WO2015001362A1

WO2015001362A1 - Method and apparatus for making cementitious components

Info

Publication number: WO2015001362A1
Application number: PCT/GB2014/052061
Authority: WO
Inventors: John Bentley
Original assignee: Supreme Concrete Limited
Priority date: 2013-07-05
Filing date: 2014-07-07
Publication date: 2015-01-08
Also published as: GB2515834B; GB201312147D0; GB2515834A; EP3016789A1

Abstract

A method of making a cementitious component (142) in a mould assembly (100). The mould assembly (100) comprises a mould body (102) and at least one moulding element (106) for moulding an external surface of the cementitious component. The method comprises introducing cementitious material into the mould body (102) in a filling direction (F) and separating the moulding element (106) from the cementitious material (142) by displacing the moulding element (106) relative to the mould body (102) in a process direction (P) that is non-parallel to the filling direction (F). The invention provides a method in which cementitious components having cross-sections of relatively complex shapes can be made in a mould assembly using relatively few process steps. In particular, features such as recesses and channels can be moulded in surfaces that, using conventional methods, would otherwise need to be planar.

Description

METHOD AND APPARATUS FOR MAKING CEMENTITIOUS COMPONENTS Field of the invention The invention relates to a method and apparatus for making cementitious components. In particular, but not exclusively, the invention relates to a method and apparatus for making elongate cementitious components, such as slotted fence posts.

Background to the invention

Figures 1A and 1 B illustrate in perspective and cross-sectional views respectively a conventional pre-cast slotted fence post 20 for supporting a fencing panel. The slotted fence post 20 is an elongate reinforced concrete component having an Ή'-shaped or T- shaped cross-section that defines elongate slots 22a, 22b on first and second sides of the post 20. In use, a plurality of fence posts 20 are installed vertically, spaced apart by a distance equal to the length of a fencing panel, with a first slot 22a on one fence post 20 facing a second slot 22b on a neighbouring fence post 20. As illustrated in Figure 2, which is a perspective view of a fence post 20 when installed for use, a fencing panel 10 is installed between each pair of neighbouring fence posts 20, such that the vertical edges of the panel 10 are received in the slots 22a, 22b. In this way, the fencing panel 10 is securely supported in an upright position between the fence posts.

The fence posts 20 are manufactured using a semi-dry process, illustrated in Figures 3A to 3J, in which a plurality of fence posts 20 are made in a mould 30. The slots 22a, 22b are moulded into the fence posts 20 during the moulding process.

The mould 30, shown in vertical cross-sectional view in Figure 3A, is divided by elongate dividing walls 32 into parallel sections 34 that extend out of the plane of Figure 3A. Each section 34 forms a single fence post 20. The fence post 20 is moulded with the slots 22 formed in upper and lower faces of the fence post 20 or, said another way, in an orientation that confers an Ή'-shaped cross-section on the fence post 20. A base 36 of each section 34 is provided with an elongate former 38 that extends along the length of the mould 30. The former 38 is fixed to the base 36. The former 38 forms a first slot 22a in each fence post 20 when the mould is filled. To make the fence posts 20, the mould 30 is first oiled, and a steel reinforcement framework (not shown) is placed in each section 34 of the mould 30. The mould 30 is manually filled to approximately 80% full with a semi-dry concrete mix 40 as shown in Figure 3B, and the mould 30 is vibrated to ensure dense packing of the concrete mix 40 between the dividing walls 32 and around the formers 38. Next, as shown in Figure 3C, removable formers 42, in the form of elongate generally rectangular bars of substantially the same size and shape as the fixed formers 38, are placed on top of the concrete mix 40, at the centre of each section 34. Then, more concrete mix 40 is poured into the mould 30 around the removable formers 42, as shown in Figure 3D, and the mould is vibrated to ensure adequate packing of the concrete mix 40. In this way, the removable formers 42 form the second slot 22b in each of the fence posts 20.

The concrete mix 40 is manually float-finished to smooth the surface of the concrete on top of the mould. After the float finishing process is complete, the concrete mix 40 in each section 34 has been moulded into the shape of a fence post 20, such that each section 34 contains an uncured or 'green' product 48.

After the float finishing stage, the removable formers 42 are removed from the second slots 22b of the green products 48 by manually lifting the removable formers 42 upwardly, as shown in Figure 3E. The semi-dry nature of the concrete mix ensures that the slots 22b keep their shape when the formers 42 are removed. Supports 44 in the form of elongate rectangular trays are then manually placed in the slots 22b, as shown in Figure 3F. A production board 46 is placed on top of the mould 30, as shown in Figure 3G, and the mould 30 is inverted, as shown in Figure 3H. The mould 30 is removed by lifting the mould 30 upwardly away from the production board 46, leaving the green products 48 and the supports 44 on the production board 46, as shown in Figures 31 and 3J.

On removal of the mould 30, the first set of slots 22a are revealed on the upper surface of the fence post 20. The second set of slots 22b have been formed in the lower surface of the fence post 20, beneath a region of cementitious material that forms the centre 28 of the Ή'-section 28. The supports 44, which are already in place in the second slots 22b at the time of de-moulding, remain in the second set of slots 22b after de-moulding, to support the cementitious material around the slots 22b when the green products 48 are cured. As most clearly shown in Figure 1 B, to allow the green products 48 to emerge cleanly from the mould 30 when the mould 30 is removed, the outer sides 24, 26 of the fence post 20 (i.e. the left and right sides when oriented for moulding) are not parallel, but taper inwardly at an angle A as they extend upwardly, which is typically a few degrees. The angle A is exaggerated in Figure 1 B for clarity. In this way, the green products 48 are tapered towards one side. To form this 'de-mould taper', the dividing walls 32 used in the moulding process to separate the mould sections 34 (see Figure 3A) are wedge-shaped. In this way, when the mould 30 is removed from the green products 48, the dividing walls 32 are not parallel to the removal direction, which reduces friction between the dividing walls 32 and the green products 48, allowing the mould 30 to be removed cleanly from the green products 48.

After the green products 48 have been cured to form the finished fence posts 20, the supports 44 are removed from the slots 22b, for use in another moulding cycle, and the fence posts 20 are sent onwards through the supply chain.

The conventional process described above has been used for many years to provide a simple and effective method of manufacturing slotted fence posts from concrete. However, the conventional process described above is relatively slow and labour- intensive, involving a large number of processing stages, as shown in Figure 3. Furthermore, the process typically requires two people to fill the mould 30, arrange the inserts 42 and supports 44 in the mould 30, and float-finish the cementitious material 40. Furthermore, the conventional semi-dry process described results in a relatively large number of pores in the surface of the fence post, and hence does not provide as good a surface finish as a wet-cast process, which would be even more time-consuming and labour-intensive.

Against this background, it would be desirable to provide an apparatus and method for manufacturing cementitious components that overcomes or mitigates at least one of the aforementioned problems.

Summary of the invention From a first aspect, the invention resides in a method of making a cementitious component in a mould assembly. The mould assembly comprises a mould body and at least one moulding element for moulding an external surface of the cementitious component. The method comprises introducing cementitious material into the mould body in a filling direction and separating the moulding element from the cementitious material by displacing the moulding element relative to the mould body in a process direction that is non-parallel to the filling direction.

By separating the moulding element from the cementitious material by displacing the moulding element relative to the mould body in a process direction that is non-parallel to the filling direction, the invention provides a method in which cementitious components having cross-sections of relatively complex shapes can be made in a mould assembly using relatively few process steps. In particular, features such as recesses and channels can be moulded in surfaces that, using conventional methods, would otherwise need to be planar. No moulding elements or supports need be left in place during subsequent curing stages, reducing the number of moulding elements needed to run further production cycles as the cementitious product is cured.

Preferably, the moulding element is elongate to define a longitudinal axis. In this way, the elongate moulding element can be used to form an elongate cementitious component. In particularly preferred embodiments, the process direction is generally aligned with the longitudinal axis of the moulding elements.

The process direction may be generally perpendicular to the filling direction. Preferably, the process direction is horizontal, so that the moulding element need not be lifted during separation from the cementitious material.

The filling direction may be generally vertical. In this way, the step of filling the mould assembly may be aided by gravity, such that the cementitious material falls generally vertically into the mould body. Displacing the moulding element relative to the mould body may comprise withdrawing the moulding element from the cementitious material. In other words, in this case, the mould body and the cementitious material remain stationary, while the moulding element is pulled out of the cementitious material in the process direction. Conceivably, as an alternative, the moulding element could remain stationary while the mould body and the cementitious material are drawn away from the moulding element in direction opposite to the process direction. In preferred embodiments, the method comprises dividing the cementitious material into a plurality of cementitious components using the moulding element. In this way, a plurality of cementitious components may be made in the same mould body, and the moulding element may be used to mould external surfaces of neighbouring cementitious components of the plurality. This increases the number of cementitious components that may be made in a moulding cycle. Furthermore, dividing the cementitious components using the moulding element avoids the need for a de-mould taper. The method may comprise wiping the moulding element along the external surface of the cementitious component when displacing the moulding element. This wiping action smooths the external surface of the component, reducing its porosity and improving the quality and appearance of the cementitious product. The method may comprise moulding a recess on the external surface of the cementitious component with the moulding element. The recess extends along the cementitious component in the process direction. The moulding element may be wiped along the external surface that includes the recess, such that the cementitious material of that external surface and the recess is compacted and smoothed by the wiping motion. This allows accurate moulding of the recess in the external surface, which is particularly advantageous for recesses having sharp features or complex shapes.

Preferably, the method comprises inserting the moulding element into the mould body in an insertion direction opposite to the process direction before introducing cementitious material into the mould body. In this way, the mould assembly may be used to mould cementitious components in a repeating cycle, with the moulding element being inserted into and withdrawn from the mould assembly in each moulding cycle.

So that two or more cementitious components can be made in each mould cycle, the mould assembly preferably comprises a plurality of moulding elements, and the method preferably comprises dividing the mould body into a plurality of mould sections using the moulding elements, each mould section being configured for moulding a cementitious component. In this case, the method preferably comprises dividing the mould body into a plurality of mould sections by inserting the plurality of moulding elements into the mould body in an insertion direction.

The mould body may be filled with cementitious material in a single mould-filling step. To facilitate de-moulding of the cementitious component, the method may further comprise inverting the mould assembly. The method may comprise arranging a production board on an upper face of the mould body and inverting the production board and the mould body together. In this way, the cementitious components are arranged on the production board, for subsequent storage and/or packing. The method may comprise displacing the mould body relative to the cementitious material to de-mould the cementitious material.

The method may comprise drying the cementitious material to cure it. This may comprise allowing the cementitious material to dry under ambient conditions. Curing may comprise either or both of heating the cementitious material, or causing an airflow around the cementitious material.

To produce a reinforced cementitious component, the method may comprise arranging one or more reinforcing bars in the mould body before introducing the cementitious material into the mould body. The method could be used to make any elongate cementitious component. The cementitious component may be a fencing component. The method is particularly suited to the manufacture of fence posts and especially slotted fence posts..

The component may be made from any suitable cementitious material. Preferably, the cementitious material is concrete. The concrete may be reinforced, for example with steel reinforcing bars (rebars).

From another aspect, the invention resides in an apparatus for making a cementitious component. The apparatus comprises a mould body and at least one moulding element for moulding an external surface of the cementitious component. The mould body is open to admit cementitious material in a filling direction and at least partially open to permit relative displacement between the moulding element and the mould assembly in a process direction that is non-parallel to the filling direction. The apparatus may comprise means for withdrawing the moulding element from the mould body in the process direction. The mould assembly may also comprise means for inserting the moulding element into the mould body in an insertion direction. For example, the means for withdrawing the moulding element from the mould body and/or inserting the moulding element into the mould body may comprise a toothed wheel, and the moulding element may comprise a set of teeth that are cooperable with the toothed wheel.

To allow for a mechanised withdrawal and/or insertion process, the means for withdrawing the moulding element from the mould body and/or inserting the moulding element into the mould body may comprise means such as a motor or hydraulic rams for driving the toothed wheel.

The insertion direction is preferably opposite to the process direction. In this way, the moulding element may be withdrawn from and inserted into the mould body from the same side of the mould body, reducing the footprint of the mould assembly.

Preferably, a top face of the mould body is open to admit cementitious material into the mould body in a generally downward vertical direction. In this arrangement, the cementitious material enters the mould body from above, and the mould-filling process is aided by gravity.

The moulding element may be elongate to define a longitudinal axis. In this case, the process direction may be generally aligned with the longitudinal axis of the moulding element. When the longitudinal axis and the process direction are aligned, withdrawal of the moulding element causes the moulding element to be wiped along a surface of the cementitious material in the mould assembly, which smooths the wiped surface providing a high-quality surface finish with low porosity.

The moulding element is preferably configured to divide the cementitious material into a plurality of cementitious components. In this way, a plurality of cementitious components may be made in the same mould body, and the moulding element may be used to mould external surfaces of neighbouring cementitious components of the plurality. This increases the number of cementitious components that may be made in a moulding cycle. Furthermore, configuring moulding element to divide the cementitious components avoids the need for a de-mould taper.

External features of the cementitious component, such as slots, channels, curved surfaces, or any other shapes, may be moulded by selecting an appropriate moulding element. For example, the moulding element may be shaped to form a recess on the cementitious component, the recess extending generally parallel to the process direction. The recess may be, for example, a slot for receiving a fencing panel in a slotted fence post. In embodiments where the moulding element is configured to mould a recess or other shape on an external surface of the cementitious component, the moulding element is wiped along the external surface that includes the recess or other shape as it is displaced. The cementitious material of that external surface is compacted and smoothed by the wiping motion. This allows accurate moulding of the shape or recess in the external surface, which is particularly advantageous for products having sharp features or complex shapes.

To guide insertion and withdrawal of the moulding element, the mould body may comprise at least one groove that extends generally parallel to the process direction for slidably receiving the moulding element to locate the moulding element in the mould body. Preferably, the groove is disposed on a base of the mould body.

To permit insertion and withdrawal of the moulding element while preventing cementitious material escaping from the mould body when it is in use, a proximal end of the mould body may be partially open to permit access for the moulding element. To this end, the apparatus may comprise one or more end plates arranged at the proximal end of the mould body. The end plates may be spaced apart to permit withdrawal of the moulding element. The end plates may be shaped substantially as a cross-section of the cementitious component perpendicular to the process direction.

Preferably, the apparatus is configured to mould the cementitious component in an orientation that defines an T-shaped cross-section perpendicular to the process direction (i.e. an Ή'-shaped cross-section rotated through 90°). The T-shaped cross-section may be achieved by shaping one or more moulding elements to confer the desired cross- section on the component.

So that a plurality of cementitious components may be made in the apparatus in a single production cycle, the apparatus may comprise a plurality of moulding elements insertable into the mould body to define a plurality of mould sections, each for moulding a cementitious component. The cementitious component may be a fencing component, and is preferably a slotted fence post. The invention also extends to a moulding element for use in the apparatus described above.

The invention extends further to a cementitious component made according to the method described above, or using the apparatus described above.

Preferred and optional features of each aspect may be used, alone or in appropriate combination, in the other aspect also.

Brief description of the drawings

Reference has already been made to Figures 1A and 1 B of the drawings, which are perspective and cross-sectional views respectively of a known slotted fence post; to Figure 2 of the drawings, which illustrates in perspective view a known slotted fence post in use in supporting fencing panels, and to Figures 3A to 3J, which illustrate schematically a known method of making such a slotted fence post from a cementitious material.

In order that the invention might be more readily understood, reference will now be made, by way of example only, to the remainder of the drawings, in which:

Figure 4 is a perspective view of part of a mould assembly according to the invention;

Figure 5 is a perspective view of part of a moulding element of the mould assembly of Figure 4;

Figures 6A to 6H illustrate schematically a method of making a cementitious component according to the invention;

Figures 7 and 8 are perspective and cross-sectional views respectively of a cementitious component made using the method of Figure 6 and the mould assembly of Figure 4. Detailed description of embodiments of the invention

Figure 4 shows part of a mould assembly 100 according to an embodiment of the invention in use in making a plurality of cementitious slotted fence posts. The fence posts are of substantially the same form as the conventional slotted fence posts described above. In particular, the cross-section of the fence posts is substantially the same Ή'- shaped cross-section above. Although substantially the same shape as the conventional fence posts described, the mould and method now described mould the fence posts in a different orientation, with the Ή' shape rotated through 90°, such that the cross-section of the fence posts defines an T rather than an Ή' relative to the horizontal.

The mould assembly 100 comprises a mould body 102 that defines an inner moulding space 104, and a plurality of elongate moulding elements 106. The moulding elements 106 are slidably received in the inner moulding space 104 of the mould body 102.

The mould body 102 comprises a base 108 and upstanding sidewalls 1 10 that define an elongate tray having a longitudinal axis L. An upper face of the mould body 102 is open to admit cementitious material 1 16 into the mould body 102 in a generally vertical and downward filling direction. A proximal end 1 18 of the mould assembly 100 is partially open to permit insertion and withdrawal of the moulding elements 1 16 into and out of the mould body 102, as will be described later.

The base 108 of the mould body 102 is provided with grooves 1 12 that extend parallel to the longitudinal axis L. Each groove 112 slidably receives the lower edge of a moulding element 106. When arranged in the grooves 112, the moulding elements 106 divide the inner moulding space 104 into a plurality of mould sections 114, each of which is shaped to mould a single fence post.

At the proximal end 118 of the mould assembly 100, each section 1 14 is provided with an end plate 120, disposed between the moulding elements 106. When the mould assembly 100 is in use, each end plate 120 moulds an end face of the respective fence post.

Each end plate 120 comprises an upstanding wall 122 that is generally perpendicular to the base 108 and the sidewalls 1 10 of the mould body 102. The upstanding wall 122 is shaped and dimensioned to fit snugly between the neighbouring moulding elements 106 to minimise the escape of cementitious material from the proximal end 1 18 of the mould assembly 100 when in use. The shape of the upstanding wall 122 therefore corresponds to the shape of the cross-section of the fence post moulded in the section 114, which defines an T shape as described above.

The upstanding wall 122 extends perpendicularly from a base plate 124 that lies on the base 108 of the mould body 102. Buttresses 128 extend between the upstanding wall 122 and the base plate 124, to guard against deformation or movement of the end plate 120. The base plate 124 is fixed to the base 108 by bolts 126.

Neighbouring end plates 120 are spaced apart to define gaps between them. In this way, the proximal end 1 18 of the mould assembly 100 is partially open to permit withdrawal and insertion of the moulding elements 106 via the gaps. The moulding elements 106 hold a dual function in the mould assembly 100. Firstly, the moulding elements 106 act as dividers that separate neighbouring sections 114 of the mould body 102. Secondly, the moulding elements 106 act as formers that shape the left and right sides of the fence posts. The moulding elements 106 therefore shape slots or channels in the fence posts.

A moulding element 106 is shown in isolation in Figure 5. The moulding element 106 is elongate and extends along the longitudinal axis L. The moulding element 106 comprises a central vertical plate 132 and two channel-forming walls 134, arranged on either side of the vertical plate 132. The vertical plate 132 and the channel-forming walls 134 are formed separately from one another, and joined together by welding to form the moulding element 106.

The vertical plate 132 is a flat, vertical plate. At its lower end 136, the vertical plate 132 protrudes from between the channel-forming walls 134 to define a lip 138. This lip 138 is dimensioned to fit into the grooves 1 12 in the base 108 of the mould body 102.

The channel-forming walls 134 are shaped so that their outer surfaces correspond to the desired shape of the left and right sides of the fence post. Each channel-forming wall 134 comprises upper and lower flange portions 146 that lie against the vertical plate 132, and a central portion 148 that extends away from the vertical plate 132 into the mould section 1 14 to define a central portion 148 of 'C'-shaped cross-section. This central portion 148 moulds one of the slots in the fence post.

As can be seen in Figure 4, two different types of moulding elements 106a, 106b are provided for use with the mould assembly 100.

Inner moulding elements 106a, of the type shown in Figure 5, provide barriers between neighbouring mould sections 1 14, and hence are used to mould surfaces of two neighbouring fence posts in the mould assembly 100. The inner moulding elements 106a therefore comprise two channel-forming walls 134, one arranged on each side of the vertical 132. A first channel-forming wall 134a moulds a slot on a first fence post, and a second channel-forming wall 134b moulds a slot on a second, neighbouring fence post.

Outer moulding elements 106b, not shown in isolation, but shown in use in Figure 4, separate the outermost fence posts in the mould assembly 100 from the upstanding sidewalls 110 of the mould body 102. The outer moulding elements 106b therefore mould a surface of only one fence post, and hence comprise a vertical plate 132 that lies against a sidewall 1 10 of the mould body 102 in use, and a single channel-forming wall 134 arranged inwardly of the vertical plate 132.

A method of making a fence post in the mould assembly 100 will now be described, with reference to Figures 6A to 6H.

The mould assembly 100 is firstly prepared for the moulding process by inserting the moulding elements 106 into the mould assembly 100 to divide the moulding space 104 of the mould body 102 into the mould sections 114, as shown in Figures 6A and 6B. The moulding elements 106 are inserted into the proximal end 118 of the mould assembly 100 in an insertion direction, indicated by the arrow D, that is generally parallel to the longitudinal axes L of the mould assembly 100 and the moulding elements 106. During insertion of the moulding elements 106, the end plates 120 (see Figure 4) and the grooves 1 12 on the base 108 of the mould body 102 act to guide the moulding elements 106 into the mould body 102, locating the moulding elements 106 in the required position. The moulding elements 106 are guided by the grooves 1 12. Insertion of the moulding elements 106 is effected by means of a cogwheel drive mechanism. Referring to Figures 4 and 5, a lower surface 142 of each moulding element 106 is provided with teeth (not shown) that cooperate with a toothed wheel or cogwheel (not shown). The cogwheel is located at the proximal end 1 18 of the mould assembly 100, above and engaged with its dedicated moulding element 106. To insert the moulding elements 106, each cog is rotated by a suitable manual or powered drive mechanism to drive the moulding element 106 into the mould body 102.

Once the moulding elements 106 are in place, the mould assembly 100 is oiled, and a reinforcement framework (not shown) of steel reinforcing bars (rebars) is placed into each section 1 14 of the mould body 102.

Next, as shown in Figure 6C, the mould body 102 is filled with cementitious material 116 through the open upper face of the mould body 102. The cementitious material 116 enters the mould assembly 100 in a filling direction indicated by the arrow F. It will be appreciated that the filling process is aided by gravity, and hence the filling direction F is a generally downward vertical direction. The cementitious material 1 16 may be any suitable cementitious material, such as that conventionally use for making cementitious products using a semi-dry process.

The cementitious material 1 16 is packed into the mould body 102 around the moulding elements 106 to mould the cementitious material 1 16 into the shape of the fence posts. The fence posts are formed with an T-shaped profile, with the channel-forming walls 134 forming the channels that provide the slots in the sides of the fence posts.

Because all the moulding elements 106 are already in place when the mould assembly 100 is filled with cementitious material 1 16, the filling stage can take place in a single step, reducing the time required to fill the mould assembly 100 compared to the two- stage filling process of the prior art.

After the filling stage, the cementitious material 1 16 is float-finished to provide a smooth finish on the top surface. Once the float-finishing process is complete, each section 114 contains cementitious material 1 16 moulded into the final form of the fence post. Each section 1 14 therefore contains an uncured or 'green' product 142. A production board 144 is placed on top of the mould body 102, as shown in Figure 6D, and the green products 144 are then ready for de-moulding. To de-mould the green products 144, the moulding elements 106 are firstly withdrawn from the proximal end 1 18 of the mould assembly 100 in a process direction indicated by the arrow P. This stage is shown in Figure 6E. The process direction P is horizontal, and generally aligned with the longitudinal axis L of the mould assembly 100 and the moulding elements 106, and opposite to the insertion direction D. The process direction P is therefore perpendicular to the vertical filling direction F.

Withdrawal of the moulding elements 106 is effected by means of the cogwheel mechanism described above. To withdraw the moulding elements 106, the cogwheels (not shown) are rotated in a reverse direction to drive the moulding elements 106 out of the mould body 102.

After the moulding elements 106 have been fully withdrawn from the mould assembly 100, the mould body 102 is inverted along with the production board 144, as shown in Figures 6F and 6G, for example by hydraulic means. The mould body 102 is inverted about a pivot 143. Once inverted, the production board 144 is disposed beneath the green products 142. The mould body 102 can then be lifted away from the production board 144, as shown in Figure 6h, and pivoted back to its original position, ready for use in the next moulding cycle. The green products 142 remain on the production board 144 and are moved to a different area of the manufacturing facility for drying, to produce the final, cured product.

The method therefore provides an efficient process for making cementitious components. The mould-filling process can take place in a single step and the production rate is therefore higher. There is no need to remove and replace formers and supports during the moulding process, so the process requires only a single worker, and. No moulding elements or supports are left on the production board 144 after de-moulding, and the production board 144 and cured products can be sent directly on in the supply chain. Furthermore, the fence posts produced by the mould assembly 100 and method described above are of superior quality to known fence posts 20 produced by known semi-dry processes.

Firstly, as the moulding elements 106 are withdrawn from the mould assembly 100, the channel-forming walls 134 are wiped against the external surfaces of the fence posts. In particular, the walls are wiped against the surfaces of the slots in the fence posts. This wiping action compacts and smooths cementitious material at those external surfaces. This ensures accurate moulding of the recess, and provides an improved surface finish, with a lower porosity than an equivalent non-wiped surface. The surface finish of the wiped surfaces is close in appearance porosity-level to the surface finish produced by a wet-cast process.

Secondly, after the moulding elements 106 have been withdrawn from the mould assembly 100, the green products 142 are spaced apart from one another and from the upstanding walls 1 10 of the mould body 102. Thus, the mould body 102 can be easily lifted away from the green products 142 without friction occurring between the mould body 102 and the green products 142. Hence, there is no need for the de-mould taper that is necessary in the conventional mould 30 previously described.

The absence of the de-mould taper can be seen in Figures 7 and 8, which illustrate fence posts 50 made according to the method and using the apparatus described. The absence of the de-mould taper means that the fence posts 50 made according to the invention are more easily and efficiently stacked than the conventional fence-posts 20 described. Furthermore, the absence of the de-mould taper means that the fence posts 50 look identical even if rotated about their longitudinal axes by 180°, and thus there is no need to orientate the de-mould taper of the fence posts in the same way during installation.

A fence post 50 made from a method according to the invention can therefore be distinguished over a fence post 20 made by known methods firstly by the relatively smooth surface finish in slots 52 and on recessed side walls 54, 56 of the fence post 50, and secondly by the absence of a de-mould taper, characterised by parallel walls 58, 60.

Although in the embodiments described above, the cementitious component is a slotted fence post, it will be appreciated that the method and mould assembly described is suitable for making any elongate cementitious component, such as, for example, lintels, pillars, beams and so on. Appropriate mould forming elements can be used to create products with a wide range of cross-sectional shape. For example, the components may have surfaces having recesses of any suitable number or shape. Additional mould forming elements may be used, for example to form recesses in upper and/or lower surfaces of the cementitious component. The method and apparatus described are particularly well-suited to making components having cross-sections of complex shapes. For example, the component may have an 'L'-shaped, T-shaped or cross-shaped cross- section, or a cross section of any other shape.

In some cases, moulding elements with flat surfaces with no channel-forming walls may be used, such that no recesses are formed in the corresponding surface of the component. In this case, the component may be of square or rectangular cross-section. In this case, the cementitious component may be, for example, a base panel or gravel board. The flat moulding elements are wiped along left and right sides of the gravel board to produce the same smooth surface finish that is provided in the slots and one the left and right sides of the slotted fence posts.

Moulding elements may additionally be used to form interior recesses or other interior features in the component. For example, the component may be a hollow-core slab, and a moulding element may be used to form an interior surface of the hollow core.

The mould assembly may be divided into any number of mould sections, using two or more moulding elements for each product, to make any number of cementitious components. To separate the moulding elements from the cementitious material, the moulding elements may be withdrawn from the cementitious material, as described above. However, other embodiments are envisaged in which the moulding elements remain stationary, and the cementitious material is moved away from the moulding elements to effect the relative displacement, for example by moving the mould body in a direction opposite to the process direction.

The moulding elements may be inserted into or withdrawn from the mould assembly by any suitable means. For example, instead of the cogwheel mechanism described above, a hydraulic system may be used. Alternatively, the moulding elements may be inserted or withdrawn by hand.

Withdrawal of the moulding elements, or displacement of the mould body, may take place before the mould body is inverted, as has been described above, or alternatively may take place after the mould body has been inverted, such that the moulding elements are inverted with the mould body. Aspects of the moulding process may be mechanised. For example, insertion and withdrawal of the moulding elements may be mechanised. Inversion of the mould assembly, removal of the mould body from the production board, and re-inversion of the mould body may each occur mechanically. The mould filling stage may be manual, fully mechanised, or partly mechanised; for example, the process may be assisted by automatic deposition of the cementitious material into the mould body, for manual packing and float-finishing. Any step that is mechanised may be pre-programmed to occur automatically in the production cycle, or may be manually triggered when required, for example by a worker triggering a switch.

It will be appreciated that many other variations of the mould assembly and method are envisaged that fall within the scope of the following claims.

Claims

1. A method of making a cementitious component in a mould assembly, the mould assembly comprising a mould body and at least one moulding element for moulding an external surface of the cementitious component, and the method comprising:

introducing cementitious material into the mould body in a filling direction; and separating the moulding element from the cementitious material by displacing the moulding element relative to the mould body in a process direction that is non-parallel to the filling direction.

2. The method of Claim 1 , wherein the moulding element is elongate to define a longitudinal axis.

3. The method of Claim 2, wherein the process direction is generally aligned with the longitudinal axis.

4. The method of any preceding claim, wherein the process direction is generally perpendicular to the filling direction.

5. The method of any preceding claim, wherein the process direction is generally horizontal.

6. The method of any preceding claim, wherein the filling direction is generally vertical.

7. The method of any preceding claim, wherein displacing the moulding element relative to the cementitious material comprises withdrawing the moulding element from the cementitious material.

8. The method of any preceding claim, comprising dividing the cementitious material into a plurality of cementitious components using the moulding element.

9. The method of Claim 8, comprising wiping the moulding element along the external surface of the cementitious component when displacing the moulding element.

10. The method of Claim 8 or Claim 9, comprising moulding a recess on the external surface of the cementitious component with the moulding element, the recess extending along the cementitious component in the process direction.

1 1. The method of any preceding claim, comprising inserting the moulding element into the mould body in an insertion direction opposite to the process direction before introducing cementitious material into the mould body.

12. The method of any preceding claim, wherein the mould assembly comprises a plurality of moulding elements, and the method comprises dividing the mould body into a plurality of mould sections using the moulding elements, each mould section being configured for moulding a cementitious component.

13. The method of Claim 12, comprising dividing the mould body into a plurality of mould sections by inserting the plurality of moulding elements into the mould body in an insertion direction.

14. The method of Claim 12 or Claim 13, comprising making a plurality of cementitous components in the plurality of mould sections.

15. The method of any preceding claim, wherein the mould body is filled with cementitious material in a single mould-filling step.

16. The method of any preceding claim, further comprising inverting the mould body.

17. The method of Claim 16, comprising inverting the mould body after displacing the moulding element.

18. The method of Claim 17, comprising arranging a production board on an upper face of the mould body and inverting the production board and the mould body together.

19. The method of Claim 18 comprising displacing the mould assembly relative to the cementitious material to de-mould the cementitious material.

20. The method of any preceding claim comprising drying the cementitious material to cure it.

21. The method of any preceding claim, comprising arranging one or more reinforcing bars in the mould body before introducing the cementitious material into the mould body.

22. The method of any preceding claim, wherein the cementitious component is a fencing component.

23. The method of Claim 22, wherein the cementitious component is a fence post.

24. Apparatus for making a cementitious component comprising a mould body and at least one moulding element for moulding an external surface of the cementitious component, the mould body being open to admit cementitious material in a filling direction and at least partially open to permit displacement of the moulding element relative to the mould body in a process direction that is non-parallel to the filling direction.

25. The apparatus of Claim 24, comprising means for displacing the moulding element relative to the mould body in the process direction.

26. The apparatus of Claim 24 or Claim 25, comprising means for inserting the moulding element into the mould body in an insertion direction.

27. The apparatus of Claim 25 or Claim 26, wherein the means for displacing the moulding element relative to the mould body and/or inserting the moulding element into the mould body comprise a toothed wheel, and the moulding element comprises teeth that are cooperable with the toothed wheel.

28. The apparatus of Claim 27, wherein the means for displacing the moulding element relative to the mould body and/or inserting the moulding element into the mould body comprise means for mechanically rotating the toothed wheel.

29. The apparatus of any of Claims 26 to 28, wherein the insertion direction is opposite to the process direction.

30. The apparatus of any of Claims 24 to 29, wherein a top face of the mould body is open to admit cementitious material into the mould body in a generally downward vertical direction.

31. The apparatus of any of Claims 24 to 30, wherein the moulding element is elongate to define a longitudinal axis.

32. The apparatus of Claim 31 , wherein the process direction is generally aligned with the longitudinal axis of the moulding element.

33. The apparatus of any of Claims 24 to 32, wherein the moulding element is configured to divide the cementitious material into a plurality of cementitious components.

34. The apparatus of Claim 33, wherein the moulding element is shaped to form a recess on the cementitious component, the recess extending generally parallel to the process direction.

35. The apparatus of any of Claims 24 to 34, wherein the mould body comprises at least one groove that extends generally parallel to the process direction for slidably receiving the moulding element to locate it in the mould body.

36. The apparatus of Claim 35, wherein the groove is disposed on a base of the mould body.

37. The apparatus of any of Claims 24 to 36, wherein a proximal end of the mould body is partially open to permit withdrawal of the moulding element.

38. The apparatus of Claim 37, comprising at least one end plate arranged at the proximal end of the mould body,

39. The apparatus of Claim 38, comprising a plurality of end plates that are spaced apart to permit withdrawal of the moulding element.

40. The apparatus of Claim 39, wherein the end plates are shaped substantially as a cross-section of the cementitious component perpendicular to the process direction.

41. The apparatus of any of Claims 24 to 40, wherein the mould assembly is configured to mould the cementitious component with an T-shaped cross-section perpendicular to the process direction.

42. The apparatus of any of Claims 24 to 41 comprising a plurality of moulding elements insertable into the mould body to define a plurality of mould sections, each for moulding a cementitious component.

43. The apparatus of any of Claims 24 to 42, wherein the cementitious component is a fencing component.

44. The apparatus of Claim 43, wherein the cementitious component is a slotted fence post.

45. Apparatus for making a cementitious component substantially as hereinbefore described with reference to Figures 4 to 6 of the accompanying drawings.

46. A method of making a cementitious component substantially as hereinbefore described with reference to Figures 4 to 6 of the accompanying drawings.

47. A moulding element for use in the apparatus of any of Claims 24 to 45.

48. A cementitious component made according to the method of any of Claims 1 to 23 or Claim 46, or using the apparatus of any of Claims 24 to 45, or using the moulding element of Claim 47.