GB2514542A

GB2514542A - A Method of, and System for, Manufacturing a Composite Sett

Info

Publication number: GB2514542A
Application number: GB1307232.7A
Authority: GB
Inventors: Derek Witchell; Leigh Chapman
Original assignee: QUICKSETTS Ltd
Current assignee: QUICKSETTS Ltd
Priority date: 2013-04-22
Filing date: 2013-04-22
Publication date: 2014-12-03
Anticipated expiration: 2033-04-22
Also published as: GB2514542B; WO2014174232A1; HK1245724A1; EP3233435A1; GB201307232D0

Abstract

A type of paving or cladding brick, known as a sett, is formed as a flexible composite from a mixture of polymeric matrix and stone aggregate. The matrix is a combination of resin, catalyst, and flexibility additive. The mixture may be moulded in a flexible mould cavity and is preferably partially cured by heating in the mould cavity, removed from the mould and then finally cured. This frees the mould for further use. The mould may have a contoured moulding surface. The aggregate may be dried prior to mixing and vacuum may be applied during mixing and/or moulding to remove bubbles. Mould walls may be coated with powder such as bauxite to aid release and to provide finished setts with a non-slip surface. A plurality of moulds may be provided on a continuous conveyor and the setts may be urged from the moulds by turning them up-side-down. A first composite set may be pressed into a layer of bedding and jointing compound and a second sett placed adjacent the first to define a gap. The second set may then be pressed into the layer causing the compound to rise in the gap until almost at the top of the setts.

Description

A Method of, and System for, Manufacturing a Composite Sett

Field of the Invention

This invention relates generally to a method of, and system for, manufacturing a composite sell, for example of the type of brick, known as a sett. More particularly this invention relates to a composite sell formulated from a mixture of polymeric matrix and stone aggregate.

Background

Stone sells are a type of brick most commonly used as a paving stone. Stone sells in pavement are also known as flagstones, bricks, briquettes, paving stone, slab, rumble stone, and block.

Traditional stone sells were Qften made by splitting them from stone blocks, such as solid granite or marble. Stone sells were subject to wear as paving stones from footfall and also horses' hooves and carriage wheels. Nowadays stone sells are subject to wear from footfall, car traffic and lorry traffic.

is Not all such sells are subjected to wear from vehicles. Some sells are used for façade coverings of wall, bathtubs, and so forth for aesthetic purposes, relying on the beauty of the particular stone pattern, such as marble or granite.

Traditional stone sells that are split from solid stone are expensive in part because of the cost to make them. Traditional stone sells made with modern manufacturing methods, such using a diamond tipped blade or abrasive water jet cutters, are expensive because of the need to cut them from large, uncracked solid boulder.

Traditional stone setts, when provided in a slab form, are brittle and prone to crack. Thermal shocks and stresses can also cause cracking in traditional stone setts Traditional stone sells are also subject to cracking by very heavy loads, shock loading (for example when an object is dropped on the traditional stone sell) or point loading.

Traditional stone setts, are made from hard dense stone such as granite.

Traditional stone sells wear into and break down the base below them. Base materials are usually bituminous tarmac or concrete which tend to crumble and crack under repeated pounding by forces applied through hard sells by foot traffic or vehicle traffic.

The usual medium for holding stone sells in place is a concrete binder. The stone setts are allached by placing them into the soft concrete. When the s concrete hardens the stone sells are permanently fixed into position. Another problem is that under shock loading or due to thermal stress, differential stresses are established between the concrete and stone and these can give rise to cracking.

Prior Art

Examples of techniques of making traditional stone sells and adhering them to a surface are taught in the documents referred to below.

European patent application EP-A2-467025 (Flato) discloses a process for the production of natural stone paving elements.

European patent EP-B1-O 958 257 (Cairn Holdings UK) discloses mixtures of materials settable on exposure to the atmosphere.

European patent application EP -A2 -1706363, (Mix U.K. Limited), which relates to filling materials for use with paving flags and the like comprising at least one base material, at least one binder, at least one cross-linking agent, a solvent and at least one cure retarder.

US patent US -5 372 676 (Lowe) relates to a method for producing replicated paving stones.

The aforementioned sells are only examples. However, all appear to relate to inexpensive methods for manufacturing bricks and for holding the bricks in position. None of the aforementioned systems or methods is concerned with the aesthetic appearance of artificial stone setts, which is often sacrificed by mass produced artificial stone sell manufacturing processes.

Another problem is that many artificial bricks are prone to cracking.

Objects of the present invention are to overcome the aforementioned problems.

Summary of the Invention

According to a first aspect of the invention there is provided a system for manufacturing a composite sett that comprises a mixing vat for receiving resin, aggregate, catalyst and a flexible additive and mixing these into a slurry; a mixer; a flexible sett mould has a contoured surface to provide a contoured surface s finish to the composite sett and defines a sell mould cavity into which the slurry is introduced; and a heater for heating the slurry in the sett mould cavity in order to initiate curing of the slurry into the composite sell in a form suitable to be cast-out from the sett mould cavity.

To split from solid stone traditional stone setts is a time consuming, and laborious process The method of making composite setts, system for making composite sells, and method for operating the system of the present invention solve this problem. The present invention does not form composite setts from solid stone.

It does not require labour intensive splitting or expensive complex machinery to cut traditional setts from solid stone.

Preferably the system comprises a means for applying a vacuum or an inert atmosphere to the slurry in the mixing vat.

According to a second aspect of the invention there is provided a system for manufacturing a composite sell that comprises: a mixing vat for receiving resin, aggregate, catalyst and a flexible additive and a means for mixing these into a slurry; a means for applying a vacuum or an inert atmoèphere to the slurry in the mixing vat; a flexible sell mould defines a sett mould cavity into which the slurry is introduced; and a heater for heating the slurry in the sell mould cavity in order to initiate curing of the slurry into the composite sell in a form suitable to be cast-out from the sell mould cavity.

Preferably the flexible sell mould has a contoured surface to provide a contoured surface finish to the composite sell.

Preferably the system for manufacturing the composite sell comprises a dryer arranged to dry the aggregate before mixing the aggregate.

Preferably a means is provided for coating inner surfaces of the sell mould cavity with a layer of powder prior to introducing slurry into the sell mould cavity. An advantage of this is Ideally a plurality of sell moulds is supported on a continuous conveyor belt. An advantage is that continuous production of composite sells is made possible by this type of continuous conveyor belt moving around in an endless loop.

Preferably there is a slurry transfer mechanism arranged to transfer slurry from the mixing vat into sell mould cavities on the conveyor belt in an efficient manner and prior to curing of adhesive is complete. Advantageously consecutive sell mould cavities are filled and consecutive sell mould cavities are emptied as the continuous conveyer belt moves around in the endless loop.

Preferably the continuous conveyor belt includes a shute located at an end thereof and arranged to receive cast-out composite sells ejected from mould cavities at an end of the continuous conveyor belt. Ideally there is a means for urging the composite sells from their respective cavities.

According to a third aspect of the invention there is provided a method of manufacturing a composite sell comprising the steps of: mixing resin; catalyst, and flexibility additive in a mixing vat into a catalyzed liquid combination; mixing the catalyzed liquid combination with an aggregate to form a slurry; transferring the slurry into a sell mould cavity; maintaining the slurry in the sett mould cavity for at least ten minutes at a temperature of at least thirty degrees C to form a cast-out-ready composite sell; casting the cast-out-ready composite sell from the sell mould cavity; and maintaining the cast out composite sell at least thirty degrees C for a period of at least one hour to cure the composite sell.

The advantage of heating the slurry in the sell mould for a short period until the cast-out -out-ready composite sell is ready to be cast out is that the sell mould cavity is relatively quickly emptied so it can receive slurry for another composite sell. Heating the cast-out-ready composite sells until they are cured takes hours, but once the composite sells have cured to the cast-out-ready condition they can support their own weight and retain their shape without the support of the sell mould. Therefore the cast-out-ready composite sell is not required to be in the sell mould.

According to a fourth aspect of the invention there is provided a method of operating a system for making a composite sell comprising the steps of: mixing resin, catalyst, and flexibility additive in a mixing vat into a catalyzed liquid combination; mixing the catalyzed liquid combination and an aggregate into a slurry: transferring the slurry into a sell mould cavity; maintaining the slurry in the sell mould cavity for at least ten minutes at a temperature of at least thirty degrees C to form a cast-out-ready-solid composite sell; casting the cast-out composite sell from the sell mould cavity; and maintaining the cast-out s composite sell at least thirty degrees C for at least one hour hours to cure the composite sell.

Preferably the method of operating a system for making a composite sell includes the step of: operating an aggregate dryer and drying an aggregate prior to mixing the catalyzed liquid combination with the aggregate.

Preferably the method comprises the step of: applying a force to the slurry so as to rempve air bubbles/discontinuities. The advantage is after the slurry is cured is it a solid mass without bubbles that could weaken it make it porous.

Preferably in the method the slurry is mixed with the catalyzed liquid combination in a vat so as to remove air bubbles/discontinuities from the slurry in the vat. The advantage is of the vat being equipped with a means to stir and mix the slurry is that the convection of stirring the slurry brings bubbles near the surface which aids in removing bubbles/discontinuities.

Ideally a vacuum apparatus is used to apply a vacuum to the slurry in the sell mould cavity. The advantage is that the mould cavity is shallow since the composite sell is as thin as a flagstone. Bubble in the slurry to do not have far to rise to the surface and so the slurry in the sell mould cavity is sucked clear of bubbles quickly.

Ideally the vacuum is applied to slurry simultaneously as heat is applied to the slurry in the sell mould cavity. The beneficial effect is that warmer slurry is less viscous so bubble rise through it more quickly and the slurry is made more devoid of bubbles more quickly.

Preferably in the method the sell mould cavity is turned upside down to urge the cast-out composite sell out of the sell mould cavity.

According to a fifth aspect of the invention there is provided a composite sell comprising a matrix which is a combination of resin, catalyst, and flexibility additive and also comprising a dried aggregate so that the aggregate is bound by the matrix.

Preferably the grade of the aggregate comprised in the composite sell is in the range of #1 to#3.

More preferably the grade of the aggregate comprised in the composite sell is in s the range of #2 to #5.

Preferably the aggregate size ranges from grains of dust to pebbles about 6 mm across.

Composite setts made from dust appear as grey stone. Composite sells made from pebbles of granite appear as traditional granite setts.

Preferably the resin comprised in the composite sell is polyester.

According to a sixth aspect of the invention there is provided a method of applying composite sells comprising steps of; applying a layer of bedding and jointing compound to the surface, pressing a first composite sell into the into the layer, laying a second composite sell adjacent to the first sell with a gap between them, and pressing the second composite sell into the layer until the compound rises in the gap almost level with the top of the first and second composite sell.

Traditional stone sells are prone to cracking especially when subject to heavy loads such as from vehicles and also fluctuations in temperature due to summer heat and winter cold. This brittleness is exacerbated because the thickness of sells is relatively small compared to their length and width. This means that the brillle stone traditional setts cannot support much weight without cracking all the way through their thickness. The composite sells which are the present invention solve this problem by binding stone aggregate in a flexible matrix. The brittleness of traditional stone setts is also exacerbated by the porosity of stone which absorbs water which cracks the stone when it freezes. The composite stone setts are not porous because the matrix which binds and covers the aggregate is not porous.

Traditional stone sells are fixed to pavement by concrete. Concrete itself is prone to crack and crumble. It is porous and absorbs water. These problems are solved by fixing composite sells with the bedding and jointing compound which is not porous. The stone sell according to the invention is flexible and does not crack or crumble.

Concrete does not stick to traditional stone setts well. The method of applying composite sells to pavement solves this problem. The bedding and jointing compound adheres well to aggregate and especially well to the matrix which S binds the stone aggregate. The bedding and jointing compound sticks physically to the composite sells and.it sticks physically and chemically to the matrix which binds and cover the aggregate.

Traditional stone setts are a hard stone such as granite. Traditional stone sells wear into and break down the base to which they are fixed. Composite sells are a combination of relatively soft and flexible matrix which stone aggregate.

Advantageously the soft matrix of composite sells means that composite sells do not wear and breakdown the base nearly as rapidly as traditional stone setts.

The bedding and joint compound cures in a few hours or preferably under an hour.

is The invention is further explained, by way of examples, by the following description, to be read in conjunction with the appended drawings, in which:

Brief Description of the Figures

Figure 1 is view of a traditional sell; Figure 2 shows a view of a composite sell; Figure 3 shows a cross section through a composite sell; Figure 4 shows a diagram flow chart for the process steps to make a composite sell; Figure 5 shows a sell mould containing a plurality of sell mould cavities; and Figure 6 shows a composite sett production apparatus with a sell mould that is conveyor belt.

List of Numbered Items in Figures Traditional Composite Sell 12 Settlhicjcness 14 Sett Length 16 Sell Width Traditional Composite Sell s 22 Top of Sett 24 Side of Sell 26 Bottom of Sell 27 Cross Section Face of Composite Sen 28 Matrix of Composite Sell 0 30 Aggregate of Composite Sen Mould for Composite Sell Mould Cavity for Composite Seft 58 Slurry Cast-Out-Ready-compojfe..5 67 Heater Vat 77 Bending Roller Detailed Description of Preferred Embodiments of the Invention Exemlary embodiments of the invention will now be described in detail.

Referring to the Figures, there is shown in Figure 1 a traditional sell 10. It is tile shaped. The thickness 12 is less than either the length 14 or the width 16.

The traditional sett is cut from single boulder. The means for cutting is splitting.

In Figure 2 there is shown a composite sett 20. The top 22 and sides 24 of the composite sett appear to have a rough surface because the composite sell is formed in a mould with split-out like indentations in the side and bottom. The composite sell 20 appears very similar the traditional sell 10. A standing person looking down on a traditional sell on a roadway beside a composite sell 20 would hardly be able to see a difference.

The bottom 26 of the composite sell though may be flat without split-out indentations. The bottom of the composite in use is pressed into bedding and jointing compound against pavement. The advantage of a bottom of the composite sell being without split-out indentations is that it presses flush against io the pavement without wobbling. Traditional sells that wobble against a hard pavement are repeatedly bashed against the hard pavement by traffic that runs over the traditional sells. The composite setts revealed by the present invention do not suffer from this bashing because their flat bottom rests squarely on the pavement.

In Figure 3 there is shown a cross section surface 27 through the composite sell.

The cross section shows a matrix 28 which binds together aggregate stones 30.

The aggregate stones are tiny and appear as specs in the matrix.

Preferably the matrix is transparent and the aggregate particles are densely packed. The net effect is that a person looking at the moulded set is able to see through the matrix to the opaque aggregate particles. Preferably the particles are tiny and hardly distinguishable by the naked eye when observed at a distance of eye-level down to the ground-level of the sell.

Therefore, just as particles of sand cannot be distinguished in sandstone, the composite sell appears nearly identical to the traditional sell because the particles of aggregate cannot be distinguished and the matrix is nearly invisible.

In Figure 4 there is shown a diagram flow chart for the process steps to make a composite sell.

As shown in Figure 4 the first step 101 is to select the type and grade of aggregate. For durable sells that stand up to repeated rollover by heavy vehicles the preferred aggregate type is granite.

A fine size of aggregate is preferred. Fine means individual particles cannot be distinguished from a distance of eye-level to ground level which is distance just over a meter.

A size of aggregate particles in the range from #2 to #5 is preferred because these particles make for a rough no skid surface which is very long lasting in a S composite sell subject to heavy traffic. A size in the range from #1 to #3 is preferred because these very fine particles appear practically the same in a composite sell as they do in a traditiona! sell.

As shown in Figure 4 the next step 102 is to dry the aggregate. Depending on the process used to crush or grind the aggregate into tiny particles, the aggregate may originally be very wet.

Moisture does not mix with the composite sell matrix. Moisture takes up volume a composite sell and weakens the grip of the binder on the aggregate particles in a composite sell, If the moisture inside a composite sell freezes, then it also expands and destroys the sell fracturing the matrix so that the composite sell crumbles. For these reasons drying the aggregate is a critical step.

Preferably the dried aggregate is dried in a kiln.

As shown in Figure 4 in step 201 liquid resin is combined with a catalyst, and a flexibility additive. This results in a catalyzed liquid combination that is a viscous m Mu re.

Preferably the liquid resin, catalyst, and flexibility additive are combined in a vat.

About ninety-eight parts liquid resin are combined with two parts catalyst. Once the resin and the catalyst are combined, the liquid mixture begins to thicken and then harden. When the resin and catalyst. are combined the liquid mixture warms. Ideally reaction, ambient temperature of the environment where the mixing occurs, and heat applied to the liquid mixture in the vat and sell mould warms the liquid mixture to between thirty degrees centigrade and fifty degrees centigrade. Preferably the temperature is between thirty-five and forty-five degrees. The step where the catalyzed liquid combination is mixed in the vat is shown as step 202 in Figure 4.

The effect of flexibility additive is to impart flexibility to the combination after it has hardened. The flexibility additive makes the solidified combination flexible. This flexibility toughens sells.

Traditional sells made from solid stone are britfle and prone to cracking.

The solidified combination is flexible. It bends without cracking.

The flexibility of the solidified combination makes composite sells in which the s width and length are at least 3 to 50 cm and the thickness is between 4 mm and 3 cm tough and sufficiently resistant to cracking to withstand heavy traffic and seasonal fluctuations in temperature and water from runoff and rain.

For a while before the catalyzed liquid combination has hardened it has the viscosity of treacle. During this time before the catalyzed liquid combination hardens it must be used in several steps.

The chemical reaction between the liquid resin and the catalyst which causes the catalyzed liquid combination to harden, can depending on the chemicals used, generate gas bubbles in the catalyzed liquid combination.

There is physical agitation of the catalyzed liquid combination by the act of mixing the liquid resin, catalyst, and flexibility additive. Physical agitation introduces air bubbles into the catalyzed liquid combination.

If there is moisture in the aggregate when it is mixed with the catalyzed liquid combination some of the moisture vaporizes and form bubbles in the catalyzed liquid combination.

If the catalyzed liquid combination hardens with internal bubbles, then the solidified combination may be weaker than a solidified combination without internal bubbles. The walls of the bubbles are internal edges where cracks may start. The bubbles take space in the solidified combination so that a given cross section of the solidified combination has less solid material and so is less strong than a cross section without bubbles.

Therefore it is preferable after the liquid resin, catalyst, and flexibility additive are combined in the vat to remove all the gas bubbles out of the catalyzed liquid combination before it hardens.

A means of forcing out the gas bubble is applied to the catalyzed liquid combination. One means is to press out the bubbles such as with a press or squeegee. Another is to apply a vacuum to the catalyzed liquid combination which is shown in Figure 4 in step 205.

The vat is covered with an airtight lid, a vacuum pump draws the air out of the vat, and the catalyzed liquid combination inside vat is degassed. This removes s the bubbles from the catalyzed liquid combination.

The aggregate is poured into the vat containing the catalyzed liquid combination and they are mixed together in the vat. This creates slurry of the aggregate and the catalyzed liquid combination is mixed by mixing both together.

The preferred ratio is about 3 Kg of catalyzed liquid combination with 9Kg of aggregate.

Preferably the aggregate is dried before pouring it into the catalyzed liquid combination to form the slurry.

In Figure 4 the slurry is formed in step 105. The agitation of mixing the catalyzed liquid combination with the aggregate causes air bubbles to be entrained.

Therefor it is preferably to have a vacuum degassing step after the slurry is formed.

Preferably the vat is covered with an airtight lid, a vacuum pump draws the air out of the vat, and the slurry inside the vat is degassed. This removes the bubbles from the catalyzed liquid combination.

Preferably the slurry is poured out of the vat or exits from the bottom of the vat after mixing as shown in step 106 of Figure 4.

Preferably there is a degassing vat separate from the vat where ingredients are mixed. The slurry is urged into the degassing vat whereupon the vacuum is applied to the slurry and gas and bubbles are sucked out of the slurry. This is step 107 of Figure 4.

Preferably while the slurry and/or the catalyzed liquid combination is being degassed in the vat, a churn is gently stirring so that bubbles in the liquid are transported with the moving liquid near the surface of the vat by the stirring action. As the bubbles get near to the surface they are drawn quickly out of the liquid by the vacuum. So removing bubbles from the liquid by stirring the liquid in a vat while a vacuum is drawn the vat is an efficient method of sucking the bubbles out of the liquid.

The slurry is now ready to be urged into a sett mould cavity. Figure 5 shows a sell mould 50 comprising a plurality of sell mould cavities.

s Each sell mould cavity 50 has the width, length, and depth of a single sell.

Preferably a single sett mould comprises a plurality of sell mould cavities so that a plurality of sells can be made from a single mould.

Preferably each mould is rubbery, and so twisty and bendy. One the slurry has hardened in the mould it is cast out of the mould by bending and twisting the mould until the hardened sett is loosened from the mould walls and releasable.

Preferably the sett mould is formed from a continuous conveyor belt. The conveyor belt is a band and has no end. A pulley moves the belt. The sell mould cavities are illustrated in the conveyor belt of the composite sell production apparatus shown in Figure 6. Sell mould cavities are placed along the entire length of the conveyor belt.

Preferably each sell mould cavity wall is coated with a layer of bauxite powder about 3 to 4 mm thick before the slurry is put into the mould. This step of coating the mould cavity wall with bauxite powder is shown in Figure 4 as step 108.

Ideally the sell mould cavity wall is dusted with bauxite powder by sprinkling the powder onto the sett mould cavity wall.

The purpose of the bauxite powder is to make a nonslip surface on the hardened sell. Another purpose of the bauxite powder is to aid release sett after the slurry hardens in the mould.

Other powders could be used in place of bauxite powder, such as alumina. A powder is particularly advantageous if it both produces a nonslip surface on the hardened sell and aids in release of the sell from the mould.

The slurry is urged into the sell mould cavity. The slurry may be spooned into the set mould cavity, poured into the set mould cavity, injected into the set mould cavity, squirted into the set mould cavity. A simple gentle gravity feed of the slurry into the sell mould cavity is preferred because this method does not reintroduce bubbles into slurry and because it is simple and reliable.

The slurry is urged into the sell mould cavity in step 109 shown in Figure 4.

Where the sell mould is a conveyor belt, set mould cavities are formed in the conveyor belt all the way around the loop. The slurry is urged into a sell mould cavity and conveyor belt moves along bringing the next sell mould cavity into position for receiving the slurry. This process of filling the next consecutive is sell mould cavity is repeated resulting in an efficient production of slurry filled sell mould cavities.

To ensure that there are no bubbles in the slurry before the slurry in the sell mould hardens, a vacuum is preferably drawn on the sell mould after the slurry is in the sell mould cavity. The mould is placed in a vacuum chamber or an airtight mould cover and then is sealed to the sell mould and the vacuum applied to the slurry in the sell mould cavity. The advantage of applying the vacuum to the slurry while it is in the mould is that the depth of the slurry only the thickness of the composite sell. Bubbles in the slurry do not have to travel far to get to the surface of the slurry and therefore degassing slurry while the slurry is in the mould cavity is efficient.

To ensure that there are no bubbles in the slurry before the slurry in the sell mould hardens a two step operation utilized where in a first step slurry is urged into the sell mould cavity until the depth of slurry in the cavity is about half the thickness of the composite sell. The advantage of this is the bubbles in the slurry only have half as far to rise to the surface. Preferably the sell mould with the slurry at half thickness is placed into the vacuum chamber to remove the bubbles and to cure until the slurry is not quite solid but very viscous and sticky. Then in a second step more slurry is urged into the sell mould as a second layer on top of the first layer of not quite solid slurry. The second layer is also about half the thickness of the composite sell. The bubbles in this layer also have half as far to travel to the surface to be removed. The vacuum does not have to be applied to the sell mould to draw bubbles out of the second layer. The second layer is on top of the first layer, but after the composite sell is cast out of the mould the second layer is on the bollom of the composite sell. The bollom surface of the composite sell is the surface applied to the pavement or road base so the bottom surface is not visible in use. Therefore if the bottom surface shows bubbles this is not a concern which is a reason why a vacuum does not have to be applied to the second layer of slurry after it is urged on top the first layer. The first layer has had the bubbles removed. So the top surface of the composite sett which can be seen in use is not pocked by bubbles.

Another advantage of the process of forming the composite sett in two layers is that composite setts made in two layers have fewer tendencies to warp while curing. The reason is that a thinner layer cannot build up high stresses though the thickness like a thin sheet of paper cannot do anything but lay flat on a table.

The second layer is applied at lower temperature than the first so that it cures in about an hour and twenty minutes. Preferably the temperature is between twenty-five and thirty-five degrees.

Thin composite sells with a thickness in the range of 3 mm to 12 mm are preferably made in a single layer as the bubbles rise to the surface and pass out of the slurry in a few minutes.

is Advantageously the table that the cast-out-ready solid sells are placed on can be a base such as a roadbed or pavement. Thus the composite setts can fully cure in-situ. On a warm day the composite setts can cure to hardness sufficient to withstand traffic in about one and a half hours. Composite sells are fixed to the base with a bedding compound that also cures in about an hour. This time is much shorter than the time to cure the concrete which secures traditional setts to a base.

Preferably the thickness of the composite sell is less than 2 cm in order to aid degassing during cure and to improve the utility of the composite sell as a brick.

More preferably the thickness of the composite sett is less than 1.5 cm. More preferably the thickness is less than 1 cm to give the best degassing and flagstone utility, and most preferably the thickness is more than 3 mm to give the composite sufficient strength to withstand the loads of use which such as foot traffic and also vehicle traffic.

While the slurry is in the sell mould cavity, the slurry is warmed. Warming is accomplished by puffing the sell mould in an oven, or by irradiating slurry in the mould with microwave energy, infra-red radiation or by blowing warm air across the mould.

The catalyzed liquid combination cures more quickly when it is warm. Therefore the slurry in the sett mould cavity hardens more quickly into a solid sell if the mould is warm than if the mould is cool.

Preferably the sell mould with the slurry in the sell mould cavity is warmed to at s least 26 degrees C. Preferably it is not warmed above 40 degrees C. Most preferably it is warmed to 28 degrees C. Preferably the sells are manufactured in a cool environment where the catalyzed liquid combination and the slurry is easily kept at an ambient temperature between 5 and 20 degrees C until after the slurry is put into the sell mould cavity.

This keeps the catalyzed liquid combination *and slurry in the liquid for hours providing plenty of time for mixing, degassing, preparing mould with bauxite powder, pulling the slurry into the sell mould cavity, and so forth before the slurry cures to a solid.

Alternatively the sells are manufactured in a warm environment where the is catalyzed liquid combination and the slurry is easily kept at an ambient temperature between 30 and 50 degrees C until after the slurry is put into the sell mould cavity. This temperature is ideal for a high production rate because the slurry cures to a near solid in about twenty minutes at 40 degrees C. Preferably the sell mould is also maintained at a temperature of about 30 to 50 degrees C. This helps to keep the thermal gradient in the composite sell to a minimum while during curing in the mould which prevents the composite sell from warping while curing.

The cure rate increases exponentially as the cure temperature increases. The time to cure and therefore solidify the sells decreases exponentially as the cure temperature increases.

After the slurry is cured into a solid sell in the sell mould cavity it must be cast out of the mould.

Slurry in the sell mould cavity cures into a cast-out-ready-solid sell in about a day if the temperature is between 5 and 10 degrees C. Slurry in the sell mould cavity cures into a cast-out-ready-solid sell in less than half an hour if the temperature is above 26 degrees C. Slurry in the sell mould cavity cures into a cast-out-ready-solid sell in about 20 minutes or less if the temperature is above 35 degrees C. The cast-out-ready-solid sett is not fully cured but it is solid enough to be removed from the sell mould cavity and maintain the mould shape under its own weight.

Preferably the cast-out-ready-solid setts are cast out onto a flat table. The bottom surface of these composite sells is placed flat against the flat table. To prevent the edges of the composite sell from curling up, the composite sell is cast out of the sell mould while it is still soft. The weight of composite sell itself and the softness of the composite sell in this cast-out-ready condition keep the composite sett flat against the table and prevent the edges from curling up. The composite sets are also maintained at a near uniform temperature throughout by maintaining the ambient temperature close to the temperature of the cast out sell resting on the table. This prevents thermal gradients building up through the sell and causing the sell to warp and prevents the edges from curling up while the composite sett cures.

Curing the slurry in the sett mould cavity into a cast-out-ready-solid sell is shown in Figure4as step 111.

A second layer of slurry is added on top of the first layer. This is shown in Figure 4 as step 112. Shown in Figure 4 step 112 the second layer is added after the first layer has cured to the cast-out-ready-solid sett stage. But preferably the second layer of slurry is added to the top of the first layer while the first layer is still sticky.

Curing the sell to the cast-out-ready-solid condition and removing it from the sell mould leaves an empty sell mould cavity. The empty sell mould cavity is available to receive slurry Curing the sell to the cast-out-ready-solid condition and then removing it from the sell mould before the set is fully cured makes sell mould cavities available sooner than if than if the sell is not cast out of the mould until it is fully cured.

Casting the sell out of the mould as soon as the sell has cured to the cast-out-ready-solid condition is advantageous for fast and efficient sell production.

The conveyor belt sell mould is arranged with the mould cavities facing upwards when the slurry is put into the cavities and as the sells cure in the cavities.

As the conveyor belt sell mould moves along eventually each sell mould cavity turns upside down as passes over the end pulley. This is illustrated in Figure 5.

Each cast-out-readysoljd sell drops out of the upside down sell mould cavity.

s This leaves the sell mould cavity ready to accept slurry as soon as the conveyor.

belt moves the sell mould cavity over the start pulley.

A bending roller sharply bends the conveyor belt sell mould where the sell mould cavities are upside down to urge each cast-out-readysolid sell to drop out of the mould.

A vibrating element shakes the conveyor belt sell mould where the sett mould cavities are upside down to urge each cast-out-readysolid sett to drop out of the mould.

Alternatively the conveyor belt is articulated like an airport luggage conveyor belt.

This type of conveyor belt never turns upside down. Each section of the is articulated belt comprises at least one sell mould cavity A bending roller sharply bends the articulate conveyor belt sell mould where each section passes over the bending roller. The sharp bend in the mould pops out the cast-out-readysolid sell from the sell mould cavity. The cast out composite sells are guided to a full cure apparatus which fully cures them.

Casting the cast-out-ready..soljd composite sell out of the sell mould cavity in the cast-out-ready-solid condition is shown in Figure 4 as step 113.

Ideally when the cast-out-readysolid composite setts are cast out of the sell mould cavities they drop into a full cure apparatus which fully cures them.

To fully cure a solid sett from the cast-out-readysolid condition takes about a day between 15 degrees C and 25 degrees C. As Figure 3 shows, the fully cured composite sells comprise a matrix which is the solidified combination of the resin, catalyst, and flexibility additive. The matrix is tough and bends without cracking.

The fully cured composite sells also comprise the aggregate. The aggregate is bound together by the matrix which is the flexible solidified combination.

The fully cured composite sells have flexibility imparted to them by the flexible matrix. The composite sells are tough. Few if any cracks form in the cured composite sett when they are subject to foot, car, and lorry traffic, If any. cracks do form in the composite setts, then the cracks are arrested by the tough flexible S matrix.

The full cure apparatus is a simple bin that the cast-out-ready-solid sells drop into.

Alternatively the full cure apparatus comprises a second conveyor that the cast-out-ready-solid composite sells drop onto. This second conveyor transports the cast-out-ready-solid composite sells to an area such as a room where they are stored and fully cured. Alternatively this second conveyor transports the cast-out-ready-solid composite setts to the bin of a waiting lorry or waiting rail freight car. The lorry or train then transports the solid composite sells which reach the fully cured state during transportation.

To reduce the amount of time that the cast-out-readysolid composite setts take to reach the fully cured state once they are cast out of the mould, the cast out composite sells are warmed to at least 20 degrees C. The invention has been described by way of explanation and examples.

Variations and procedures readily apparent to those skilled in the art may be made without departing from the scope of the invention. Such embodiments and modifications fall within the scope of the present invention.

* The invention is made clear and further explained in the appended claims.

Claims

Claims: 1. A system for manufacturing a composite sett comprises: a mixing vat for receiving resin, aggregate, catalyst and a flexible additive and mixing these into a slurry; amixer; a flexible sell mould has a contoured surface to provide a contoured surface finish to the composite sell and defines a sell mould cavity into which the slurry is introduced; and a heater for heating the slurry in the sell mould cavity in order to initiate curing of the slurry into the composite sell in a form suitable to be cast-out from the sell mould cavity.
2. A system according to claim 1 comprising a means for applying a vacuum to the slurry in the mixing vat.
3. A system for manufacturing a composite sell comprises: a mixing vat for receiving resin, aggregate, catalyst and a flexible additive and mixing these into a slurry; a mixer; a means for applying a vacuum to the slurry in the mixing vat; a flexible sell mould defines a sett mould cavity into which the slurry is introduced; and a heater for heating the slurry in the sell mould cavity in order to initiate curing of the slurry into the composite sen in a form suitable to be cast-out from the sell mould cavity.
4. A system according to claim 3 in which the flexible sell mould has a contoured surface to provide a contoured surface finish to the composite sell.
A system according to any preceding claim comprising an aggregate dryer arranged to dry the aggregate before mixing the aggregate.
6. A system according to any preceding claim comprising a means for covering the walls of the sell mould cavity with a layer of powder prior to pouring slurry into the sell mould cavity.
7. A system according to any preceding claim wherein a plurality of sell moulds is supported on a continuous conveyor belt.
8. A system according to claim 7 comprising a slurry transfer mechanism s arranged to transfer slurry from the mixing vat into sell mould cavities on the conveyor belt.
9. A system according to claim 7 or 8 wherein the continuous conveyor belt includes a shute located at an end thereof and arranged to receive cast-out composite setts ejected from mould cavities at an end of the continuous conveyor belt.

1O.A system according to claim 9 comprising: a means for urging composite sells from their respective cavities.hA method of operating a system for making a composite sell comprising the steps of: mixing resin, catalyst, and flexibility additive in a mixing vat into a catalyzed liquid combination; mixing the catalyzed liquid combination and an aggregate into a slurry; transferring the slurry into a sell mould cavity; maintaining the slurry in the sett mould cavity for at least ten minutes at a temperature of at least thirty degrees C to form a cast-out-ready-solid composite sell; casting the cast-out-ready-solid composite sell from the sell mould cavity; and maintaining the cast-out-ready-solid composite sett at least thirty degrees C for at least one hour to cure the composite sell.12.A method of operating a system for making a composite sell according to claim 11 including the step of: operating an aggregate dryer and drying an aggregate prior to mixing the catalyzed liquid combination with the aggregate.13.A method of operating a system for making a composite sell according to claim 11 or 12 comprising the step of: applying a force to the slurry so as to remove air bubbles/discontinuities 14.A method of operating a system for making a composite sell according to claim 13 in in which the slurry is mixed with the catalyzed liquid combination in a vat so as to remove air bubbles/discontinuities from the slurry in the vat.15.A method of operating a system according to any of claims 11 to 14 in which a vacuum apparatus is used to apply a vacuum to the slurry in the sell mould cavity.16.A method of operating a system according to claim 15 wherein the step of applying a vacuum to the slurry in the sell mould cavity and step of heating the slurry in the sell mould cavity occur simultaneously 17.A method of operating a system for making a composite set comprising the step of: turning the sell mould cavity upside down to urge the cast-out composite sell out of the sell mould cavity.lftA composite sell comprising a matrix which is a combination of resin, catalyst and flexibility additive and also comprising a dried aggregate so that the aggregate is bound by the matrix.19.A composite set according to claim 18 in which the aggregate grade is in the range of #1 to #3.20.A composite set according to claim 18 in which the aggregate grade is in the range of #2 to #5.21.A composite sell according to claims 18 to 20 in which the resin is a polyester.22.A composite sell according to claims 18 to 21 in which the width and length are at least 10 cm and the thickness is between O.5 cm and 2 cm.23.A method of applying composite sells defined according to claims 181022 to a surface comprising steps of; Step 1; applying a layer of bedding and jointing compound to the surface, Step 2; pressing a first composite soft into the into the layer, Step 3; laying a second composite sell adjacent to the first sell with a gap between them, s Step 4; pressing the second composite sell into the layer until the compound rises in the gap almost level with the top of the first and second composite soft: 24. A method of manufacturing a composite sell comprising the steps of: mixing resin, catalyst, and flexibility additive in a mixing vat into a catalyzed liquid combination; mixing the catalyzed liquid combination and an aggregate into a slurry; transferring the slurry into a sell mould cavity; heating the slurry in the sett mould cavity for at least ten minutes at a temperature of at least thirty degrees C to form a cast-oUt-ready-solid composite sell; casting the cast-out-ready-solid composite sell from the sell mould cavity; and maintaining the cast out composite sell at least thirty degrees C for at least one hour to cure the composite sell.25.A composite sell substantially as herein described with reference to the Figures