Patent Description:
In certain applications it is desirable to form structures having voids within the structures. The voids are typically provided for drainage, attenuation, and/or aeration.

It is desirable to provide such structures more economically. It is also desirable to provide such structures having greater void volumes within the structure.

It is a nonexclusive aim of this disclosure to provide these desiderata.

Examples of prior art can be found in documents <CIT>, <CIT>, <CIT>, <CIT> and <CIT>.

There is provided a void forming module having the features of claim <NUM>, a method of preparing a structure including said void forming module having the features of claim <NUM> and a use of said void forming module having the features of claim <NUM>.

Further preferred embodiments are defined by the features of dependent claims <NUM>-<NUM>.

Embodiments will now be described with reference to the accompanying drawings, in which:.

There is provided a void forming module, the module including a support surface including a first generally planar upper region, a second generally planar lower region, and a third generally convex region joining the first region and the second region. At least one of the first region, the second region, and/or the third region includes at least one aperture for the passage of fluid through the void forming module. There is also provided a structure including the void forming module, a method of preparing a structure, and the use of the void forming module.

As shown with reference to <FIG>, and <FIG> in particular, there is provided a void forming module, indicated generally at <NUM>. The module <NUM> includes a support surface <NUM> including: a first generally planar upper region <NUM>, a second generally planar lower region <NUM>, and a third generally convex region <NUM> joining the first region <NUM> and the second region <NUM>. At least one of the first region <NUM>, the second region <NUM>, and/or the third region <NUM> includes at least one aperture <NUM>,<NUM> for the passage of fluid through the void forming module <NUM>.

The fluid may be or include a liquid and/or a gas. The fluid may be water.

The void forming module <NUM> may be used in the construction of a structure.

It is thought that by providing a convex third region <NUM> when e.g. aggregate (e.g. large aggregate) is supported on the support surface <NUM> the resulting structure including the void forming module <NUM> and aggregate has good compressive strength, perhaps approaching or exceeding that of aggregate alone. This may be advantageous as substantially less aggregate is used in the structure including the void forming module <NUM> and aggregate than if aggregate alone was used to provide the same layer height. Accordingly, since the combination of void forming module <NUM> and aggregate may be provided for a substantially lower cost than a comparable layer height of aggregate alone and, further, since the void forming module <NUM> and aggregate may be transported for a substantially lower cost than a comparable amount of aggregate which would provide a particular layer height (due to a lower weight), a structure may be provided for a substantial cost saving without reducing the compressive strength of the structure.

Initial testing of 3D printed prototype void forming modules were conducted using a <NUM> tonne press and a <NUM> diameter plate to replicate an HGV tyre. The prototype was loosely filled with <NUM>-<NUM> kiln dried rounded aggregate, to <NUM> above the top face of the product. The prototype yielded at a load of <NUM> tonnes with minimal deflection. This performance is regarded as exceptionally good. For comparison, the maximum legal load on an HGV wheel in the UK is <NUM> tonnes.

It was expected that production void forming modules would have even better performance than the prototype void forming modules. Further testing of injection moulded production void forming modules did show such improved performance. An array of void forming modules was filled with Type <NUM> aggregate forming a <NUM> layer above the void forming module. Type <NUM> aggregate is aggregate conforming to the Type <NUM> specification of the UK Ministry of Transport. The surface was then compacted with a bomag vibration roller to ensure proper compaction. It was found that the surface prepared in this way (i.e. including the void forming modules) was more stable than a layer of Type <NUM> aggregate prepared on a flat surface. This effect was immediately apparent to the vibration roller operator. Without wishing to be bound by theory, it is thought that the convex third region forms a plug for the aggregate such that the surface of the aggregate atop the void forming module is improved. The following testing was carried out by an independently UCAS accredited testing contractor. As above, a <NUM> diameter plate was used. The void forming modules and Type <NUM> aggregate withstood a load of <NUM> tonnes with minimal deflection. This <NUM> tonne load was the maximum load of the testing equipment. At no point during the testing did the void forming module show any apparent signs of failure. It is thought that the void forming modules and Type <NUM> aggregate could withstand a further load if testing equipment capable of providing greater loads was available and used. Seven testing locations above the void forming modules were tested, all provided similar excellent performance.

Additional testing showed excellent water flow through the void forming module and Type <NUM> aggregate combination.

Many other materials may be supported on the support surface <NUM> of the void forming module <NUM> and may provide the advantages described, as nonlimiting examples these include concretes, soils, and plastics.

Additionally, the void forming module <NUM> has advantages over other known constructions. For example, the structural module disclosed in <CIT> is an alternative to an aggregate subbase and provides structural modules which occupy an entire layer. The cuboid shape of the modules of WO'<NUM> is such that they must support the entire weight of anything above them. However, the whole void forming module <NUM> is not subject to the entire force of what is above it in use, as aggregate, which is supported by the support surface <NUM>, provides substantial compressive strength in the shapes formed as a result of the shape of the support surface <NUM> (specifically, the shape of first, second, and third regions <NUM>,<NUM>,<NUM>). Accordingly, the void forming module <NUM> with aggregate atop is thought to be able to withstand greater compressive stress than the void forming module <NUM> alone. Such an effect is particularly useful where it is desired to make the void forming module <NUM> economically, for example, it may be made relatively thin or from weaker and cheaper materials, if desired.

In summary, a key advantage which may be provided by the void forming module <NUM> is that the void forming module <NUM> can hold the shape of aggregate (or other subbase or base course) in a shape which provides increased void space and optimised strength from the aggregate (or other subbase or base course).

An aggregate only subbase or base course typically provides <NUM>% void space for the volume occupied by the aggregate layer. The disclosed void forming modules <NUM> and aggregate together may provide approximately <NUM>% void space for the volume occupied by the void forming module <NUM> and aggregate (or other subbase or base course) together.

As shown with reference to <FIG>, <FIG>, and <FIG>, the third region <NUM> of the support surface <NUM> may at least partially conform to a lateral surface of an imaginary curved truncated cone. Alternatively, the third region <NUM> of the support surface <NUM> may at least partially conform to a lateral surface of an imaginary curved frustum.

It is thought that by providing a third region <NUM> of the support surface <NUM> having such a shape that when aggregate (e.g. large aggregate) is supported on the support surface <NUM> the resulting structure including the void forming module <NUM> and aggregate has particularly good compressive strength, approaching that of aggregate alone. This may be advantageous for the reasons discussed above.

As shown with reference to <FIG>, <FIG>, <FIG>, and <FIG> in particular, the void forming module <NUM> may further include a void forming surface <NUM> including a first generally planar upper region <NUM>, a second generally planar lower region <NUM>, and a third generally concave region <NUM> joining the first region <NUM> and the second region <NUM>. Accordingly, the void forming module <NUM> may provide a void <NUM> between the first region <NUM> of the void forming surface <NUM> and the second region <NUM> of the void forming surface <NUM>.

The presence of the void <NUM> as empty space or air (and accordingly presence of the void forming surface <NUM>) is optional; in particular, even in the absence of the void <NUM> as empty space or air, the void forming module <NUM> can still be considered to form voids in an otherwise complete aggregate layer and provide the above mentioned advantages. However, the presence of the void <NUM> may provide advantages, in particular, the void <NUM> may provide for (increased) fluid (e.g. water) attenuation and/or drainage.

As shown with reference to <FIG>, <FIG>, and <FIG>, the third region <NUM> of the void forming surface <NUM> may at least partially conform to a lateral surface of an imaginary curved truncated cone. Alternatively, the third region <NUM> of the void forming surface <NUM> may at least partially conform to a lateral surface of an imaginary curved frustum.

It is thought that by providing a third region <NUM> of the void forming surface <NUM> having such a shape that when aggregate (e.g. large aggregate) is supported on the support surface <NUM> the resulting structure including the void forming module <NUM> and aggregate has particularly good compressive strength. In particular, that the void forming module <NUM> and aggregate together may have good compressive strength for the size of void <NUM> provided. Additionally, the features may also be advantageous for the reasons discussed above. Additionally, where the third region <NUM> of the void forming surface <NUM> has such a shape and the third region <NUM> of the support surface <NUM> at least partially conforms to a lateral surface of a (different) imaginary curved frustum or curved truncated cone, as will be apparent, the void forming module <NUM> may be relatively thin. Accordingly, such a void forming module <NUM> may be provided relatively cost effectively.

As shown with reference to <FIG> and <FIG>, in particular, the second region <NUM> of the support surface <NUM> may be generally circular.

As shown with reference to <FIG> and <FIG>, in particular, the third region <NUM> of the support surface <NUM> may meet the first region <NUM> of the support surface <NUM> at a generally circular edge <NUM>.

As shown with reference to <FIG> and <FIG>, in particular, the second region <NUM> of the void forming surface <NUM> may be generally circular.

As shown with reference to <FIG> and <FIG>, in particular, the third region <NUM> of the void forming surface <NUM> may meet the first region <NUM> of the void forming surface <NUM> at a generally circular edge <NUM>.

Such features can provide an optimised shape of the void forming module <NUM>. Providing an optimised shape can allow the void forming module <NUM> filled with aggregate to have good compressive strength for the size of voids <NUM> provided. In particular, circular shaped features can provide for the retention of aggregate in a form in which the aggregate provides substantial compressive strength, perhaps comparable to the compressive strength of a layer of aggregate alone, without the void forming module <NUM> having to be capable of such compressive strength when not filled with aggregate. Accordingly, an effective void forming module <NUM> may be provided economically.

Such features can also provide a void forming module <NUM> having mutually compatible support and void forming surfaces <NUM>, <NUM>. Accordingly, the void forming modules <NUM> so provided may be stackable. This can provide easier to transport void forming modules <NUM>.

As shown with reference to <FIG> and <FIG>, in particular, the void forming module <NUM> may further include a strengthening formation <NUM> supporting the third region <NUM> of the support surface <NUM> and/or the first region <NUM> of the support surface <NUM>.

The strengthening formation <NUM> may be or include a fillet (as shown), protrusion, rib, and/or fin.

The strengthening formation <NUM> may extend from the second region <NUM> of the void forming surface <NUM> to the first region <NUM> of the void forming surface <NUM>. As will be apparent from the Figs, although the function of the strengthening formation <NUM> is to support the support surface <NUM>, the strengthening formation <NUM> may be provided on the void forming surface <NUM>.

The strengthening formation <NUM> may be integrally formed as part of the void forming module <NUM>.

Providing a strengthening formation <NUM> having any or all of the above features can provide a more economical void forming module <NUM>. In particular, by providing a void forming module <NUM> having such a strengthening formation <NUM>, the void forming module <NUM> can be fabricated from less material. Further, the void <NUM> formed by the void forming module <NUM> may be larger relative to the height occupied by the void forming module <NUM>, which in turn means that less aggregate may be used in combination with the void forming module <NUM>, again providing an economic benefit (in that less aggregate is required and any required excavation may be reduced).

As shown with reference to <FIG>, <FIG>, <FIG>, and <FIG>, in particular, the second region <NUM> of the support surface <NUM> and the second region <NUM> of the void forming surface <NUM> may be or include a grid having apertures <NUM>. As will be apparent, the apertures <NUM> of the grid form at least one of the at least one apertures <NUM> mentioned above. Alternatively, apertures may be provided in the second region <NUM> of the support surface <NUM> and the second region <NUM> of the void forming surface <NUM> in any other way.

As shown with reference to <FIG>, the third region <NUM> of the support surface <NUM> and the third region <NUM> of the void forming surface <NUM> may, additionally or alternatively, include at least one aperture <NUM> of the at least one apertures <NUM>,<NUM>.

The first region <NUM> of the support surface <NUM> and the first region <NUM> of the void forming surface <NUM> may include at least one aperture of the at least one apertures (not shown).

As will be apparent, the apertures <NUM>,<NUM> may be sized to prevent or inhibit the passage of various specifications of aggregate through the apertures <NUM>,<NUM>. For example, the apertures <NUM>,<NUM> may sized and shaped so as not to allow coarse aggregate to pass through the apertures <NUM>,<NUM>. Coarse aggregate typically has an average particle diameter of from <NUM> to <NUM>. Therefore, as examples, the apertures <NUM>,<NUM> may be sized and shaped so as not to allow spherical particles of <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, mm, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or greater to pass through the apertures <NUM>,<NUM>.

As shown with reference to <FIG>, <FIG>, and <FIG>, in particular, the support surface <NUM> may further include a plurality of further second generally planar lower regions <NUM>, and a plurality of third generally convex regions <NUM> joining the first region <NUM> and the further second regions <NUM>.

The plurality of second regions <NUM> of the support surface <NUM> may form an array.

The plurality of second regions <NUM> of the support surface <NUM> may be coplanar.

The plurality of third regions <NUM> of the support surface <NUM> may form an array.

As shown with reference to <FIG>, <FIG>, and <FIG>, in particular, the void forming surface <NUM> may further include a plurality of further second generally planar lower regions <NUM> and a plurality of third generally concave regions <NUM> joining the first region <NUM> and the further second regions <NUM>.

The plurality of second regions <NUM> of the void forming surface <NUM> may form an array.

The plurality of second regions <NUM> of the void forming surface <NUM> may be coplanar.

The plurality of third regions <NUM> of the void forming surface <NUM> may form an array.

As will be apparent, including a plurality of second regions <NUM> and/or third regions <NUM> of the support surface <NUM> and/or a plurality of second regions <NUM> and/or third regions <NUM> of the void forming surface <NUM> provides the benefits of these regions over a larger surface area. Accordingly, where it is desired to cover a large area, a smaller number of void forming modules <NUM> may be used. This can facilitate coverage of a larger surface area with a lower installation burden.

As will be apparent from the Figs, the plurality of second regions <NUM> and/or third regions <NUM> of the support surface <NUM> and/or the plurality of second regions <NUM> and/or third regions <NUM> of the void forming surface <NUM> may be provided in a <NUM> × <NUM> array.

Each of the additional plurality of second regions <NUM> and/or third regions <NUM> of the support surface <NUM> and/or additional plurality of second regions <NUM> and/or third regions <NUM> of the void forming surface <NUM> may have any or all of the features of the second region <NUM> and/or the third region <NUM> of the support surface <NUM> and/or the second region <NUM> and/or the third region <NUM> of the void forming surface <NUM> described herein, respectively.

In particular, as shown with reference to <FIG> and <FIG>, the void forming module <NUM> may include strengthening formations <NUM> which support neighbouring third regions <NUM> of the support surface <NUM> and/or the first region <NUM> of the support surface <NUM> between neighbouring third regions <NUM> of the support surface <NUM>. In this way, a stronger support surface <NUM> may be provided; in particular, for a given amount of material forming the void forming module <NUM>.

As shown with reference to <FIG>, the void forming module <NUM> may further include a mating formation <NUM>, <NUM> adapted to mate with a mating formation of another corresponding module. In this way, a plurality of void forming modules <NUM> may be assembled to form an array of void forming modules <NUM>. The mating formations <NUM>, <NUM> can prevent lateral movement of neighbouring void forming modules <NUM>.

The void forming module <NUM> may be provided with male formations <NUM> and female formations <NUM>. Alternatively, the formations may be non-gendered. Where male and female formations <NUM>,<NUM> are provided, the male formations <NUM> may be provided on adjacent edges and the female formations <NUM> may also be provided on adjacent edges.

As shown with reference to <FIG>, where the void forming module <NUM> includes both a strengthening formation <NUM> and mating formations <NUM>, <NUM> the strengthening formation <NUM> may extend to a mating formation <NUM>, <NUM>. In this way, when a plurality of void forming modules <NUM> are mated together, the strengthening formation <NUM> of neighbouring void forming modules <NUM> extend towards each other. This may result in a stronger array of void forming modules <NUM> with each void forming module <NUM> providing strength to neighbouring void forming modules <NUM>.

As shown with reference to <FIG>, the void forming module <NUM> may have a width X of at most <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>. Additionally or alternatively, the void forming module <NUM> may have a width X of at least <NUM>, <NUM>, or <NUM>. A width X of around <NUM> may be preferred for particular applications.

The void forming module <NUM> may have a depth Y of at most <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>. Additionally or alternatively, the void forming module <NUM> may have a depth Y of at least <NUM>, <NUM>, or <NUM>. A depth Y of around <NUM> may be preferred for particular applications.

The void forming module <NUM> may have a height Z of at most <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>. Additionally or alternatively, the void forming module <NUM> may have a height Z of at least <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>. A height Z of around <NUM> may be preferred for particular applications.

The second region <NUM> of the support surface <NUM> may have a diameter of at most <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>. Additionally or alternatively, the second region <NUM> of the support surface <NUM> may have a diameter of at least <NUM>, <NUM>, <NUM>, or <NUM>. A second region <NUM> of the support surface <NUM> having a diameter of around <NUM> may be preferred for particular applications.

The edge <NUM> at which the third region <NUM> of the support surface <NUM> meets the first region <NUM> of the support surface <NUM> may have a diameter of at most <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>. Additionally or alternatively, the edge <NUM> at which the third region <NUM> of the support surface <NUM> meets the first region <NUM> of the support surface <NUM> may have a diameter of at least <NUM>, <NUM>, <NUM>, or <NUM>. A void forming module <NUM> in which the edge <NUM> at which the third region <NUM> of the support surface <NUM> meets the first region <NUM> of the support surface <NUM> has a diameter of around <NUM> may be preferred for particular applications.

The second region <NUM> of the void forming surface <NUM> may have a diameter of at most <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>. Additionally or alternatively, the second region <NUM> of the void forming surface <NUM> may have a diameter of at least <NUM>, <NUM>, <NUM>, or <NUM>. A second region <NUM> of the void forming surface <NUM> having a diameter of around <NUM> may be preferred for particular applications.

The edge <NUM> at which the third region <NUM> of the void forming <NUM> surface meets the first region <NUM> of the void forming surface <NUM> may have a diameter of at most <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>. Additionally or alternatively, the edge <NUM> at which the third region <NUM> of the void forming surface <NUM> meets the first region <NUM> of the void forming surface <NUM> may have a diameter of at least <NUM>, <NUM>, <NUM>, or <NUM>. A void forming module <NUM> in which the edge <NUM> at which the third region <NUM> of the void forming surface <NUM> meets the first region <NUM> of the void forming surface <NUM> has a diameter of around <NUM> may be preferred for particular applications.

The void forming module <NUM> may be manufactured from conventional materials and using conventional techniques. For example, the void forming module <NUM> may be of or comprise plastics. The void forming module <NUM> may be manufactured using conventional injection moulding techniques.

Alternatively, the void forming module <NUM> may be manufactured using 3D printing techniques.

The void forming module <NUM> may be of or comprise an impermeable material (save for the apertures <NUM>,<NUM>, if present).

As shown with reference to <FIG>, there is also provided a structure <NUM> including a void forming module <NUM> as described above. The structure <NUM> is typically a framework or fabric of assembled material parts. The structure <NUM> may be any man-made construction. The structure will typically be a structure in which drainage, attenuation, and/or aeration is required or desired.

As shown in <FIG>, the structure <NUM> is a pavement structure, however the structure <NUM> may be another structure, for example, a structure for providing an environment for plants, wherein the upper layers will typically include soil having plants growing therein; a sports pitch, where the upper layers will typically be playing surface including, for example, natural or artificial grass or some other playing surface; a field; a green roof, typically a roof having plants growing thereon; an urban tree supporting structure; a plant environment; a gas ventilation system; or a soil aeration system; for example.

The structure <NUM> may include a subbase <NUM>. The subbase <NUM> may have an upper surface <NUM>. The void forming module <NUM> may be supported by the subbase <NUM>.

The structure <NUM> may further include a permeable or impermeable base course <NUM> supported by the first, second, and/or third regions <NUM>,<NUM>,<NUM> of the support surface <NUM>. The base course <NUM> may be provided as a layer. The base course <NUM> may be within, and optionally on top, of the void forming module <NUM>. The base course <NUM> may be coarse aggregate, as described above.

In other structures <NUM> (not shown), the void forming module <NUM> may be part of the subbase layer. In such a case the, subbase layer will be supported on the void forming module <NUM>.

As the subbase or base course <NUM> may be impermeable, it will be apparent that the apertures <NUM>,<NUM> may be omitted. Accordingly, there is also provided a void forming module <NUM> without apertures <NUM>,<NUM>.

The structure <NUM> may further include a surface course <NUM>. The surface course <NUM> may be permeable or impermeable. The surface course <NUM> may be provided as a layer. The surface course <NUM> may provide a pavement surface <NUM>; for example, a trafficable pavement surface (as shown). Alternatively, the surface course <NUM> may provide an environment for plants; a sports pitch surface, including, for example, natural or artificial grass or some other playing surface; a field surface; a green roof surface, typically a surface providing an environment for living plants; an urban tree supporting surface; a plant environment surface; a surface of a gas ventilation system; or a surface of a soil aeration system; for example.

There is also provided a method of preparing a structure <NUM>. The method includes providing a void forming module <NUM>. The void forming module <NUM> provided by the method may have any of the features of the void forming module <NUM> described above. The method further includes providing a permeable or impermeable subbase layer or base course layer <NUM> on the first, second, and/or third regions <NUM>,<NUM>,<NUM> of the support surface <NUM>. Alternatively, the method may include providing a permeable or impermeable subbase layer on the first, second, and/or third regions <NUM>,<NUM>,<NUM> of the support surface <NUM>.

Claim 1:
A void forming module (<NUM>) for forming structures for drainage, attenuation and/or aeration, the module (<NUM>) including a support surface (<NUM>) including:
a first generally planar upper region (<NUM>),
a second generally planar lower region (<NUM>), and
a third generally convex region (<NUM>) joining the first region (<NUM>) and the second region (<NUM>), wherein the third region (<NUM>) of the support surface (<NUM>) at least partially conforms to a lateral surface of an imaginary curved frustum or curved truncated cone;
wherein at least one of the first region (<NUM>), the second region (<NUM>), and/or the third region (<NUM>) includes at least one aperture (<NUM>, <NUM>) for the passage of fluid through the void forming module (<NUM>).