WO2017201566A1

WO2017201566A1 - Aerated alkali activated material

Info

Publication number: WO2017201566A1
Application number: PCT/AU2017/000120
Authority: WO
Inventors: David Dirk Visser; Duc Tuan Ngo; Priyantha Mendis
Original assignee: Speedpanel Holdings Pty Ltd
Current assignee: Speedpanel Holdings Pty Ltd
Priority date: 2016-05-27
Filing date: 2017-05-29
Publication date: 2017-11-30
Anticipated expiration: 2018-11-27

Abstract

The present invention is a wet geopolymer mixture including a premade foam. The foam has the effect of aerating the mixture prior to curing. The result of the addition of the premade foam is an aerated geopolymer material that becomes a lightweight cellular geopolymer after curation has occurred.

Description

Aerated Alkali Activated Material

Field of the Invention

[0001 ] This invention relates to alkali acti vated material (geopolymer), and in particular to a lightweight cellular geopolymer and the method used to manufacture them.

Background of the Invention

[0002] There are a wide variety of building panels manufactured for use in the construction industry. Both homogeneous and composite panel types are produced.

[0003] Composite building panels may comprise a hard outer shell with a hollow interior. The interior is then filled with a suitable material to enhance strength, sound attenuation properties, and improve fire resistance. Flexure resistance is also an important consideration in the case of composite panels that are used in flooring applications.

[0004] In many geographic areas, it is also a critical consideration that the building panel is able to withstand the motion and tremor forces generated by a geological event, such as an earthquake. The primary consideration, when selecting the material from which either the homogeneous or fill for a composite panel is constructed, is whether it provides all the features required for the specific use of the panel in the particular building construction while being lightweight.

[0005] There are many kinds of material used as in- fill material on composite panels, including, but not limited to, polystyrene, polyurethane and polyisocynurate foams. The common problem associated with all these oil-derived materials is sustainability and that they are environmentally unfriendly to produce. Another major problem with them is that they are combustible, and will therefore burn when exposed to fire, and most will emit toxic fumes, which can have a serious negative effect on the health and safety of both the occupants of the building and people in the vicinity. Emergency service personnel are also put at risk when responding to an emergency involving these kinds of building panel materials. [0006] In addition to their respective chemical properties, particularly when subjected to heat and flame, there are also issues with their structural properties, effective usable lifespan and their proper disposal when a building containing these types of panels is demolished.

[0007] Conventional insulation materials are mostly used for interior applications, and are generally unsuitable for use on exterior parts of buildings due to the fact that many of these materials will degrade over time when exposed to outdoor condition e.g. UV rays. Polyurethane and polyisocynurate foams will adsorb moisture and can grow moulds, which may be toxic to people living and working in the vicinity of the mould. The mould may also be unsightly, or emit an unpleasant odour that adversely affects the enjoyment of the building by either the occupants or people living nearby.

[0008] Organic -based foams are also not recyclable or naturally degradable, and the production and application of most organic-based insulation materials releases toxic fumes, creating health and safety concerns for the workers involved, and the need for suitable personal protective equipment.

[0009] The other type of lightweight materials, used for both composite and homogeneous panels is inorganic-based, such as autoclaved aerated concrete (AAC), and lightweight cellular concrete (LCC) based on Portland cement. These materials have a cellular structure with high porosity and high strength to weight ratio. However, they also have significant sustainability problems associated with their production methods in addition to considerable C0₂ emissions associated with cement production. It is estimated that the cement production contributes around 7% of the total anthropogenic emissions of C0₂. In addition, the manufacturing process for AAC involves a high temperature and pressure process which requires substantial energy input, mainly supplied by the burning of the fossil fuels. Not only is this energy consumption environmentally unfriendly, but the cost of energy is considerable, and increasing, thereby AAC production is becoming increasingly expensive.

[0010] A general method of making AAC or LCC requires the use of aluminum powder for aeration. Aluminum dust generated in the process of making AAC creates an occupational health and safety concern for workers involved in its production. Aluminum powder is potentially explosive if exposed to certain chemicals, static electricity, high temperature and humid conditions. Furthermore, use of aluminum powder as a source of aeration in AAC or LCC is often un-controllable and results in a non-homogenous void structure within the final product which deteriorates the structural properties of the building panel.

[001 1] The new generation of inorganic lightweight materials, such as vacuum insulated panels (VIP) and silica aerogels, promise excellent mechanical and insulation properties, however they are currently very expensive to produce, and not suitable for many construction projects.

[0012] Lightweight cellular geopolymers could become a popular competitive alternative for Portland cement-based material and they can also be used as homogeneous panels, or as an in-fill material for composite panels. Geopolymer overcomes many of the limitations and problems associated with the aforementioned types of common building materials including:

• significantly less greenhouse gas emissions during their manufacture.

• less energy intensive in their fabrication due to the lower curation temperature.

• cheaper component materials and use of industrial by-product materials.

• high strength to weight ratio.

• higher heat tolerance while retaining structural integrity.

• long structural life time-span.

• excellent fire resistance properties.

• excellent acoustic attenuation properties.

• excellent thermal insulation properties.

[0013] Conventional geopolymers are highly sensitive to water content in the slurry mixture. Geopolymers also require a high pH for curing. To achieve an optimum balance between properties, such as workability (rheology), apparent density, strength, porosity and durability, for lightweight cellular geopolymer, an appropriate combination of precursors, activators, aeration method, foaming agents, water to solid (w/s) ratio and chemical admixtures is necessary.

[0014] It is a goal of the present invention to create a lightweight cellular geopolymer that ameliorates at least some of the aforementioned problems.

Disclosure of the Invention

[0015] In one form, the present invention is a wet geopolymer mixture including a premade foam. The foam has the effect of aerating the mixture prior to curing. The result of the addition of the premade foam is an aerated geopolymer material that becomes a lightweight cellular geopolymer after curation has occurred.

[0016] Preferably, the foam is water based.

[0017] Preferably, the foam is non-toxic and safe for the environment.

[0018] Preferably, the foam is manufactured from naturally derived ingredients.

[0019] Alternatively, the foam is manufactured from synthetic ingredients.

[0020] Alternatively, the foam is manufactured from a mixture of both synthetic and naturally derived ingredients.

[0021] Preferably, the foam includes either, or both, natural and/or mineral particles to thereby enhance the stability of the foam when included in the wet geopolymer mix, and during the curation process.

[0022] Preferably, the quantity of foam added to the wet geopolymer mix is between 5 and 20 wt. %.

[0023] Preferably at least one type of 0.1 to 2.0 wt. % polycarboxylic ether-based water reducer admixture is added to control the water content of the mixture, and thereby control the pH balance of the mixture while retaining workabi lity, and lower the vi scosity, and preserving the distribution of bubbles in the aerated mixture prior to, and during curation.

[0024] Preferably, the mix includes from 10 to 35 wt. % of added water.

[0025] Preferably, the material includes up to 80 wt. % of Class F or Class C fly ash, or a combination of both.

[0026] Preferably, the fully cured aerated geopolymer material has a comparatively very low thermal conductivity when compared to non-aerated geopolymer solid material.

[0027] Preferably the Class F or C fly ash, or combination of both includes up to 30 wt. % of calcium oxide.

[0028] Alternatively, the material includes up to 80 wt. % of granulated ground blast furnace slag.

[0029] In another form of the invention, the material includes a combination of Class F or Class C fly ash and granulated ground blast furnace slag, and the combined total is up to 80 wt. %.

[0030] Preferably, the material includes from 3 to 10 wt. % of alkali silicate or alkali hydroxide activators.

[0031] Preferably, the material includes from 0.1 to 2.0 wt. % of foaming agents, and it is the foaming agents that provide the aeration to the geopolymer.

[0032] Preferably the minimum pH balance is controlled to be 10 so that the aerated wet geopolymer mix sets rapidly, within a range of 12 to 24 hours at room temperature, or at a temperature no greater than 60°C, and fully cures by 28 days, thereby producing a solid aerated geopolymer material that includes small-sized and evenly distributed voids throughout the material. [0033] In yet another form, the present invention is an aerated geopolymer solid material, where the aeration is provided by a plurality of small-sized evenly distributed air filled voids throughout the material, so that the material has a comparatively high strength to weight ratio when fully cured, when compared to traditional aerated Portland cement- based concrete.

[0034] Preferably the cured geopolymer incl udes a sufficient number of voids so that the cellular lightweight geopolymer has a volume percentage of air included within the range of 20% to 80% by volume.

[0035] Preferably the structure of the plurality of voids in the fully cured geopolymer is a combination of open and closed cells.

[0036] Preferably the voids in the material give the material a comparatively very low thermal conductivity between 0.1 to 1.0 W/m°C when compared to non-aerated geopolymer solid material.

[0037] When fully cured, preferably the aerated geopolymer has a compressive strength from 1.0 to 20MPa.

[0038] Also when fully cured, preferably the geopolymer has a tensile to compressive strength ratio between 0.1 and 0.2.

[0039] Preferably the fully cured geopolymer has a flexural to compressive strength ratio between 0.1 and 0.3.

[0040] Preferably the percentage of shrinkage as the geopolymer cures is between 0.1 to 3.0%.

[0041 ] Preferably the fully cured geopolymer has an apparent density within the range from 300 to 1,600 kg/m³. [0042] Preferably the fully cured geopolymer has high fire resistant properties characterised by no spread of flames and an F rating greater than 120 minutes based on the ASTM E814/UL 1479 standard.

[0043] In yet another form, the present invention is a method of manufacturing a solid aerated geopolymer material, including the steps of: a) mixing at least one of either or combination of Class F or C fly ash or granulated ground blast furnace slag (GGBFS) with at least one solid alkali activator to form a homogeneous solid admixture wherein the wt. % of the fly ash, or GGBFS, or a combination of both, is no greater than 80, and the wt. % of solid/liquid alkali activator is in the range of 3 to 10, and b) then adding water, at least one superplasticizer and at least one type of suitable fibrous material with the solid mixture that was produced in step a) above with agitating to form homogeneous slurry, and c) mixing in at least one of either a synthetic or natural foaming agent, or a combination of both with water and then subjecting it to a source of compressed air so that a foam is created with an apparent density within the range of 50 to 120 kg/m³, and d) mixing the foam created in step c) with the slurry created in step b) to produce a homogenous aerated wet geopolymer with workable consistency and an apparent density within the range of 300 to 1 ,600 kg/m³, and e) wait a sufficient time for the dissolved alkali activator to provide silicate nucleation sites for the formation of geopolymer binder around the particles of fly ash or slag thereby increasing the viscosity of liquid between the bubbles in the aeration, and to stabilise the foam, and f) pouring the aerated wet geopolymer into a mould, or the core of a building panel, and g) maintaining either room temperature, or subjecting the wet aerated geopolymer to a temperature up to 60°C for a minimum of 24 hours.

[0044] Preferably the at least one type of suitable fibrous material is either

polypropylene, or polyethylene, or nylon, or glass, or basalt fibers.

Brief Description of the Drawings

[0045] Figure 1 is a schematic diagram showing a prior art aerated concrete material and also shows an exploded view that diagrammatically shows how an applied force upon the material is distributed.

[0046] Figure 2 is a schematic diagram showing the aerated geopolymer of th e present invention and also shows an exploded view that illustrates how an applied force is distributed within the material.

Detailed Description of the Preferred Embodiments

[0047] Developments in structural mechanics and material technologies have created a trend towards using composites based on lightweight, green and sustainable materials in the construction industry. The present invention is a lightweight cellular alkali activated concrete (geopolymer) which uses premade foam for aeration of the activated geopolymer and the resulting aerated geopolymer is an ideal material for use in the construction industry, either alone, or as the core of a composite building panel because it offers thennal and sound insulation, a high strength to weight ratio, fire resistance properties and sustainable production with lower costs and greenhouse gas emissions compared to traditional Portland cement-based lightweight cellular concrete.

[0048] The invention offers solutions to the problems associated with currently marketed building insulation materials by the invention of lightweight cellular alkali activated concrete (geopolymer). The problems and their associated solutions are listed as follows: i. Sustainability and environmental: Utilising mineral by-products (slag and fly ash) as the precursors for geopolymers results in less C0₂ emissions compared to Portland cement. The aeration process is environmentally- friendlier as it utilises non-hazardous, natural and water-based premade foam; ii. Economic and cost-effectiveness: better energy efficiency at room temperature (or up to 60°C) compared to autoclaved aerated concrete (up to 200°C) will reduce costs. Also, slag and fly ash as by-products are cheaper than Portland cement; iii. Combustibility and flammability: Fire-resistant compared to combustible insulation materials and also tolerates higher temperatures whilst retaining its strength compared to Portland cement-based lightweight concrete; iv. Structural properties and space limitation: High strength, durability, sound and thermal insulation can be achieved based on the type and dosage of activators and precursors for various applications such as precast or cast-in-situ masonry wall elements, slabs, blocks and facades, insulation screeds, oil-well cementing or as the core for sandwich panels; v. Process-ability: Controllable and safe premade foam for aeration compared to hazardous chemical blowing agents such as aluminium powder for AAC; vi. Toxicity, health and safety issues: Alkali activators are corrosive materials. Slag and fly ash are not hazardous materials but protection against its dust is necessary.

Although certain safety measures must be taken into account, it is very limited compared to toxic fumes out of organic-based insulation materials or safety issues associated with the usage of aluminium powder; vii. Durability: A combination of the activators can be used based on the type of precursors and foam to achieve mechanical and durability properties comparable to AAC and Portland cement-based cellular concrete. Durability and strength is certainly higher than organic insulation materials; viii. Recyclability: Lightweight geopolymer is a recyclable product (it can be crushed and used as recycled lightweight aggregates) with no end-of-life issues and environmental hazards; ix. Moisture sensitivity: Alkali-activated lightweight concrete will not mechanically deteriorate in humid conditions nor allow mould growth common in some organic-based insulation materials. x. Material Consumption, handling, and transportation: Products using the aerated geopolymer consume considerably less geopolymer. The cost of the consumed geopolymer material is lower. Less geopolymer raw material needs to be kept in storage at the manufacturing facility, and the resulting products are comparatively lighter and easier to handle, store, and transport.

[0049] Geopolymer materials offers much lower embodied greenhouse gas emissions than common Portland cement (up to 64% lower), as well as lower cost and also lower thermal conductivity (excellent thermal insulation).

[0050] By aerating the geopolymer, a lightweight cellular geopolymer having comparable properties is resulted. This product has high strength-to-weight ratio, as well as fire-resistant, thermal and sound insulation properties, in addition to lower greenhouse gas emissions, lower costs and a sustainable product that utilises by-products such as slag and fly ash. The present invention also helps to minimise the consumption of natural resources for heating and cooling in buildings, which results in less carbon dioxide emissions and more sustainable infrastructure due to superior thermal insulation properties. It also offers in-situ application with flexibility of being poured or sprayed on various substrates or into cavities and tight spaces. Superior fire-resistant properties to any currently-marketed insulation materials, and excellent sound and thermal insulation properties with a controllable air void structure based on premade foam are other advantages. Alkali- activated lightweight concrete (geopolymer) is also a durable product with minimum water/humidity sensitivity and cracking; 100% green and recyclable with no end-of-life environmental hazards.

[0051] This present invention introduces a novel lightweight cellular alkali activated concrete (geopolymer) comprising: Class F or C fly ash or combination of those (40 wt.% or less calcium oxide), granulated ground blast furnace slag (GGBFS), one or a

combination of alkali activators i.e. sodium/potassium hydroxide, sodium/potassium carbonate, sodium/potassium sulphate and/or sodium/potassium silicate, one or more synthetic/natural foaming agents (or surfactant), one or more types of polycarboxylic ether- based water reducer (superplasticizer) admixtures, one or more polymeric (polypropylene, polyethylene and/or nylon), glass and/or basalt fibres, and tap water.

[0052] An example of the composition of the lightweight alkali activated concrete (geopolymer) is shown in Table 1. The molar ratios of key chemical ingredients used for the formation of alkali activated binder (geopolymer) in this invention are 0.1<Ca/Si<1.3, 1.5<Si/Al<2 and 0.15<M/Si<0.25 (M: Na and/or ).

[0053] Table 1. An example of the composition of the lightweight alkali activated concrete (geopolymer)

Materials wt. %

Class F fly ash 0-80

GGBFS 0-80

alkali activators 3-10

foaming agents 0.1 -1.0

superplasticizers 0.1-1.0

fibres 0.1-2.0

tap water 10-35

[0054] The present invention provides a method comprising the following steps: (a) mixing of solid materials i.e. Class F or C fly ash or combination of those, GGBFS and one or more solid alkali activators to form a homogenous solid mixture; (b) mixing tap water, one or more superplasticizers, one or more liquid alkali activators and one or more polymer fibres (polypropylene, polyethylene, polyvinyl alcohol and/or nylon), glass and/or basalt fibres with the solid mixture with enough agitation to form a homogenous and fluid-like slurry; (c) mixing one or more synthetic/natural foaming agents with tap water; (d) with compressed air and a pump, premade foam with an apparent density between 50 to 120 kg/m³ is generated out of the mixture of water and one or more foaming agents; (e) mixing the premade foam with the geopolymer slurry to get a homogenous aerated geopolymer with workable consistency and an apparent density between 300 to 1600 kg/m³ based on the application; (f) pouring the geopolymer foam mixture into the moulds or premade panels; and (g) maintaining lightweight alkali activated concrete (geopolymer) at either room temperature or up to 60°C for at least 24 hours to allow the lightweight geopolymer to set and cure.

[0055] The lightweight geopolymer has between 20% to 80% volume percentage of air content (porosity) and a compressive strength of 1 to 20MPa, tensile to compressive strength ratio between 0.1 to 0.2, flexural to compressive strength ratio between 0.1 to 0.3, thermal conductivity between 0.1 to 1.0 W/m°C and drying shrinkage between 0.1 to 3.0% based on the formulation and the target apparent density of the aerated geopolymer i.e. between 300 to 1600 kg/m³. It also has excellent fire resistant properties characterised by no spread of flames and an F rating greater than 120 min (based on ASTM E814/UL 1479 standard). The structure of the voids is a combination of open and closed cells.

[0056] Turning to Figure 1 , we are shown an illustration of "prior art" aerated concrete material 1 utilizing Portland cement. The material 1 is aerated, so there is a plurality of bubbles 3. To give some perspective on the scale of the illustration, both dimensions x and y are approximately 1 mm each in length, and in the exploded view, both x and y^' are each respectively 0.01 mm in length. As shown in the exploded view, the concrete portion of the aerated concrete is a matrix of Portland cement parti cles mixed and attached with large hydration products 9 and small hydration products 11 . It can be seen in the illustration that at least some of the Portland cement particles 7 cross the boundary of at least some of the bubbles 3. In other instances, the comparatively large particles 7 occupy the entire region between adjacent bubbles 3. This has a number of undesirable affects. Firstly, it may compromise the integrity and stability of the aerated mix during any, or all of, the mixing, pouring, and curing phases, of the manufacturing process, by causing the bubbles to collapse. Secondly, if the bubble 3 remains after the curing phase has completed, the close proximity of the particle 7, or especially if the particle breaches the boundary of the bubble 3, then it may have a significant adverse effect on the way an applied load is transferred within the material matrix as illustrated by the force direction arrows 21 and 2 . Arrow 21 shows the applied force, and arrows 2 illustrate how that force is distributed within the material. The particle 7 may act as a crack initiator at the bubble 3 boundary, thereby locally weakening the matrix of material, and may also lead to catastrophic failure of the aerated cement.

[0057] In Figure 2 we are shown an illustration of the present invention. In this illustration, an aerated geopolymer material 13 is utilised that includes a plurality of bubbles 3 within the geopolymer material matrix 15. Once again, each of the x and y lengths are approximately 1 mm. In the exploded view, each of the x^' and y^" lengths are approximately 0.01 mm. Once again, arrow 21 represents the applied force, and arrows 2 illustrate how the force is distributed within the material matrix. The geopolymer material includes ultra-fine particles of fly ash 17 and particles of geopolymer 19. None of these particles are large enough to have an adverse effect on the neighbouring bubbles 3. Also, the load is distributed more evenly within the matrix 15, and is constrained more effectively to remain within the geopolymer material. The result of this preferred behaviour is greater integrity and stability of the aerated mix during any, or all of, the mixing, pouring, and curing phases, resulting in a significantly improved aerated material.

[0058] While the above description includes the preferred embodiments of the invention, it is to be understood that many variations, alterations, modifications and/or additions may be introduced into the constructions and arrangements of parts previously described without departing from the essential features or the spirit or ambit of the invention.

[0059] It will be also understood that where the word "comprise", and variations such as "comprises" and "comprising", are used in this specification, unless the context requires otherwise such use is intended to imply the inclusion of a stated feature or features but is not to be taken as excluding the presence of other feature or features. [0060] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any fonn of suggestion that such prior art forms part of the common general knowledge.

Claims

1. A wet geopolymer mix including a premade foam wherein said foam has the effect of aerating the mix prior to the curing of said mix, wherein the result of the addition of the premade foam is an aerated geopolymer material that becomes an aerated solid geopolymer material after curation has occurred.

2. The geopolymer mix as defined in claim 1 wherein the foam is water based.

3. The geopolymer mix as defined in claim 1 wherein the foam is non-toxic and safe for the environment.

4. The geopolymer mix as defined in claim 1 wherein the foam is manufactured from naturally derived ingredients.

5. The geopolymer mix as defined in claim 1 wherein the foam is manufactured from synthetic ingredients.

6. The geopolymer mix as defined in claim 1 wherein the foam is manufactured from a mixture of both synthetic and naturally derived ingredients.

7. The geopolymer mix as defined in any one of claims 4 to 6, wherein the foam includes either, or both, natural and/or mineral particles to thereby enhance the stability of the foam when included in the wet geopolymer mix, and during the curation process.

8. The geopolymer mix as defined in claim 1 wherein the quantity of foam added to the wet geopolymer mix is between 5 and 20 wt. %.

9. The geopolymer mix as defined in claim 1 wherein at least one type of polycarboxylic ether-based water reducer admixture is added to the mix in the range of 0.1 to 2 wt.%, to control the water content of the mixture, and thereby control the pH balance of the mixture, while retaining workability, and lowering the viscosity, and preserving the distribution of bubbles in the aerated mixture prior to, and during, curation.

10. The geopolymer mix as defined in claim 1 wherein the mix includes from 10.0 to 35.0 wt. % of added water.

1 1. The geopolymer mix as defined in claim 1 wherein the material includes up to 80 wt. % of Class F or Class C fly ash , or a combination of both.

12. The geopolymer mix as defined in claim 1 wherein the fully cured aerated geopolymer material has a comparatively very low thermal conductivity within the range of 0.1 to 1.0 W/m°C, when compared to non-aerated geopolymer solid material.

13. The geopolymer mix as claimed in claim 1 1 wherein either the Class F, or Class C, fly ash, or a combination of both, includes up to 30 wt. % of calcium oxide.

14. The geopolymer mix as claimed in claim 11 wherein the material includes up to 80 wt. % of granulated ground blast furnace slag.

15. The geopolymer mix as claimed in claim 1 1 wherein the material includes a combination of Class F or Class C fly ash and granulated ground blast furnace slag, and the combined total is up to 80 wt. %.

16. The geopolymer mix as defined in claim 1 1 wherein the material includes from 3.0 to 10.0 wt. % of alkali silicate or alkali hydroxide activators.

17. The geopolymer mix as claimed in claim 1 1 wherein the material includes from 0.1 to 2.0 wt. % of foaming agents, and wherein it is the foaming agents that provide the aeration to the geopolymer.

18. The geopolymer mix as claimed in claim 1 1 wherein the material includes from 0.1 to 2.0 wt. % of superplasticizers.

19. The geopolymer mix as defined in claim 9 wherein the pH balance is controlled to within the minimum of above 10 so that the aerated wet geopolymer mix sets rapidly, within a range of 12 to 24 hours at room temperature, or at a temperature no greater than 60°C, and fully cures by 28 days, thereby producing a solid aerated geopolymer material that includes small-sized and evenly distributed voids throughout the material.

20. An aerated geopolymer solid material wherein the aeration is provided by a plurality of small-sized evenly distributed air filled voids throughout the material, so that the material has a comparatively high strength to weight ratio when fully cured, when compared to fully cured non-aerated geopolymer material .

21. The aerated geopolymer solid material as defined in claim 20 wherein the cured geopolymer includes a sufficient number of voids so that the solid geopolymer has a volume percentage of air included within it within the range of 20% to 80% by volume.

22. The aerated geopolymer solid material as defined in claim 20 wherein the structure of the plurality of voids in the fully cured geopolymer is a combination of open and closed cells.

23. The aerated geopolymer solid material as defined in claim 20 wherein the voids in the material give the material a comparatively very low thennal conductivity between 0.1 and 1.0 W/m°C when compared to non-aerated geopolymer solid material.

24. The aerated geopolymer solid material as claimed in claim 20 wherein the geopolymer has a compressive strength from 1.0 to 20MPa.

25. The aerated geopolymer solid material as claimed in claim 20 wherein the geopolymer has a tensile to compressive strength ratio between 0.1 and 0.2.

26. The aerated geopolymer solid material as claimed in claim 20 wherein the geopolymer has a flexural to compressive strength ratio between 0.1 and 0.3.

27. The aerated geopolymer solid material as claimed in claim 20 wherein the percentage of shrinkage as the geopolymer cures is between 0.1 to 3.0%.

28. The aerated geopolymer solid material as claimed in claim 20 wherein the geopolymer has an apparent density within the range from 300 to 1,600 kg/m³.

29. The aerated geopolymer solid material as claimed in claim 20 wherein the geopolymer has high fire resistant properties characterised by no spread of flames and an F rating greater than 120 minutes based on the ASTM E814/UL 1479 standard.

30. A method of manufacturing a solid aerated geopolymer material as previously defined, including the steps of: a) mixing at least one of either or combination of Class F or C fly ash or granulated ground blast furnace slag (GGBFS) with at least one solid alkali activator to form a homogeneous solid admixture wherein the wt. % of the fly ash, or GGBFS, or a combination of both, is no greater than 80, and the wt. % of solid/liquid alkali acti vator is in the range of 3 to 10, and b) then adding water, at least one superplasticizer and at least one type of suitable fibrous material with the solid mixture that was produced in step a) above with agitating to form homogeneous slurry, and c) mixing in at least one of either a synthetic or natural foaming agent, or a combination of both with water and then subjecting it to a source of compressed air so that a foam is created with an apparent density within the range of 50 to 120 kg/m³, and d) mixing the foam created in step c) with the slurry created in step b) to produce a homogenous aerated wet geopolymer with workable consistency and an apparent density within the ranee of 300 to 1 ,600 kg/m³, and e) wait a sufficient time for the dissolved alkali activator to provide silicate nucleation sites for the formation of geopolymer binder around the particles of fly ash or slag thereby increasing the viscosity of liquid between the bubbles in the aeration, and to stabilise the foam, and f) pouring the aerated wet geopolymer into a mould, or the core of a building panel, and g) maintaining either room temperature, or subjecting the wet geopolymer to a temperature up to 60°C for a minimum of 24 hours.

31. The method defined in claim 38 wherein the at least polymer fibres is either polypropylene, or polyethelene, or polyvinyl alcohol, or nylon.

32. The method as defined in claim 38 wherein the at least one type of suitable fibrous material is either glass or basalt fibres.