GB2480807A

GB2480807A - A low density construction material

Info

Publication number: GB2480807A
Application number: GB1008904A
Authority: GB
Inventors: John Parry; Margret Macey
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-05-27
Filing date: 2010-05-27
Publication date: 2011-12-07
Also published as: GB201008904D0

Abstract

A composition for a construction material 10 is described including the following ingredients: a cementitious component; a polymer foam component 12; and a clay component. Also described is a method of manufacturing such a construction material including the steps of: adding water, a clay component, a cementitious component and a polymer foam component to a container; mixing the ingredients to form a homogenous mixture.

Description

Title: A Construction Material and Method of Manufacturing such a Material

Description of Invention

This invention relates to a construction material and a method of making such a material. More particularly, this invention relates to a low density constructional material.

It has been desired for many years to produce relatively low density construction material as a light weight' (in comparison) replacement for much heavier construction materials such as, for examples, concrete and brick, which can have a density in excess of 2200 KgIm3. In particular, it has been desirable to produce a construction material which has a density less than water, e.g. below 1000 KgIm3, so that the resultant material, when formed, for example into a planar element, floats.

Numerous attempts have been made to produce such a construction material and these have included aerating liquid concrete -in other words forcing small air bubbles in to the concrete mix such that the bubbles remain once the concrete has set. This method produces a lower density material, in some cases having a density less than 1000 KgIm3, however, the resulting material is much weaker than solid concrete and in addition requires expensive manufacturing machines in order to achieve the aeration. Such machines cannot, for example, be used in non-developed countries, where light weight constructional materials are desired, and it is not cost-effective to transport such constructional materials to those locations.

Another prior art material involves forming liquid concrete with low density aggregates, in order to achieve a composite material which has a lower density than that of formed with heavy aggregates. However, the low density aggregate is expensive to source and thus the resultant material is too expensive for mass manufacture, and also far too expensive for use in non-developed countries. In addition, the resulting material is denser than 1000 KgIm3.

A further prior art material is the combination of concrete with particles/chips of wood, but the inherent sugar content of the wood gives rise to difficulties in the concrete setting.

A yet further prior art material has been to mix into the concrete polystyrene balls/particles, in order to reduce the density of the material. However, due to the difference in density, the polystyrene balls/particles float to the surface before the material sets, thus rendering the material inhomogeneous and not suitable for purpose. Furthermore, round shapes are undesirable for concrete aggregates as they leave gaps between adjacent particles which is wasteful of cement.

According to a first aspect of the invention, we provide a composition for a construction material including the following ingredients:-a cementitious component; a polymer foam component; and a clay component.

According to a second aspect of the invention, we provide a set or dried construction material being a substantially homogeneous mixture of a cementitious component, a polymer foam component and a clay component.

According to a third aspect of the invention, we provide a method of manufacturing a construction material including the steps of:-adding water, a clay component, a cementitious component and a polymer foam component to a container; mixing the ingredients to form a substantially homogenous mixture; permitting the mixture to set.

Further features of the invention are set forth in the dependent claims.

Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, of which: figure 1 is a cross-sectional view of a composition of a construction material in accordance with the present invention; and figure 2 is a perspective view of a construction material in accordance with the present invention.

Referring to the figures, these show schematic views of a construction material which has been manufactured in accordance with the method of the present invention to provide a low density construction material suitable for many uses.

The construction material 10 in the present example has been formed (by pressing or rolling) into a rectangular component, and includes, primarily, three component parts, namely a cementitious component, a clay component and a polymer foam component. The polymer foam component is shown in the figures by reference numeral 12 and in this example is an expanded polystyrene foam having a density of about 4kg per m3. The cementitious (e.g. cement) and clay components are homogenously mixed with each other such that they cannot be distinguished from one another, and thus the matrix which holds to the polymer foam component 12 in place is a mixture of the cementitious component, the clay component and water.

The construction material of the present invention is manufactured using an alluvial clay, although it should be appreciated that other types of clay or clay equivalent could be used. In addition, it should be noted that although expanded polystyrene foam has been used in the present example, other types of polymer foam could well be utilised. The polymer foam in the present example is provided as granules or particles of expanded polystyrene from which are graded' so as to achieve a range of different sizes (e.g. diameter) of the foam. This helps with the packing' of the foam within the matrix to achieve a desired structural strength.

In the present example the ratio of the cementitious component to polymer foam component to clay component is substantially 2:2:15 by volume. This has been found by the applicant to provide beneficial properties balancing the lightweight/low density characteristic of the resulting material and its strength.

Most preferably, but not essentially, the polymer foam component should be at least 70% by volume of the construction material.

The construction material is manufactured as follows. In broad terms, the clay, cementitious and polymer foam components are mixed together with water to form a substantially homogenous mixture which is then formed (e.g. by pressing or rolling) to a desired shape and permitted to dry so that it sets'. It has been found by the applicant that the order in which the ingredients are mixed can affect the integrity/quality of the end material and thus it is preferable to mix the water, clay and cementitious components with each other until a substantially homogenous mix has been achieved prior to adding the polymer foam component. The polymer foam granules/particles are then gradually added to the mixture and mixed into the other ingredients until a homogenous mixture is achieved.

In one example the ingredients are added to a mixing container as follows.

Firstly water is added, then a clay component is added, then the cernentitious component is added and then the polymer foam component is mixed into the existing ingredients in the container. It is desirable to mix each existing ingredient in the container with the next added ingredient prior to adding the further ingredient(s) as this permits the ingredients to mix more homogenously with each other. In a more preferred embodiment the clay and cernentitious components are each split into at least two portions which are then alternated in their addition to the container. For example, water is firstly added to the container followed by a portion of the clay component, followed by a portion of the cementitious component, followed by a portion of the clay component, followed by a portion of the cementitious component and then finally followed by the polymer foam component. Again, the existing ingredients in the container are mixed thoroughly with each other before the subsequent ingredients are added.

Of course, rather than splitting the clay and cementitious components each into two portions, it is possible to split them into a greater number of portions whilst again alternating their addition to the container. This assists in providing an homogenous mixture to which the polymer foam component is added and avoids any difficulties in achieving homogenous distribution of the polymer foam granules/particles within the mixture.

In one example the polymer foam component could be added evenly throughout the mixing process, e.g. in portions thereof after each particular portion of the clay component has been added or after a portion of the cementitious component has been added to the mixture. By adding the polymer foam component gradually throughout the mixing process ensures that the polymer foam granules can mix into the material and do not simply sit on the surface of the mixture.

The present invention is highly advantageous because it produces a low density material which can be used for many types of construction (i.e. relatively low strength construction) which has a density less than that of water. This means that parts manufactured from the construction material in accordance with the present invention will float on water, which has many advantages in both developed and undeveloped countries.

The addition of the clay to the cementitious mixture produces a relatively viscous liquid which coats and traps the polystyrene granules/particles within the mixture and prevents them from easily rising to the surface of the mixture whilst the material is setting'. The addition of clay to the mixture is contrary to the understanding of skilled persons in this field. Experts in cernentitious materials would necessarily avoid using clay because the more clay that is contained in a mixture, the more cementitious component one would need in order to coat each clay particle, so that the material can set'. This is because clay particles are relatively small as compared with sand and gravels, for example, which are used with cement to provide concrete construction materials.

The present invention can be utilised to make lightweight bricks, for example, or can be pressed/cast into bricks or blocks which may then broken down to create a lightweight aggregate which has many uses in the building industry.

One proposed use of the present invention would be to manufacture jetties from the material. Such jetties would be beneficial over the known wooden structures because they would not be porous and would not be subject to rotting. They would also be structurally strong enough to support the weight of persons walking along the jetties and could be lifted into place easily as a single component parts.

The present example of the mixture of this constructional material achieves a density of about 800kg per m3, which is significantly less then the circa 1000kg per m3 for water. The present invention can also be used as a support platforms (whether provided as a single moulding or as a plurality of rnouldings connected together) for buildings, caravans, working machines, sheds etc for areas which tend to be subject to regular floods. There is also the possibility of using the material for floating airstrips for temporary runways for relatively light aircraft and also as helipads for helicopters.

When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

CLAIMS1. A composition for a construction material including the following ingredients:-a cementitious component; a polymer foam component; and a clay component.

2. A composition according to claim 1 wherein the ingredients of the composition are mixed such that the material is substantially homogenous.

3. A composition according to claim 1 or claim 1 wherein the material includes water.

4. A composition according to any preceding claim wherein the polymer foam component is an expanded foam provided as a plurality of granules/particles.

5. A composition according to claim 4 wherein polymer foam granules/particles of at least two different sizes are provided in the material.

6. A composition according to claim 4 wherein the polymer foam granules/particles are provided across a range of different sizes.

7. A composition according to any preceding claim wherein the clay component is earth including a proportion of aluminium silicate.

8. A composition according to any preceding claim wherein the cementitious component is a cement.

9. A composition according to any preceding claim wherein the clay is alluvial clay.

10. A composition according to any preceding claim wherein the ratio of the ingredients cementitious component' : polymer foam component' : clay component' is substantially 2:2:15 by volume.

11. A composition according to any preceding claim wherein the polymer foam component is at least 70% by volume.

12. A set or dried construction material being a substantially homogeneous mixture of a cementitious component, a polymer foam component and a clay component.

13. A set or dried construction material having a composition as set forth in any one of claims 1 to 11.

14. A method of manufacturing a construction material including the steps of:-adding water, a clay component, a cementitious component and a polymer foam component to a container; mixing the ingredients to form a substantially homogenous mixture.

15. A method according to claim 14 wherein the water, clay and cementitious components are mixed in the container before the polymer foam is added thereto.

16. A method according to claim 14 or claim 15 wherein the polymer foam is gradually added to the mixture and mixed with the other ingredients.

17. A method according to claim 14, claim 15 or claim 16 wherein the ingredients are added in the following order:-water; the clay component; the cementitious component; the polymer foam component.

18. A method according to claim 17 wherein the ingredients are mixed before each component is added.

19. A method according to claim 14, claim 15 or claim 16 wherein the ingredients are added in the following order:-water; a portion of the clay component; a portion of the cementitious component; a portion of the clay component; a portion of the cementitious component; the polymer foam component.

20. A method according to claim 17 wherein the ingredients are mixed before each component/proportion of component is added.

21. A composition substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

22. A construction material substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

22. A method substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

24. Any novel feature or novel combination of features described herein and/or in the accompanying drawings.