Geopolymeric foam comprising triple-layered structure for protecting a substrate

Abstract

A structure for protecting a substrate. The structure comprises an inner tie coat layer which can bond to the substrate, a geopolymer foam layer, and an outer protective layer. The geopolymer foam layer is the reaction product of a mixture comprising an aluminosilicate source, an alkali activator, reinforcing fibres, and a plurality of microparticles.

Claims

1. A structure for protecting a substrate, the structure comprising: an inner tie coat layer which can bond to the substrate, a geopolymer foam layer, and an outer protective layer; wherein the geopolymer foam layer is the reaction product of a mixture comprising an aluminosilicate source, an alkali activator, reinforcing fibres, a plurality of microparticles, and water, wherein the mixture comprises 20 to 50 weight % of the plurality of microparticles; and wherein the inner tie coat layer comprises an epoxy resin.

2. A structure according to claim 1, wherein the mixture comprises 20 to 45 weight % of the aluminosilicate source and 10 to 35 weight % of the alkali activator.

3. A structure according to claim 1, wherein the mixture comprises 0.5 to 2 weight % of the reinforcing fibres.

4. A structure according to claim 1, wherein the mixture comprises a water soluble polymer, wherein the water soluble polymer comprises any of: methyl cellulose, (poly)vinyl acetate, (poly)methyl methacrylate, (poly)vinyl alcohol, or vinyl esters.

5. A structure according to claim 1, wherein the mixture comprises a foaming agent and wherein the foaming agent comprises a sulphonate.

6. A structure according to claim 5, wherein the mixture comprises 0.05 to 1 weight % of the foaming agent.

7. A structure according to claim 1, wherein the mixture comprises a water repellent, and wherein the mixture comprises 0.01 to 10 weight % of the water repellent.

8. A structure according to claim 1, wherein the mixture comprises 2 to 15 weight % of water.

9. A structure according to claim 1, wherein the geopolymer foam layer comprises a support material.

10. A structure according to claim 9, wherein the support material comprises a plurality of spaced apart support materials.

11. A structure according to claim 9, wherein the support material comprises a mesh extending in a plane through the geopolymer foam layer.

12. A structure according to claim 11, wherein the mesh comprises any of: stainless steel mesh, natural fibre mesh, glass mesh, carbon fibre mesh, poly-para-phenylene terephthalamide mesh, basalt mesh, or plastic mesh.

13. A structure according to claim 9, wherein the support material comprises rods, and the rods comprise basalt or steel.

14. A structure according to claim 1, wherein the inner tie coat layer comprises a support material, the support material comprising a mesh or rods.

15. A structure according to claim 1, wherein the outer protective layer comprises woven cloth or non-woven cloth.

16. A method of applying a structure to a substrate, the method comprising: applying an inner tie coat layer to the substrate, wherein the inner tie coat layer comprises an epoxy resin; applying a geopolymer foam layer to the inner tie coat layer, the geopolymer foam layer being the reaction product of a mixture comprising an aluminosilicate source, an alkali activator, reinforcing fibres, a plurality of microparticles, and water, wherein the mixture comprises 20 to 50 weight % of the plurality of microparticles; and applying an outer protective layer to the geopolymer foam layer.

17. A method according to claim 16, wherein the mixture is applied to the inner tie coat layer as a wet mixture, and the mixture forms the geopolymer foam layer upon curing.

18. A structure according to claim 1, wherein the inner tie coat layer is the reaction product of a mixture comprising the epoxy resin and an amine curing agent.

19. A structure according to claim 1, wherein the inner tie coat layer comprises 60 to 90 weight % of epoxy resin.

20. A structure for protecting a substrate, the structure comprising: an inner tie coat layer which can bond to the substrate, a geopolymer foam layer, and an outer protective layer; wherein the geopolymer foam layer is the reaction product of a mixture comprising an aluminosilicate source, an alkali activator, reinforcing fibres, a plurality of microparticles; and wherein the inner tie coat layer comprises an epoxy resin.

Description

DETAILED DESCRIPTION

(1) Examples of the disclosure relate to a structure for a protecting substrate, and to a method of applying a structure to a substrate. The substrate may have a concrete or steel surface, and may be the deck of a sea vessel transporting LNG, or flooring at a storage facility or wharf.

(2) Example Structures

(3) In a first example of the disclosure, the structure comprises an inner tie coat layer which can bond to a substrate, a geopolymer foam layer, and an outer protective layer. The geopolymer foam layer is provided between the inner tie coat layer and the outer protective layer. The geopolymer foam layer is the reaction product of a mixture comprising an aluminosilicate source, an alkali activator, reinforcing fibres, and a plurality of microparticles.

(4) The inner tie coat layer increases adhesion between the geopolymer foam layer and the substrate. The outer protective layer provides a moisture barrier, improves impact and abrasion resistance, and increases the overall strength of the structure.

(5) In a second example of the disclosure, the structure is the same as the first example but with the following differences. The inner tie coat layer comprises a support material in the form of a mesh. The mesh extends in a plane through the inner tie coat layer.

(6) The geopolymer foam layer is provided on the inner tie coat layer. The support material in the form of a mesh in the inner tie coat layer increases adhesion to the geopolymer foam layer, and provides reinforcement.

(7) The geopolymer foam layer comprises two spaced apart support materials in the form of a first mesh spaced from a second mesh. Each respective mesh of the geopolymer foam layer extends in a plane through the layer. The first mesh is provided substantially at a midpoint in the geopolymer foam layer, and the second mesh is provided toward the top of the geopolymer foam layer, which in use is a side of the geopolymer foam layer farthest from the inner tie coat layer. The support materials in the form of the first mesh and the second mesh increase the mechanical strength of the geopolymer foam layer. The second mesh also provides a flat and course surface on which to apply the outer protective layer.

(8) In the second example, a tile is provided on the outer protective layer and therefore forms the visible surface of the structure. The tile provides a moisture barrier, improves impact and abrasion resistance, and can provide a required aesthetic finish.

(9) In a third example of the disclosure, the structure is the same as the second example, except that a tile is not provided. Accordingly, in the third example the outer protective layer forms the visible surface of the structure.

(10) In a fourth example of the disclosure, the structure is the same as the second example, except that the inner tie coat layer does not comprise a support material.

(11) In a fifth example of the disclosure, the structure is the same as the second example, except that the geopolymer foam layer comprises a single support material in the form of a mesh which is provided substantially at a midpoint in the geopolymer foam layer.

(12) In a sixth example of the disclosure, the structure is the same as the second example, except that the geopolymer foam layer comprises a single support material in the form of a mesh which is provided toward the top of the geopolymer foam layer, which in use is a side of the geopolymer foam layer farthest from the inner tie coat layer.

(13) The mesh could be provided at any position in the geopolymer foam layer.

(14) In a seventh example of the disclosure, the structure is the same as the second example, except that the geopolymer foam layer does not comprise a support material.

(15) Example mixtures for providing an inner tie coat layer, a geopolymer foam layer, and an outer protective layer according to the disclosure are provided in the tables below.

(16) Example Mixtures for Providing a Geopolymer Foam Layer

(17) TABLE-US-00001 Specific Specific Specific Specific example of example 1 example 2 example 3 Component component (wt %) (wt %) (wt/%) Aluminosilicate metakaolin 33.44 28.37 39.32 source Alkali activator Mixture of 24.21 20.55 28.47 potassium hydroxide & potassium silicate Reinforcing Basalt fibres 1.00 1.00  1.00 fibres Hollow Hollow ceramic 29.13 42.59 20.34 microspheres microspheres Foaming agent sulphonate 0.24 0.48 None Water repellent silicone material 4.00 0.01 None Water Tap water 7.98 7.00 11.86

(18) In some examples, such as indicated in the table above, the microparticles are microspheres, and in particular hollow ceramic microspheres, which are lightweight fillers. Microparticles, for example microspheres, such as hollow ceramic microspheres prevent cracking, reduce shrinkage, enhance passive fire resistance and improve insulation. Hollow microspheres may be cenospheres. Microparticles, such as microspheres, are low density beads, which may be hollow or solid.

(19) Reinforcing fibres, such as basalt fibres, provide structural reinforcement, increase impact resistance, increase resiliency of material and provide slump control.

(20) Foaming agents reduce viscosity, improve dispersion of components, reduce density and improve processing.

(21) Water repellents reduce water absorption.

(22) The geopolymer foam layer has a density of about 80 to 800 Kilograms per cubic meter, and may have a density of about 750 Kilograms per cubic meter. The geopolymer foam layer weighs about 300 to 1000 kilograms per cubic meter. The compressive strength of the geopolymer foam layer is about 8 megapascals.

(23) In some examples, the mixture comprises lightweight beads. The lightweight beads may comprise polymeric beads such as expanded polypropylene and/or lightweight inorganic beads such as expanded glass or expanded clay. The mixture may comprise about 2.5 weight percent of the lightweight beads. The lightweight beads may be foamed beads. The lightweight beads may be expanded materials, and may comprise voids. The resulting geopolymer foam layer formed from a mixture comprising lightweight beads has a reduced weight.

(24) In some examples, the mixture comprises a water soluble polymer such as methyl cellulose, (poly)vinyl acetate, (poly)methyl methacrylate, (poly)vinyl alcohol, vinyl esters, or mixtures thereof. The mixture may comprise about 5 weight percent of the water soluble polymer. The resulting geopolymer foam layer formed from a mixture comprising a water soluble polymer has improved tensile strength and impact resistance.

(25) Example Mixture for Providing an Inner Tie Coat Layer

(26) TABLE-US-00002 Specific Specific Specific example of example 1 example 2 Component component (wt %) (wt %) epoxy resin Bis-A epoxy resin 76.42 None Bis-F epoxy resin None 51.65 curing agent Isophoronediamine 17.92 None Ancamide 3444 None 30.99 Filler Aluminium tri-hydrate  5.66 None Metakaolin None 16.53 Coupling Gamma- None  0.83 agent chloropropyltrimethoxysilane

(27) Ancamide 3444™ is a mixture of different amines.

(28) Example Mixture for Providing an Outer Protective Layer

(29) TABLE-US-00003 Specific Specific Specific example of example 1 example 2 Component component (wt %) (wt %) epoxy resin Bis-A epoxy resin 19.16  None Aluminosilicate Metakaolin None 40.50 source curing agent isophoronediamine 6.73 None Alkali activator Mixture of None 29.34 potassium hydroxide and potassium silicate Reactive diluent Epoxy functional 6.47 None glycidyl ethers Fire retardant Triethyl phosphate 2.92 None (TEP) Water Water None 12.56 Filler aluminium 64.72  17.46 tri-hydrate Foaming agent sulphonate None  0.14 Reinforcing cloth Chopped strands 5:1 resin/glass 5:1 resin/glass mat cloth in weight cloth in weight

(30) Example Method of Applying a Structure to a Substrate

(31) Examples of the disclosure also provide a method of applying a structure to a substrate.

(32) In a first example of the disclosure, the method comprises in a first step, applying an inner tie coat layer to the substrate; in a second step, applying a geopolymer foam layer to the inner tie coat layer; and in a third step, applying an outer protective layer to the geopolymer foam layer.

(33) The components of the geopolymer foam layer, which may be, for example, the components listed in any of the examples provided in the table above, are mixed to form a mixture prior to application of the mixture to the inner tie coat layer to form the geopolymer foam layer upon curing. Accordingly, in such examples a wet mixture is applied to the inner tie coat layer. As the mixture is at least partially syntactic and foamed, the components are mixed until a required volume (and hence density) is achieved. The Reinforcing fibres are the final components added to the mixture. The mixture may be mechanically mixed.

(34) The mixture is poured onto the inner tie coat layer.

(35) Although water is added to the reaction mixture, it is thought to evaporate once the mixture has cured. The reaction mixture may comprise 5 to 10% by weight of water. Water reduces system viscosity, improves dispersion of components and improves processing.

(36) In a second example of the disclosure, the method is the same as the first example but in this case a support material in the form of a mesh is applied to the inner tie coat layer, and may be applied before the inner tie coat layer has cured such that it at least partially sinks into the uncured mixture which once cured forms the inner tie coat layer.

(37) Furthermore, two spaced apart support materials in the form of a first mesh and a second mesh are provided in the geopolymer foam layer. The first mesh may be provided substantially at a midpoint in the geopolymer foam layer. In practice, the first mesh is applied after half the mixture which forms the geopolymer foam layer upon curing has been applied. The second half of the mixture is then applied on top of the mesh, such that the mesh is located substantially at a midpoint in the geopolymer foam layer. The mixture is sufficiently viscous for the mesh to be held in position during this process. The second mesh is provided toward or at the top of the geopolymer foam layer. In practice, after all the mixture which forms the geopolymer foam layer has been applied, the second mesh is applied on top of the mixture before the mixture has cured.

(38) In some examples, a tile may optionally be applied to the outer protective layer.

(39) There is thus described a structure for protecting a substrate, and particularly a structure for protecting a substrate from extreme temperatures, with a number of advantages as detailed above, and as follows.

(40) Examples according to the present disclosure provide a structure for a substrate which can protect the substrate from the extreme temperatures associated with an LNG leak or spillage and subsequent LNG fire.

(41) Furthermore, the geopolymer foam layer is significantly lighter than, for instance, concrete. The geopolymer foam layer has a high compressive strength, and is not therefore damaged, for instance, by driving heavy equipment over the structure. The geopolymer foam layer comprises only inorganic materials which are harmless and non-combustible. The geopolymer foam layer is free of phenyls and formaldehydes which are harmful.

(42) Although embodiments of the present invention have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the invention as claimed. For example, the outer protective layer could be provided by surface treating the geopolymer foam layer to provide a nonporous moisture resistant surface. For example, the geopolymer foam layer may be preformed as a tile, and the tile applied to the inner tie coat layer.

(43) Features described in the preceding description may be used in combinations other than the combinations explicitly described.

(44) Although functions have been described with reference to certain features, those functions may be performable by other features whether described or not.

(45) Although features have been described with reference to certain embodiments, those features may also be present in other embodiments whether described or not.

(46) The term “comprise” is used in this document with an inclusive not an exclusive meaning. That is any reference to X comprising Y indicates that X may comprise only one Y or may comprise more than one Y. If it is intended to use “comprise” with an exclusive meaning then it will be made clear in the context by referring to “comprising only one . . . ” or by using “consisting”.

(47) In this brief description, reference has been made to various examples. The description of features or functions in relation to an example indicates that those features or functions are present in that example. The use of the term “example” or “for example” or “may” in the text denotes, whether explicitly stated or not, that such features or functions are present in at least the described example, whether described as an example or not, and that they can be, but are not necessarily, present in some of or all other examples. Thus “example”, “for example” or “may” refers to a particular instance in a class of examples. A property of the instance can be a property of only that instance or a property of the class or a property of a sub-class of the class that includes some but not all of the instances in the class. It is therefore implicitly disclosed that a features described with reference to one example but not with reference to another example, can where possible be used in that other example but does not necessarily have to be used in that other example.

(48) Whilst endeavoring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

(49) I/we claim: