GB2428698A - Hardcore substitute - Google Patents

Abstract

A building material for use as a hard core substitute, and a method of laying a floor and a laid floor incorporating the same are described. The building material makes use of granulated or particulate polymeric material 2 in particular polyurethane waste, contained and enclosed within a closed envelope of sheet material 1 so as to form a closed bag.

Description

BUiLDING MATERIAL AND METHOD The invention relates to a building material,

especially for use as a hard core substitute, and to a method of providing the same in a building.

Foundation hard core is widely used in the building industry, especially to provide the basis for a concrete or other solid floor. Building hard core is conventionally composed of lumps of rock, brick or other rubble which might be freshly quarried, recycled, or some mixture thereof. It is laid in cavities dug to the required depth below the floor or other surface level within a building, or in a similar situation, and the floor or surface is then laid on top.

Intermediate layers, for example as a key for the floor surface, to provide insulation or moisture resistance or for other purposes, may be laid between the hard core and the final floor surface.

Conventional hard core is heavy, relatively dense and bulky. It can consequently be relatively expensive to transport and inconvenient to use, requiring equipment capable of handling heavy loads. If recycled hard core materials are not available or not applicable to the purpose, quarried rock materials might be used, which do not necessary meet ideal environmental considerations.

Conventional hard core is selected primarily for its mechanical properties as a mechanical base for the floor or other surface laid on top of it. It is unlikely to exhibit, for example, good thermal insulation properties, moisture resistance or the like, and it will often be necessary, especially in a case of buildings, for additional insulation andlor moisture barrier layers to be provided on top of the hard core before the floor can be laid in order to comply with building regulations.

It has been suggested that a possible replacement for hard core, particularly for example in relation to the building of small extensions to a building, where the hard core layer needs to serve only as a stable underlayer for the floor, but where some insulating property is also required, sacks of low density granular ceramic materials may be used, the material comprising expanded clay aggregate with a hard ceramic shell and a honeycomb core. This combines light weight with effective insulation, but needs to be specially manufactured for the purpose.

It is an object of the present invention to provide a building material and method which mitigates some or all of the above disadvantages.

It is a particular preferred object of the invention to provide a hard core substitute which is lower in density than conventional hard core for ease of transportation in use and/or more environmentally friendly and/or has greater inherent insulating properties.

It is a particular preferred embodiment of the invention to provide a hard core substitute which is readily suited to use in the construction of concrete-floored buildings, and in particular of concrete-floored extension to existing buildings.

Thus, in accordance with the invention in a first aspect a building material for use as a hard core substitute comprises granulated or particulate polymeric material contained and enclosed within a closed envelope of sheet material so as to form a closed bag.

Each bag contains a large plurality of grains or particles of the polymeric material, with the sheet as a whole acting as a closure envelope. The resultant bag is a readily handled and light weight product offering low density but which is conformable with reasonable structural rigidity to the sub-surface volumes into which it will be laid in a similar manner to conventional hard core.

The reduced weight for unit volume eases transportation to site, and both the reduced weight and the conveniently bagged structure assist in handling and use on site. The polymeric material making up the granules is inherently more insulating than conventional hard core material, and will inherently reduce the need for an additional insulating layer above the substitute hard core layer once it is laid.

Unlike light weight ceramic hard core alternatives is of standard structure and the polymeric material need not specifically be fabricated for purpose. It may include recycled waste. Any low density polymeric material granulated to suitable size can be used. Lower density polymer waste and its disposal is a huge issue. Far from requiring quarrying of new material, with the attendant environmental impact, as can be the case with conventional hard core, the present invention can make a positive environmental contribution by making use of polymeric waste and solving a waste disposal problem.

In a preferred embodiment therefore the granulated polymeric material comprises at least 50%, and more preferably at least 75%, granulated recycled waste.

The granules or particles are suitably dimensioned having consideration to the practicalities of filling the bags, transporting the bags, and providing a product which is reasonably structurally stable but has a degree of conformability in situ. Preferably at least a majority of granules have mean linear dimension across of less than 20 mm, and for example of between I and 10 mm.

As used herein, the term granulated is intended to convey that the polymeric material is in a particulate form, with a particle size such that a large plurality of particles may be contained in each bag. Granulated therefore includes shredded, pelletised, chopped, sliced or otherwise in made into particulate form, as well as directly formed for purpose.

More preferably, the fill includes at least a proportion of pelletised polymeric material, and in particular pelletised recycled polymeric material. That is to say, pellets are used which are formed via a powder pelletisation process which will be familiar to those skilled in the art. Such pellets are readily formable into suitably sized particles to act as a lower density substitute for conventional hard core. The pelletisation process is particularly suited to a raw material derived in whole or in part from recyclable waste.

Further preferably, the polymeric material includes shredded polymeric material. Again, it will be preferably if at least some of the shredded material is shredded polymeric waste. For a give raw polymeric material, when compared with bulk pelletised polymer, bulk shredded polymer bagged for the application of the present invention will generally be appreciably less dense, but appreciably better as a thermal insulator. Accordingly, the use of shredded material is favoured by the desire to give insulating properties, and the use of pelletised material favoured by the desire to give the structural properties It follows that in its most preferred form, the invention makes use of both shredded and pelletised material. In a particular preferred embodiment, each bag is filled with a mixture of shredded and pelletised material. The precise ratio of shredded and pelletised material might be determined by the intended application, but the ratio between major and minor component of any mixture of the two materials preferably does not excess three to one and for many applications broadly equal quantities will be preferred. In the alternative, the same principle can be exploited if a substitute hard core layer is laid using a mixture of bags each filled substantially entirely with one or other of pelletised or shredded polymeric material.

The polymeric materials making up the granulated filling of the bag are lower in density than conventional hard core aggregates.

Suitable materials for the granulated filling of the bag include polyurethanes.

Preferably the listed materials make up at least 50% of the composition of a granulated bag fill and more preferably substantially all of the fill. In particular, the listed materials comprise at least majority recycled waste. Most preferred filling includes polyurethane waste from fridges, insulation products, and manufacturing processes.

The sheet envelope serves as a container, and is at least robust enough to fulfil this purpose. The sheet envelope material might also have other properties, for example further insulation, fire retardant, moisture resistant etc. Preferred materials for the sheet envelope include any nondegradable polymer, preferably recycled.

Each filled bag preferably has a generally cushion-shaped structure. That is to say is it relatively flat in profile, and preferably has a generally square or rectangular shape in plan. Such shape bags are most suited to be laid together in a generally tessellating manner across a floor area whilst still retaining some degree of conformability within the under floor volume.

individual bag volumes will be dictated by the intended application, and by considerations of ease of handling verses conformability into and across the under floor volume before the floor is laid. Suitable volumes might be in the range of 20 to 200 litres and for example 50 to 25 when uncompressed prior to use. The overall bag density in such a filled state should be preferably of the order of 0.2 to 1 kg 1', and more preferably below 0.5 kg 11.

in accordance with a further aspect of the invention, a method of laying a precursor surface as an alternative to laying hard core comprises filling a floor precursor cavity with a plurality of bags as hereinbefore described in order to fill an under floor volume.

In conventional manner, the method preferably further comprises the steps of applying a suitable web membrane comprising a damp-proof and/or keying surface for the floor material such as a concrete sereed, and applying the floor material such as a concrete screed.

In accordance with a third aspect of the invention there is provided a laid floor laid in accordance with the foregoing method. That is to say that the floor comprises an under floor layer comprising a plurality of bags as hereinbefore described laid within an under floor volume below the intended floor surface, an intermediate covering layer, comprising at least one covering web, for example having damp-proofing and/or floor surface keying properties, and a floor surface comprising at least one layer of floor material, for example, concrete.

The invention will now be described by way of example only with reference to Figures 1 to 3 of the accompanying drawings. Wherein: Figure 1 is an illustration of a single bag in accordance with the invention; Figure 2 is a prospective view of a floor subsurface laid with a plurality of bags in accordance with the invention as a hard core substitute; Figure 3 is a cross section through a laid floor incorporating the invention.

Referring first to Figure 1, a single bag in accordance with the invention is shown. The bag has a generally rectangular, cushion-shaped conformance, and in the example is designed to have a volume of 75 1, and linear dimensions of approximately 450- 700 mm. It is shown in plan view in Figure la, and in cross section through A-A in Figure 1 b.

The bag consists of a sheet of webbing material (1), made up of polypropylene sacking material, and granulated low density polymeric material (2), made up of a roughly equal mixture of pelletised and shredded polyurethane waste.

Polyurethane insulating material, which is in wide spread use as an insulator, for example in fridges and freezer, in insulating boards, and as a by product of the insulating industry, is a major environmental problem today. Frequently sent to land fill, it lends itself well to both the powder pelletisation and the shredding processes which are envisaged to produced the filling of the bags in accordance with the invention. Pelletised polyurethane waste offers a low density alternative to both conventional hard core and lower density ceramic hard core substitutes with adequate rigidity and stability. Shredded polyurethane waste maximises the insulating effect, and reduces the overall density of the mixture still further.

The sheet forms an envelope (3) containing the granulated polymeric material (2) and making the bag. The bag, containing the pelletised and shredded mixture, can substitute for both the structural role of conventional hard core and the insulating role of the separate insulating layer, so that a separate insulating layer is not required.

In use, a plurality of such bags are provided. Bags of the same or varying sizes may be provided depending upon the requirement. In the example, a sub-floor layer has been laid comprising a plurality of such bags (3) in two layers. In other applications, a single layer might suffice or more than two layers might be required. In the given example, the bag comprises a roughly equal mix of the primarily structural pelletised polyurethane, and a primarily insulating shredded polyurethane, so that each bag performs both functions. It would be apparent that, in cases where more than one layer of bags were to be laid, the same general effect could be obtained by, for example, laying a first layer of bags essentially filled with pelletised material and a second layer of bags essentially filled with shredded material or vice versa.

In the example illustrated in Figures 2 and 3, the layers of bags contained within a preliminary retaining wall (7). Additionally or alternatively, the volume into which a layer or layers of bags (3) is placed might be defined as a sub-surface excavation. A conventional subsurface foundation excavation might be more preferable for larger scale building construction. Laying of the bags on an existing surface might be acceptable in the construction of a building extension, or where a raised surface of the eventual floor is desirable or not accessibly detrimental.

Depending on the required depth, more than one layer of bags (3) may be laid.

Any gaps between them may be filled by any suitable granulated fill.

The remaining steps in the preparation of the floor are best illustrated by the cross section of Figure 3, which illustrates a floored laid as the floor of a building.

The floor area is defined by conventional dual leaf walls (lOa, lOb) supported on conventional foundations (12) below ground level (11). As desired, ground level (11) may correspond to the existing ground level, or may be lowered to accommodate the hard core substitute of the invention. This will depend on considerations of where the eventual floor level should lie relative to the external ground.

In the example, two layers of bags in accordance with the invention make up a substitute hard core layer (13) optionally (not shown) granular in fill between the layers, or immediately below or above the layers, which may be of the same form as the granular fill of the bags, or any other suitable form, may be used to improve the layer conformance. This layer replaces the hard core in a conventionally built floor, and in addition to doing so in a more light weight and easily handleable manner confers increased thermal insulation. As a result, the insulation layer can be dispensed with, and a simple damp-proof membrane (14) can be applied directly to the hard core substitute layer. In use this membrane will form part of the damp-proof course layer of the building (not shown).

The concrete layer (15) is then laid directly on this damp-proof membrane to complete the floor.

In this way, the floor is fabricated along existing principles, but using a hard core substitute which is readily handled, light weight, allows in many instances the user to dispense entirely with an additional insulation layer, makes use of recycled materials, and is eminently suited to the task. In particular, it offers a simplified build option for smaller scale structures, such as small outbuilding, building extensions and the like.

Claims (13)

1. A building material for use as a hard core substitute comprising granulated or particulate polymeric material contained and enclosed within a closed envelope of sheet material so as to form a closed bag.

2. A building material in accordance with claim 1 wherein the polymeric material includes at least 50% recycled low density polymeric waste.

3. A building material in accordance with claim 1 or 2 wherein at least a majority of granules have mean linear dimension across of less than 20 mm.

4. A building material in accordance with claim 3 wherein at least a majority of granules have mean linear dimension across of between 1 and 10 mm.

5. A building material in accordance with claim any preceding claim wherein the fill includes at least a proportion of pelletised polymeric material formed via a powder pelletisation process.

: * :

6. A building material in accordance with claim any preceding claim ::: :* wherein the fill includes at least a proportion shredded polymeric material. he

7. A building material in accordance with any preceding claim wherein the polymeric material includes at least 50% polyurethanes.

I.... * * *

8. A building material in accordance with claim 7 wherein the polymeric material includes polyurethane waste from fridges, insulation products, and manufacturing processes.

9. A building material in accordance with any preceding claim wherein the closed bag has a generally cushion-shaped structure relatively flat in profile, and with a generally square or rectangular shape in plan.

10. A building material in accordance with any preceding claim wherein the bag has a volume of 20 to 200 litres.

11. A method of laying a precursor surface as an alternative to laying hard core comprising filling a floor precursor cavity with a plurality of bags in accordance with any preceding claim in order to fill an under floor volume.

12. The method of claim 11 further comprising the steps of applying a suitable web membrane comprising a damp-proof and/or keying surface for the floor material such as a concrete screed, and applying the floor material such as a concrete screed.

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13. A laid floor comprising an under floor layer comprising a plurality of *.. . :* bags in accordance with one of claims 1 to 10 laid within an under floor volume below an intended floor surface, an intermediate covering layer, * 25 comprising at least one covering web, and a floor surface comprising at * least one layer of floor material.

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