cylindrical brick. However, the invention may be applied to construction units of different sizes and shapes, for example in the form of blocks, or slabs. In some embodiments, the construction unit may, for example, be a cylindrical construction unit having a circular cross section, while in other embodiments it may have a cross section which is quadrilateral in shape, e.g. rectangular. The construction unit may be solid or hollow.

The present invention seeks to provide an alternative form of construction unit, and, particularly, a construction unit which is environmentally friendly.

In accordance with a first aspect of the present invention, there is provided a construction unit comprising a metal outer shell and a glass insert, the metal outer shell extending overat least a part of the glass insert.

The present invention thus provides a metal-glass composite construction unit, having an insert in the form of a body of glass, and a metal outer shell which extends over the glass insert to cover at least a portion of the outer surface of the insert. The metal shell and glass insert together provide a single piece unitary metal-glass composite construction unit.

The glass insert provides the construction unit with a relatively high thermal mass, reducing the temperature fluctuations which may be experienced in buildings or structures constructed from the units, and potentially reducing the cost of heating or cooling the buildings. For example, the units may effectively store heat during the day, and gradually release the heat during cooler periods or nights, reducing the level of heating required in cooler climates, and similarly may reduce the level of air conditioning required in warmer climates. In this way, the units may provide energy savings, and benefits in terms of environmental friendliness and cost savings. The construction units may also exhibit advantageous freeze/thaw capabilities due to their high thermal mass, as well as resistance to crack propagation caused by thermal stresses, allowing them to be used reliably under relatively extreme conditions of use.

By forming the units from metal and glass, it has been found that the resulting composite construction units may have a relatively low tendency to absorb water in comparison to conventional units, potentially helping to alleviate dampness in buildings and other structures incorporating the construction units.

The metal shell may impart the composite construction unit with levels of mechanical strength, especially compression resistance, and toughness, which may be comparable to, or higher than those exhibited by conventional clay bricks of a similar size and shape. The metal shell provides a ductile outer covering, overcoming the inherent bnttleness of the glass insert, and imparting the overall composite unit with mechanical properties rendering it suitable for use in construction of structures in a manner similar to a conventional clay brick.

It will therefore be appreciated that the combination of materials used in the construction unit, i.e. a glass insert, and metal outer covering, provides the overall composite unit with a combination of properties which would not be exhibited by the use of glass or metal alone, and which are particularly advantageous in the context of a construction unit.

In addition to potentially providing benefits in terms of environmental friendliness in use, it has been found that construction units in accordance with the invention may also be produced using environmentally friendly and cost effective processes, using lower levels of energy than typical processes used to produce conventional bricks. In preferred embodiments, the units may be produced using waste or recovered glass and metal.

In accordance with the invention, the metal shell is a hollow metal shell configured to at least partially cover the glass insert. Preferably the shell provides the outermost layer of the construction unit in the regions where it is provided. The outer surface of the metal shell thus preferably defines the exposed outer surface of the unit over the extent of the shell. Preferably the shell is continuous over its extent. Preferably the shell is a unitary shell.

Preferably the shell encloses at least a part of the glass insert. The shell may be in the form of a sleeve, i.e. having two open ends However, preferably the shell is configured to cover an end and side portions of the glass insert. Preferably the shell thus defines a base and side portions. Preferably the glass insert defines a base and side portions, and the metal shell covers the base and side portions of the insert.

Preferably the glass insert is contiguous with the base and side portions of the shell over the extent of the glass. In these embodiments, the shell defines at least one closed end, which may provide a base for the unit, and side portions extending therefrom. in these embodiments, the shell defines a central cavity in which the glass insert is received.

Preferably the metal shell includes a base which is substantially planar. This may facilitate construction and use of the construction unit, providing it with an end upon which it may stand.

The side portions of the shell may be in the form of a side wall or walls.

Preferably the side portions extend perpendicular to the base of the shell. Preferably the base and side walls of the unit are integrally formed. Preferably the side portions extend around the entire circumference of the base of the shell. Preferably the shell is configured to fully encircle the sides of the insert along the length of the shell.

Preferably the ends of the shell are of identical shape and size In embodiments where the shell has a closed end, the other end of the shell may also be a closed end which covers the glass insert, in these embodiments, the shell may completely surround and enclose the glass insert. In other embodiments, the other end of the shell is an open end, and the glass insert may be exposed at one end, or the unit may be provided with a separately formed and attached lid covering the glass insert at one end. The lid may be a metal lid. As described in more detail below, the metal shell may extend beyond the end of the glass insert, in which case the closed end, or lid of the shell may be spaced from the end of the glass insert.

However, in other embodiments, the glass insert may extend to the end of the shell, and may contact the end of the shell, or lid where provided. In these embodiments, a lid may advantageously be retained in place by being adhered to the material of the glass insert. In certain embodiments, this may be achieved without the use of external adhesives, with the material of the glass insert itself acting to adhere the lid to the glass insert. For example, in some embodiments, a lid may be placed over the glass insert while the glass is still warm. As the glass cools, the lid may become adhered to the solidified insert of glass.

The shell may be elongate in shape, having a length or height greater than its width. Such a shape may more closely resemble a conventional brick. In some embodiments, the longitudinal length of the shell measured between its ends is greater than its transverse width measured across the ends of the shell. In other embodiments, the length or height of the shell may be less than its width. The most appropriate dimensions for the unit will depend upon its intended application. For example, a unit whose width exceeds its height or length may provide a unit with a greater surface area of exposed glass at the end thereof in embodiments where one end of the shell is open to expose the insert. Such a unit may be embedded in a wall with the exposed end face of the glass insert outermost, with the glass providing a graffiti resistant surface to the wall in the region where it is provided. It will be appreciated that where the unit is cylindrical, then the width mentioned above will correspond to the diameter of the unit.

Preferably the shell is a self supporting shell for receiving the glass insert. In preferred embodiments, the metal shell is in the form of an open ended container configured to hold or receive the glass insert. The shell then defines a central cavity for receiving the glass insert. The shell may then be in the form of a tray with side portions covering the lower part of the glass insert, or the side portions may be of greater height relative to the glass insert therein. In preferred embodiments, the shell is in the form of a can.

In embodiments where the shell is in the form of a container, preferably the container is a container capable of holding molten or fused glass. In these preferred embodiments, the shell may provide a mould for holding molten or fused glass which is allowed to cool and solidify to provide the glass insert during production of the unit. The glass may, as discussed below, be introduced into the shell in molten or fused form, or the shell may receive a quantity of solid glass which is heated therein to fuse or melt the glass. In these embodiments, the shell therefore acts as a permanent mould, remaining in place subsequent to manufacture of the unit to become an integral part of the finished unit.

In some embodiments where the shell is in the form of a molten or fused glass holding container, the glass holding container may be a water tight container.

The shell may thus have a base and side walls which are free from apertures.

However, it will be appreciated that while the shell should be impermeable at least to molten or fused glass in embodiments where it provides a container for the glass insert, the shell need not necessarily be liquid tight with respect to other, less viscous liquids, such as water. As glass is a relatively viscous substance, it has been found that rather than leaking out of any relatively small holes in the shell, it will tend to bridge the holes, or simply bulge out of the holes. Furthermore, in accordance with preferred embodiments, where pieces of glass are heated in the container to fuse the fragments, the glass may not necessarily be heated to its melting point, provided that it is heated to the extent that the edges of the pieces are softened and fused to one another to provide a coherent single piece glass insert on cooling. However, in such cases, the shell will still provide a container which is suitable for containing the main body of molten glass during manufacture to allow production of the units.

Thus, in some embodiments, the shell may include some relatively small apertures while still being able to act as a relatively liquid tight container to the main body of the glass insert as it is heated. In these embodiments, the shell will cover the glass insert, and provide the outermost layer of the unit at least in the non-apertured portions.

In some embodiments described below, the shell comprises at least one aperture. The aperture is an aperture located in the body of the shell, in addition to any open end of the shell. The aperture is relatively small in diameter in comparison to any opening at the end of the shell. The aperture may be located in the side walls of the shell, or more preferably in an end or ends thereof. Preferably at least one aperture is provided in the base of the shell. In these embodiments, as described below, the aperture may be used to receive linking means for facilitating linking of the construction unit to an adjacent unit in use. For example, linking means in the form of a linking member may be inserted in the shell through the aperture such that one end of the linking member lies within the shell, and the other extends outwardly through a side or end of the shell to facilitate joining the unit to another structure, e.g. an adjacent unit in use. The end of the linking member within the shell may then be anchored securely in place by the material of the glass insert. This may be achieved by inserting the linking member into the shell and allowing the molten or fused material of the glass insert to solidify around the linking means, binding it to the insert. The linking member may act to substantially plug the aperture to prevent the leakage of molten or fused glass therethrough during manufacture, but need not necessarily provide a watertight seal with the shell. The skilled person will understand how to select the size of any apertures having regard to the nature of the glass to be inserted in the shell, the manufacturing conditions, the diameter of any linking member and other relevant factors to avoid any substantial leakage of glass insert material during production of the unit.

In preferred embodiments the only outer covering for the glass insert is provided by the metal shell, and only the parts of the glass insert over which the metal shell extends are covered. In these embodiments, the glass insert is exposed in regions not covered by the metal shell. Preferably at least the sides of the glass insert are covered by the metal shell. This may impart the unit with greater mechanical toughness.

Preferably the shell comprises an end which is open to expose the glass insert therein. In these embodiments, the glass insert may provide an exposed glass surface at one end of the unit. In embodiments, the unit has a pair of ends and at least one side wall extending there between, wherein the glass insert is exposed at one of the ends, and is covered by the metal shell at the other of the ends. The glass insert may extend beyond an open end of the metal shell, or may lie flush therewith, or not extend to the end of the metal shell. The extent of the glass insert will depend upon the quantity of glass inserted in the metal shell, and the conditions of manufacture.

In some embodiments, an exposed end of the glass insert extends out of the shell at one end and may provide a rounded exposed glass end to the unit. The glass insert may extend in a mound beyond an end of the shell. The exposed glass end of the unit may be arranged to face outwardly when the unit is inserted in a structure in use, to provide an aesthetically appealing effect, and may also provide a more graffiti resistant exterior surface. In these embodiments, the glass insert is preferably a glass core in the form of a block of glass. In embodiments of the invention, the shell extends a distance along the length of the sides of the glass insert selected from the group consisting of: at least 75%; at least 85%, or at least 95% of the length of the sides of the glass insert.

in preferred embodiments, however, the glass insert resides fully within, and is fully enclosed by the shell at least along its sides. In these embodiments, the metal shell therefore extends beyond the at least one end of the glass insert. Where the shell defines an open end, preferably the shell extends beyond the end of the glass insert towards its open end, such that the open end is spaced from the end of the glass insert. Preferably, therefore, the glass insert does not extend beyond the metal shell at any point.

Preferably the shell extends a distance along the length of the sides of the glass insert selected from the group consisting of: at least 100%; at least 105%; at least 115%; or at least 130% of the length of the sides of the glass insert.

Preferably the shell covers an area of the outer surface(s) of the glass insert selected from the group consisting of; at least 70%; at least 85%; or at least 95% or at least 100% of the area of the outer surfaces.

In embodiments where the glass insert does not extend beyond the ends of the metal shell, the unit may exhibit greater resistance to sideways forces. The shape of the construction unit will then be defined predominantly by the shape of the metal shell. The shape of the metal shell may therefore be any shape desired for the construction unit and suitable for use in constructing structures.

The metal shell may be of any suitable shape. Preferably the metal shell is an elongate metal shell. In some preferred embodiments, the metal shell comprises at least one longitudinally extending surface which is axially curved. Preferably the metal shell is generally cylindrical. In these embodiments, the metal shell may therefore define a circular transverse cross section, and the ends of the shell are preferably circular. Embodiments in which the metal shell is cylindrical are preferred in that the shell may then be provided directly using a waste container, without needing to reshape the container e.g. a metal can, and therefore may be advantageous in providing cost savings, and environmental benefits. Suitable cans may be cans complying with the British Standard ISO TRI 1761: 1992 "Light-Gauge Metal Containers -Round Open-Topped Cans -Classification of can sizes by construction type', or ISO TR 11762: 1992 In other embodiments, the metal shell may have a transverse and/or longitudinal cross section which defines a plurality of sides, most preferably four, and in preferred embodiments is square or rectangular shaped in transverse and/or longitudinal cross-section. For example, the metal shell may be in the form of a hollow square or rectangular prism, or a cube. Such a shape may allow a plurality of the units to be built up more readily in modular fashion to provide a structure in the same manner as conventional bricks. It will be appreciated that the construction unit may therefore in some embodiments be straight sided, and may include only straight edges.

The dimensions of the shell may be chosen as desired, depending upon the dimensions desired for the construction unit, and its intended use. For example, the unit may be intended to replace a standard brick for decorative or environmental reasons, or for the technical performance benefits it may provide under certain conditions. The unit may be used with other units in accordance with the invention to produce a structure consisting only of units in accordance with the invention, or may be used in combination with conventional construction units in a structure. The units in accordance with the invention may then be used in isolation, or dispersed at intervals within a structure to produce a desired effect. The units may be used as bricks, paving stones, or larger breeze block type units in structures such as walls, houses, bridges, tower blocks, pavements, etc. In embodiments, the shell may have a length selected from the group consisting of any of: at least 5 cm, at least 10cm, at least 15 cm, at least 20cm or at least 30 cm. The shell may have a length selected from the group consisting of any of: less than 30 cm, less than 20 cm, or less than 15 cm. Preferably the width or diameter of the shell is at least 5 cm, and preferably less than 15 cm. Preferably the width or diameter of the shell is in the range of from 7 to 12 cm. Where the shell has a non-square or non-circular cross-section, the width is the greatest dimension perpendicular to the length of the shell. Where the dimensions of the shell perpendicular to the length, i.e. the width and depth differ, e.g. when the shell is of rectangular cross-section, preferably the depth lies in the same ranges as the width.

In some embodiments, the shell may have a thickness selected from the group consisting of: less than 5 mm; less than 1 mm; less than 0.5 mm; or less than 0.33 mm. In some embodiments, the thickness of the shell may be selected from the group consisting of any one of: at least 0.2 mm, at least 0.5 mm, at least 1 mm; at least 3m; or at least 5 mm.

It will be appreciated that the above numerical ranges are not intended to be limiting, and metal shells having dimensions outside these ranges may be used. The above ranges represent ranges which have been found to correspond to certain readily available cans, and which may therefore be conveniently used to provide a shell in accordance with the invention without modification. The shell may have dimensions within the range defined by any combinations of the above ranges which are not mutually exclusive. The skilled person will understand that shells of differing dimensions may be selected with regard to the intended use of the unit.

In some embodiments the ratio of the length to the width of the shell is in the range of from 1:2 to 7:1, and preferably from 1:1 to 5:1. The length is the longest dimension of the shell. In embodiments the ratio of the thickness of the shell to the width of the shell is in the range of from 1:500 to 1:10, and preferably in the range of from 1:200 to 1:50.

As mentioned above, preferably the metal shell is provided by a waste can, and may therefore suitably have the dimensions of such a can, e.g. used for food, such as a soup or tinned fruit or vegetable can. By way of example, the can may be a can originally used to contain tinned tuna, tinned fruit, tinned soup, etc. Other cans, such as paint or oil cans might be used if a larger shell were required. In some embodiments, where it is desired to produce a unit of dimensions differing to those of standard cans, for example, which is relatively wide in relation to its height, a standard can may be reshaped e.g. by crushing the can. The lid of the can may be removed to allow insertion of the glass insert, and then may or may not be replaced to provide a lid for the unit. In general, food cans have been found to be particularly suitable, being able to withstand heat applied to melt the glass therein in accordance with a preferred method for making the units as described below, and being relatively malleable, allowing reshaping when necessary to render them suitable for a wide variety of end uses. Preferably the shell is a waste beverage or food can.

Preferably the internal surface of the metal shell provides a continuous glass insert contacting surface or surfaces. Preferably the material forming the shell is continuous over the extent of the shell. Preferably at least a part, and more preferably the entire interior surface or surfaces of the metal shell directly contact the outer surface or surfaces of the glass insert. Preferably the glass insert rests on a base of the metal shell. Preferably the glass insert is contiguous with a base and side waIls of the metal shell. In those embodiments there is a direct glass-metal interface. Preferably the glass insert is contiguous across its entire metal shell facing surface area with the internal surface or surfaces of the shell.

Preferably the glass insert is not removable from the metal shell. in preferred embodiments, the metal shell is adhered to the glass insert. In preferred embodiments, this is achieved without the use of any additional adhesives, and the glass insert is bonded directly to the metal shell. As discussed below, in preferred embodiments this is achieved by allowing molten or fused glass to cool and solidify in the metal shell to provide the unit. In this way, as the glass cools in the shell, the glass may become firmly bonded and adhered to the metal shell. Preferably the glass insert is thus provided by a quantity of heated glass which has been allowed to cool and solidify in the shell. Preferably the glass insert is provided by a quantity of glass which has been heated in the shell and allowed to cool and solidify therein.

In preferred embodiments, the interior surface of the metal shell is provided with configurations to promote adherence between the metal shell and glass insert.

In some embodiments, the metal shell may comprise at least one, and preferably a plurality of grooves on its internal and/or external surface for this purpose.

Preferably the grooves are circumferentially extending grooves. Preferably the grooves are located in a longitudinally central section of the shell between its ends, and preferably are located only in such a region. Preferably the grooves are provided on at least the internal surface of the shell. It has been found that the heated glass may then flow into and around such grooves during manufacture in

-II -

accordance with the preferred embodiments, and set within the grooves providing improved bonding between the glass and metal shell.

In preferred embodiments, the metal shell includes at least one, and preferably a plurality of nbs. Preferably the stiffening ribs are circumferentially extending ribs, and preferably are provided on the internal surface of the shell.

Preferably the ribs are provided in a longitudinally central portion of the metal shell between its ends, and are preferably located only in such a region. It has been found that the presence of such ribs may help to promote adherence between the metal shell and the glass located therein in a similar manner to the grooves. The ribs may also function to provide stiffening of the shell, promoting strength and robustness of the unit. In some preferred embodiments, the metal shell comprises a series of alternating grooves and ribs on its internal surface.

In embodiments where internally facing grooves and/or ribs are provided, preferably each rib or groove defines a corresponding groove or rib on the external surface of the shell. In a particularly preferred embodiment, as discussed above, the metal shell is provided by a metal can, and the stiffening ribs/grooves may be provided by selecting a suitable can having such ribs/grooves in its midsection.

The metal shell may comprise any metal or metals. The metal shell may include certain non-metal contaminants in relatively small quantities by weight.

Preferably the shell does not include any non-metal component, and consists of metal. Preferably the shell comprises or consists of tin andlor steel. In preferred embodiments the metal shell is a plated metal shell. Preferably the outer surface of the shell comprises tin, and the shell is formed from a tin plated metal. Preferably the shell is a tin plated steel shell. These embodiments are advantageous, as the metal shell may then be provided by a waste container, preferably a waste can, which are commonly formed of such materials. The metal shell may, however, comprise any metal or metals commonly used to provide such cans. It will be appreciated that the metal should, however, not have a melting point lower than the temperature which the glass insert may attain during manufacture, when the unit is required to hold molten or fused glass in accordance with the preferred methods of manufacture, to avoid the shell itself melting. For example, certain aluminium -12-beverage or aerosol cans may not be suitable for use in these preferred embodiments for this reason.

Preferably the shell is a rigid metal shell.

As described above, preferably the glass insert is provided by a quantity of solidified fused or melted glass, and preferably by a quantity of molten or fused glass which has been allowed to solidify within the shell.

In accordance with a second aspect of the present invention there is provided a method of producing a construction unit having a glass insert and a metal outer shell, the method comprising: providing a metal shell in the form of a container for receiving a quantity of molten or fused glass; providing a quantity of molten or fused glass in the metal shell; and allowing the molten or fused glass to cool in the metal shell to provide a composite metal-glass construction unit.

The present invention in accordance with this further aspect may incorporate any or all of the features described above and below in relation to the first aspect of the invention. Thus, for example, the metal shell and glass insert may be of any of the forms described above or below.

It is believed that a construction unit in which an outer non-glass shell surrounds a glass insert in the form of a quantity of molten or fused glass which has been allowed to solidify therein, is advantageous inits own right. In accordance with yet another aspect of the invention, there is provided a construction unit comprising a glass insert and a non-glass outer shell extending over at least a part of the glass insert, wherein the glass insert is formed by a quantity of molten or fused glass which has been allowed to solidify in the outer shell.

In accordance with yet another aspect of the present invention there is provided a method of producing a construction unit having a glass insert and a non-glass outer shell, the method comprising: providing a non-glass shell in the form of a container for receiving a quantity of molten or fused glass; providing a quantity of molten or fused glass in the shell; -13-and allowing the molten or fused glass to cool in the shell to provide a composite construction unit.

For example, in these aspects, rather than being a metal shell, the shell may be a ceramic shell. Preferably the shell is provided by a waste container. The shell should have suitable properties providing it with structural integrity of the level required for a given application, and which may resist melting on heating to temperatures required to fuse the glass therein during manufacture. While the present invention is described with reference to the preferred embodiments in which the shell is a metal shell, it will be appreciated that the other features of the Unit 1 0 described above and below in connection with the other aspects of the invention, e.g. the dimensions, configuration, composition and use of the unit, are applicable to the invention in accordance with these further aspects, to the extent that they are not contradictory thereto. References to the "metal" shell may therefore be understood as applying to the "shell" in these further aspects of the invention, unless otherwise 1 5 stated, or in contradiction thereto.

In accordance with the present invention in any of its aspects or embodiments, the quantity of molten or fused glass may be provided by a quantity of glass which has been melted or fused before or afler being introduced to the shell, and allowed to cool in the shell to provide a glass insert. Thus, the glass insert might be provided by a quantity of glass introduced in the shell in its molten or fused state, and the method may further comprise the step of introducing a quantity of molten or fused glass into the shell. Such methods are particularly suitable for mass production. The glass maybe melted e.g. in a furnace and poured or otherwise introduced into the shell in its molten or fused form.

However, in some preferred embodiments the quantity of molten or fused glass is provided by heating a quantity of solid glass in the shell to melt or fuse the glass. In these embodiments, the method further comprises introducing a quantity of solid glass into the shell and heating the glass within the shell to melt or fuse the glass.

In preferred embodiments the solid glass is in the form of a plurality of pieces of solid glass which are heated to melt or fuse the pieces of glass within the shell. The pieces of glass should be heated to an extent which allows them on -14 -cooling to provide a coherent single piece glass insert. During this process, the glass may also become firmly bonded to the shell at the interface therewith. The pieces of glass may have melted and flowed to the extent that the glass insert is homogenous, or only to the extent necessary to soften and bond by fusing the glass pieces to one S another and to the shell, e.g. at their edges. Thus, the outlines of the glass pieces may be discernable in the construction unit, or the insert may present smooth outer surfaces.

In embodiments where the glass is heated in the shell, preferably the step of heating the glass in the metal shell is camed out in a furnace. As the glass is heated, when in the form of pieces, it will tend to settle, as the fused glass flows into the gaps originally present between the pieces. If necessary, the shell may be topped up with further solid glass as the heating progresses to provide an insert of a desired height.

The temperature required to fuse the glass in the shell will depend upon various factors, such as the size of the shell, the quantity of glass inserted therein, the composition of the glass and metal, the nature of any furnace used, as well as e.g. the number of construction units being produced at the same time.

Preferably the method comprises heating the metal shell with the glass therein to the melting point of the glass, and preferably to a temperature of at least 800 C, and preferably at least 900 C. As the glass is heated in the shell, heat will be transferred from the outer layers of glass into the inner layers by conduction and to a lesser extent by thermal radiation. It will be appreciated that the glass need not necessarily be heated to the extent that it fully melts, but at least to the extent that the edges of any pieces become fused to one another and to the shell to form a coherent body within the shell. References to "melting" or "molten" glass herein should be understood in this manner. The heating should be carried out to a temperature which is less than the melting point of the shell. Preferably the heating is carried out at a temperature of less than 1400 C, preferably less than 1300 C, and preferably less than 1100 C. Preferably heating is carried out in a range of from 900 to 1200 C, more preferably from 900 to 1100 C.

Heating times may be selected as appropriate depending upon the nature of the glass, shell, furnace and other conditions. Preferably the heating is carried out at -15-a temperature in the above ranges for a period of at least 15 minutes, and more preferably at least 25 minutes. Preferably the heating is carried out at a temperature in this range for a period of less than 1 hour. A suitable time for heating has been found to at least 15 minutes, preferably 25 minutes at a temperature of around 900 C. These times refer to the heating time once the furnace has reached the desired temperature, i.e. the "soaking time", and do not include the initial time required for the furnace to reach these temperatures. Often furnaces are ramped up to the final desired temperature gradually to avoid thermal shock damaging the furnace walls or heating element.

The shells may be covered with or embedded in a heat absorbing medium to reduce the likelihood of their being degraded by the molten or fused glass, and reducing brittleness of the resulting composite. The heat absorbing medium may be sand. For example, the shells may be buried in sand. This may be carried out prior to heating the shells or prior to introducing molten or fused glass in the different embodiments of the invention. In some embodiments the shells are buried in sand with only their open ends exposed during the heating process or for receiving the molten glass when the glass is introduced in an already heated state. The shells may be retained in a steel tray in these embodiments.

In accordance with any of the embodiments, whether the glass is melted or fused before or after introduction to the shell, preferably the method comprises a step of annealing the heated glass in the metal shell. As is known in the art, an annealing process involves allowing the metal-glass composite to slowly cool in order to promote toughness, and reduce brittleness of the composite thus obtained.

Preferably annealing is carried out by allowing the molten or fused glass to cool in the metal shell after heating. By allowing the glass to slowly cool in the metal shell, the resulting metal-glass composite may be imparted with greater resistance to thermal shock and fractures. This may be achieved by placing the shell with the glass therein in an annealing oven at a temperature less than that of the furnace used to melt the glass, e.g. at 800 C, and gradually reducing the temperature of the annealing oven. The annealing oven may be the same furnace used to heat the glass, or a different annealing oven may be used. It has been found that annealing may, in simple embodiments, be carried out by allowing the metal-glass composite to cool in -16-the furnace in which it was heated e.g. with the doors closed. The furnace may simply be turned off and the composites left therein overnight. Preferably the annealing is carried out by allowing the melted glass to cool in the metal shell in this manner for a period of at least 8 hours, and preferably at least 10 hours following heating. Preferably the annealing is carried out for a period of less than 15 hours, and preferably less than 13 hours. A suitable time has been found to be around 12 hours of cooling.

In other embodiments, it may be desired to quench the metal-glass composites comprising the molten or fused glass in the metal shell to produce more rapid cooling. A quenching step may, in preferred embodiments, be carried out prior to a step of annealing the composite. Quenching may be appropriate if it is desired to cause the glass to become amorphous, and hence transparent. Suitable quenching may be carried out in air.

It has been found that construction units in accordance with the invention may be produced using lower residence times, and heating temperatures than conventional bricks. For example, typically clay bricks require an average firing temperature of at least 1050 C. Construction units in accordance with the invention may also be produced with shorter drying times, and under less closely controlled conditions than clay bricks. This is because clay bricks are susceptible to the presence of moisture during the drying period, requiring close control of humidity in the region surrounding the bricks during the drying process. If the atmosphere is too moist, the surface of the brick may remain damp for a considerable time, and it is important that suitable means of ventilation e.g. fans is provided. These problems are not encountered with metalglass composite construction units in accordance with the present invention due to their inherently low tendency to absorb moisture.

The glass insert is in the form of a coherent body of glass. In some preferred embodiments the glass insert is a glass core. In accordance with a further aspect of the invention there is provided a construction unit comprising a glass core and a metal outer shell extending over at least a part of the glass core. In these embodiments, preferably the unit is then a solid construction unit. In these aspects and embodiments, the core is preferably in the form of a block of glass. Thus, the glass insert may be provided in these aspects and embodiments by filling the shell to a desired level with a quantity of glass, wherein the glass is molten, or is solid glass which is then fused or melted in the shell, and allowing the molten or fused glass to cool to provide a body of solidified melted or fused glass within the shell.

Preferably the glass core then extends across the entire width or diameter of the space defined within the shell.

In other embodiments, the glass insert may be in the form of a sleeve. In preferred embodiments the construction unit may further comprise a non-glass insert, and the glass sleeve may be located between the outer metal shell and the inner non-glass insert. Preferably the non-glass insert is a metal insert. These embodiments may facilitate production of the unit in accordance with the preferred method in which molten or fused glass is allowed to solidify in the shell, as the shell and inner insert may together act as a mould to constrain the glass and facilitate formation of a sleeve of glass within the outer shell. The glass insert may act to adhere the non-glass insert to the metal shell, e.g. by allowing the glass material to solidify within the cavity between the metal shell and non-glass insert. In these embodiments the metal shell and non-glass insert may therefore define a cavity therebetween in which the glass sleeve is received. The glass sleeve may then surround the non-glass insert, and preferably extends around the entire circumference of the non-glass insert. Preferably the glass sleeve is then contiguous with the adjacent inner walls of the metal shell and the outer walls of the non-glass insert.

In accordance with a further aspect of the invention there is provided a construction unit comprising a metal outer shell, a metal inner insert, and a glass insert in the form of a sleeve located in a cavity defined between the metal shell and the metal inner insert.

In these embodiments, the construction unit may be advantageously produced in a similar manner to those embodiments which do not include a non-glass insert, the only difference being that the non-glass insert is located in the metal shell prior to glass being inserted into the shell. The glass is inserted into the space defined between the outer glass shell and inner non-glass insert. The glass may be inserted either in solid form and then melted or fused in the space between the shell and insert, or may be introduced in already molten form as described above, before being allowed to cool and sohdify in the space between the non-glass insert and shell.

In accordance with further embodiments, the method of the present invention may further comprise the steps of locating a non-glass metal insert in the metal shell, and providing the quantity of molten or fused glass in a cavity defined between the metal shell and the non glass insert, and allowing the molten or fused glass to cool in the cavity between the metal shell and non-glass insert to provide the composite construction unit, in embodiments formed in accordance with these preferred embodiments, the non-glass insert should be formed from a material with a sufficiently high melting point to withstand the temperatures to which it will be exposed during the method.

Preferably the non glass insert rests against an end of the metal shell. in these embodiments, preferably the glass insert does not extend across the entire base of the shell, and preferably does not extend across the region of the base covered by the non-glass insert.

The non-glass insert may be of any form. For example, the insert might be a solid body e.g. block of material. In these embodiments, the non-glass insert may be in the form of a non-glass core. Preferably, however, the non-glass insert is hollow.

In embodiments where the non-glass insert is hollow, preferably the glass insert does not extend within the non-glass insert. In these embodiments, the construction unit may be a hollow unit. The unit may define a central cavity through which e.g. a pipe may be passed, with the glass insert and walls of the metal shell and non-glass insert providing an insulating sleeve therearound. In these embodiments, an opening may be made in the base of the shell and non-glass insert where appropriate to allow a tube such as a pipe to be inserted therethrough. This may be most readily achieved after insertion of the glass insert in the cavity between the metal shell and non-glass insert.

in embodiments including a non-glass insert, the metal insert may be in the form of a sleeve, but preferably defines a base and side walls. Most preferably the non-glass insert is in the form of a can, preferably a metal can. In these embodiments, the construction unit preferably comprises a first can of greater diameter which provides the outer metal shell, and a second can of lesser diameter located therein which provides the metal insert, with the glass insert located in the cavity defined between the cans.

Advantageously, the non glass insert may be of the same general shape and configuration as the metal outer shell. Preferably the non- glass insert is provided by a waste can. For example, the insert may be a baked beans can located in a larger tinned peaches can. Any type of can suitable for use in providing the metal shell may be used to provide the metal insert, and the insert may be formed of any of the materials described in relation to providing the metal shell. The metal insert may, e.g. comprise ribs and/or grooves to facilitate adherence to the glass insert.

In these preferred embodiments in which the glass insert is located between the metal shell and an inner non glass, preferably metal insert, the non-glass insert may be of any shape or size provided that it is of lesser diameter than the metal shell such that a cavity is defined between the walls of the shell and non-glass insert for receiving the glass insert. The non-glass insert may or may not extend to the end of the shell. For example, the non-glass insert may be of lesser length than the shell.

Where the non-glass insert is of different length to the metal shell, preferably the glass insert is provided only over the length of the unit where the non-glass insert and shell are coextensive to define a glass receiving cavity.

While the non-glass insert is preferably a separately formed insert located in the shell, and which is preferably bonded to the shell by the glass sleeve, it is envisaged that in some embodiments the non-glass insert may be integrally formed with the metal shell.

Of course, while it has been discussed above that the shell may comprise a glass insert in the form of a sleeve or a core, it is contemplated that the shell might comprise a plurality of glass inserts, in the form of a plurality of e.g. concentrically arranged sleeves, or a combination of a sleeve or sleeves and a core. For example, a plurality of cans of progressively smaller diameter may be arranged concentrically within one another with glass sleeves arranged in the spaces defined between any or all of the walls of the cans. In embodiments where the unit includes a hollow metal insert, a further quantity of glass may be located in the cavity defined by the metal insert to provide a glass core in addition to a glass sleeve surrounding the metal insert.

-20 -In accordance with the present invention in any of its aspects and embodiments, the glass material forming the insert may be in the form of a solid mass of glass, or may comprise one or more internal cavities. It will be appreciated that any such cavities are cavities defined between the inner and outer walls of the glass insert where present, i.e. within the material of the insert, and are in addition to any central cavity defined by the insert by virtue of its overall shape, and not within the body of the material forming the insert e.g. at the centre of the insert when in the form of a sleeve. Whether the material is in the form of a solid mass of glass, or defines one or more internal cavities, the material may be porous, or may be non-porous.

When the material is in the form of a non-porous, solid mass of glass, the glass insert is free from internal cavities or pores. The material of the glass insert may then be continuous in all directions within the body of the insert. In embodiments where the glass comprises pores or internal cavities, any pores or internal cavities may be of any desired shape or size, and may be deliberately introduced during manufacture. The pores or internal cavities may be regular or irregular in shape, and may be of the same or different shapes and sizes. Pores or internal cavities may be introduced using commonly known techniques in the art e.g. by introducing pockets of air into the glass while molten by adding appropriate chemicals that produce gas bubbles on heating, or by leaving gaps between pieces of solid glass to be fused together to provide the insert. For example, pores or cavities may be more readily obtained as known in the art where the solid glass pieces are placed in the shell such that there are gaps between them, and are not heated to fully melt the pieces but instead to just soften their edges. Where internal pores or cavities are present, these are preferably voids in the glass material. The body of the glass insert then preferably is free from any non glass solid material. However, it is envisaged that in some embodiments the pores or cavities may be defined by or contain particles of a non-glass substance, such as aluminium foil or crushed metal cans. Where non-glass particles are present in the glass material they may advantageously be provided by particles of a solid material with a lower melting point than glass, preferably a waste metal substance. -21 -

In accordance with the invention in any of its aspects and embodiments, the glass may be any suitable type of glass. In preferred embodiments, as previously described, the glass insert is provided by fusing or melting a quantity of pieces of solid glass and allowing the fused or melted glass to solidify in the shell. The pieces may be of any size or shape, and may be irregular or regular in shape. The pieces may be of differing or the same sizes and shapes. For example, the pieces may be relatively small particles, e.g. in the form of a glass powder, or may be larger fragments or granules of glass. The pieces may be of any desired size, with the only limitation being that they should be smaller than the diameter of the metal shell to allow them to be inserted into the shell, or, in embodiments including an inner non-glass insert, of dimensions allowing them to be introduced into the cavity defined between the shell and non glass insert. Preferably the glass is in the form of granulated glass.

While virgin glass may be used, in preferred embodiments, the glass insert comprises waste glass, and is preferably formed by fusing or melting a quantity of waste glass. Preferably the waste glass is glass cullet. Glass cullet is a quantity of fragmented waste glass which may be remelted, with or without the addition of new material. The glass cullet may be further crushed to reduce the size of the fragments if desired. In some embodiments granulated glass cullet is used.

The use of glass cullet has been found to be particularly advantageous, in that such glass may melt at a lower temperature than raw glass making materials.

Thus, in addition to providing a way to reuse waste glass, producing construction units from glass cullet in accordance with the invention may allow those units to be provided using less energy than would be needed to make the construction unit in the same manner using new glass produced from raw materials. Using glass which may melt at a lower temperature also reduces the temperatures to which the shell may be exposed during manufacture, increasing the range of materials which may be used to provide the shell without risk of its melting or becoming too brittle. As mentioned above, the latter possibility may be alleviated by placing the unit in a sand tray prior to heating and burying the shell in sand during the heating process.

Suitable glass cullet may be obtained from a variety of sources. The waste glass may be glass including pieces of waste liquid containers e.g. beer and wine -22 -bottles, and/or jam jars. However, the cullet may of course comprise glass from a single source, or plurality of different sources, and may be granulated to provide fragments of any desired size allowing them to be introduced into the shell.

Granulation of the cullet may be carried out using any suitable apparatus, e.g. by mechanical methods or using an ultrasound imploder. For example, a suitable glass cullet may be obtained by granulating cullet using an imploder purchased from Krysteline Limited.

The glass maybe of any colour. In accordance with the present invention in any of its aspects and embodiments, preferably the glass insert comprises soda lime glass. The glass cullet may be pure glass, or may include trace quantities of certain non glass contaminants. Preferably the glass insert comprises less than I % metal, and preferably less than 0.1% metal contaminant.

Preferably the glass insert does not include any non-glass substance, and preferably consists only of glass.

In accordance with any of the aspects or embodiments of the invention, preferably the construction unit comprises linking means for facilitating joining of the unit to an adjacent unit in use. The linking means may extend from the side and/or end or ends of the shell. In some preferred embodiments, the construction unit further comprises linking means inserted into the glass insert, and extending from one or both ends andlor sides of the unit. Preferably the linking means extends from the glass insert through the metal shell to project outwardly therefrom.

Preferably the glass insert bonds the linking means to the unit.

Preferably the linking means comprises at least one linking member, and preferably a plurality of linking members, which preferably extend through at least a portion of the glass insert. It will be appreciated that where linking means extends from both ends of the unit, such means may be provided by a single linking member extending from one end of the unit to the other, or by separate linking members associated with each end thereof Similarly, linking means extending from the sides of the unit may be provided by a single linking member extending through the entire width of the unit, or by a plurality of separate linking members. Preferably a linking member extends through an aperture in a base and/or side of the shell. In some -23 -preferred embodiments, the unit comprises at least one linking member extending right through the unit through the glass insert from one end and out of the other end.

The linking members may extend laterally or longitudinally relative to the unit, and may be straight, curved or bent. The linking members may extend from the unit in any direction or directions. The linking members may be rigid or flexible, or both rigid and flexible members may be provided.

The linking members may include wires, nails, bolts, ropes etc. and combinations thereof. Preferably the linking member is a metal linking member, and preferably is in the form of at least one metal wire. Preferably the wire is a flexible wire. In this manner, adjacent linking members may be joined to one another by deforming them or bending them around each other.

Preferably the exposed part of the linking means or member comprises a hook. The hook may be a rigid hook.

The linking means may be incorporated in the unit by locating it in the metal shell with the glass, preferably prior to insertion of the glass in the shell, or at least to fusing of the glass where the glass is inserted into the shell in the form of solid pieces. In preferred embodiments the method therefore comprises the step of inserting a linking member, preferably a metal wire, into the metal shell before or after providing the fused or molten glass, and allowing the glass to solidify around the linking member. For example, where the glass is heated in the shell to melt or fuse the glass, the linking member may be inserted in the container with the solid glass, or may be inserted therein after the glass has been softened on heating.

Similarly, where the glass is introduced into the shell in already melted or fused form, the linking member may be provided in the shell before the glass is introduced, or while it is still warm. In this manner, the melted glass will flow in and around the linking member or metal wire, and on cooling, will bond the member securely to the insert and shell of the unit. Where the unit includes a glass insert in the form of a sleeve surrounding a non-glass or metal insert, the linking member may be inserted into the region between the insert and shell where the glass is present.

Where apertures are provided in the shell, e.g. to receive linking members, preferably such apertures are formed prior to introducing the glass into the shell.

In use, units may be joined to one another by directly joining linking means associated with each unit with one another, or by indirectly joining respective linking means of each unit to one another via an additional connector. The additional connector may be in the form of a flexible connector, such as a length of wire, rope etc. The linking means facilitate joining of unit to one another by improving the bonding between units, particularly where mortar or concrete is used to join the units. It has been found that mortar may not adhere as strongly to glass or metalas conventional building materials, and the presence of linking means, particularly extending from any exposed glass surfaces of the unit, may enhance the strength of bonding between units, especially where mortar is used.

In some preferred embodiments, the method may further comprise reshaping the metal shell in order to provide a construction unit of a desired shape. Reshaping the shell may be carried out before or after insertion of the glass therein. For example, reshaping could be carried out after introduction of the glass, and while the shell is warm. Reshaping may be used to change the cross sectional shape and/or the dimensions of the shell. For example a metal can which is cylindrical in shape may be reshaped to provide it with a cross-section closer to a rectangular shape i.e. the shape of a more conventional clay brick, to facilitate building of structures using the units. In other cases, a can may be compressed or squashed to increase the ratio of its width to height. Reshaping may allow a standard waste container to be customised to provide a unit of desired form without needing to obtain or produce a container specifically for this purpose. In some embodiments, the method therefore further comprises reshaping the metal shell, or the metal glass composite obtained after introducing the glass into the shell. Preferably reshaping is carried out before insertion of glass into the shell. Preferably the step of reshaping the shell comprises changing the shape of the shell from a cylindrical to a straight edged e.g. rectangular shape.

In particularly preferred embodiments, the present invention provides a construction unit which may be produced using waste materials i.e. a waste metal can, preferably tin plated can, and a quantity of fragments of waste glass e.g. glass cullet. Preferably the metal shell is provided by a waste metal container, and the -25 -glass insert by waste glass cullet. Where a non glass insert is provided, preferably the insert is in the form of a further waste metal container.

The construction unit may be of any desired shape and size. As discussed above, the configuration of the construction unit is preferably predominantly dictated by the configuration of the metal shell, and may therefore be of the size and shape discussed above in relation to the metal shell. Preferably the construction unit defines a pair of transverse extending end faces, and at least one surface extending longitudinally therebetween. Preferably at least one end face of the construction unit is planar. The construction unit may be of any desired shape in transverse cross-section, and may be regular or irregular in shape.

In some embodiments, the length of the construction unit is greater than its width. Preferably the construction unit is an elongate construction unit. In other embodiments, the width of the unit is greater than its height. In some preferred embodiments, the construction unit is generally cylindrical. In thesc embodiments, the unit may therefore define a circular transverse cross-section. Embodiments in which the construction unit is cylindncal may be readily produced using directly from recycled waste materials, e.g. metal cans and waste glass as described in more detail below, and therefore may be advantageous in providing Cost savings, and environmental benefits. In other embodiments, the construction unit may be prism shaped. For example, the unit may be in the form of a square or rectangular prism, or a cube. In these embodiments, the unit may have a transverse cross-section which defines a plurality of sides, most preferably four, and in preferred embodiments is square or rectangular shaped in transverse and/or longitudinal cross-section. Such a shape may allow a plurality of the construction unit to be built up more readily in modular fashion to provide a structure in the same manner as conventional bricks.

The dimensions of the construction unit may be selected as desired for a suitable particular context. In embodiments, the unit may have a length selected from the group consisting of any of, at least 5 cm, at least 10 cm, at least 1 5 cm, at least 20 cm or at least 30 cm. Preferably the unit has a length of less than 30cm, more preferably less than 20 cm, more preferably less than 15 cm. Preferably the width or diameter of the unit is at least 5 cm, and preferably less than 15 cm.

Preferably the width or diameter of the unit is in the range of from 7 to 12 cm. Such -26 -dimensions may allow the construction unit to be produced using readily available tin cans as the metal outer shell.

Preferably the ratio of the length to the width of the unit is in the range of from 1:2 to 7: 1, and preferably from 1:1 to 5:1. The length is the longest dimension of the unit.

The construction unit is a substantially rigid unit. The construction unit is preferably a solid unit, although in other embodiments it may be a hollow unit as descnbed above.

Preferably the construction unit is in the form of a brick. However, the unit may be of any other configuration, e.g. a block.

The construction unit may or may not be transparent. In some embodiments the unit is opaque. These embodiments may allow the unit to simply be annealed in the same furnace used to heat the units, without needing to carry out a quenching step to render the glass transparent. It will be appreciated that in contrast to conventional glass bricks which may be used in construction, the presence of the metal shell will, in some embodiments of the invention prevent light from being transmitted from one side of the construction unit to the other.

Depending upon the intended context of use, theextemal surface or surfaces of the metal shell may be treated to provide the unit with a desired finish. For example, the surface may be treted to impart it with a desired property, e.g. to enhance aesthetic appeal andlor provide functional benefits e.g. in terms of resistance to some substance e.g. the elements, wearability or ability to adhere to mortar in use. In some embodiments the surface may be coated. The coating may be e.g. a polymer material, resin paint. In some embodiments, the outer surfaces of the shell are treated with an anti-graffiti coating.

Effectively, the construction unit includes an outer shell which is at least predominantly formed from metal, and preferably entirely formed from metal, and a glass core, which is at least predominantly and preferably entirely formed from glass, and preferably free from any metal. Preferably the unit consists only of metal and glass i.e. the metal shell and the glass insert, and, in some embodiments, a metal inner insert and/or linking means for linking the unit to an adjacent unit andlor an inner metal insert.

-27 -The construction units obtained in accordance with the invention may be used by embedding a plurality of such units in mortar in a desired configuration to provide a structure in the same manner as when using conventional bricks. In some embodiments, the construction unit comprises mortar covering at least a part of a surface thereof.

The construction unit may be used as a module in constructing a structure such as a wall, or may be a paving stone, or decorative element which may be included in a structure. The construction unit may not necessarily be joined with other like units to form a structure, but may be used in isolation to provide a decorative feature within a conventional e.g. concrete wall, or to impart the structure with anti-graffiti properties.

The present invention extends to the use of a plurality of construction units in accordance with the present invention in any of its embodiments to construct a structure.

The present invention also extends to a plurality of construction units in accordance with the invention joined to one another, preferably by mortar and/or linking means associated with each respective unit to provide a structure. The linking means may be directly or indirectly joined to one another. In the latter case, connectors such as ropes may be used. Preferably the units are joined to one another in an end-to-end relation. Where a plurality of construction units are used, those units may be identical, or may be different from one another. Preferably the construction unit is attached at one, and preferably both ends to a like construction unit.

The present invention extends to a construction unit obtained in accordance with the method of the present invention in any of its aspects or embodiments.

It is believed that a metal-glass composite construction unit is advantageous in its own right. Thus, in accordance with yet another aspect of the invention there is provided; a construction unit comprising a body of glass and a body of metal disposed in or around said body of glass.

The present invention in its further aspects and embodiments may include the features described with respect of any of the other aspects and embodiments of the invention to the extent that they are not inconsistent with one another.

While the invention has been described in respect of the units being construction units, it will be appreciated that the units may be used in other contexts, and thus, from a broader aspect, the present invention may provide a composite unit in accordance with any of the aspects or embodiments described above. However, most preferably the unit is a construction unit.

The present invention in these further aspects may incorporate any or all of the features described in respect of the other aspects and embodiments of the invention.

It will be understood that numerical values or ranges referred to herein are not limited to the exact value(s) or range(s) specified but encompass ranges or values of or about those specified. Similarly, terms such as "impermeable", "perpendicular", "water tight", "porous", "non-porous", "free from" etc., are not limited to the features being precisely as specified e.g. non-porous, and should be understood to encompass arrangements according to or substantially according to the specified features e.g. substantially non-porous or non-porous.

Some preferred embodiments of the present invention will now be described by way of example only, and with reference to the accompanying drawings of which:-Figure 1 is a perspective view from one side of a metal-glass composite construction unit in accordance with one embodiment of the invention incorporating linking means; Figure 2 is a cut away view illustrating the interface between the glass core and metal shell in the embodiment of Figure 1 in more detail in the region of the stiffening ribs and grooves; Figures 3A-C illustrate the steps in a preferred method which may be used to produce a construction unit in accordance with the embodiment of Figures 1 and 2; Figure 4 illustrates schematically the Joinrng of a plurality of construction units in accordance with the invention to one another to produce a structure; and -29 -Figure 5 illustrates a composite metal-glass construction unit in accordance with a second embodiment of the invention.

A construction unit I in accordance with a preferred embodiment of the present invention is in the form single piece unitary metal-glass composite unit. The construction unit I includes a metal shell in the form of an open-topped waste tin-plated steel can 3 having a glass core 5. The glass core 5 is a solid glass core provided by a quantity of glass cutlet which has been heated in the can 3 to melt and fuse the cutlet, before being allowed to cool in the can. The can therefore acted as a permanent mould containing the glass cutlet during the melting process, during which process the fragments of cullet became firmly bonded to one another and the can.

The can 3 is a cylindrical can having a closed bottom end 4 and a longitudinally extending axially curved surface 6 extending perpendicular therefrom to provide side walls. The bottom end or base 4 of the can is substantially planar.

The top end 8 of the can is open, and the walls of the can 3 extend a short distance beyond the end of the glass core 5 furthest from the bottom end 4. The can is a can of the type which may be used to hold liquids, e.g. such as a soup can. The can may, for example, have a height or length of from 8 cm to 20 cm.

As shown in more detail in Figure 2, a plurality of circumferentially extending grooves 9 are provided in the longitudinally central section of the can 3 on its internal surface, defining respective stiffening ribs 11 therebetween. Each internal groove 9 or rib 11 defines a corresponding rib 11' or groove 9' on the extenor surface of the can 3.

The construction unit I has a plurality of linking members in the form of metal wires 7 extending from one end to the other through the entire length of the glass core 5, and projecting beyond each of its ends 4, 8. The wires are metal wires which are relatively rigid. The wires extend through apertures in the base 4 of the can. Despite having apertures in its base through which the wires 7 extend, the can 3 is substantially impermeable to fused glass so that it may provide a container for the fused glass cullet during heating of the glass in the can. One of the wires has been bent into a hook-shape to cooperate with wires extending from the end of an adjacent similar construction unit in use to aid linking between the adjacent units.

Such an arrangement is illustrated in Figure 4. The linking members may facilitate bonding of the units to one another and to surrounding mortar.

Manufacture of a construction unit in accordance with the embodiment shown in Figure 1 will now be described with reference to Figures 3 A to 3C. A typical waste tin can e.g. a soup can is emptied, and apertures provided in its base. A quantity of glass cullet placed in the can (Figure 3A). It is not necessary to remove any paper label from the can before using it to form the construction unit in accordance with the invention. One or more steel wires 7 are inserted into the can 3, extending through the glass cullet 5 and through apertures in the base of the can out of the other end of the can. The can 3 is filled with the glass cullet up to a level just above its open end (Figure 3B).

The tin can 3 containing the glass cullet 5 and steel wires 7 is then placed in a furnace (Figure 3C). The can 3 may be embedded in sand during the heating process to reduce the likelihood of it becoming bnttle. l'he glass cullet 5 is heated in the can 3 at a temperature of 908 C. The heating causes the glass cullet to melt and run into the regions between the stiffening ribs corresponding to the internal grooves 9. The can 3 acts as a permanent mould for the glass therein. As the glass is heated and fuses, its level in the can drops, and the can may be topped up with new solid glass cullet to obtain a desired height for the core. When the molten glass cools, it sets and bonds firmly to the interior of the tin can, forming a single piece metal-glass composite, from which the glass core may not be removed.

In tests it has been found that a total heating time of around 1 hour may be suitable to achieve sufficient fusing between the fragments of cullet to bond them to one another and form an integral core, and to adhere them to the interior of the can.

The actual "soaking time" once the furnace has reached a desired temperature may be as little as 15 minutes for a temperature of around 900 C. At this temperature, using a can in the form of a baked bean can, soaking times of from 15 to 25 minutes have been found to be acceptable. In one example it took 45 minutes for the temperature of a furnace to reach 908 C, and then the furnace was maintained at that temperature for a further 15 minutes of "soaking time" to give a total heating time of 1 hour.

-31 -After the heating period, the furnace is turned off, and the metal-glass composite units are annealed by allowing them to cool in the closed furnace. A period of 12 hours of annealing time with the furnace door closed has been found to be suitable. Thus, it will be seen that the construction units in accordance with embodiments of the invention may have a firing temperature of 908 C, along with a total production of 13 hours i.e. 1 hour of heating time and 12 hours of annealing or cooling time.

Heating may be conducted in any suitable furnace. For example a kiln may be used. Advantageously, the furnace is of the type which may be opened while heating is in progress. Annealing may be carried out in the same, or a different furnace to that used to fuse the glass.

Rather than annealing the can, the can may be cooled more rapidly i.e. quenched in air after fusing of the glass therein. This may provide a transparent glass core, as the glass becomes amorphous. in some embodiments sequential quenching and annealing may be carried out.

It has been found that the provision of ribs and/or grooves on the internal surface of the mid-section of the can, may be beneficial in enhancing the level of bonding between the glass core and the tin can in the final construction unit obtained after annealing.

It will be appreciated that it is not necessary for the can to necessarily be a tin plated steel can. However, it has been found that a tin-plated can is particularly beneficial in promoting bonding between the glass core and in the interior of the can.

It will be appreciated that if a construction unit of different dimensions is desired, the depth of the glass cullet relative to the walls of the can may be varied, e.g. by cutting the can, or selecting a can of a different original height, or changing the level to which the can is filled with cullet.

In some applications, it may be desired for the final construction unit to have a rectangular or square horizontal cross-section, rather than a circular one. In some embodiments, reshaping of the can may be carried out to provide it with a desired shape e.g. to facilitate joining of a plurality of such units to one another to provide a modular structure. Reshaping may be carried out before introducing the glass into -32 -the can. Food cans have been found to be easily malleable and may particularly simply be reshaped prior to heating.

It has been found that a glass cullet comprising soda lime glass may be particularly advantageous.

One exemplary form of glass cullet usable in accordance with the invention may be a granulated glass cullet granulated by the waste glass imploder obtainable from Krysteline Ltd., having the composition set out below. This cullet was used in the examples described above.

Colour Tonnes Clear 306,250 50 Green 437,500 35 Amber 131,250 15 Total. 875,000 100 -_____ By way of example, a suitable tin-plated steel can is a can which comprise with the British Standard ISO TR 1176:1992 "Light-gauge metal containers -Round open-top cans -Classification of can sizes by construction type".

Of course, other forms of glass or metal shell may be used, and when glass cullet or metal cans are used they need not be of the composition exemplified above, which examples are intended for the purposes of illustration only.

Effectively, the tin can provides a mould for the glass during the production of the unit, and also remains permanently adhered to the glass core in the final product to provide the composite metal glass unit with suitable properties for use as a construction unit. The can is in effect a type of permanent mould.

In an alternative embodiments of the method of the present invention, not illustrated, rather than melting or fusing the glass cullet in the can, it is melted prior to be introduced to the can, and poured into the can in fused form. Such a method may be more suitable for mass manufacture. The linking members may be inserted in the can before the molten glass is introduced. In these embodiments, the cans may be buried in sand to reduce the likelihood of their being deformed when they come into contact with the molten glass. The units obtained may be annealed and/or -33 -quenched as described above, and the composite units obtained may have any of the features described in respect of the unit shown in Figure 1, or other units produced in accordance with the first embodiment of the method. This further embodiment of the method differs only in the manner in which the glass is introduced to the can i.e. in liquid rather than solid form, removing the need to carry out a step of heating the glass in the can.

A further embodiment of the invention will now be described with reference to Figure 5. The construction unit 30 in accordance with this further embodiment is similar to that described above, except that rather than being a solid glass core, the glass insert 36 is in the form of a sleeve which surrounds an inner metal insert 34 located in the metal shell 32. The metal shell 32 is in the form of a waste metal can.

The metal insert 34 is also a waste metal can, but of smaller diameter than that which provides the metal shell 32. For example, the cans may be respectively, a baked beans can for the inner metal insert 34, and a tinned peaches can for the outer metal shell 32. The glass insert 36 is provided by a quantity of fused or melted glass cullet which has been provided in the cavity between the walls of the inner metal insert and outer metal shell and allowed to cool therein to produce a coherent body of glass.

The unit 30 in accordance with this further embodiment thus defines a central cavity into which e.g. a pipe may be introduced. If desired, a hole may be provided in the base 38 of the unit to allow a pipe to extend fully therethrough. In these embodiments, the unit may provide an insulating lagging to surround a pipe.

The unit in accordance with this further embodiment may be produced in the same manner as described with respect to the first embodiment, with glass being introduced into the cavity defined between the metal shell and metal insert in a solid state, followed by heating of the glass in the cavity, or being introduced to the cavity in an already molten or fused state. The shell containing the glass sleeve and metal insert is then allowed to cool with the glass solidifying as discussed above.

Quenching and/or annealing may be carried out. The unit may comprises linking means and any of the other further features described above with respect to the other embodiments to the extent that they are not inconsistent therewith.

The units obtained in accordance with embodiments of the invention may be used in the manner of a conventional clay bnck, by embedding them into mortar in a suitable configuration to create a required construction. In use, the wires extending from the ends of the cans in preferred embodiments may be used as a physical linkage to enhance attachment between adjacent units as shown in Figure 4. Figure 4 schematically illustrates a joining of a pair of construction units 10, 20 in the form of bricks in accordance with the present invention to provide a part of a structure.

The bricks 10, 20 are set in mortar 30 in the same way as conventional bricks, and the metal wires 12 and 22 extending from the opposed end faces of the bricks are linked to one another to facilitate attachment between the bricks. Linking members may of course extend from any side or sides of the unit, and need not only extend from the end thereof.

In accordance with any of the aspects or embodiments of the invention, internal cavities or pores may be introduced into the glass material of the glass insert during manufacture to provide cavities or pores in the final solidified glass insert. In other embodiments, the glass material of the glass insert may be non-porous.

It has been found that metal glass composite construction units in accordance with the present invention have properties which allow them to perform similarly, or better than conventional clay bricks, while being more environmentally friendly.

For example, it has been found that in tests of compression strength, on a Denison apparatus, a construction unit in accordance with the above described example of the present invention when placed horizontally may fail at a higher stress than a conventional clay brick tested on the same rig. In some tests, the metal-glass construction units have been found to fail at 30 MPa when tested in this way, while a conventional clay brick failed at 7 MPa.

It is believed that the outer shell provided by the metal can may provide the brick with high levels of mechanical strength and toughness, and may alleviate the brittleness which the use of glass alone would exhibit.

The metal-glass construction units in accordance with the invention have also been found to exhibit other advantageous properties. In particular, the use of metal and glass materials may provide a construction unit with greater resistance to water absorption than a conventional clay brick, thus allowing the problem of -35 -dampness to be reduced in buildings or structures formed from such bricks.

Furthermore, the combination of metal and glass may provide the construction unit with greater ability to withstand extremes of temperature, and thus freeze-thaw capabilities.

Structures formed from metal-glass construction units in accordance with the invcntion may be more efficient to heat and/or cool due to the high thermal mass of the construction units. Thus, the level of heating required in cooler climates may be reduced, and the level of air-conditioning required in hotter climates accordingly also may be lower. The units may absorb heat during the day, and slowly release during the night, thus aiding thermal insulation of the building, reducing the need for heating or air-conditioning. This may help to conserve energy and provide environmental benefits. The use of the construction units may allow a better micro-climate inside the building to be obtained, with a low level of temperature variation or fluctuation.

As the construction units in accordance with the invention may be formed entirely from waste materials, they may help to conserve raw materials, thus providing environmental benefits. Furthermore, the process used to form the construction units may be more energy efficient than conventional brick-making processes using raw materials. For example, a metal glass construction unit weighing around 0.8 Kg may cost around 5 pence in terms of electrical energy to produce, while 1 Kg of standard clay brick may cost 30-80 pence (CES 2005 Edupack Materials selection database, www.grantadesign.com). This is due to the lower temperatures and residence times required to fire the metal-glass construction units of the present invention due to the inherent properties of their constituent materials in comparison to a standard clay brick.

For example, while construction units in accordance with the invention may be produced using a furnace temperature in the order of around 900 C, and within an overall production time of 13 hours, including 1 hour of heating, clay bricks may require an average firing temperature of over 1000 C i.e. 1050 C (www.191lencyclopedia.org/Brick), and longer drying times. Furthermore, construction units in accordance with the invention are not so susceptible to moisture content of surrounding atmosphere during the drying process due to their -36 -low levels of moisture absorption. In contrast, clay bricks which have a strong tendency to absorb water must be dried in a controlled environment.

As described above, in particularly preferred embodiments the construction units of the present invention are formed entirely from waste materials, in this way, the units may provide one way of reducing the need for land filling, and may be provided by using locally produced waste glass and cans, reducing the high transportation costs associated with glass recycling. Furthermore, the use of waste glass and metal may further reduce temperatures and residence times required to fire the units in comparison to standard clay bricks as the above example illustrates.

This is because recycled glass, or glass cullet may be melted at lower temperatures than may be the raw materials used to produced virgin glass.

It will be appreciated that it is not necessary to wash and sort theglass cullet prior to being used in accordance with the present invention, in contrast to some conventional construction techniques wiuch add glass fragments to a concrete mixture. In those arrangements, as the glass cullet directly contacts the concrete, it is necessary to know the residues and composition of the glass cullet to a high degree in order to be able to reliably predict the curing time for the concrete. These arrangements therefore require that the waste glass washed and sorted prior to use.

Such methods of attempting to reinforce concrete using glass alone also fail to provide significant improvements in the mechanical properties of the aggregate containing the glass in contrast to the present invention, in which the glass cullet is first inserted in a metal container to provide a metal-glass composite unit.

Claims (36)

-37 - CLAIMS

1. A construction unit comprising a metal outer shall and a glass insert, the metal outer shell extending over at least a part of the glass insert.

2. The construction unit of claim I, wherein the shell defines a base and side portions extending over a base and side portions of the glass insert.

3. The construction of unit of any preceding claim, wherein the shell is open at one end to expose the end of the glass insert.

4. The construction unit of claim 3, wherein the shell is longer than the glass insert and extends beyond the exposed end of the glass insert.

5. The construction unit of any preceding claim, wherein the shell is in the form of an open ended container which receives the glass insert.

6. The construction unit of any preceding claim, wherein the shell is a can, preferably a waste can.

7. The construction unit of any preceding claim, wherein the unit comprises at least one linking member extending therefrom for facilitating joining of the unit to an adjacent unit in use.

8. The construction unit of any preceding claim, wherein the metal shell includes a plurality of grooves on its inner surface.

9. The construction unit of any preceding claim, wherein the unit is generally cylindrical.

10. The construction unit of any preceding claim, wherein the glass insert is in the form of a glass core.

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ii. The construction unit of any of claims I to 9, wherein the glass insert is in the form of a sleeve.

12. The construction unit of claim 11, wherein the unit further comprises a metal inner insert, and the glass insert is located in a cavity defined between the metal outer shell and metal inner insert.

13. The construction unit of claim 12, wherein the construction unit is hollow.

14. The construction unit of claim 12, wherein the metal inner insert is a can, preferably a waste can.

15. The construction unit of any preceding claim, wherein the glass insert is directly bonded to the metal outer shell.

16. The construction unit of any preceding claim, wherein the glass insert is provided by a quantity of molten or fused glass which has been allowed to cool and solidify in the shell.

17. The construction unit of claim 16, wherein the quantity of glass is in the form of a plurality of pieces of glass which have been heated in the shell to bond the edges of the pieces to one another and the shell.

18. A construction unit comprising a glass insert and a non-glass outer shell extending over at least a part of the glass insert, wherein the glass insert is formed by a quantity of molten or fused glass which has been allowed to solidify in the outer shell.

19. A method of producing a construction unit having a glass insert and a metal outer shell, the method comprising: providing a metal shell in the form of a container for receiving a quantity of glass; -39 -providing a quantity of molten or fused glass in the metal shell, and allowing the molten or fused glass to cool in the metal shell to provide a composite metal/glass construction unit.

20. A method of producing a construction unit having a glass insert and a non-glass outer shell, the method comprising: providing a non-glass shell in the form of a container for receiving a quantity of molten or fused glass; providing a quantity of molten or fused glass in the shell; and allowing the molten or fused glass to cool in the shell to provide a composite construction unit.

21. The method of claim 19 or 20, further comprising locating an inner metal insert in said shell, and providing said quantity of molten or fused glass in a cavity defined between said shell and said metal insert.

22. The method of claim 21, wherein said metal insert is in the form of a metal can.

23. The method of any of claims 19 to 22, wherein the step of providing a quantity of molten or fused glass in the shell comprises heating a quantity of solid glass in the shell to melt or fuse the glass.

24. The method of claim 23, wherein the quantity of solid glass is in the form of a plurality of pieces of solid glass.

25. The construction unit or method of any of claims 16 to 24, wherein the molten or fused glass is molten or fused glass cullet.

26. The method of any of claims 19 to 25, further comprising annealing the unit by allowing the melted or fused glass to cool gradually in the shell.

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27. The method of any of claims 19 to 26, further comprising quenching the unit in air.

28. The method of any of claims 19 to 27, further comprising inserting a linking member in the shell for facilitating linking of the unit to an adjacent unit in use before or after introduction of the molten or fused glass, and allowing the glass to solidify around the linking member to anchor it to the unit.

29. The method of any of claims 19 to 28, further comprising reshaping the shell.

30. A construction unit obtained in accordance with the method of any of claims 19 to 29.

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31. The use of a plurality of construction units in accordance with any of claims I to 18, to construct a structure.

32. A plurality of construction units in accordance with any of claims I to 18, joined to one another by mortar and/or linking means associated with the respective units to define a structure.

33. A construction unit comprising a metal outer shell, a metal inner insert, and a glass insert in the form of a sleeve located in a cavity defined between the metal shell and the metal inner insert.

34. A construction unit comprising a glass core and a metal outer shell extending over at least a part of the glass core.

35, A construction unit comprising a body of glass and a body of metal disposed in or around the body of glass. -41 -

36. A construction unit, or method of making a construction unit, substantially as herein described and with reference to any one of the accompanying drawings.