A structural fill block

Abstract

A lightweight structural fill block 3 manufactured from EPS. The block is for use in a construction structure. The block 3 has an array of recessed female locator portions 13, and an array of protrudi

Description

Field of the Invention The present invention concerns structural fill blocks for use in the construction industry, methods of using structural fill blocks and cap sections and base sections for use above and beneath structural fill blocks. Background of the Invention Structural fill blocks are well known and are used in the construction industry. For example, structural fill blocks may be used in hard landscaping beneath surfaces intended for pedestrians and / or for transport infrastructure, or in soft landscaping, to create landscape with complex shapes. Structural fill blocks may also be used for other construction applications such as podium slabs. Structural fill blocks are typically arranged to distribute loads from the structure above them and imposed loads, into the structure below, such as the underlying substrate in landscaping applications. They may be used to permanently, or temporarily, fill a volume, whilst avoiding the need for the use of other heavier, more expensive and / or less environmentally-friendly products. Structural fill blocks are often made from a lightweight material such as Expanded Polystyrene (EPS); as such, these structural fill blocks are often referred to more generally as ‘lightweight structural fill blocks’. An example of a known lightweight structural fill block is the Filcor ™ product by Cordek. Structural fill blocks may be arranged in a number of different ways, depending on the particular scenario in which they are being used. In some scenarios, it may be desirable to layer the blocks on top of one another. In which case, the blocks are typically staggered in a brick bond pattern to avoid through joints. Relative movement between the blocks in each layer may be prevented by mechanically fixing the blocks in adjacent layers together, for example by driving a metal spike through a pair of blocks in adjacent layers. In other cases, the friction between the two layers may be sufficient to inhibit relative movement such that no fixing is deemed necessary. It is desirable to provide other ways of effectively securing layers of structural fill blocks and to prevent relative movement between them. With changes to the global climate there are increased risks of exceptional rainfall, both in terms of its frequency and the volume of rain falling. It is therefore increasingly important that an arrangement of structural fill blocks has adequate drainage, especially to cope with extreme rainfall. This is especially important for lightweight structural fill blocks because the blocks tend to be less dense than water and can therefore become buoyant in waterlogged conditions. In existing arrangements, drainage is achieved by either leaving gaps between structural fill blocks, and / or by creating holes within the blocks and filling those holes with free-draining material such as gravel. It is desirable to provide other ways of ensuring effective drainage in an arrangement of structural fill blocks. Summary of the Invention According to a first aspect, there is provided a structural fill block for use in construction. The structural fill block has an upper surface and a lower surface, wherein one of the upper surface or the lower surface comprises a plurality of recessed female locator portions, and the other of the upper surface or the lower surface comprises a plurality of protruding male locator portions. The structural fill block is configured such that when the structural fill block is positioned with its lower surface on top of the upper surface of a second, identical, structural fill block, a male locator portion of one of the structural fill blocks is received in a female locator portion of the other of the structural fdl blocks. Providing male and female locator portions in this manner may enable the structural fill blocks to be accurately positioned relative to one another, especially when in adjacent layers. This accurate positioning may be especially important when providing a drainage solution because correct alignment can be critical. Each of the male and the female locator portions may comprise a drainage hole. The drainage holes may be located such that when the structural fill block is positioned with its lower surface on top of the upper surface of a second, identical, structural fill block, and a male locator portion of one of the structural fill blocks is received in a female locator portion of the other of the structural fill blocks, the drainage holes of those respective male and female locator portions align. In preferred embodiments, each of the female locator portions in the plurality of female locator portions is paired with a respective male locator portion. The drainage holes in the female locator portion and the male locator portion of each pair, are preferably connected by a conduit extending through the structural fill block. Providing a conduit extending through the structural fill block may be beneficial in allowing efficient drainage of water from the upper surface of the block through to the lower surface of the block. For the avoidance of doubt, the conduit need not be an item separate from the structural fill block; preferably the conduit is instead defined by a void within the structural fill bock, extending between the two drainage holes in the pair of locator portions. For example, the conduit may be pre-formed within the block during manufacture, or the conduit may be formed by drilling through the block. The combination of the male and female locator portions with an arrangement in which the structural fill block comprises drainage holes, connected by a conduit, has been found to be especially beneficial, because the locator portions enable those drainage holes to be correctly aligned, thereby ensuring efficient drainage through each block and through layers of such blocks. It will be appreciated that the drainage holes may also provide other functions. For example the drainage holes may also be arranged to receive a securing member for fixing two adjacent layers of structural fill blocks together. Correctly-aligned holes are especially important in this context as they allow the securing member to readily extend through the drainage holes and between the two blocks (and optionally, in some embodiments, the blocks in additional layers too). The securing member may take a number of forms. In preferred embodiments, the securing member may be a scaffold pole. The drainage holes are preferably configured for receiving a scaffold pole - for example the drainage holes may be at least 48.3mm wide at their narrowest part. The drainage hole may be in the form on an opening, and preferably (but not necessarily) a circular opening. In embodiments in which the opening is circular, the diameter of the opening may be at least 48.3mm wide. At least some of the drainage holes may, alternatively or additionally, be configured to receive a lifting mechanism for moving the structural fill block. For example the drainage holes may be sized and / or shaped to receive a mechanical lifting mechanism (for example prongs of a scissor lifting mechanism). Embodiments of the invention may therefore facilitate easy manoeuvre of the structural fill blocks. According to another aspect of the invention, there is provided a method of manoeuvring a structural fill block, the structural fill block having drainage holes therein, the method comprising the steps of: (a) inserting part of a lifting device into the drainage holes to engage the lifting device with the structural fill block; (b) lifting the structural fill block and manoeuvring the block into a desired location using the lifting device; (c) disengaging the lifting device from the structural fill block and withdrawing the part of the lifting device from the drainage holes. The structural fill block may be the structural fill block according to any other aspect of the invention described herein. It will be appreciated that when installed in situ as part of a construction structure, the holes and / or conduit may be subsequently filled. For example a free-draining material, such as shingle, may be used to fill the holes and / or conduit. In some embodiments the uppermost portion of the drainage holes may receive a grille, grate or outlet to support the layers placed over. The structural fill block is preferably a lightweight structural fill block. The density of the structural fill block is preferably less than the density of water. The structural fill block may be made from expanded polystyrene (EPS). EPS has been found to be an especially attractive material for forming structural fill block because it may be readily shaped and it also may exhibit the structural properties required for use in a construction structure. Aspects of the invention have been found to be especially useful in structural fill blocks made from expanded polystyrene (EPS). This is because EPS is less dense than water and an EPS structural fill block can therefore become buoyant, and potentially prone to movement, if there is not adequate drainage. The skilled person will appreciate what is meant by Expanded Polystyrene (EPS). EPS is typically a closed cell, thermoplastic foam material. EPS is typically produced from solid beads of polystyrene, which is polymerised from styrene monomer and contains an expansion gas (for example pentane) dissolved within the polystyrene bead. In preferred embodiments of the invention, the structural fill block comprises, and more preferably substantially consists of, EPS. The male locator portions and the female locator portions may be shaped such that when the structural fill block is positioned with its lower surface on top of the upper surface of a second, identical, structural fill block, and a male locator portion of one of the structural fill blocks is received in a female locator portion of the other of the structural fill blocks, the male and female locator portions form an interlock. The interlock may inhibit relative translational movement between the structural fill block and the second structural fill block below it. Providing male and female locator portions that form an interlock to inhibit relative translational movement has been found to be especially beneficial because it may alleviate the need for separate securing members between blocks and / or an assessment of the frictional force between adjacent surfaces. The translational movement is preferably a translational movement in two mutually orthogonal directions. The mutually orthogonal directions are preferably in a direction across the width and along the length of the block. These directions are preferably in the horizontal plane, and are both perpendicular to a vertical plane aligned with the depth of the block. It will be appreciated that any references to orientations are, unless otherwise specified, made with reference to the block during normal use (for example in the orientation in which a block is intended to be installed). In principle the male and female portions may be any shape that achieves the interlock. In preferred embodiments, each male locator portion is a frustum-shaped protrusion and each female locator portion is a correspondingly frustrum-shaped recess. The frustum-shape may be a frusto-conical shape, but is more preferably a frusto-pyramidal shape. The pyramidal shape may be a quadrilateral-based, and preferably a square-based, pyramidal shape. In embodiments in which the locator portions comprise a drainage hole, the drainage holes may be positioned at the converging end (i.e. towards the peak) of the frustum shape. In this manner, the hole is typically positioned at the lowest point of the female locator portion and the highest point of the male locator portion, thereby facilitating effective drainage. The spacing between two adjacent female locator portions may be the same as the spacing between two adjacent male locator portions. The plurality of female locator portions may be arranged in a uniformly spaced array. The male locator portions may be arranged in a uniformly spaced array. The uniformly spaced arrays in which the female locator portions and the male locator portions are arranged, preferably have the same layout. Providing an array of locator portions has been found to be especially beneficial. Each array may be at least two locator portions long, by two locator portions wide. Such an arrangement enables the structural fill blocks of adjacent layers to be staggered with respect to each other, whilst still having a male locator portion received in a corresponding female locator portion. Each array may be more than two locator portions long; for example it may be four locator portions long. The spacing between locator portions in the length direction is preferably the same as the spacing between locator portions in the width direction. Such an arrangement may enable structural fill blocks to be orientated at 90 degrees to one another (as well as allowing the structural fill blocks to be aligned with one another) yet still allowing a male locator portion of one of the structural fill blocks to be received in a female locator portion of the other of the structural fill blocks. In some embodiments, each of the upper or lower surface may comprise male locator portions as well as female locator portions, or vice versa. In preferred embodiments, the locator portions of the upper surface are only one of male or female locator portions, and the locator portions of the lower surface are only the other one of the male or female locator portions. The structural fill block may be substantially cuboidal. The block may have a length, a width and a depth, defining three mutually orthogonal directions. The upper and lower faces of the structural fill block typically lie in the length / width plane. The end faces of the structural fill block typically lie in the width / depth plane. In embodiments of the invention the upper and lower surfaces of the block comprise the male protruding locator portions and the female recess locator portions. Those surfaces themselves are therefore not planar. It will be appreciated however, that the locator portions on the upper surface typically lie in a planar array, within the plane defining the notional upper face of the cuboidal structural fill block. Likewise, the locator portions on the lower surface typically lie in a planar array, within the plane defining the notional lower face of the cuboidal block. The structural fill block may have a length that is an integer-multiple of its width. The length of the structural block may be twice the width of the structural fill block. In embodiments in which the structural fill block is made from EPS, the structural fill block may be made from shape-moulded EPS. Using shape-moulding to construct the structural fill block has been found to be especially beneficial because a relatively complex shape can be achieved in a mould (for example to create the locator portions) without there necessarily being a need for a second stage of manufacture. The structural fill block may have a length of at least 1.2m. The structural fill block may have a width of at least 0.6m. The structural fill block may have a depth of at least 0.3m. In preferred embodiments, the structural fill block has a length of 2.4m. In preferred embodiments, the structural fill block has a width of 1.2m. The structural fill block may have depth of 0.6m. The structural fill block may have a depth of no greater than 1,2m. The structural fill block is for use in construction, for example of a construction structure. The construction structure is preferably for a civil engineering construction. For example the construction structure may be in the form of hard or soft landscaping. The landscaping may be for supporting pedestrian and / or motorised transport. In some embodiments, the construction structure may be below ground level, but in other embodiments the construction structure may be, or may extend, above ground level. The structural fill block preferably exhibits sufficient structural load bearing properties for use in a construction structure. For example, the structural fill block may have a compressive strength at 1% strain, of at least 20kPa, or at least lOOkPa, or at least 190kPa. The density of the structural fill block may be at least 15 kg / m3. The density of the structural fill block may be no more than 55 kg / m3. In preferred embodiments, the upper surface of the structural fill block comprises the plurality of recessed female locator portions, and the lower surface comprises the plurality of protruding male locator portions. Such an arrangement has been found to be especially beneficial, particularly in embodiments of the invention comprising drainage holes, because the female locator portions may naturally funnel the water being drained by virtue of being recessed. According to another aspect of the invention, there is provided a pair of structural fill blocks, comprising a first structural fill block according to any aspect herein, and a second structural fill block according to any aspect herein. The pair of structural fill blocks may be configured such that when the first structural fill block is positioned with its lower surface on top of the upper surface of the second structural fill block, a male locator portion of one of the first or second structural fill blocks is received in a female locator portion of the other of the first or second structural fill blocks. According to another aspect of the invention, there is provided a multiplicity of the structural fill blocks according to any aspect herein. The multiplicity of structural fill blocks may be arranged in a first layer on top of a second layer, the male locator portion of the blocks in one of the layers of structural fill blocks being received in the female locator portion of the other layer of the structural fill blocks. The layers may be part of a construction structure. The construction structure may be in the form of a hard or soft landscaping. According to another aspect of the invention, there is provided a method of filling volume in a construction structure, the method comprising the step of layering a multiplicity of structural fill blocks in a first layer, above a multiplicity of structural fill blocks in a second layer, each structural fill block in the first layer being located with its lower surface on top of the upper surface of one or more structural fill blocks in the second layer. The step of layering the structural fill block in the first layer comprises receiving a male locator portion of one of the structural fill blocks of the first or second layer, in a female locator portion of one of the structural fill blocks of the other of the first or second layer. It has been recognised that in some uses of the structural fill blocks of the above-mentioned aspects of the invention, it may be desirable for the upper surface of the upper-most layer in a construction to exhibit a planar face. This may allow other materials to be placed on that surface, such as geotextile and filter layers, paving systems, road structures etc. Accordingly, a further aspect of the invention provides a cap section for covering the upper surface of a structural fill block, the cap having a lower surface comprising a plurality of protruding male locator portions, and a substantially planar upper surface, the male locator portions being configured to be received in the female recessed portions of a structural fill block according to any aspect herein. Such an arrangement allows the cap section to be installed on top of the upper surface of the upper layer of blocks, thereby facilitating a planar surface on an arrangement of structural fill blocks that exhibit the female and male locator portions. The planar surface may be substantially horizontal. In some embodiments, the planar surface may be arranged at an inclination to the horizontal. In both the above-mentioned embodiments, the lower surface of the cap section is preferably horizontal. It has been recognised that in some uses of the structural fill blocks of the above-mentioned aspects of the invention, it may be desirable for the lower surface of the lower-most layer in a construction to exhibit a planar face. This may allow the maximum contact area of the lower-most layer with the underlying substrate, which may be beneficial in transferring loads into that underlying substrate and / or in ensuring a stable base for the over-lying structural fill blocks. Accordingly, a further aspect of the invention provides a base section for use beneath a structural fill block, the base section having an upper surface comprising a plurality of recessed female locator portions, and a substantially planar lower surface. The recessed female locator portions are configured to receive the protruding male portions of a structural fill block according to any aspect herein. Such an arrangement allows the base section to be installed below the lower surface of the lower layer of blocks, thereby facilitating a planar lower surface, on an arrangement of structural fill blocks that exhibit the female and male locator portions. It will be appreciated that for embodiments of the structural fill block in which the upper surface of the structural fill block comprises the protruding male portions and the lower surface comprises the recessed female portions, the cap section according to the above-mentioned aspect of the invention may then be suitable as the base section of the other aspect of the invention (and vice versa). According to further aspects of the invention there is provided a base section corresponding to the cap section of the above-mentioned aspect of the invention, and there is provided a cap section corresponding to the base section of the above-mentioned aspect of the invention. According to yet another aspect of the invention, there is provided an insert for inserting in a recessed female locator portion of a structural fill block according to any aspect herein. The insert includes a drainage structure for dictating the rate of drainage flow through the insert, into the female locator portion. The insert preferably exhibits a geometry that is complementary with the recessed female locator portion. The insert is preferably a close-fit in the recessed female locator portion. The provision of such an insert has been found to be especially beneficial when used with the structural fill blocks according to other aspects of the invention because it may be used to tailor the drainage properties of the construction structure in which the structural fill block is used. The drainage structure of the insert may take a number of forms. For example the drainage structure may comprise a hole for alignment with a corresponding hole in the structural fill block. By way of another example, the drainage structure may comprise a free-draining structure (such as a percolated structure) for allowing an increased water flow through the insert. In some other embodiments the insert may comprise a water-retaining structure that is arranged to prevent water passing through the insert, and / or to retain water above or in the insert. The latter may be useful in arrangements in which retention or control of water is desirable, for example in a soft landscaping structure. In some other embodiments the insert may comprise a combination of these drainage features. The use of an insert has been found to be especially beneficial because it allows these drainage properties at the upper surface of the construction structure to be tailored in particular locations within that structure (in some cases even reducing drainage locally), whilst still allowing the use of a multiplicity of identical structural fill blocks within that construction structure. According to another aspect of the invention, there is provided a method of tailoring drainage flow through a structural fill block. The method may comprise the steps of: (a) selecting an insert according to an aspect described herein; (b) placing the insert into a female recessed portion of the structural fill block; (c) repeating steps (a) and (b) for one or more of the other female recessed portions of the structural fill block. It will of course be appreciated that features described in relation to one aspect of the present invention may be incorporated into any and all other aspects of the present invention. For example, the methods of aspects of the invention may incorporate any of the features described with reference to the structural fill block, the pairs of structural fill blocks and / or the layers of structural fill blocks according to other aspects of the invention, and vice versa. Description of the Drawings Embodiments of the present invention will now be described by way of example only with reference to the accompanying schematic drawings of which: Figure 1 shows a construction structure in which a multiplicity of structural fill blocks according to a first embodiment of the invention have been used, along with corresponding cap sections and base sections; Figures 2a and 2b are perspective views of one of the structural fill blocks used in the construction structure of Figure 1; Figure 3 is a perspective view of one of the cap sections used in the construction structure of Figure 1; Figure 4 is a perspective view of one of the base sections used in the construction structure of Figure 1; Figures 5a and 5b are perspective views of two different inserts used in the construction structure of Figure 1; Figure 6 is a plan view of a structural fill block according to a second embodiment of the invention; Figure 7 is a perspective view of a cap section according to a third embodiment of the invention: Figures 8a, 8b and 8c are perspective views of three different inserts according to other embodiments of the invention; and Figure 9 is a flowchart showing a method according to a further embodiment of the invention. Detailed Description Figure 1 shows part of a construction structure 1 in which a multiplicity of lightweight structural fill blocks 3 according to a first embodiment of the invention have been used (referred to herein after as ‘structural fill blocks’ or ‘blocks’). The construction structure is part of a mix of hard landscaping (comprising road and pavement structures (not shown)) and soft landscaping (comprising green areas and areas of water attenuation (not shown)). In accordance with known structural fill block arrangements per se, the structural fill blocks are located within the construction structure and rest between an underlying substrate and the material above, such as foundations (not shown in Figure 1) for the roads / pavements etc. The structural fill blocks act to fill this space in an efficient manner, whilst also allowing effective load distribution into the underlying substrate. In the arrangement in Figure 1, the structural fill blocks 3 are arranged in a bottom layer LI and a top layer L2. In other embodiments of the invention, additional layers may, of course, be provided. The details of the structural fill blocks 3 are described in more detail below with reference to Figures 2a and 2b. Referring still to Figure 1, the lower layer LI of blocks 3 is located on a series of base sections 5. In addition, part of the lower layer LI without an upper layer above it, has a cap section 7 installed thereon. The details of the base section 5 and the cap section 7 are described in more detail below with reference to Figures 4 and 3 respectively. Finally, Figure 1 also shows two inserts 9 received in the upper surface on a block 3 in the upper layer L2. The details of the inserts 9 are described in more detail below with reference to Figures 5a and 5b. Referring now to Figures 2a and 2b, these two Figures show a structural fill block from above (Figure 2a) and from below (Figure 2b). Each of the structural fill blocks 3 in Figure I are substantially identical so the description of the block with reference to Figures 2a and 2b reflects a description of each of the blocks 3 in layers LI and L2. The structural fill block (also referred to below in shorthand as ‘the block’) 3 is generally cuboidal and has a length 1 of 2.4m, a width w of 1.2m and a depth d of 0.6m. The block is shape-moulded from expanded polystyrene (EPS). The upper surface 11 of the block 3 comprises a 2x4 array of eight recessed female locator portions 13. Each recessed locator portion 13 is in the form of a frusto-pyramidal shaped recess, set back from the notional upper face of the cuboidal block 3. In the centre of each female locator portion 13 there is a drainage hole 15. The drainage hole connects to another hole on the lower surface (described below with reference to Figure 2b) via a conduit 17. The lower surface 19 of the block 3 comprises a 2x4 array of eight protruding male portions 21. The 2x4 array is in a uniform pattern that matches the corresponding array of female locator portions on the upper surface 11. Each protruding male locator portion 21 is in the form of a frusto-pyramidal shaped protrusion raised above the notional lower face of the cuboidal block 3. In the centre of each male locator portion 21 there is a drainage hole 23. The drainage hole 23 connects to the hole 15 on the upper surface via the conduit 17 (the conduits being shown in phantom in Figure 2b). This novel structural fill block 3 described above, is advantageous in a number of ways: Firstly, the layout and shape of the male and female locator portions 21,13 are such that when a structural fill block 3 is positioned with its lower surface 19 on top of the upper surface 11 of a second, identical, structural fill block 3, the male locator portions 21 on the lower surface 19 of the upper block 3, are each received in a respective female locator portion 13 on the upper surface 11 of the structural fill blocks 3 below. This allows accurate locating of the blocks relative to each other when assembled in layers LI, L2. Furthermore as each block 3 has the same uniform array of locator portions, the blocks may be staggered, with different male locator portions 21 being received in the female locator portions 13 of different blocks (for example see the staggered arrangement in layer L2 above LI in Figure 1). Secondly, the blocks are configured such that when a male locator portion 21 is received in a female locator portion 13, the drainage holes 23, 15 of those respective male and female locator portions 21,13 align. Such an arrangement is beneficial because it ensures a relatively free-draining arrangement of the structural fill blocks. This is especially beneficial in the context of lightweight structural fill blocks, such as the first embodiment of the invention that is made from EPS, because it reduces the risk of the blocks being surrounded by water, which may otherwise cause such blocks to become buoyant. Thirdly, in the first embodiment of the invention, the drainage holes 15, 23 and conduit 17 are around 70mm diameter, and are configured to receive a securing member in the form of a scaffold pole (having a diameter of 48.3mm). Each pole (not shown) extends through, and between, the blocks on adjacent layers LI, L2. These poles can be used, where necessary, to inhibit relative translational movement between the layers of blocks. It will be appreciated that other securing members may also be used, but it has been recognised that scaffold poles may be especially beneficial because they tend to be readily available at the construction site. Fourthly, the complementary frusto-pyramidal shapes of the male and female locator portions are such that, when a male locator portion 21 is received in a female locator portion 13, those male and female locator portions form an interlock to inhibit relative translational movement between the respective structural fill blocks and the second structural fill block below. In this context, translational movement will be understood to mean translational movement in both the length direction 1, and the width direction w of the blocks 3 (i.e. parallel to the 1-w plane). Such an arrangement may alleviate the need for fasteners and / or the need for a prior calculation on whether the frictional force between planar surfaces would be sufficient to prevent movement between the layers of blocks L1 / L2. In the first embodiment of the invention, the construction structure 1 also includes a cap section 7, which will now be described with reference to Figure 3. The cap section 7 has a lower surface 25 comprising a plurality of protruding male locator portions 27, but a substantially planar upper surface 29. The protruding male locator portions 27 are substantially identical in shape and layout to the protruding male locator portions 21 on the lower surface of each block 3 and each comprise a through hole 31. They are therefore configured to be received in the female recessed portions 13 of a structural fill block 3 in the manner described above with reference to a block 3. The cap section 7 has the same width and length as the structural fill blocks 3 but the depth of the cap section is significantly smaller than the depth of the blocks 3. The cap section can therefore be used on the upper-most layer of parts of the construction structure (either locally upper-most or globally upper-most in the structure - see Figure 1 illustrating the former) to present a planar surface 29 without adding significant height to the overall structure. This planar surface may be beneficial for receiving particular parts of the structure above the structural fill blocks, such as geotextile and filter layers, or road material. Thus, the cap section 7 provides a way of obtaining a planar surface whilst still making use of the structural fill blocks 3 illustrated in the first embodiment of the invention. In the first embodiment of the invention, the construction structure 1 also includes a multiplicity of base sections 5, one of which will now be described with reference to Figure 4. The base section 5 has an upper surface 35 comprising a plurality of recessed female locator portions 37, but a substantially planar lower surface 39. The recessed female locator portions 37 are substantially identical in shape and layout to the recessed female locator portions 13 on the upper surface of each block 3 and each comprise a through hole 41. They are therefore configured to be received in the protruding male portions 21 of a structural fill block 3 in the manner described above with reference to a block 3. The base section 5 has the same width and length as the structural fill blocks 3 but the depth of the base section is significantly smaller than the depth of the blocks 3. The base section can therefore be used on the lower-most layer of some or all of the construction structure to present a planar surface 39. This planar surface may be beneficial for effectively transferring load into the underlying substrate. Thus, the base section 5 provides a way of obtaining a planar surface at the base of the overall structure, whilst still making use of the structural fill blocks 3 illustrated in the first embodiment of the invention. Figures 5a and 5b are perspective views of two different inserts 9 used in the construction structure of Figure 1. Both the inserts are of a shape and size that is complementary with the shape and size of the female recessed portions 13 of the upper surface of the block 3. Thus, the inserts 9 are able to be received in the female portions in a close fit (see Figure 1). The two different inserts 9a, 9b shown in Figures 5a and 5b respectively allow the drainage behaviour in the vicinity of the structural fill block to be tailored to meet the designer’s requirements. Figure 5a shows a standard insert comprising a central aperture 43 arranged to align with the drainage hole 15 in the underlying recessed female portion 13. The insert thus allows water to readily drain from above the insert 9a into, and through, the underlying block 3. Figure 5b shows a different insert without any aperture. Instead, the insert is blanked-off and inhibits drainage flow into the underlying block 3. This arrangement may be used where it is desirable to retain water above the structure, for example in selected areas of the soft landscaping. Inserts 9a and 9b may thus be placed in selected recessed female portions 13 of selected block 3 in the construction structure to tailor the drainage performance. Figure 6 is a plan view of a structural fill block 103 according to a second embodiment of the invention. The structural fill block 103 is the same as the block 3 of the first embodiment except where indicated below. Where appropriate, the same reference numerals are used to describe corresponding features from the first embodiment, but those numerals have been incremented by 100. In Figure 6 the block 103 is shown from above in plan view looking at the upper surface 111. The block comprises an array of recessed female portions 113 with central drainage holes 115. As illustrated using the phantom lines in Figure 6, the block 103 comprises additional drainage channels 145 extending diagonally across the block. The channels intersect the conduits 117 (not visible in Figure 6) extending between the drainage holes 115,123 on the upper and lower surfaces of the block 103. Such an arrangement has been found to improve the drainage performance of the block. Figure 7 is a perspective view of a cap section according to a third embodiment of the invention. The cap section 207 is the same as the cap section 7 of the first embodiment except where indicated below. Where appropriate, the same reference numerals are used to describe corresponding features from the first embodiment, but those numerals have been incremented by 200. In the arrangement of Figure 7, the planar upper surface is non-parallel to the nominal plane of the lower surface of the cap section. By providing a ramped surface as shown in Figure 7, the upper level of the construction structure may be better tailored to its location (for example where the ground level also exhibits a slope). Figures 8a, 8b and 8c are perspective views of three different inserts that could be used instead of, or in conjunction with, the inserts 9a and 9b in the first embodiment. Where appropriate, the same reference numerals are used to describe corresponding features from the first embodiment, but those numerals have been incremented by 300. Figure 8a shows an insert 309a that includes a water collecting region 347, in which a series of raised drainage outlets 349 are located. The raised drainage outlets are configured to drain the water once the level in the water collecting region reaches a threshold depth. This insert 309a is especially useful in arrangements where it is desirable to retain some surface water (for example to sustain an area of soft landscaping). Figure 8b shows an insert 309b that is formed from a fully draining structure, such as percolated structure 351. This insert 309b is especially useful in arrangements where it is desirable to maximise the drainage of surface water. Figure 8c shows an insert 309c that is formed partly from the fully draining percolated structure 351, and partly from a surrounding impervious structure 353. This insert 309c is especially useful in arrangements where it is desirable to provide a balanced drainage solution. Figure 9 is a flowchart showing steps in a method of filling a volume in a construction structure. The method comprises the initial step 402 of laying a series of base sections 5 on a suitably free-draining substrate of an excavation. It will be appreciated that other steps will also have been undertaken prior to laying the base sections, such as engineers calculating the required overall drainage requirements for the layers and conducting an assessment (and any modification if required) of the underlying substrate drainage. Next, a step 404 is conducted to layer a multiplicity of structural fill blocks 3 in a first layer LI and then a second layer L2, above the first layer. Each structural fill block in the second layer L2 is located with its lower surface on top of the upper surface of one or more structural fill blocks in the first layer LI. Furthermore, the male locator portions of the structural fill blocks 3 of the second layer L2 are received in respective female locator portions on the structural fill blocks of the first layer LI, such that the drainage holes in respective locator portions are aligned. In step 406, one or more cap sections 7 are located on the upper-most surfaces of the structural fill blocks, in order to provide a planar surface at the top of the assembly of structural fill blocks. In step 408, the drainage flow through part of the structure is tailored by selecting an insert 9a from the available inserts 9a, 9b, 309a, 309b and 309c, and placing the chosen insert into a female recessed portion of one of the structural fill blocks. The process is repeated for one or more of the other female recessed portions of the structural fill blocks until the desired drainage is achieved (for example in a soft landscaping part of the structure). It will be appreciated that amongst the steps in the method of Figure 9, other construction steps are also undertaken to create a final construction structure, such as laying pavements / roads on parts of the above-mentioned arrangement, and installing soft landscaping on other parts of the arrangement. Whilst the present invention has been described and illustrated with reference to particular embodiments, it will be appreciated by those of ordinary skill in the art that the invention lends itself to many different variations not specifically illustrated herein. Where in the foregoing description, integers or elements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present invention, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the invention that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims. Moreover, it is to be understood that such optional integers or features, whilst of possible benefit in some embodiments of the invention, may not be desirable, and may therefore be absent, in other embodiments.

Claims

1. A structural fill block for use in construction, the structural fill block being made from expanded polystyrene (EPS), and wherein,the structural fill block has an upper surface and a lower surface, whereinone of the upper surface or the lower surface comprises a plurality of recessed female locator portions, and the other of the upper surface or the lower surface comprises a plurality of protruding male locator portions,and whereinthe structural fill block is configured such that when the structural fill block is positioned with its lower surface on top of the upper surface of a second, identical, structural fill block, a male locator portion of one of the structural fill blocks is received in a female locator portion of the other of the structural fill blocks,and whereineach of the male and the female locator portions comprises a drainage hole, the drainage holes being located such that when the structural fill block is positioned with its lower surface on top of the upper surface of a second, identical, structural fill block, and a male locator portion of one of the structural fill blocks is received in a female locator portion of the other of the structural fill blocks, the drainage holes of those respective male and female locator portions align,and whereineach of the female locator portions in the plurality of female locator portions is paired with a respective male locator portion, andwhereinthe drainage holes in the female locator portion and the male locator portion of each pair, are connected by a conduit extending through the structural fill block.

2. A structural fill block according to claim 1, wherein each pair of female and male locator portions are vertically aligned, and the conduit extends substantially vertically through the structural fill block.

3. A structural fill block according to any preceding claim, whereinthe male locator portions and the female locator portions are shaped such that when the structural fill block is positioned with its lower surface on top of the upper surface of a second, identical, structural fill block, and a male locator portion of one of the structural fill blocks is received in a female locator portion of the other of the structural fill blocks, the male and female locator portions form an interlock to inhibit relative translational movement between the structural fill block and the second structural fill block below it.

4. A structural fill block according to claim 3, whereineach male locator portion is a frustum-shaped protrusion and each female locator portion is a correspondingly frustrum-shaped recess.

5. A structural fill block according to any preceding claim,whereinthe plurality of female locator portions are arranged in a uniformly spaced array, and the plurality of male locator portions are arranged in a uniformly spaced array.

6. A structural fill block according to claim 5, whereineach array is at least two locator portions long, by two locator portions wide.

7. A structural fill block according to any preceding claim, wherein the block is made from shape-moulded EPS.

8. A structural fill block according to any preceding claim,wherein the block has a length of at least 1.2m, a width of at least 0.6m and adepth of at least 0.3m.

9. A structural fill block according to claim 8, wherein the block has a length of 2.4m, and a width of 1.2m.

10. A structural fill block according to claim 8 or claim 9 wherein the depth is no greater than 1.2m.

11. A structural fill block according to any preceding claim,whereinthe upper surface comprises the plurality of recessed female locator portions, and the lower surface comprises the plurality of protruding male locator portions.

12. A pair of structural fill blocks, comprising a first structural fill block according to any preceding claim, and a second structural fill block according to any preceding claim,whereinthe pair of structural fill blocks is configured such that when the first structural fill block is positioned with its lower surface on top of the upper surface of the second structural fill block, a male locator portion of one of the first or second structural fill blocks is received in a female locator portion of the other of the first or second structural fill blocks.

13. A multiplicity of the structural fill blocks according to any of claims 1 to 11, the multiplicity of structural fill blocks being arranged in a first layer on top of a second layer, the male locator portion of the blocks in one of the layers of structural fill blocks being received in the female locator portion of the other layer of the structural fill blocks.

14. A multiplicity of structural fill blocks according to claim 13, wherein the layers are part of a construction structure, preferably in the form of a hard or soft landscaping.

15. A method of filling volume in a construction structure, the method comprising the step of layering a multiplicity of EPS structural fill blocks in a first layer,above a multiplicity of EPS structural fill blocks in a second layer, each structural fill block in the first layer being located with its lower surface on top of the upper surface of one or more structural fill blocks in the second layer, whereinthe step of layering the structural fill block in the first layer comprises receiving a male locator portion of one of the structural fill blocks of the first or second layer, in a female locator portion of one of the structural fill blocks of the other of the first or second layer.

16. A cap section for covering the upper surface of a structural fill block, the cap having a lower surface comprising a plurality of protruding male locator portions, and a substantially planar upper surface, the male locator portions being configured to be received in the female recessed portions of a structural fill block according to claim 11.

17. A base section for use beneath a structural fill block, the base section having an upper surface comprising a plurality of recessed female locator portions, and a substantially planar lower surface, the recessed female locator portions being configured to receive the protruding male portions of a structural fill block according to claim 11.

18. An insert for inserting in a recessed female locator portion of a structural fill block according to claim 11, the insert including a drainage structure for dictating the rate of drainage flow through the insert, into the female locator portion.

19. A method of tailoring drainage flow through a structural fill block, the method comprising the steps of:a. selecting an insert according to claim 18;b. placing the insert into a female recessed portion of the structural fill5 block;c. repeating steps a. and b. for one or more of the other female recessed portions of the structural fill block.

20. A method of manoeuvring a structural fill block, the structural fill block being10 made from expanded polystyrene (EPS), and having drainage holes therein,the method comprising the steps of:a. inserting part of a lifting device into the drainage holes to engage the lifting device with the structural fill block;b. lifting the structural fill block and manoeuvring the block into a desired15 location using the lifting device;c. disengaging the lifting device from the structural fill block and withdrawing the part of the lifting device from the drainage holes.

21. The method according to claim 20, wherein the structural fill block is the20structural fill block according to any of claims 1 to 11.

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