NZ578307A - Lightweight geopolymer and method for preparing - Google Patents

Abstract

Disclosed is a method for producing a lightweight inorganic polymer material that includes the following steps in order: A. prepare activator solution; B. add activator solution to a metakaolin and mix; C. add a finely divided form of aluminium and a calcium additive then mix; where the activator solution is made by combining a group 1 metal soluble silicate solution with a group 1 metal hydroxide until the hydroxide concentration is between 3.5 and 10.5 molar, such that the mixing of the activator solution and metakaolin forms an Inorganic Polymer Matrix (IPM) paste, such that the calcium additive is at least food grade with a low magnesium (less than about 2%) content.

Description

COMPLETE SPECIFICATION New Zealand Patent Application No. 578307 Filed: 9 July 2009 TITLE: LIGHTWEIGHT GEOPOLYMER AND METHOD FOR PREPARING Technical Field The present invention is a lightweight foamed inorganic material and method for producing it, in particular a foamed silicon based polymer sometimes called a 10 geopolymer.

Background Art Concrete and similar construction materials are heavy and, being solid, not particularly 15 good insulators (thermal conductivity around 1.3 W/m.K). This has led to the development of foamed or aerated concrete materials which are strong, lightweight and have better insulation properties than standard concrete (thermal conductivity between 0.1 and 0.4 W/m.K). Some of these materials can be cast in place, but many are produced off-site.

One method of producing foamed/aerated concrete onsite uses a foam concentrate (protein or synthetically based) to form a stable foam which is then mixed with sand, cement and water. This material is most often produced by a machine and the resulting material pumped into moulds or boxing. The foam concentrate must keep 25 the uncured material foamed until it cures sufficiently to maintain the cell structure. The equipment and foam concentrate add to the cost of producing foamed/aerated concrete this way, but it can be used to form large areas without joins needing to be made. The foam concentrate may leach out of the foamed/aerated concrete over time and this can be undesirable in some ecologically sensitive areas.

A common method of producing foamed/aerated concrete off site uses cement, sand and a pozzolan (often flyash) with a foaming agent. The foaming agent reacts with one or more of the ingredients to form a gas which causes the fluid material to foam, this gas is trapped as the material cures. To increase the strength and chemical 35 resistance the 'green' material is autoclaved in an atmosphere of steam to form the 1 final product. Even after autoclaving the chemical resistance is limited to that of concrete.

Concrete is not particularly resistant to chemical attack and over time dilute 5 acids/bases (such as acid rain) and atmospheric gases can break it down. Aerated/foam concrete has a very much greater surface area than standard concrete and as such it can experience accelerated degradation.

Concrete undergoes recarbonation, the conversion of lime to calcium carbonate, which 10 causes the concrete to effloresce. Aerated/foam concrete, with its increased surface area to adsorb carbon dioxide would be expected to recarbonate much faster than a solid structure. There is therefore the potential for aerated/foam concretes to weaken in a much shorter period of time, perhaps as short as 10 years compared to the projected 50 years or more for a solid concrete structure.

To overcome the limitations of foam concrete some workers in the field have proposed using alternative materials.

For example US 3396112 suggests using a dry mixture of an alkali metal silicate with 20 aluminium which is then contacted with water. The aluminium reacts to form hydrogen which aerates the alkali metal silicate forming a foam as it cures. The raw materials are expensive and later workers teach away from adding aluminium to commercial grades of alkali metal silicate due to the free silica content which appears to prevent the aluminium reacting. To overcome the free silica problem US3700470 suggests 25 contacting the aluminium powder with an aqueous base solution and allowing this to react before carefully folding it into an aqueous alkali metal silicate. The reaction time before mixing the reacting aluminium with the alkali metal silicate is actually very short, between 0 and 5 seconds, so this mixing must be done as the alkali is added to the alkali metal silicate. The alkali sources mentioned are an alkali metal oxide, an alkali 30 metal hydroxide and an alkali metal aluminate. Most of the examples provided are cured at 200°C which is impractical for larger components or onsite construction. The short time between reacting the aluminium with the alkali and adding it to the silicate, combined with a careful folding step makes this process difficult to use onsite. 2 US4963515 suggests the use of sodium aluminate combined with sodium silicate and aluminium combined to form a hydrogel binder for holding aggregates together. This hydrogel aggregate produces a lightweight building material. This is a CIP from 4814300 which sinters the foam material produced at 1800°F to 2600°F to finalise the foam ceramic. If the product is to be sintered then the soluble sodium salts need to be leached out to prevent them forming a low temperature glass. If not removed from finished panels it is likely these soluble sodium salts would leach out in use affecting the aesthetics. W089/05285 uses a similar process, i.e. a sodium aluminate based composition, and specifically requires sintering to prevent the soluble salts from migrating out It is an object of the present invention to provide a lightweight material that overcomes one or more of the deficiencies outlined above, or at least provide the consumer with a useful choice.

Disclosure of Invention The present invention provides a method for producing a lightweight inorganic polymer material that includes the following steps in order: A. prepare activator solution; B. add activator solution to a metakaolin and mix; C. add aluminium and a calcium additive then mix; where the activator solution is made by combining a group 1 metal soluble silicate solution with a group 1 metal hydroxide until the hydroxide concentration is between 3.5 and 10.5 molar, such that the mixing of the activator solution and metakaolin forms an Inorganic Polymer Matrix (IPM) paste.

In a highly preferred form the calcium additive is Calcium Hydroxide or calcium oxide. Preferably said Calcium additive is at least food grade with minimal Magnesium. In a still more preferred form the Calcium additive is added at a rate of between 2% and 12%, by weight, of the IPM paste. In a highly preferred form between 2% and 5% of the calcium additive is added.

In a highly preferred form the group 1 metal in the soluble silicate and the hydroxide are independently selected from the list consisting of Li, Na and K. Preferably the silicate activator solution includes more than one Group 1 metal. In a still more preferred form the group 1 metal hydroxide is potassium hydroxide. In a preferred 5 form the Si02:M20 ratio (where M is a Group 1 metal) in the soluble silicate is between 2 and 3.5 Preferably the aluminium is in a finely divided form. In a highly preferred form the aluminium is powdered aluminium.

Preferably in step C a humectant is added. In a highly preferred form the humectant is one or more finely dispersed long chain fatty alcohols. Preferably said humectant is one or more species selected from cetyl alcohol, pentaerithritol, lauryl alcohol, 1,2 pentanediol, ethylene glycol, diethylene and dipropylene glycols, 2,2,dimethyl propane diol, 2, butylamino ethanol, amino methyl propanol and a blend of long chain (C12 to 15 C14) fatty alcohols as a fine dispersion.

Preferably in step C one or more aggregate is added. In a preferred form the particle size for the aggregate is between 30 micron and 1000 micron. In a highly preferred form the aggregate includes one or more silica sands or silica flours.

Preferably the uncured lightweight inorganic polymer material from step C is injected or transferred into moulds to cure. Preferably this transfer or injection occurs shortly after the mixing in step C is completed.

The present invention also includes a lightweight inorganic polymer foam material made by the method described above.

Brief Description of Drawings By way of example only, a preferred embodiment of the present invention is described 30 in detail below with reference to the accompanying drawings, in which: Figure 1 is a flowchart showing the method of making the lightweight geopolymer; Figure 2 is photograph showing a cross section of a lightweight geopolymer made by the method described; 4 Best Mode for Carrying Out the Invention The present invention relates broadly to a composition and method of creating a foam geopolymer material without the use of an autoclave. The foam geopolymer is useful for preparing a lightweight building material that can be formed into sheets, panels, blocks and preformed shapes as well as use on site. The selection of raw materials and size ranges used has been found to be critical to the success of this composition.

The preferred method of making the composition is shown in Figure 1 where the following steps, in order are undertaken: A. prepare activator solution; B. add activator solution to a metakaolin and mix; C. add aluminium and a calcium additive then mix; The resulting composition is then transferred or injected into moulds or otherwise used to prepare the form of lightweight material required.

So basically the composition is prepared using a highly alkaline soluble silicate activator solution and a dehydroxylated clay (Metakaolin) to form the inorganic polymer matrix (IPM) solution. This IPM is then mixed with aluminium powder, a calcium additive (normally calcium hydroxide) and a humectant to form a lightweight IPM. At this point any aggregates can also be added but if a pure lightweight IPM is required then no other additions need be made, in fact with some recipes it may not be necessary to add a humectant. Mixing is carried out in a paste mixer but any other low shear high viscosity mixer should also work, the aim is to minimise heat generation In step A a highly alkaline soluble silicate activator is made and allowed to cool before it is added to the metakaolin in step B. The highly alkaline soluble silicate used is a mixed Group I (Li, Na, K, Cs) silicate solution, though a single Group I solution may also work. It has been found that an alkali concentration of between 3.5 M and 8M is needed (though most of the examples provided are around 5 M). Though an alkali concentration of up to 10.5 M may be used in some cases. The highly alkaline soluble silicate activator preferred is created by combining a standard commercially available sodium silicate solution, with a Si02:Na20 ratio of 3.22 (Sodium Silicate N), with potassium hydroxide until the potassium hydroxide concentration is between 3.5 and 8 molar. Much below 3.5M the activator solution does not appear to extract sufficient aluminium from the metakaolin. Concentrations above 8M appears to affect the calcium and it does not appear to contribute to the calcium silicate formed, in addition above 8M the added calcium has less or no affect on the setting time. This activator 5 solution is allowed to cool, and can be stored for later use. Though Sodium Silicate N is used in this specific example any soluble group 1 metal silicate with a Si02:M20 ratio (where M is a Group 1 metal) between 2 and 3.5 could be used.

In step B the activator solution, cooled, is added to commercial grade metakaolin and 10 mixed. Water may be added in this step to improve viscosity or other IPM rheological properties. It has been found that the source of, and the processing used to create the dehydroxylated clay, or metakaolin, has an effect on the composition. To separate the metakaolin raw material so that the optimum method could be determined we found it necessary to broadly classify the commercially available metakaolins by processing 15 and purity. We came up with the following divisions: Type 1: Water washed, high purity, with a high level of dehydroxylation (typically around 90% dehydroxylation, and a minimum of 80%), with a high whiteness, less than about 0.5% CaO and less than 3% silica. These metakaolins are typically made 20 of high purity clays with substantial (>40%) fines concentration below 1 micron. Mean particle size of around 2 micron, and a range of between 200nm and 10 micron. Because of the high fines concentration they form highly dialatant pastes which tend to stick to trowels and other finishing equipment.

Type 2: Dry processed, medium purity, with a high level of dehydroxylation, (minimum of 80%, but typically around 90%) and less than about 0.5% CaO. The particle size is close to the type 1 metakaolins, i.e. a mean particle size of around 2 micron, and a range of between 200nm and 10 micron. Type 2 is thought to contain less material below 1 micron than the Type 1.

Type 3: Dry processed, lower quality and a moderate level of dehydroxylation. The level of dehydroxylation is less than about 75%, and is thought to be in the range of around 40% to 65%. CaO is present at a minimum level of about 3%, and it is believed that without this CaO the level of dehydroxylation would make the metakaolin 35 unreactive (though this is not confirmed). The particle size range for type 3 is between 1 micron and 20 micron with a mean of about 3.5 micron. Some iron oxides may be present in the pale terracotta and brown forms. At this time we are only aware of one commercial source of Type 3 Metakaolin.

There is a physical and chemical difference between the Type 3 metakaolins and the 5 others. For most of the examples given here we use Type 1 and/or Type 2 metakaolins.

In step C powdered aluminium and the calcium additive are added to the IPM formed in step B and mixed. The aluminium acts as the foaming agent forming hydrogen gas 10 which 'aerates' the IPM creating a foam IPM. The calcium additive has been found to reduce the setting time, without it the setting time can be 4 hours or more, with a calcium additive the setting time can be below 1 hour. The calcium additive preferred is a food grade of calcium hydroxide, at a concentration of around 3.5%. The food grade of calcium hydroxide used has a relatively high purity and this is necessary as it 15 has been found that impurities such as magnesium detrimentally affect the stability of the final product. Unfortunately common grades of hydrated lime often contain these impurities which cause the resultant material to spall badly, this was surprising as some workers in the field have used raw materials with magnesium present (though they were using alumininates not metakaolins.

At step C it is normal to add a humectant as geopolymers are 3 dimensional inorganic polymers. They have a high volume change on cross linking and, being inorganic, cannot relieve internal stress through elastic behaviour in the manner of an organic polymer. The result is a tendency to crack on curing which can affect the strength and 25 stability of the geopolymer foam structure. We have found that the addition of humectants to the geopolymer paste appears to retain water sufficiently to allow the geopolymer to gain sufficient strength to resist the cracking and stabilise the foam produced. We have found cetyl alcohol is effective, but the forms we have tried thus far have been difficult to disperse effectively. Potential humectants include 30 pentaerithritol, cetyl alcohol (also lauryl alcohol), 1,2 pentanediol, ethylene glycol, diethylene and dipropylene glycols, 2,2,dimethyl propane diol, 2, butylamino ethanol and amino methyl propanol. Two proprietary materials that perform well are based on long chain, C12 and C14 fatty alcohols of the same type as lauryl and cetyl alcohols. A preferred humectant is made by Cognis and sold under the trade mark Loxanol 35 DPN, it appears to be a fine particle dispersion of long chain fatty alcohols. 7 To use the foam composition without any further additives is possible, and for certain applications it may be preferred, however in many cases aggregate material is likely to be added in step C. These aggregates may simply be fillers or reactive additives that improve the desirable characteristics of the resultant composition.

Once the composition in step C is properly mixed it should be poured, injected or otherwise transferred to moulds or used without delay.

Referring to Figure 2 a photograph showing a cross section of a lightweight geopolymer produced by this method is shown. Note the even size range and distribution of the cells.

We have found the following aggregates particularly suitable for producing lightweight geopolymeric materials: Silica Sand Relatively high purity silica sand with a narrow size distribution of, roughly, 200 micron to 250 micron. The product used in the examples is J61 Fine Silica Sand but any similar narrow range silica sand could be used. 18 to 36 mesh Silica sand, this sand has a size range of about 420 micron to 800 micron.

Silica Flour Usually 325 to 450 mesh crushed silica sand with an average particle size of about 50 micron It should be noted that the silica sand is thought to react with the other ingredients and become part of the material, at least on the surface. 8 The Chemical Ratios and their significance and inter-relationship.

The factors affecting the chemical setting and the final properties are: 1. The silicon to aluminium molar Ratio; 2. The alkali cation to aluminium molar ratio; 3. The alkali concentration in moles per litre; 4. calcium content.

The Silicon to Aluminium Ratio The molar content of silicon is calculated from the silicon content of the added soluble silicate plus the quantity of silicon present in the kaolin clay, assuming that the kaolin is a typical 1:1 layer aluminosilicate and allowing for the content of impurities, particularly free silica (which is not reactive in this system). The aluminium is 15 calculated in a similar manner to the silicon in the kaolin aluminosilicates. Natural kaolin has the generalised formula AI2O3.2SiO2.2H2O. metakaolin is similar but without the water molecules e.g. AI203.2Si02 The ratio of silicon to aluminium may vary anywhere from 1.2 to 2.0 but for many of the 20 examples given the optimum strength was found to be at a ratio of around 1.68. The examples below use a type 1 or type 2 metakaolin at close to the ideal ratios.

The ideal ratio for a type 3 metakaolin would generally be at about 1.45 using the optimum compressive strength as a criterion.

The Alkali Cation Ratio The molar ratio of sodium plus potassium to Aluminium is calculated assuming that the aluminium is fully reacted and present in a tetrahedral environment that forces it to carry one anionic charge (positive charge) for each aluminium atom in the geopolymer 30 matrix. The aluminium is calculated as above from the assumed 1:1 layer structure of the kaolin, allowing for impurities. The alkali cation is the aggregate of the sodium and potassium from the sodium silicate plus the added alkali which in this case is almost always potassium hydroxide. Some international workers make a great fuss about the accuracy required for this ratio but it is dependant on the actual quantity of aluminium 35 extracted from the metakaolin, a value that is anywhere between 10% and 30% less 9 than the theoretical. We have obtained good values for compressive strength at anywhere between 0.8 and 1.2 moles of Na+KIAI.

In this work we prefer a 1:1 ratio but noting that there is a dependence on the molar 5 concentration as described below.

Alkali Concentration The concentration of the alkali metal hydroxide, potassium hydroxide (in general), is important but can vary over quite a wide range. It has been found that a hydroxiyl 10 level much below 3.5M the activator solution does not appear to extract sufficient aluminium from the metakaolin. Hydroxyl concentrations above 8M appears to affect the calcium activity and the added calcium has less or no affect on the setting time. Some workers report that compressive strength falls off with a hydroxyl concentration of greater than 8. We have not observed this but we aim to keep within the range of 15 5.0 to 7.0 molar in hydroxyl, [OH"].

The contributing factor is the quantity of added water that is required to produce a workable paste. The more aggregate that is added the more water is required to make a workable paste and the lower the alkali concentration as a consequence. In many of 20 these examples, the hydroxyl concentration is kept close to 5.5.

Calcium Content The addition of about 3M> % of calcium as calcium hydroxide in the geopolymer paste accelerates the setting. It is thought this occurs by the formation of calcium silicate 25 and aluminosilicate structures that allow the geopolymer to nucleate through the formation of drierkette structures or similar. As mentioned above, these calcium silicates appear to form at alkali concentration below about 7.5 molar.

Above about 5% the accelerating effect reduces but compressive strength starts to be 30 significantly compromised so at present this appears to limit calcium concentrations above this. The calcium should be added as either the hydroxide or the oxide at a level that gives a setting time of about 1 to 114 hours. Calcium hydroxide is preferred on account of the price and availability as a food grade source. Calcium in the form of lime, either burnt or hydrated, is not recommended as the magnesium present appears 35 to cause the matrix to expand and spall.

Examples: Strength testing Compressive strength measurements were made according to ASTM C30M-01 based 5 on a test cylinder with a diameter of 40mm and a length of 80mm. The test specimens were cast in sets of 3 in a PVC tube to ensure even content of foam in all three samples. Samples were post cured at about 30°C and then cut into three equal cylinders. The ends were machined to ensure the ends of the cylinders were parallel. A layer of specialised casting cement was used to ensure that the machined end was 10 sufficiently flat and parallel.

The test specimens were all made using a range of fillers and filler contents. In many of these examples we have used silica sand as the principle aggregate.

The laboratory tests using fine aggregates were done using a 100 kilonewton Instrom crosshead testing machine.

For all of the examples given the following manufacturing procedure was followed: Manufacturing of Examples The activator solution is prepared by dissolving the potassium or sodium hydroxide in the sodium silicate solution first and then allowing it to cool. In full production, an intermediate would be manufactured by this route and then allowed to cool to ambient temperature before storage in a closed container (to avoid carbonate formation).

The activator solution is then weighed into a mixing vessel, and the metakaolin added with stirring. The stirrer is then left running until the mixture is lump free and homogeneous. A paste mixer is preferable because it handles very heavy viscous and highly filled pastes without excessive heating. A concrete mixer does not properly mix 30 this material without balling up and a rotational mixing blade tends to heat the mixture accelerating setting in the mixer before it can be used. Though if a rotational mixer is used it is preferable to make relatively small amounts of about 10 to 15kg to avoid over heating.

After mixing the metakaolins, to create the IPM, the rest of the additives and aggregates are added in the order shown. The mixture will start to foam and so once 11 the ingredients are properly mixed the composition should be poured or injected into the mould without delay.

Example 1 Geopolymer Matrix Low density Material kg manufacturing A Sodium Silicate 397.00 Add item B to item A with stirring. When dissolves, cover and allow to cool to cool B Potassium Hydroxide 93.00 C Water 52.00 Add items C and D in order with stirring. Stir until lump free.

D Type 1 Metakaolin 350.00 E Aluminium powder 0.86 Add items E to H in order shown and mix well. Immediately transfer to required mould.

F Calcium Hydroxide 28.00 G Loxanol DPN 9.40 H Silica 400 mesh powder 69.74 Total 1000.00 Density kg/mJ 488.0 Compressive Strength MPa 3.5 Example 2 Geopolymer matrix Medium Density Material kg manufacturing A Sodium Silicate 397.00 Add item B to item A with stirring. When dissolves, cover and allow to cool to cool B Potassium Hydroxide 93.00 C Water 52.00 Add items C and D in order with stirring. Stir until lump free.

D Type 1 Metakaolin 350.00 E Aluminium powder 0.59 Add items E to H in order shown and mix well. Immediately transfer to required mould.

F Calcium Hydroxide 28.00 G Loxanol DPN 9.40 H Silica 400 mesh powder 70.01 Total 1000.00 Density kg/mJ 660.0 Compressive Strength MPa 6.9 12 Example 3 Geopolymer matrix Higher Density Material kg manufacturing A Sodium Silicate 397.00 Add item B to item A with stirring. When dissolves, cover and allow to cool to cool B Potassium Hydroxide 93.00 C Water 52.00 Add items C and D in order with stirring. Stir until lump free.

D Type 1 Metakaolin 350.00 E Aluminium powder 0.29 Add items E to H in order shown and mix well. Immediately transfer to required mould.

F Calcium Hydroxide 28.00 G Loxanol DPN 9.40 H Silica 400 mesh powder 70.31 Total 1000.00 Density kg/m3 955 Compressive Strength MPa .2 Example 4 Concrete with Silica Sands Material kg manufacturing A Sodium Silicate 191.79 Add item B to item A with stirring. When dissolves, cover and allow to cool to cool B Potassium Hydroxide 45.13 C Water 24.82 Add items C and D in order with stirring. Stir until lump free.

D Type 1 Metakaolin 169.23 E Aluminium powder 0.42 Add items E to J in order shown and mix well. Immediately transfer to required mould.

F Calcium Hydroxide 13.54 G Loxanol DPN 4.51 H Silica 400 mesh powder 33.85 I J61 Sand 381.85 J Silica Sand 18/36 mesh 134.86 Total 1000.00 Density kg/m3 870 Compressive Strength MPa 3.3 13 Example 5 Concrete with Silica Sands Material kg manufacturing A Sodium Silicate 191.36 Add item B to item A with stirring. When dissolves, cover and allow to cool to cool B Potassium Hydroxide 45.03 C Water 24.76 Add items C and D in order with stirring. Stir until lump free.

D Type 1 Metakaolin 168.85 E Aluminium powder 0.28 Add items E to J in order shown and mix well. Immediately transfer to required mould.

F Calcium Hydroxide 13.51 G Loxanol DPN 4.50 H Silica 400 mesh powder 33.77 I J61 Sand 381.72 J Silica Sand 18/36 mesh 135.23 Total 1000.00 Density kg/m3 988 Compressive Strength MPa .5 14

Claims (19)

1. A method for producing a lightweight inorganic polymer material that includes the following steps in order: 5 A. prepare activator solution; B. add activator solution to a metakaolin and mix; C. add a finely divided form of aluminium and a calcium additive then mix; 10 where the activator solution is made by combining a group 1 metal soluble silicate solution with a group 1 metal hydroxide until the hydroxide concentration is between 3.5 and 10.5 molar, such that the mixing of the activator solution and metakaolin forms an Inorganic Polymer Matrix (IPM) paste, such that the calcium additive is at least food grade with a low magnesium (less than about 2%) content. 15

2. The method as claimed in claim 1 characterised in that the calcium additive is calcium hydroxide or calcium oxide.

3. The method as claimed in claim 2 characterised in that the calcium additive 20 contains minimal magnesium.

4. The method as claimed in any one of claims 1 to 3 characterised in that the calcium additive is added at a rate of between 2% and 12%, by weight, of the IPM paste. 25

5. The method as claimed in claim 4 characterised in that the calcium additive is added at a rate of between 2% and 5%, by weight, of the IPM paste.

6. The method as claimed in any one of the preceding claims characterised in 30 that the group 1 metal in the soluble silicate and the hydroxide are independently selected from the list consisting of Li, Na and K.

7. The method as claimed in any one of the preceding claims characterised in that the Si02:M20 ratio (where M is a Group 1 metal) in the soluble silicate is between 35 2 and 3.5. 15

8. The method as claimed in any one of the preceding claims characterised in that the activator solution includes more than one Group 1 metal.

9. The method as claimed in any one of the preceding claims characterised in 5 that the group 1 metal hydroxide is potassium hydroxide.

10. The method as claimed in claim 1 characterised in that the finely divided form of aluminium is powdered aluminium. 10

11. The method as claimed in any one of the preceding claims characterised in that in step C a humectant is added.

12. The method as claimed in claim 11 characterised in that the humectant is one or more finely dispersed long chain fatty alcohols. 15

13. The method as claimed in claim 11 or 12 characterised in that the humectant is one or more species selected from cetyl alcohol, pentaerithritol, lauryl alcohol, 1,2 pentanediol, ethylene glycol, diethylene and dipropylene glycols, 2,2,dimethyl propane diol, 2, butylamino ethanol, amino methyl propanol and a blend of long chain (C12 to 20 C14) fatty alcohols as a fine dispersion.

14. The method as claimed in any one of the preceding claims characterised in that in step C one or more aggregate is added. 25

15. The method as claimed in claim 14 characterised in that the particle size of the aggregate is between 30 micron and 1000 micron.

16. The method as claimed in claim 13 or 14 characterised in that aggregate includes one or more silica sands or silica flours. 30

17. The method as claimed in any one of the preceding claims characterised in that the uncured lightweight inorganic polymer material from step C is injected or transferred into moulds to cure. 35

18. The method as claimed in claim 17 characterised in that this transfer or injection occurs shortly after the mixing in step C is completed. 16

19. A lightweight inorganic polymer foam material made by the method claimed in any one of claims 1 to 18. 17