GB2458925A

GB2458925A - A composite material comprising laminated elements embedded in a cohesive material

Info

Publication number: GB2458925A
Application number: GB0805952A
Authority: GB
Inventors: Niall John Mackay
Original assignee: EKO TEK PRODUCTS Ltd
Current assignee: EKO TEK PRODUCTS Ltd
Priority date: 2008-04-02
Filing date: 2008-04-02
Publication date: 2009-10-07
Anticipated expiration: 2028-04-02
Also published as: GB0805952D0; GB2458925B

Abstract

A composite material is disclosed which comprises a body of cohesive material and a plurality of laminated elements embedded therein, each said laminated element comprising at least two layers of different materials which have been bonded to one another prior to being embedded in the body of cohesive material, said composite material optionally comprising laminated elements which are partially de-laminated. The cohesive material may be a cement, concrete, resin or ceramic material. The laminated elements may comprise thermoplastic materials, cellulose-based materials or metallic materials.

Description

1 2458925

COMPOSITE MATERIAL

This invention relates to composite material and to a method for production of composite material.

It relates in particular, though not exclusively, to composite material of a substantially rigid and reinforced type, such as reinforced cement and concrete, and to the production of said composite material.

It is well-known that the quality of products made from concrete can suffer due to plastic shrinkage crack formation and to dry shrinkage cracking when newly mixed concrete dries and solidifies.

The presence of conventional metal reinforcements in the concrete can assist in reducing the tendency for plastic shrinkage crack formation, but that reinforcement can in some cases adversely restrict the flexural or tensile strength of a concrete product in at least some directions of applied loading.

Furthermore, difficulty can arise in achieving an effective bond or mechanical inter-lock between constituents of the concrete and embedded reinforcement.

That can result in a need, for example, to provide metal reinforcing rods with a textured surface for aiding a mechanical inter-lock, and that inevitably adds to the cost of the reinforcement.

The present invention seeks to provide an improved composite material, and an improved method of production of an article of composite material, in which some of the aforedescribed difficulties are mitigated or overcome.

The present invention seeks also to provide a method and product which utilises recycled and/or recyclable waste material.

In accordance with one aspect of the present invention a composite material comprises a body of a first and substantially cohesive material and a plurality of laminated elements embedded therein, each said laminated element comprising at least two layers of different materials which have been bonded to one another prior to being embedded in said first material.

In accordance with another aspect of the present invention a method for production of an article of a substantially cohesive composite material comprises providing a plurality of laminated elements which each comprise two layers of different materials which are bonded to one another, then combining said laminated elements with a body of processable material whereby said laminated elements are embedded in said body of processable material, and then processing said body of processable material to render it substantially cohesive.

The substantially cohesive material may be a substantially rigid material, and said processable material may be of a type which may be processed to render it substantially rigid.

The invention provides also a processable premix, for example substantially wholly in particulate form, comprising said body of processable material and said plurality of laminated elements interspersed within said body.

The term "bonded" is used above and elsewhere in this specification to relate to any two layers which have been united in any manner which may, for example, be by chemical bonding between two materials, heat welding, use of an interposed adhesive, or an interposed layer such as a thin film which serves to form a connection between the two layers of the laminated element.

The laminated elements typically may be formed by cutting of preformed laminated material though the invention does not exclude the alternative of forming a laminated element from two pieces of different materials which are each preformed to a required size. In the latter case the two pieces optionally may be of different sizes.

The process of cutting of laminated material may comprise use of any of the techniques well-known per se, such as stamping, pulverising, slitting and shredding. The cutting process may be arranged to provide the laminated elements with straight edge portions or non-linear edges, for example edges of a zig-zag shape whereby such shape facilitates a mechanical inter-lock with the embedding material of the resultant composite article.

Other processes for preparing the laminated elements include granulating, agglomerating, pelletising and pulverising.

Suitable materials for the laminated elements include thermoplastic polymers such as polyethylene, polyethylene terephthalate, polypropylene and polycarbonate, cellulose based material such as paper, cardboard and carton board material, and metallic materials such as aluminium foil.

The present invention teaches that preferably the laminated elements comprise two different materials from two or more of the groups of (a) thermoplastic materials, (b) cellulose based materials and (c) metallic materials. However, it is to be understood that said laminated elements may be used in combination with other types of laminated elements including elements comprising two identical materials or two materials which are each from the same of the aforementioned groups but different from one another.

The present invention particularly envisages that advantageous use may be made of recycled packaging material, such as cartons, for forming the laminated elements. Thus, use may be made of cartons which have been designed to contain liquids or food products and which typically may comprise a laminate of a layer of a thermoplastics such as polyethylene and a layer of a cellulose based material such as paper. Such packaging material may be employed in the present invention even if any of the layers bear printing or have been treated with wax or other chemicals, or include for example a layer of aluminium foil.

In addition or as an alternative to providing a reinforcing effect, the use of laminated elements formed from recycled packaging material is a potentially cost effective technique for adding bulk volume to the composite article.

The present invention is considered to be particularly advantageous for the production of composite articles, and premixes, comprising a body of an embedding matrix of cement or concrete but may be applied to the production of other composites including those comprising an embedding matrix of resin or ceramic material.

Irrespective of whether the raw material employed for forming the laminated elements is unused material or material which is being recycled, it may be subjected to a treatment prior to being embedded in the body of processable matrix material in order, for example, (a) to facilitate size reduction, (b) improve performance properties in the final processed product and/or (c) facilitate retention of moisture. The treatment performed for one or more of these purposes may comprise one or more of the following:-heating for example by convection, or conduction or by radiant heaters, or cooling, either by the use of chemicals or positioning in a low temperature or refrigerated zone in order to modify properties of the material prior to further processing; exposure to microwaves or radio waves in order tochange the molecular structure of the material; densification by mechanical means, such as compression; extrusion into fibres, or pellets; chemical or heat bonding with other polymers and or fibrous materials; soaking or exposure to water and/or other chemical agents, for example to provide a source of moisture within a body of concrete as the latter solidifies, thereby reducing the tendency for the concrete to crack during the phase of drying and solidifying; fibrillation to form fibres.

One or more of the aforementioned, or other processing steps may be employed to partially de-laminate the laminated material thereby to form recesses or other interstitial spaces to contain water and/or other chemicals, and also to provide spaces into which the embedding matrix material may migrate and thereby tend to create an enhanced mechanical inter-lock.

One embodiment of the present invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings in which:-Figure 1 is a sectional view of part of a composite element manufactured in accordance with the present invention; Figure 2 is a plan view of a reinforcing element of the composite element of Figure 1; Figure 3 is a section on the line 3 -3 of Figure 2, and Figure 4 is a section on the line 4 -4 of Figure 2.

A composite 10 comprises a body 11 of concrete comprising a conventional mix of sand, aggregate and cement, and a plurality of reinforcing elements 12 some of which, I 2a, are wholly embedded in the body 10 and some of which, 12b, lie exposed at the surface 13 of the body 10.

Each reinforcing element is formed by shredding used carton material, such as, for example, tetra-pak cartons. As viewed in Figure 2, in this embodiment of the invention the shredding process is arranged to provide cut side edges of a zig-zag shape and straight end edges 16. The shredding operation is performed using rotating cutters which also deform the originally flat form of the majority of the used carton material to a corrugated section as shown in Figure 3.

Additionally, either during said shredding operation or in consequence of subsequent application of heat or other processing conditions, end 16 and edge 15 regions of the reinforcing element become de-laminated so as to create recess regions 17 (see Figure 4).

Accordingly, the resultant reinforcing element has a shape which is well adapted to provide a mechanical inter-lock and thus enhanced reinforcing effect in the resultant concrete product, and the recesses 17, in addition to contributing to that mechanical inter-lock effect, may be wetted prior to incorporation into the initial concrete mix so as to provide localised internal sources of moisture which minimise the conventional adverse effects of differential shrinkage as the concrete dries and solidifies.

A particularly significant advantage of the present invention is that it provides a most advantageous and cost-effective use for recyclable packaging material notwithstanding the fact that that packaging material comprises two or more different materials which have been laminated together and are not readily separable for independent recycling.

Other significant advantages which may be achieved by the present invention, particularly in respect of incorporating the laminated elements in cement or concrete, include the aforementioned reduction of cracking during the drying process of the concrete, reduced plastic shrinkage crack formation, reduced segregation of constituent parts of the concrete, improved impact and abrasion performance, improved flexural strength, improved tensile strength and the opportunity for providing a reduced cement content in concrete for the same level of performance.

ETPDe3

Claims

Claims.1. A composite material comprising a body of a first and substantially cohesive material and a plurality of laminated elements embedded therein, each said laminated element comprising at least two layers of different materials which have been bonded to one another prior to being embedded in said first material.
2. A composite material according to claim I wherein said substantially cohesive material is a substantially rigid material.
3. A composite material according to claim 2 wherein said substantially rigid material comprises an embedding matrix of cement or concrete.
4. A composite material according to any one of the preceding claims wherein said substantially cohesive material comprises an embedding matrix of resin or ceramic material.
5. A composite material according to any one of the preceding claims wherein each said laminated element comprises two layers which have been united by one or more of chemical bonding, heat welding, use of an interposed adhesive or use of an interposed layer which serves to form a connection between the two layers of the laminated element.
6. A composite material according to any one of the preceding claims wherein each said laminated element comprises a non-linear edge thereby to facilitate a mechanical interlock with the embedding material. * S. * * I * I. *SI
7. A composite material according to any one of the preceding claims and ***.* comprising laminated elements which comprise two pieces of different S...materials and which are of different sizes.S..... * . *SIS S...SI SS IS S.
8. A composite material according to any one of the preceding claims and comprising laminated elements which are partially de-laminated.
9. A composite material according to claim 8 wherein said partially de-laminated elements define recesses or other interstitial spaces.
10. A composite material according to any one of the preceding claims and comprising laminated elements which each comprise two different materials from two or more of the groups of (a) thermoplastic materials, (b) cellulose based materials and (c) metallic materials.
II. A composite material according to any one of the preceding claims and comprising laminated elements formed from recycled packaging material.
12. A composite material according to claim 11 wherein said laminated elements comprise a layer of a thermoplastics such as polyethylene and a layer of a cellulose based material such as paper.
13. A composite material according to claim I and substantially as herein before described.
14. A processable pre-mix comprising a body of processable material and a plurality of laminated elements interspersed within said body, said laminated elements being elements of a type as defined in any one of claims I to 12.
15. A method for production of an article of a substantially cohesive *: composite material comprising providing a plurality of laminated elements which each comprise two layers of different materials which are bonded to S...one another, then combining said laminated elements with a body of processable material whereby said laminated elements are embedded in said body of processable material, and then processing said body of processable ** material to render it substantially cohesive. ** .S SS S.
16. A method according to claim 15 wherein said body of processable material is processed to render it substantially rigid.
17. A method according to claim 15 or claim 16 wherein said laminated elements are formed by cutting of pre-formed laminated material.
18. A method according to claim 17 wherein said process of cutting of laminated material comprises one or more of stamping, pulverising, slitting and shredding.
19. A method according to claim 17 or claim 18 wherein said cutting process provides the laminated elements with non-linear edges thereby to facilitate a mechanical interlock with the embedding processable material when the processable material has been processed to form a substantially rigid material.
20. A method according to any one of claims 15 to 19 wherein said laminated elements are prepared by one or more granulating, agglomerating, pelletising and pulverising.
21. A method according to any one of claims 15 to 20 wherein the laminated element material is subjected to a treatment prior to being embedded in the body of processable material, said treatment comprising one or more of heating for example by convection, or conduction or by radiant heaters, or cooling, either by the use of chemicals or positioning in a low temperature or refrigerated zone in order to modify properties of the material prior to further processing; S* * . exposure to microwaves or radio waves in order to change the molecular structure of the material; **** ** S * * a * ** densification by mechanical means, such as compression; extrusion into fibres, or pellets; chemical or heat bonding with other polymers and or fibrous materials; soaking or exposure to water and/or other chemical agents, for example to provide a source of moisture within a body of concrete as the latter solidifies, thereby reducing the tendency for the concrete to crack during the phase of drying and solidifying; fibrillation to form fibres.
22. A method according to claim 21 wherein one or more of said treatments is employed to partially de-laminate laminated material thereby to form recesses or other interstitial spaces to retain water and/or other chemicals, and also to provide spaces into which the embedding processable material may migrate and thereby tend to create an enhanced mechanical interlock in a final product.
23. A method according to claim 15 and substantially as hereinbefore described.
24. A product comprising a composite material according to any one of claims Ito 13. * ** *S * * *** ..
25. A product comprising a substantially cohesive composite material *S.produced by a method according to any one of claims 15 to 23. * * I* *I..... * S ETCL1 ** * * S * *5