Process for preparation of geopolymer material foam and geopolymer material foam

Abstract

The invention relates to the use of water-based emulsions of silane / siloxane and fatty acid salt to improve the properties of geopolymer material foams, and processes for the preparation of geopolymer material foams. The geopolymer material foams are used for insulation and construction, and have a density in a range of from 20 to 800 kg / m3, a compressive strength in a range of from 0.1 to 5 MPa, and a thermal conductivity in a range of from 40 to 80 mW / m·K.

Description

[0001] Synthos Dwory 7 23 December 2025

[0002] SH 1909-02WO Process for preparation of geopolymer material foam and geopolymer material foam Field of the Invention

[0003] The present invention relates to the use of water-based emulsions of silane / siloxane and fatty acid salt, to improve the properties of geopolymer material foams. The invention also relates to processes for the preparation of geopolymer material foams, the geopolymer material foams, and the use of the geopolymer material foams for construction.

[0004] Background of the Invention

[0005] There is an increasing demand for construction materials that combine good mechanical stability with good thermal conductivity and high fire resistance. Geopolymer material foams are a promising candidate to substitute autoclaved aerated concrete in construction due to potentially lower required energy consumption in the preparation process. However, the requirements to have both flexibility in the preparation process and high control, as well as low amounts of waste byproduct and efficient energy usage in preparing said materials are similarly demanding. Therefore there is an increasing need to reduce emissions in building and cement industries both via implementation of sustainable substitutes or better materials and continuous improvement of insulation capabilities.

[0006] According to the International Energy Agency (IEA), the construction industry accounts for approximately 26% of global CO2emissions, equivalent to around 9.6 gigatons (Gt) of CO2annually. Additionally, the cement industry alone contributes approximately 8% of global CO2emissions, which corresponds to roughly 2.96 Gt CO2per year based on total global emissions of 37 Gt (2022 data). This makes cement one of the largest single contributor to construction-related emissions, driven primarily by the calcination of limestone and energy-intensive production processes. This underscores an urgent need to reduce emissions from both sectors. The production of 1 ton of Portland cement - the primary binding material in traditional concrete - generates approximately 0.91 CO2, with global cement production exceeding 4.4 billion tons annually. This accounts for nearly 2.64 Gt of direct emissions from cement production, plus additional emissions from energy use and related processes.

[0007] DE102004006563A1 discloses a method for preparing inorganic-organic hybrid foams comprising the steps of a) mixing at least one inorganic, stone-forming reactive component, at least one hardener comprising water, at least one foaming agent, at least oneorganic silicon compound and at least one surfactant, and b) at least partial hardening of the mixture.

[0008] According to EP 2 868 637 A1 , a geopolymer foam formulation comprises at least one inorganic binder; at least one alkaline activator; at least one surfactant; a gas phase; and water.

[0009] Dong et al. (Cement and Concrete Research (2022), Vol. 160, p. 106919) teach the simultaneous foaming and hydrophobization of geopolymer foams by using polymethylhydrosiloxane (PMHS) as the double-functional agent and calcium stearate as foam stabilizer.

[0010] WO2018091482A1 discloses a noncombustible mineral foam comprising: pozzolanic inorganic binder comprising polymerized metakaolin, thickener, at least one anionic surfactant selected from the group consisting of Cs-Cis-alkyl sulfates, Cs-Cis-alkyl ether sulfates, Cs-Cis-alkyl aryl sulfonic acids, Cs-Cis fatty acids and mixtures thereof, at least one nonionic surfactant selected from the group consisting of alkyl polyglucosides; and a gaseous phase.

[0011] WO 2011 / 068830 A2 teaches a method of fabricating a porous material, the method comprising: combining a geopolymer resin and a liquid to form a mixture; solidifying the mixture to form a solid embedded with the liquid; and removing at least a portion of the liquid from the solid to yield the porous material. WO 2011 / 068830 A2 also teaches a wide range of materials fabricated according to the method, and a wide range of uses of these materials.

[0012] A common challenge of the known foam preparation is to prepare foams that have both high mechanical stability and low thermal conductivity, and that can be used safely in construction. Additionally, the preparation is often time intensive, with curing taking a day or more, and / or requires heating for curing that may introduce internal stress upon cooling, frequently leading to crack formation and loss of output.

[0013] It has now surprisingly been found that these problems are overcome by a process of preparing geopolymer material foams, comprising the following steps:a. mixing of a1) at least one aluminosilicate, a2) at least one alkaline constituent, a3) at least one pozzolanic additive, a4) emulsion of microstructure modifier, a5) emulsion of nucleating agent, and a6) foaming agent precursor, to form a gel;

[0014] b. pouring the gel into a mould, the mould having a bottom part and at least two side parts, and then closing the mould with a lid part;

[0015] c. foaming and curing the gel in the closed mould at a temperature in a range of from 60 to 80 °C, to obtain foamed partially cured gel;

[0016] d. at a temperature in a range of from 60 to 80 °C,

[0017] d. i. removing the lid part from the mould;

[0018] d. ii. then further curing the foamed partially cured gel;

[0019] d. iii. then removing at least one side part from the mould; and d. iv. then further curing with at least one side part present, to obtain fully cured foam;

[0020] e. cooling the fully cured foam to a temperature in a range of from 10 to 30 °C; and

[0021] f. removing any remaining side parts, to obtain the geopolymer material foam,

[0022] wherein

[0023] component a4) comprises at least one agent selected from silanes and siloxanes, the silane or siloxane having 1) one or more Ci- to Cs-alkoxy groups and 2) one or more Ci- to Cso-alkyl groups, and

[0024] component a5) comprises salt of Ci6 to C20 fatty acid.

[0025] Summary of the Invention

[0026] According to the invention, a geopolymer material is produced by preparing a modified gel using emulsions of 1) calcium stearate and 2) silane or siloxane, then foaming and subsequently curing, with stepwise demoulding, to prepare geopolymer material foams for a wide range of applications.

[0027] The present invention overcomes the disadvantages according to the prior art by:

[0028] 1. Developing a substitute for autoclaved aerated concrete (AAC).2. Implementing materials with significantly lower thermal conductivity coefficients to enhance energy efficiency.

[0029] By substituting conventional (cement-based) AAC with the material geopolymer material foam of the present invention, a significant reduction in embodied carbon is achieved. The geopolymer material foam of the present invention reduces CO2emissions by at least 75%, compared to AAC of equivalent density (300 kg / m3), achieving a reduction from approximately 1.7 t CO2 / m3to just 0.41 CO2 / m3.

[0030] Moreover, the material demonstrates excellent insulation properties, which are critical for reducing energy consumption in buildings and contributing to overall sustainability goals.

[0031] In a first aspect, the invention relates to the use of emulsions of calcium stearate and silane or siloxane in a gel stage of a process for preparing a geopolymer material foam. In a second aspect, the invention relates to a process for preparing a geopolymer material foam. A third aspect of the invention is a geopolymer material foam. A fourth aspect is a process of construction, a fifth aspect is a thermal insulation or building system, and a sixth aspect is a building comprising a block or a panel of the geopolymer material foam.

[0032] List of figures

[0033] Figure 1: Scheme of process steps according to the invention.

[0034] Figure 2: Blocks of fully cured, demoulded geopolymer material foam before cutting.

[0035] Figure 3a: Overview microscopy image of geopolymer material foam.

[0036] Figure 3b: Enlarged microscopy image of geopolymer material foam (80x magnification).

[0037] Detailed Description of the Invention

[0038] Thus, in a first aspect, the invention relates to the use of

[0039] a water-based emulsion of at least one agent selected from silanes and siloxanes, the silane or siloxane having 1) one or more Ci- to Cso-alkyl groups and optionally 2) one or more Ci- to Cs-alkoxy groups, and

[0040] a water-based emulsion of salt of Ci6 to C2o fatty acid,

[0041] in a gel stage of a process for preparing a geopolymer material foam,- to increase the surface area of a foamed gel in a foaming stage of the process, and / or

[0042] - to reduce shrinkage and crack formation during a curing stage of the process, and / or

[0043] - to increase compressive strength and decrease thermal conductivity of the geopolymer material foam, the geopolymer material foam having a density in a range of from 20 to 800 kg / m3.

[0044] Nucleating agents, such as salts of C16 to C20 fatty acid, were found to improve the foaming in a process for preparing geopolymer material foam when added to the geopolymer material in the gel stage before foaming and curing. This leads to a fine and homogenous structure which increases the foam surface area and results in comparatively lower thermal conductivity of the cured geopolymer material foam.

[0045] Preferably, the water-based emulsion of salt of C16 to C20 fatty acid comprises of from 35 to 45 wt.% of salt of C16 to C20 fatty acid with respect to the weight of the emulsion, wherein the weight of the salt of C16 to C20 fatty acid is calculated as calcium salt.

[0046] In a preferred embodiment, the amount of water-based emulsion of salt of C16 to C20 fatty acid is in a range of from 0.1 to 1.3 wt.%, more preferably in a range of from 0.25 to 0.65 wt.%, most preferably in a range of from 0.3 to 0.4 wt.%, with respect to the weight of the geopolymer material gel.

[0047] Microstructure modifiers, such as silane or siloxane having 1) one or more Ci- to C3-alkoxy groups and 2) one or more Ci- to Cso-alkyl groups, improve the stability of geopolymer material foam during curing and cooling down, when added to the geopolymer material in the gel stage before foaming and curing. The proper use of silane or siloxane increases internal hydrophobicity of the geopolymer material and regulates water sorption and retention by the structure. In tandem with the nucleating agent, it also regulates the structure to be finer, with more pores created in the struts, which creates a bimodality. The achieved bimodality relaxes the structure and prevents cracking when applied with proper temperature profile curing and step-by-step demoulding.

[0048] In a preferred embodiment, the amount of emulsion of at least one agent selected from silanes and siloxanes is in a range of from 0.01 to 0.5 wt.%, more preferably in a range of from 0.02 to 0.2 wt.%, most preferably in a range of from 0.05 to 0.15 wt.% with respect to the weight of the geopolymer material gel.

[0049] Preferably, the silane or siloxane has 1) one or more C2- to Cs-alkoxy groups and 2) one or more C2- to C2o-alkyl groups, the silane or siloxane more preferably has 1) one or more C2- to Cs-alkoxy groups and 2) one or more C2- to Cw-alkyl groups.In a second aspect, the invention relates to a process for preparing a geopolymer material foam, comprising the following steps

[0050] a. mixing of a1) at least one aluminosilicate, a2) at least one alkaline constituent, a3) at least one pozzolanic additive, a4) emulsion of microstructure modifier, a5) emulsion of nucleating agent, and a6) foaming agent precursor, to form a gel;

[0051] b. pouring the gel into a mould, the mould having a bottom part and at least two side parts, and then closing the mould with a lid part;

[0052] c. foaming and curing the gel in the closed mould at a temperature in a range of from 60 to 80 °C, to obtain foamed partially cured gel;

[0053] d. at a temperature in a range of from 60 to 80 °C,

[0054] d. i. removing the lid part from the mould;

[0055] d. ii. then further curing the foamed partially cured gel;

[0056] d. iii. then removing at least one side part from the mould; and d. iv. then further curing with at least one side part present, to obtain fully cured foam;

[0057] e. cooling the fully cured foam to a temperature in a range of from 10 to 30 °C; and

[0058] f. removing any remaining side parts, to obtain the geopolymer material foam,

[0059] wherein

[0060] component a4) comprises at least one agent selected from silanes and siloxanes, the silane or siloxane having 1) one or more Ci- to Cs-alkoxy groups and 2) one or more Ci- to Cso-alkyl groups, and

[0061] component a5) comprises salt of Ci6 to C20 fatty acid.

[0062] In step a., the components that react to form a geopolymer material are mixed with the emulsions of microstructure modifier and nucleating agent, and with foaming agent precursor, to form a gel. Sufficient liquid is present as a reaction medium and results in a viscous gel that can be poured in step b. A foaming agent precursor is a component that releases gas, by itself or in combination with a reactant, once the activation energy for the gas-releasing reaction is supplied, typically upon heating to a certain temperature. Other foaming agents are volatile compounds that change from their liquid to the gaseous form.During foaming and initial curing in step c., the mould is kept closed, to prevent water evaporation. The mould is then, in step d., only opened and removed in a stepwise manner, first the lid, than after some time one or more side parts (but not all). This allows the curing of the geopolymer material to proceed, and water to evaporate in a controlled manner, i.e. over a certain period of time, at a certain temperature.

[0063] Preferably, the mould has four side parts, more preferably the four side parts can be separately removed from the bottom part.

[0064] In a preferred embodiment, the mould has two longer side parts and two shorter side parts. In a more preferred embodiment, during the process, first a longer side part is removed, then the shorter side parts are removed, and then the second longer side part is removed. Finally the geopolymer material foam is taken from the bottom part.

[0065] In one embodiment, the obtained fully cured foam in step e. is cooled within three side parts of the mould. The conditions during cooling alleviate the internal stress in the foam and depend on the dimension of the mould and the heat capacity of the material.

[0066] Preferably,

[0067] the duration in step c. is in a range of from 1 to 10 h,

[0068] the duration in step d.ii. is in a range of from 1 to 10 h, and / or

[0069] the duration in step d.iv. is in a range of from 1 to 10 h.

[0070] More preferably,

[0071] the duration in step c. is in a range of from 6 to 10 h,

[0072] the duration in step d.ii. is in a range of from 6 to 10 h, and / or

[0073] the duration in step d.iv. is in a range of from 6 to 10 h.

[0074] The cooling duration depends on the dimensions of the mould and can be controlled using an insulated mould or a gradual decrease of heating around the mould instead of switching off the heating entirely. The durations of said steps is adjusted depending on the size of mould and mass of material. For example, if the volume of the mould is increased four-fold, the durations are preferably doubled, and if the volume of the mould is increased eight-fold, the durations are preferably increased four-fold. Additionally, insulation of the mould and dryer performance influence the preferred durations of the steps to prevent cracking.

[0075] The process according to the invention results in geopolymer material foams with a combination of desired properties, namely controllable material density, compressive strength and thermal conductivity. The process also leads to significantly less crackingand fracturing of the geopolymer material foams and thereby resulting in less waste material and increased yield from the process.

[0076] The process according to the invention also results in foams of good compressive strength and thermal conductivity even without a maturing process over days or even weeks. Since those principal material properties do not change, maturing is optional, reducing the need for large storage areas or waiting time.

[0077] In a preferred embodiment, the process comprises a further step

[0078] g. maturing the geopolymer material foam.

[0079] In a more preferred embodiment, the maturing of the geopolymer material foam prepared according to the invention is done before cutting the foam into blocks of dimensions specific to their intended purpose. In another more preferred embodiment, the maturing of the geopolymer material foam prepared according to the invention is done after cutting the foam into blocks of dimensions specific to their intended purpose.

[0080] In all aspects of the invention, it is preferred the agent selected from silanes and siloxanes has 1) one or more Ci- to Cso-alkyl groups and 2) one or more Ci- to Cs-alkoxy groups.

[0081] Preferably, mixing step a. comprises

[0082] a. i. mixing of the a1) aluminosilicate component, the a2) alkaline component, and the a3) pozzolanic additive component, for a duration of from 5 to 30 minutes;

[0083] a. ii. adding the a4) microstructure modifier component, and mixing, then adding the a5) nucleating agent component, and mixing; a. iii. adding the a6) foaming agent precursor component, and mixing, to form the gel.

[0084] This sequence is favourable to form an initial, unmodified geopolymer gel from a1), a2) and a3), establishing the network that is later the geopolymer backbone of the foam. By then adding a4) the microstructure modifier, the silane or siloxane reacts with sialate groups of the unmodified geopolymer before adding a5). Adding a6) as last component ensures that the formation of geopolymer and its modification is well advanced before the foaming agent precursor is added and the geopolymer material gel is poured into the mould.

[0085] In a preferred embodiment, the a5) nucleating agent component comprises, based on the weight of the emulsion, from 35 to 45 wt.% salt of Ci6 to C20 fatty acid, wherein theweight of the salt of C16 to C20 fatty acid is calculated as calcium salt. This range is desirable to have a proper emulsion of the nucleating agent in water and results in more homogenous foams.

[0086] Calcium stearate has attracted great interest for its applicability as heat stabilizer, lubricant, flatting agent, water-proofing or releasing agent for several industries, such as plastics, coating, papermaking and petrochemical industry. For a time, it had been a challenge to prepare concentrated emulsions due to the poor water-solubility of calcium stearate and steric acid. CN 103276625 A and CN 102210994 A each teach a method to overcome this challenge and enable the preparation of emulsions having 35 to 45 wt.% of salt of C16 to C20 fatty acid.

[0087] Preferably, the amount of component a5) is in a range of from 0.1 to 1.3 wt.%, based on the weight of the gel. More preferably, the amount of the nucleating agent is in a range of from 0.25 to 0.65 wt.%, most preferably in a range of from 0.3 to 0.4 wt.%.

[0088] Preferably, the total amount of the nucleating agent is in a range of from 0.05 to 0.5 wt.%, based on the weight of the gel. More preferably, the amount of the nucleating agent is in a range of from 0.1 to 0.25 wt.%, most preferably in a range of from 0.12 to 0.16 wt.%. In a preferred embodiment, a4) comprises at least one agent selected from silanes and siloxanes, the silane or siloxane having 1) one or more C2- to C2o-alkyl groups and optionally 2) one or more C2- to Cs-alkoxy groups, the silane or siloxane more preferably having 1) one or more C2- to Cw-alkyl groups and optionally 2) one or more C2- to C3-alkoxy groups.

[0089] The length of the alkoxy groups determines the reactivity of the silane or siloxane both for the condensation with another molecule of silane or siloxane and also for the reactivity with functional groups in the geopolymer gel. The alkoxy group also determines the reaction product, e.g. what kind of alcohol results from either reaction. The length of the alkyl group determines the properties of hydrophilicity and efflorescence resistance in the geopolymer material foam, and influences water retention in the curing process. The length of both the alkoxy group and of the alkyl group have an impact on solubility, volatility and reactivity. The preferred lengths have proven to work particularly well in the process according to the invention.

[0090] It is feasible that the agent in component a4) is prepared in-situ by using silanols, polysiloxanes, chlorinated silanes, or silazanes.

[0091] In a preferred embodiment, the amount of component a4) is in a range of from 0.01 to 0.5 wt.%, based on the weight of the gel, more preferably in a range of from 0.02 to 0.2 wt.% and most preferably in a range of from 0.05 to 0.15 wt.%.In one embodiment, a4) comprises of from 20 wt.% to 70 wt.% active component with respect to the weight of a4). The amount of active component ensures that a suitable emulsion of the microstructure modifier is formed before use in the process.

[0092] Preferably, the total amount of the microstructure modifier is in a range of from 0.005 to 0.2 wt.%, based on the weight of the gel, more preferably in a range of from 0.01 to 0.1 wt.%, most preferably in a range of from 0.02 to 0.07 wt.%. This range has been found to advantageously increase the internal hydrophobicity of the geopolymer material foam and to regulate water sorption and water retention by the gel and / or foam structure. In a preferred embodiment, the a6) foaming agent precursor is hydrogen peroxide solution. This foaming agent precursor upon heating generates only oxygen gas and water without any other by products. It is also most suitable to enable foaming at a temperature in a range of from 60 to 80 °C. In a preferred embodiment, the a6) foaming agent precursor is an aqueous solution of 20 to 35 wt.% hydrogen peroxide.

[0093] Preferably, the hydrogen peroxide solution is used in an amount of from 0.15 to 5 wt.%, based on the weight of the gel. According to the process according to the invention, geopolymer material foam in a wide range of density can be prepared with this amount of hydrogen peroxide.

[0094] More preferably, hydrogen peroxide is used in an amount of from 0.3 to 3 wt.%, most preferably in an amount of from 0.5 to 2 wt.%, particularly in an amount of from 1 to 2 wt.%, based the weight of the gel.

[0095] It is preferred that the a1) aluminosilicate component is selected from furnace slag, metakaolin, and mixture thereof. These have been found to be reliably available and result in good geopolymer material foam.

[0096] In a more preferred embodiment, the a1) aluminosilicate component is a mixture of furnace slag and metakaolin, and the weight ratio of the furnace slag to the metakaolin is in a range from 2:1 to 1:2, preferably in a weight ratio in a range from 1.5:1 to 1:1.5, and more preferably in a weight ratio of about 1:1. The composition is favourable to achieve low density and good compressive strength of the geopolymer material foam.

[0097] Preferably, the a2) alkaline component is an alkali metal water glass solution, more preferably a sodium water glass solution. Most preferably, the sodium water glass solution has a molar ratio of SiC>2 to Na2O in a range of from 1.2:1 to 2.2:1, in particular to a molar ratio in a range of from 1.4:1 to 1.8:1. In particular, the molar ratio can be adjusted by adding sodium hydroxide to an sodium water glass solution with a higher molar ratio. Adjusting the molar ratio allows for fine tuning of alkalinity and reactivity of component a2).In a preferred embodiment, component a2) is a sodium water glass solution having x. a water content in a range of from 40 to 80 wt.%, with respect to the weight of the water glass solution, preferably in a range of from 50 to 70 wt.%, and

[0098] y. the weight ratio of component a2) to component a1) is in a range of from 0.6 to 2.2, preferably in a range of from 0.6 to 1.2.

[0099] The amount of water in the alkaline component a2) and in the resulting geopolymer material gel determine the resulting viscosity and resulting foamability. With the preferred amount, a balance is struck between a sufficient amount of liquid for good workability and leading to good foam upon heating the gel, and reasonable excess of water that has to evaporate during curing or afterwards.

[0100] Preferably, the a3) pozzolanic component is selected from recycled geopolymer material foam, amorphous silica, pozzolana powder, and mixture thereof. Using said additive in the process regulates water retention in the formed gel and reduces shrinkage of the geopolymer material foam before it is fully cured.

[0101] In a preferred embodiment, the recycled geopolymer material foam is used in milled form, and makes up in a range of from 0.1 to 10 % by weight, based on the total weight of the a3) pozzolanic component, preferably 1 to 5 % by weight.

[0102] In a preferred embodiment, the mixing in step a. is of at least:

[0103] 20 to 30 wt.% of furnace slag,

[0104] 20 to 30 wt.% of metakaolin,

[0105] 0.3 to 5 wt.% of amorphous silica, preferably 0.5 to 2 wt.%,

[0106] 0.3 to 5 wt.% of pozzolana powder, preferably 0.5 to 2 wt.%, and 40 to 50 wt.% sodium water glass solution, the sodium water glass solution having a water content in range of from 50 to 70 wt.%,

[0107] each based on the weight of the gel.

[0108] In a preferred embodiment, the mould has a rectangular bottom part, separately removable side parts, and a lid part, wherein at least the inner sides of the bottom part and of the side parts are coated with PTFE, a PTFE-based material or polycarbonate-based material or polyurethane-based material, or a mixture thereof.

[0109] In a preferred embodiment, the inside of the mould is resistant to water, elevated temperature and abrasion.

[0110] In one embodiment, the mould consists of extruded polystyrene (XPS) and a coating on the inner areas of the bottom part and the side parts.In another embodiment, the mould consists of stainless steel and a coating on the inner areas of the bottom part and the side parts.

[0111] In another embodiment, the mould consists of stainless steel and a coating on the inner sides of the bottom part and the side parts, and is insulated and / or comprises a heat jacket. In this manner, the heat release and resulting cooling of the geopolymer material foam can be better controlled which reduces thermal shock of the contained material during the cooling.

[0112] In a third aspect, the invention relates to a geopolymer material foam comprising A. geopolymer,

[0113] B. moieties derived from C16 to C20 fatty acid,

[0114] C. moieties derived from an agent selected from silanes and siloxanes, the silane or siloxane having 1) one or more Ci- to Cso-alkyl groups and optionally 2) one or more Ci- to Cs-alkoxy groups,

[0115] wherein the geopolymer material foam comprises from 19.0 to 28.0 wt.% of silicon, from 8.5 to 13.0 wt.% of calcium, from 7.0 to 12.0 wt.% of sodium, from 7.2 to 10.8 wt.% of aluminium, from 0.9 to 1.5 wt.% of magnesium, and from 0.45 to 0.75 wt.% of iron, with respect to the weight of the geopolymer material foam, each measured by X-ray fluorescence spectroscopy,

[0116] and wherein the geopolymer material foam has

[0117] a density in a range of from 20 to 800 kg / m3, as measured according to EN 771-13:2000,

[0118] a compressive strength in a range of from 0.1 to 5 MPa, as measured according to EN 772-1:2001, measured after 1 or more days after complete demoulding, and

[0119] a thermal conductivity in a range of from 40 to 90 mW / m K, as measured according to ISO 8301:1991.

[0120] Density, compressive strength and thermal conductivity of the geopolymer material foam according to the invention may be measured according to standards for construction materials, such as for autoclaved aerated concrete. The foams achieve the required compressive strength and thermal conductivity at a set density, with lower required energy input during preparation than other construction materials, such as autoclaved aerated concrete.

[0121] Preferably, the agent is selected from silanes or siloxanes has 1) one or more C2- to C20-alkyl groups and optionally 2) one or more C2- to Cs-alkoxy groups. More preferably theagent selected from silanes or siloxanes has 1) one or more C2- to Cw-alkyl groups and optionally 2) one or more C2- to Cs-alkoxy groups.

[0122] Preferably, the geopolymer material foam comprises

[0123] - from 20.5 to 26.0 wt.% of silicon, preferably from 21.5 to 25.0 wt.%, more preferred from 22.5 to 24.0 wt.%,

[0124] - from 9.2 to 12.0 wt.% of calcium, preferably from 9.7 to 11.5 wt.%, more preferred from 10.2 to 11.0 wt.%,

[0125] - from 8.0 to 11.0 wt.% of sodium, preferably from 9.1 to 10.5 wt.%, more preferred from 9.4 to 10.2 wt.%,

[0126] - from 7.6 to 10.3 wt.% of aluminium, preferably from 8.3 to 9.6 wt.%, more preferred from 8.6 to 9.3 wt.%,

[0127] - from 1.0 to 1.35 wt.% of magnesium, preferably from 1.05 to 1.30 wt.%, more preferred from 1.10 to 1.25 wt.%, and

[0128] - from 0.51 to 0.70 wt.% of iron, preferably from 0.54 to 0.66 wt.%, more preferred from 0.57 to 0.63 wt.%,

[0129] each with respect to the weight of the geopolymer material foam, and each measured by X-ray fluorescence spectroscopy.

[0130] In a preferred embodiment, the geopolymer material foam has a content of organic material of 1 wt.% or less, determined according to DIN EN 771-4+A1:2015-10. Geopolymer material foam with such a low content of organic material is classified as fire proof category A2 and does not require further testing before use in construction.

[0131] Preferably, the geopolymer material foam has a density in a range of from 50 to 800 kg / m3, more preferably in a range of from 100 to 650 kg / m3and most preferably in a range of from 300 to 350 kg / m3, as measured according to EN 771-13:2000.

[0132] Preferably, the geopolymer material foam has a thermal conductivity in a range of from 50 to 85 mW / m K, preferably in a range of from 65 to 80 mW / m K, and more preferably in a range of from 67 to 75 mW / m K, as measured according to ISO 8301:1991.

[0133] Preferably, the geopolymer material foam has a compressive strength in a range of from 0.5 to 4 MPa, preferably in a range of from 1 to 3 MPa, and more preferably in a range of from 1.6 to 2.4 MPa, as measured according to EN 772-1:2001, measured after 1 or more days after complete demoulding.

[0134] The ranges of density, thermal conductivity and compressive strength according to the invention and different levels of preference are shown in Table 1.Table 1

[0135]

[0136] In a most preferred embodiment, the geopolymer material foam has

[0137] a density in a range of from 300 to 350 kg / m3, as measured according to EN 771-13:2000,

[0138] a compressive strength in a range of from 1.6 to 2.4 MPa, as measured according to EN 772-1:2001, measured after 1 or more days after complete demoulding, and

[0139] a thermal conductivity in a range of from 70 to 80 mW / m K, as measured according to ISO 8301:1991.

[0140] In one embodiment, the geopolymer material foam has a bimodal structure with two kinds of pores. The larger pores, also called cells, make up the majority of the volume of the voids in the foam. They are responsible for lowering the density of the geopolymer material foam and for reducing the thermal conductivity. The cells are surrounded by walls of geopolymer material that make up the solid part of the foam and provide compressive strength. It has been found to be beneficial when the wall thickness of the cells at their thinnest point is in a range of from 0.01 to 0.15 mm to provide good compressive strength with low amounts of solid volume in the geopolymer material foam.

[0141] In order to decrease the thermal conductivity of the geopolymer material foam, the walls between the cells should be made thinner. This can be accomplished by increasing the amount of blowing agent precursor in the process according to the invention and thereby increasing the size of the cells of the geopolymer material foam.

[0142] Smaller pores can be found within the intersections of multiple cell walls to provide additional voids and further lower the density of the geopolymer material foam. The smaller pores in tandem with the larger pores create a bimodal structure which allows the material to relax during cooling and avoid a build-up of thermal stress, which would lead to cracking.In a preferred embodiment, the cells of the geopolymer material foam have an ellipsoid cross-section, and the length of the major axis is 1 mm or less, preferably 0.8 mm or less, more preferably 0.6 mm or less, measured according to the method in the example section below. Cross-sections of the foam are cut and images of the cross-section are recorded under a microscope. From the images, the dimensions of the foam cells are measured, in particular, the wall thickness at the thinnest point and the major axis and the minor axis of the ellipsoid 2-dimensional representation of the larger voids. From the squares of the values of the major and minor axis, eccentricity can be calculated.

[0143] It is also preferred that the cells have an eccentricity e, calculated from the major and the minor axis of the cell cross-sections, in a range of from 0.2 to 0.9, more preferably in a range of from 0.25 to 0.85 and most preferably in a range of from 0.3 to 0.8. Such values give improved three dimensional packing of larger voids and reduce density, without detrimentally affecting mechanical stability.

[0144] The eccentricity (e) can be calculated for each cell as a parameter to quantify the deviation of the elliptical shape from circularity, where e — > 0 indicates an increasingly circular geometry. The eccentricity is calculated using the following formula:

[0145] (II).

[0146]

[0147] Preferably, the geopolymer material foam has an absolute value of total movement coefficient Alc / I of less than 1 mm / m, as measured according to DIN EN 772-14:2002. Material foam with such low total movement does not expand or contract unduly, which would otherwise be detrimental to the stability of constructions comprising the foams. Preferably, the geopolymer material foam has

[0148] a water vapour permeability of less than 0.5- 10-10kg / (m s Pa), and / or a water vapour resistance factor of more than 4, as measured according to ISO 12572:2016.

[0149] Material foam outside those values requires excessive care to prevent moisture from entering and traversing the material foam.

[0150] Preferably, the geopolymer material foam has a radioactive concentration index "I" smaller than 1, preferably smaller than 0.8, more preferred smaller than 0.6, as measured according to Handbook No. 455 / 2010 of the Polish Building Research Institute. Those value have been deemed save for construction purposes. Using components with high radioactivity in the preparation of the geopolymer material foam would pose a health hazard during production and later use.In a preferred embodiment, the geopolymer material foam is resistant against freezethaw damage as measured according to DIN EN 153042010-06. This allows the geopolymer material foam to be used in construction in areas with at least some humidity and temperatures dropping seasonally below 0 °C.

[0151] In a preferred embodiment, the geopolymer material foam is prepared or preparable by the process according to the second aspect of the invention.

[0152] In a preferred embodiment, the geopolymer material foam is in the form of a block or a panel. Blocks enable to easily form larger elements, such as walls, in a construction process and the joining of the blocks according to established processes, such as joining blocks by mortar. A panel allows to cover a larger section of wall, such as attaching an insulating panel of low-density, low-thermal conductivity material to a wall. Blocks and panels are particularly useful for transport and construction due to their rectangular cross-sections and flat sides.

[0153] In a fourth aspect, the invention relates to a process of construction comprising the steps of

[0154] a. joining at least two of the blocks or panels with mortar;

[0155] b. at least partially curing the mortar.

[0156] In a fifth aspect, the invention relates to a thermal insulation or building system comprising the block or panel. The geopolymer material foam according to the invention unites good compressive strength and low thermal conductivity making it particularly suitable for insulation or buildings systems. The combination of properties allows to use fewer building components to achieve both stability and insulation.

[0157] Preferably, the thermal insulation or building system further comprises mortar. The block or panel of the thermal insulation or building system can be joined by mortar to other blocks or panels to make up larger structures of a building. More preferably, the mortar is of suitable strength for the block or panel.

[0158] In a sixth aspect, the invention relates to a building comprising the block or panel according to the third aspect of the invention, or the thermal insulation or building system according to the fourth aspect of the invention.Examples

[0159] Geopolymer foam preparation according to the invention - Example 1

[0160] In a first step, I, 100 parts per weight of a ready-to-foam gel composition was prepared by mixing components in the following manner:

[0161] First, in step I. A,

[0162] an equivalent mixture (50 / 50%) of furnace slag (Arcelor slag) and metakaolin (Ar-gical M1000 marketed by AGS Mineraux) in a sum amount of 50.53 parts per weight,

[0163] pozzolana powder (ASTRA Z-50) in an amount of 0.52 parts per weight,

[0164] amorphous silicon dioxide powder (Sidistar T-120LI silica powder from ELKEM) in an amount of 0.52 parts per weight, and

[0165] sodium silicate solution with a molar ratio of SiO2:Na2O of 1.6:1 in an amount of 46.40 parts per weight

[0166] were added to a planetary mixer and mixed for 15 minutes until gel consistence was observed, to give a geopolymeric gel.

[0167] The water glass solution with the above molar ratio of SiO2:Na2O of 1.6 had been prepared starting from a commercial solution (sodium water glass by Z. Ch. Rudniki) of 35 wt.% oxide content and with a molar ratio of SiO2:Na2O of 1.8 and adding solid sodium hydroxide. The solution was then left for 1 day before use in the gel preparation.

[0168] Second, in step I.B, the microstructure modifier, a water-based emulsion of alkoxysilane homopolymer (CoatOSil PRIM2 from Momentive, stated to be a silicone emulsion) was added to the mixer and mixed with the gel for 5 minutes, to allow for the reaction between geopolymeric gel and microstructure modifier to take place.

[0169] Subsequently, in step I.C, the nucleating agent (surfactant) - an emulsion of calcium stearate (Hydrocast 40 from FACI Metalest S.L.ll) - was added in an amount of 0.35 parts per weight to the mixer and was mixed for one minute with the gel. Finally, in step I.D., the blowing agent precursor, a 33% concentrated water solution of hydrogen peroxide, in an amount of 1.6 parts per weight, was added to the mixer and the gel was mixed for another one minute, to obtain a ready-to-foam gel composition.

[0170] In step II, directly after mixing, 11.5 kg of the ready-to-foam gel composition were poured into a rectangular mould having an internal size of 60 cm x 20 cm x 35 cm. The mouldwas then closed to prevent water evaporation. The mould in the process is made of acid-resistant steel and coated on the inside with PTFE, has four sidewalls that can be removed individually, and has a tight-sealing lid.

[0171] For foaming and curing in the next step, step III, the closed mould was introduced to a tunnel dryer at 68 °C and first, as step 111. A, kept for 2 hours at this temperature.

[0172] Next, in step I II. B, the foamed gel was further cured in the same dryer at a temperature of 68 °C, with the mould being opened stepwise, to evaporate excess water: After 30 minutes, the lid was unsealed, opened and removed by an automatic handling system in the tunnel dryer. Then, after an additional 3 hours, one long side cover was removed, and the foam was further cured for 3 hours with the three remaining side parts present.

[0173] Finally, in step I II. C, heating was stopped and the mould left to slowly self-cool to room temperature in closed conditions inside the dryer, to avoid a thermal shock and cracking. After taking the cooled mould from the dryer, the remaining sidewalls were removed completely, to demould the fully cured geopolymer foam.

[0174] Then, in step IV, the cured geopolymer foam was left to mature (“conditioning”) for 7 days (Fig. 3) before, step V, cutting the foam into the desired dimensions for testing and / or packing and storage. The cut-off geopolymer foam could be dedusted and milled to recycle waste material from cutting to the mixer.

[0175] The obtained material has a density in a range from 300 to 350 kg / m3, a compressive strength in a range from 1.7 to 2.2 MPa and a thermal conductivity in a range from 72-75 mW / m-K.

[0176] Comparative example 1 (CE1)

[0177] CE1 was prepared by the same process as Example 1, but calcium stearate was added in the form of a powder instead of as an emulsion.

[0178] The resulting foam had a very inhomogeneous structure and showed significant cracks throughout the entire volume. It was thus not useful for sample cutting and measurements.

[0179] Comparative example 2 (CE2)

[0180] CE2 was prepared by the same process as Example 1 , but the siloxane microstructure modifier was replaced with sodium dodecylbenzenesulfonate (SDS), at the same concentration of active substance (about 0.5 part per weight).The resulting foam density was 335 kg / m3, with a compressive strength of 1.82 MPa and a thermal conductivity coefficient of 80 mW / m K, but the resulting block of foam was not stable and collapsed easily. Samples prepared for thermal conductivity measurement cracked further at the surface when dried at 50°C according to the norm conditions.

[0181] Comparative example 3 (CE3)

[0182] CE3 was prepared with the same composition and mixing as Example 1 , but the foaming and cooling was performed according to an established procedure for foam preparation without a microstructure modifier. After mixing, the ready-to-foam geopolymer gel was left for 24 h in the closed mould at room temperature. The closed mould was then placed for 24 hours in a tunnel dryer at 70°C, followed by self-cooling and subsequent demoulding.

[0183] The resulting blocks showed cracking during the following maturing stage after about 2 days.

[0184] The foam density was 330 kg / m3, with a compressive strength of 2.0 MPa and a thermal conductivity coefficient of 75 mW / m-K.

[0185] Comparative example 4 (CE4)

[0186] CE4 was prepared with the same mixing as Comparative Example 3 and with a similar composition but without the silane / siloxane emulsion.

[0187] The resulting block of foam significantly cracked throughout the whole of its volume during cooling. The foam had a density of 340 kg / m3, with a compressive strength of 1.85 MPa and a thermal conductivity coefficient of 81 mW / m K.

[0188] Testing material according to the invention

[0189] The obtained geopolymer material foam prepared according to the invention (Example 1) was cut into smaller dimensions depending on the requirements of the specific test method and used for further testing.

[0190] Composition of the foam (XRF)

[0191] The geopolymer material foam according to the invention was analyzed by X-ray fluorescence spectroscopy. The geopolymer material foam was prepared by milling in a ballmill to less than 0.1 mm, and was mixed with binder (boric acid based material) in a ratio of 1:3. The obtained foam-binder-sample was homogenized in a mortar and was then transferred to an aluminum form and pressed at a pressure of 140 MPa. Pressed samples were measured in a WDXRF Axios mAX spectrometer (Rh lamp, 4 kW). The results were evaluated by analysis in the software SuperQManager (Malvern Panalytical) which allows to detect element concentration at ppm level. The composition of the major elements (>0.5 wt.%) in the geopolymer material is shown in Table 2.

[0192] Table 2

[0193]

[0194] Pore structure of the geopolymer material foam according to the invention

[0195] For foam samples according to the invention, a plate with a thickness of approximately 2-3 mm was sectioned, followed by the acguisition of microscopic images at different magnifications to accurately assess pore dimensions (Fig. 3a, Fig. 3b).

[0196] The images were subseguently processed using the Imaged software for cell dimension analysis. Microscope images at 20x magnification (showing approximately 6.24 mm by 4.68 mm in an image of 2048 by 1536 pixels) were suitable to capture a reasonably number of cells in an image and accurately assess pore dimensions.

[0197] A total of 20 pore cells were measured for each image. Cells along the image diagonal were prioritized, and the remaining cells were selected based on the clarity of their boundaries. An elliptical geometry was selected to describe the cells, as this shape is characteristic of the obtained geopolymer microstructures. For each pore cell, two dimensions were recorded: the major axis (a) and the minor axis (b), corresponding to the semi-axes of an ellipse. The semi-axes were oriented to intersect approximately at a right angle, with manual measurements performed for each cell.Additionally, the eccentricity (e) was calculated for each cell as a parameter to quantify the deviation of the elliptical shape from circularity, where e — > 0 indicates an increasingly circular geometry. The eccentricity was calculated using the following formula:

[0198] (II).

[0199]

[0200] From the microscopy images, the thickness of the walls in the foam can be measured and is taken at the thinnest point between two voids.

[0201] An exemplary distribution of the pore dimensions and wall thickness of the geopolymer foam is shown in Tables 3a and 3b.

[0202] Table 3a Table 3b

[0203]

[0204]

[0205] Dimensional and mechanical testing for construction materials

[0206] Geopolymer masonry units do not have the standardized test regime of other long-time established masonry units and were therefore tested according to standards for autoclaved aerated concrete (AAC) masonry units.

[0207] i. Dimensional deviations

[0208] Six blocks were cut to the nominal dimensions of 570 x 200 x 200 mm and measured according to DIN EN 772-16:2011 and DIN EN 771-4:2011+A1:2015 to determine the obtained dimensions, average dimensions and average dimensional deviations. The results are shown in Table 4.

[0209] Table 4

[0210]

[0211] The average dimensional deviations [mm] are within the limits of the deviations for use with mortar of the categories GPLM, TLMA and TLMB according to DIN EN 771-4:2011+A1:2015. The deviations of the single specimen comply with the specifications of GPLM and TLMA. The blocks can be generated to be usable with thin bed mortar.

[0212] ii. Determination of average gross density and average compressive strength Samples with dimensions of 100 x 100 x 100 mm were cut from six different blocks, which were matured for 7 days, of which on three samples from each block the density and compressive strength were measured according to DIN EN 771-4:2011+A1:2015 and converted according to Annex A thereof. The average test results are given in Table 5. The conditioning was done in accordance with section 7.3.3 of DIN EN 772-1 :2011 Annex A (oven dry conditions 70 °C, measured within 24 h).Table 5

[0213]

[0214] The coefficient of variation for compressive strength is 8.1%.

[0215] According to the norm DIN EN 771-4:2011+A1:2015, the average compressive strength of masonry units should be no less than 1.5 N / mm2for loadbearing masonry and no single result should have a compressive strength less than 80% of the average declared value. The samples according to the invention satisfy this requirement of the norm.

[0216] iii. Determination of shrinkage on drying

[0217] From three different blocks three samples each were cut, each sample measuring 40 x 40 x 160 mm, on which shrinkage was measured according to DIN EN 680:2006. The average dry density of the samples was about 310 kg / m. The average test results are given in Table 6.Table 6

[0218]

[0219] After saturation, the samples have an initial moisture content of 103 to 109 %. Upon drying, the samples first show an expansion until a moisture content of about 35 % is observed, followed by shrinkage at lower values of moisture content. The samples equilibrate at about 9 % moisture after 7 days.

[0220] The samples show a mean value of conventional shrinkage on drying of Scs, ref = 1.15 mm / m and a mean total value of shrinkage on drying of £cs. tot = 1.28 mm / m.

[0221] iv. Linear changes - expansion due to moisture and shrinkage due to drying Six blocks were randomly selected, three blocks for shrinkage testing and three blocks for expansion testing according to DIN EN 772-14:2002. The results of the tests are given in Tables 7 and 8.Table 7

[0222]

[0223] Table 8

[0224]

[0225] The overall total movement coefficient Alc / I is 0.803 mm / m. This is in line with the ranges of expansion under moisture for concretes on lightweight aggregates according to Eurocode 6 Part 1-1.

[0226] Thus, the new material has properties that are comparable with other construction materials, such as concrete of lightweight aggregates.

[0227] v. Determination of the thermal conductivity coefficient "A" of cellular concrete in the dry state

[0228] Five blocks of the new material were tested according to ISO 8301:1991. Samples measuring 240 x240 x 40 mm were cut each, on which the thermal conductivity coefficient was measured at an average measurement temperature of 10 °C. The results of the tests are given in Table 9.Table 9

[0229] ""

[0230]

[0231] Thus, the geopolymer foam according to the invention has a thermal conductivity suitable to substitute other construction materials, such as autoclaved aerated concrete.

[0232] vi. Determination of organic material content

[0233] In accordance with DIN EN 771-4+A1:2015-10, the organic material content was measured in order to check the reaction to fire. The determination was carried out according to “Test Procedure No. 34.0 Determination of Organic Material Content in Autoclaved Cellular Concrete”, Research Laboratory of Ceramics and Building Materials ICiMB Warsaw, edition 3, 18.01.2018. The result of the test is given in Table 10.

[0234] Table 10

[0235]

[0236] According to the provisions of DIN EN 771-4 masonry units containing < 1.0 % by weight and by volume of homogeneously distributed organic materials can be declared Class A1 without further testing. Thus, the new material satisfies fire safety requirements.

[0237] vii. Determination of the water vapour resistance factor "u"

[0238] Specimens with a diameter of approximately 85 mm and a thickness of approximately 30 mm were cut from three blocks on which the water vapour permeability W and the water vapour transmission coefficient 5 were measured according to ISO 12572:2016. The average test results are given in Table 11.Table 11

[0239]

[0240] With a water vapour permeability of air of <5a= 1.950-10'10kg / (m s Pa), the water vapour 5 195O-1O-10

[0241] resistance factor is: u = = - - — = 6.25 « 6. Thus, the new material is comparable

[0242]

[0243] to other material for masonry units, such as aerated autoclaved concrete.

[0244] viii. Survey of natural radioactive isotope concentrations

[0245] The signals of radioactive isotopes were determined according to "Badanie promieniot-worczosci naturalnej wyrobow budowlanych" (Natural radioactivity testing of building products) of the Polish Poradnik Instytutu Techniki Budowlanej No. 455 / 2010 (Handbook No. 455 / 2010 of the Building Research Institute).

[0246] Part of a block was powdered and 1368 g of that powder were used for 11 measurements of 2000 s each. The Dose power was 70.35 nGy / h. The measuring system has performance factors of OK = 1.1574, ORa= 0.3824 and aTh = 0.1477, with a self-absorption coefficient of k = 0.9180. The results are given in Table 12.Table 12

[0247]

[0248] The resulting concentrations are:

[0249] Potassium (K-40): CK = 73.32 ± 38.09 Bq / kg,

[0250] Radium (Ra-226): CR3‘ = 80.09 ± 11.54 Bq / kg,

[0251] Thorium (Th-232): CTh= 49.02 ± 5.51 Bq / kg.

[0252] Thus, with the radioactive concentration index "I" calculated according to the Polish Regulations of the Council of Ministers of 17 December 2020, the l-index is

[0253] I= 0.53 ± 0.05

[0254]

[0255] "

[0256] This is well below the regulation threshold of 1.16 and comparable to established, safe building materials.ix. Determination of freeze-thaw resistance

[0257] Samples of 100 x 100 x 100 mm each were cut from two different blocks and observed during 15 freeze-thaw cycles according to DIN EN 15304:2010-06. The results are given in Table 13.

[0258] Table 13

[0259]

[0260] No damage was observed before or after the 15 freeze-thaw cycles. The changes are within the acceptable limits for weight loss (10%) and reduction in strength (15 %) for blocks with average dry density of below 450 kg / m3in accordance with DIN EN 15304:2010. The new material is thus a suitable alternative to established materials.

[0261] x. Determination of flexural tensile strength of wall elements

[0262] Ten test wall elements were fabricated according to DIN EN 1052-02:2016. Five elements were designed to test the bending tensile strength for failure in the plane perpendicular to the support welds and five elements for failure in the plane parallel to the support welds. The flexural tensile strength fxis calculated according to

[0263] >

[0264]

[0265] wherein b is the height or width a masonry specimen perpendicular to the direction of span. The test results are given in Tables 14 and 15.

[0266] a) Calculation of the characteristic flexural strength for a plane of failure perpendicular to the bed joints (with butt welds).Table 14

[0267]

[0268] The average flexural strength of elements made from the new material for a plane of failure perpendicular to the bed joints is fmean = 0.143 N / mm2. In comparison, elements made from AAC masonry units had a perpendicular flexural tensile strength of 0.11 to 0.13 N / mm2.

[0269] The resulting characteristic value of the flexural tensile strength of masonry calculated in perpendicular direction is

[0270]

[0271] 0.095 - m^m2.

[0272] b) Calculation of the characteristic flexural strength for a plane of failure paral- lei to the bed joints (with butt welds).

[0273] Table 15

[0274]

[0275] The average flexural strength joints of elements made from the new material for a plane of failure parallel to the bed joints is fmean = 0.105 N / mm2. In comparison, elements made from AAC masonry units had a parallel flexural tensile strength of 0.15 to 0.19 N / mm2.

[0276] The resulting characteristic value of the flexural tensile strength of masonry calculated in parallel direction is

[0277]

[0278] Thus, elements made from the new material have comparable flexural tensile strength in perpendicular and parallel direction compared to elements made from AAC units and also satisfy Eurocode 6 (EC6) requirements.

[0279] xi. Determination of the shear strength of a joint in masonry

[0280] Nine test pieces were made from 18 masonry units by bonding them with thin-bed mortar and subjected to testing according to DIN EN 1052-3:2002. The test pieces were tested for shear in three variants of initial compressive stress values in the direction perpendicular to the mortar joints.

[0281] For the bonding Franspol's ZC-1 thin-bed mortar was used which was prepared by mixing the dry mixture with water using a slow mixer for about 3 minutes. The mortar has an average spread of 190 mm (according to the mortar spread test of EN 1015-3:1999) and an air content of 17% (measured using the pressure method in accordance with EN 1015-7:1998). The average compressive strength of the mortar tested after 28 days was 11.78 N / mm2(according to EN 1015-11:2001). The average flexural strength of mortar tested after 28 days was 3.07 N / mm2(according to EN 1015-11:2001).

[0282] The bonded sample elements were stored covered with foil for 28 days at a temperature of 20 °C ± 2 °C and a humidity of 70 % ± 5 % before subjecting to the shear testing. The different shear strength values and compressive stresses are given in Table 16.

[0283] Table 16

[0284]

[0285] As measured according to DIN EN 1052-3:2002, the maximum load before destruction achieved by the test pieces was 53001 N at a precompression load of 21600 N, corresponding to a shear strength of 0.36 N / mm2. The mean value of initial shear strength was fvo= 0.29 N / mm2and the characteristic value corresponds to fvok = 0.8 fvo = 0.23 N / mm2. At lower preliminary compressive strength, a shear failure in the unit / mortar bond area is observed (A.1), partially accompanied by shear failure in the masonry unit (A.3). At higher preliminary compressive strength, crushing and / or splitting failure occurs predominantly in the masonry units (A.4).

[0286] Further experiments

[0287] Example T, Examples 2 to 5 and Comparative Example 5

[0288] Further experiments were performed, to show that various compositions can be used in accordance with the invention, under a variety of conditions. Comparative Example 5 was prepared in a procedure not according to the invention, using canola oil instead of salt of fatty acid.

[0289] The following geopolymer foams were prepared using the same mixing protocol as in Example 1 , with the same stirring techniques and stirring times. The same raw materials were used, except when expressly stated otherwise.

[0290] The protocol was as follows: Furnace slag and metakaolin, pozzolana and amorphous silicon dioxide were poured into a water glass solution (molar ratio of SiC>2:Na2O 1.6:1 in the water glass) and mixed in a planetary mixer for 15 min until a homogeneous gel was achieved. Then, the emulsion of additives (Example T and Examples 2 to 5: emulsion of polysiloxanes / silanes; Comparative Example 5: 3-aminopropyl)trimethoxysilane) was added to the gel and mixed for 5 min.

[0291] Subsequently, the dose of surfactant (Example T and Examples 2 to 5: watery emulsion of 40 wt.% of Ca stearate; Comparative Example 5: emulsion of canola oil) was added to the gel and mixed for an additional 1 min. At the end, foaming agent (33% wt. solution of hydrogen peroxide) was added to gel, in different amounts, and mixed for the next 1 min.

[0292] 2400 g of slurry of the prepared gels were each poured into a mould with a base size of 35 cm by 35 cm, and each mould was closed and sealed. The moulds were put into a heated oven at 60°C for foaming. After the mould had been removed, and after maturing at ambient conditions for 7 days, the resulting blocks of foam were each cut, to produceone block (dimension: 30 x 30 cm) to examine for cracking and to measure thermal conductivity, and

[0293] 6 cubes (dimension: 5 x 5 x 5 cm) for compressive strength testing.

[0294] Table 16. List of experiments.

[0295]

[0296] 1SiO2:Na2O 1.6:1.

[0297] Adjusted measurement conditions

[0298] Before compressive strength measurements, the height of each cube was adjusted, to obtain cubes with the dimensions of 5 x 5 x 5 cm. All measurements of compressive strength were done after 7 days of conditioning at room temperature after disassembling the mould.

[0299] Before thermal conductivity measurements, the height of all blocks was adjusted to about 5 cm. In case where foaming was not enough to obtain 5 cm high blocks, thermal conductivity was measured without cutting. Before measuring thermal conductivity, the blocks were conditioned in an oven, overnight at 60 °C. The measurements of thermal conductivity were conducted with LaserComp FOX 314 SpectroLab.

[0300] Different amounts of hydrogen peroxide in Example T and Examples 2 to 5 Examples T and 2 to 5 were prepared with the similar raw materials and ratios as Example 1 but using different amounts of hydrogen peroxide as foaming agent (Table 16). The resulting densities and compressive strengths (of the cubes) are shown in Table 17, and the observed thermal conductivities (of the blocks) are shown in Table 18.Table 17.

[0301]

[0302] Table 18.

[0303]

[0304] Tables 17 and 18 above show that geopolymer foam blocks can be produced having advantageous values for density, compressive strength and thermal conductivity.

[0305] Surfactant use in Comparative Example 5 (CE5) and Example T

[0306] Example T used CoatOSil PRIM2 as additive and an emulsion of calcium stearate as surfactant, Comparative Example 5 was prepared similar to Example T, but using (3-aminopropyl)trimethoxysilane as additive, and canola oil as surfactant. A comparison of resulting densities and compressive strength (of the cubes) is shown in Table 19, and the observed thermal conductivities (of the blocks) are shown in Table 20.

[0307] Table 19.

[0308]

[0309] Comparative Example 5 shows similar thermal conductivity to Example T and Example 1 , but is significantly lower in compressive strength, even at a density that is higher than Example T or Example 1. Also, the geopolymer foam block prepared with canola oil and (3-aminopropyl)trimethoxysilane showed cracking after demoulding, as shown in Figures 4a and 4b.

Claims

Synthos Dwory 7 23 December 2025SH 1909-02WO Claims1. Use ofa water-based emulsion of at least one agent selected from silanes and siloxanes, the silane or siloxane having 1) one or more Ci- to Cso-alkyl groups and optionally 2) one or more Ci- to Cs-alkoxy groups, anda water-based emulsion of salt of Ci6 to C20 fatty acid,in a gel stage of a process for preparing a geopolymer material foam,- to increase the surface area of a foamed gel in a foaming stage of the process, and / or- to reduce shrinkage and crack formation during a curing stage of the process, and / or- to increase compressive strength and decrease thermal conductivity of the geopolymer material foam, the geopolymer material foam having a density in a range of from 20 to 800 kg / m3.

2. A process for preparing a geopolymer material foam, comprising the following stepsa. mixing of a1) at least one aluminosilicate, a2) at least one alkaline constituent, a3) at least one pozzolanic additive, a4) water-based emulsion of microstructure modifier, a5) water-based emulsion of nucleating agent, and a6) foaming agent precursor, to form a gel;b. pouring the gel into a mould, the mould having a bottom part and at least two side parts, and then closing the mould with a lid part;c. foaming and curing the gel in the closed mould at a temperature in a range of from 60 to 80 °C, to obtain foamed partially cured gel;d. at a temperature in a range of from 60 to 80 °C,d. i. removing the lid part from the mould;d. ii. then further curing the foamed partially cured gel;d. iii. then removing at least one side part from the mould; and d. iv. then further curing with at least one side part present, to obtain fully cured foam;e. cooling the fully cured foam to a temperature in a range of from 10 to 30 °C; andf. removing any remaining side parts, to obtain the geopolymer material foam,whereincomponent a4) comprises at least one agent selected from silanes and siloxanes, the silane or siloxane having 1) one or more Ci- to Cso-alkyl groups and optionally 2) one or more Ci- to Cs-alkoxy groups, andcomponent a5) comprises salt of Ci6 to C20 fatty acid.

3. The process according the claim 2, wherein mixing step a. comprisesa. i. mixing of the a1) aluminosilicate component, the a2) alkaline component, and the a3) pozzolanic additive component, for a duration of from 5 to 30 minutes;a. ii. adding the a4) microstructure modifier component, and mixing, then adding the a5) water nucleating agent component, and mixing; a. iii. adding the a6) foaming agent precursor component, and mixing, to form the gel.

4. The process according to one of claims 2 or 3, wherein the a5) nucleating agent component comprises, based on the weight of the emulsion, from 35 to 45 wt.% of salt of C16 to C20 fatty acid, wherein the weight of the salt of C16 to C20 fatty acid is calculated as calcium salt.

5. The process according to one of claims 2 to 4, wherein the amount of component a5) is in a range of from 0.1 to 1.3 wt.%, based on the weight of the gel, preferably in a range of from 0.25 to 0.65 wt.%, more preferably in a range of from 0.3 to 0.4 wt.%.

6. The process according to one of claims 2 to 5, wherein component a4) comprises at least one agent selected from silanes and siloxanes, the silane or siloxane having 1) one or more C2- to C2o-alkyl groups and optionally 2) one or more C2- to Cs-alkoxy groups,the silane or siloxane preferably having 1) one or more C2- to Cw-alkyl groups and optionally 2) one or more C2- to Cs-alkoxy groups.

7. The process according to one of claims 2 to 6, wherein the amount of component a4) is in a range of from 0.01 to 0.5 wt.% based on the weight of the gel, morepreferably in a range of from 0.02 to 0.2 wt.% and most preferably in a range of from 0.05 to 0.15 wt.%.

8. The process according to one of claims 2 to 7, wherein the a6) foaming agent precursor is hydrogen peroxide solution, preferably in an amount of from 0.15 to 5 wt.%, based on the weight of the gel, more preferably in an amount of from 0.3 to 3 wt.%, most preferably in an amount of from 0.5 to 2 wt.%, particularly in an amount of from 1 to 2 wt.%.

9. The process according to one of claims 2 to 8, wherein the a1) aluminosilicate component is selected from furnace slag, metakaolin, and mixture thereof.

10. The process according to claim 9, wherein the a1) aluminosilicate component is a mixture of furnace slag and metakaolin, and the weight ratio of the furnace slag to the metakaolin is in a range from 2:1 to 1 :2, preferably in a weight ratio of in a range from 1.5: 1 to 1 : 1.5, and more preferably in a weight ratio of about 1:

1.

11. The process according to one of claims 2 to 10, wherein the a2) alkaline component is an alkali metal water glass solution, preferably a sodium water glass solution, more preferably a sodium water glass solution having a molar ratio of SiC>2 to Na2O in a range of from 1.2:1 to 2.2:1, most preferably in a range of from 1.4:1 to 1.8:1.

12. The process according to claim 11, wherein component a2) is a sodium water glass solution havingx. a water content in a range of from 40 to 80 wt.%, with respect to the weight of the water glass solution, preferably in a range of from 50 to 70 wt.%, and y. the weight ratio of component a2) to component a1) is in a range of from 0.6 to 2.2, preferably in a range of from 0.6 to 1.2.

13. The process according to one of claims 2 to 12, wherein the a3) pozzolanic component is selected from recycled geopolymer material foam, amorphous silica, pozzolana powder, and a mixture thereof,preferably wherein the recycled geopolymer material foam is used in milled form, and makes up in a range of from 0.1 to 10 % by weight, based on the total weight of the a3) pozzolanic component, more preferably 1 to 5 % by weight.

14. The process according to one of claims 2 to 13, wherein the mixing in step a. is of at least:20 to 30 wt.% of furnace slag,20 to 30 wt.% of metakaolin,0.3 to 5 wt.% of amorphous silica, preferably 0.4 to 2 wt.%, 0.3 to 5 wt.% of pozzolana powder, preferably 0.4 to 2 wt.%, and40 to 50 wt.% sodium water glass solution, the sodium water glass solution having a water content in range of from 50 to 70 wt.%,each based on the weight of the gel.

15. The process according to one of claims 2 to 14, wherein the mould has a rectangular bottom part, separately removable side parts, and a lid part, wherein at least the inner sides of the bottom part and of the side parts are coated with PTFE, a PTFE-based material, a polycarbonate-based material, a polyurethane-based material, or a mixture thereof.

16. A geopolymer material foam comprisingA. geopolymer,B. moieties derived from Ci6 to C20 fatty acid,C. moieties derived from an agent selected from silanes and siloxanes, the silane or siloxane having 1) one or more Ci- to Cso-alkyl groups, optionally 2) one or more Ci- to Cs-alkoxy groups,wherein the geopolymer material foam comprises from 19.0 to 28.0 wt.% of silicon, from 8.5 to 13.0 wt.% of calcium, from 7.0 to 12.0 wt.% of sodium, from 7.2 to 10.8 wt.% of aluminium, from 0.9 to 1.5 wt.% of magnesium, and from 0.45 to 0.75 wt.% of iron, with respect to the weight of the geopolymer material foam, each measured by X-ray fluorescence spectroscopy,and wherein the geopolymer material foam hasa density in a range of from 20 to 800 kg / m3, as measured according to EN 771-13:2000,a compressive strength in a range of from 0.1 to 5 MPa, as measured according to EN 772-1:2001, measured after 1 or more days after complete demoulding, anda thermal conductivity in a range of from 40 to 90 mW / m K, as measured according to ISO 8301:1991.

17. The geopolymer material foam according to claim 16, wherein the agent selected from silanes or siloxanes has 1) one or more C2- to C2o-alkyl groups and optionally 2) one or more C2- to Cs-alkoxy groups,preferably wherein the agent selected from silanes or siloxanes has 1) one or more C2- to C -alkyl groups and optionally 2) one or more C2- to Cs-alkoxy groups.

18. The geopolymer material foam according to claim 16 or 17, comprising- from 20.5 to 26.0 wt.% of silicon, preferably from 21.5 to 25.0 wt.%, more preferred from 22.5 to 24.0 wt.%,- from 9.2 to 12.0 wt.% of calcium, preferably from 9.7 to 11.5 wt.%, more preferred from 10.2 to 11.0 wt.%,- from 8.0 to 11.0 wt.% of sodium, preferably from 9.1 to 10.5 wt.%, more preferred from 9.4 to 10.2 wt.%,- from 7.6 to 10.3 wt.% of aluminium, preferably from 8.3 to 9.6 wt.%, more preferred from 8.6 to 9.3 wt.%,- from 1.0 to 1.35 wt.% of magnesium, preferably from 1.05 to 1.30 wt.%, more preferred from 1.10 to 1.25 wt.%, and- from 0.51 to 0.70 wt.% of iron, preferably from 0.54 to 0.66 wt.%, more preferred from 0.57 to 0.63 wt.%,each with respect to the weight of the geopolymer material foam, and each measured by X-ray fluorescence spectroscopy.

19. The geopolymer material foam according to one of claims 16 to 18, having a content of organic material of 1 wt.% or less, determined according to DIN EN 771-4+A1:2015-10.

20. The geopolymer material foam according to one of claims 16 to 19, having a density in a range of from 50 to 700 kg / m3, preferably in a range of from 100 to 550 kg / m3, and more preferably in a range of from 300 to 350 kg / m3, as measured according to EN 771-13:2000.

21. The geopolymer material foam according to one of claims 16 to 20, having a thermal conductivity in a range of from 50 to 85 mW / m K, preferably in a range of from 65 to 80 mW / m K, and more preferably in a range of from 67 to 75 mW / m K, as measured according to ISO 8301:1991.

22. The geopolymer material foam according to one of claims 16 to 21, having a compressive strength in a range of from 0.5 to 4 MPa, preferably in a range of from 1 to 3 MPa, and more preferably in a range of from 1.6 to 2.4 MPa, as measured according to EN 772-1:2001, measured after 1 or more days after complete demoulding.

23. The geopolymer material foam according to one of claims 16 to 22, wherein the cells of the geopolymer material foam have an ellipsoid cross-section, and the length of the major axis is 1 mm or less, preferably 0.8 mm or less, more preferred 0.6 mm or less, as measured according to the method in the description.

24. The geopolymer material foam according to one of claims 16 to 23, having an absolute value of total movement coefficient Alc / I of less than 1 mm / m, as measured according to DIN EN 772-14:2002.

25. The geopolymer material foam according to one of claims 16 to 24, having a water vapour resistance factor of more than 4, as measured according to ISO 12572:2016.

26. The geopolymer material foam according to one of claims 16 to 25, having a radioactive concentration index "I" smaller than 1, preferably smaller than 0.8, more preferred smaller than 0.6, as measured according to Handbook No.455 / 2010 of the Polish Building Research Institute.

27. The geopolymer material foam according to one of the claims 16 to 26, wherein the geopolymer material foam is resistant against freeze-thaw damage as measured according to DIN EN 153042010-06.

28. Geopolymer material foam prepared or preparable by the process according to one of claims 2 to 15.

29. The geopolymer material foam according to one of claims 16 to 26 in the form of a block or a panel.

30. A process of construction of a building comprising the steps ofa. joining at least two of the blocks or panels according to claim 29 with mortar;b. at least partially curing the mortar.

31. A thermal insulation or building system comprising the block or panel according to claim 29.

32. The thermal insulation or building system of claim 31, further comprising mortar.

33. A building comprising the block or panel according to claim 29, or the thermal insulation or building system according to one of claims 31 or 32.

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