Geopolymer sheet

Abstract

Geopolymer sheets can be formed by applying a geopolymer composition on a sheet. In some aspects, the sheet can be a porous sheet or non-porous sheet. The geopolymer composition can be prepared from an aqueous formulation of one or more metal silicates, one or more metal oxides, one or more water-soluble caustic agents, and water. In some implementations, the geopolymer composition can be free of, or substantially free of, large solid particles comprised of the metal silicate, metal oxide and water-soluble caustic agent. Such geopolymer sheets can be readily applied to an underlying substrate to transfer a geopolymer thereon and improve the fire resistance of the underlying substrate.

Description

GEOPOLYMER SHEETCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and all benefit of U.S. Provisional Patent Application No. 63 / 706,023, filed on October 10, 2024, the entire disclosure of which is fully incorporated herein by reference.TECHNICAL FIELD

[0002] The present disclosure is directed to sheets having a geopolymer. Such sheets can be prepared from a porous sheet impregnated with a geopolymer composition. Alternatively, such geopolymer sheets can be prepared from a non-porous sheet coated on at least one major surface thereof with a geopolymer composition. Geopolymer sheets can be used to protect an underlying substrate by fastening or bonding to same.BACKGROUND

[0003] Many items used in the construction industry are composed of inherently flammable materials including, for example, poles, beams, columns, decking, walls, etc. Many of these materials can be broadly classified as cellulosic (e.g., wood products) and / or organic polymeric (e.g., thermoplastic and thermoset resin products). All organic materials (i.e., carbon-containing materials) can degrade thermolytically and / or combust at sufficiently high temperatures in the presence of air (oxygen). Some ways to mitigate the combustibility of such materials are to add chemical components into the material to resist combustion or to coat the materials to slow the migration of heat and oxygen into a part and hinder the release of flammable fragments from the part. Such methods, however, generally require handling chemical components by a manufacturer and are generally not applicable to use in the field.

[0004] Other ways to mitigate the combustibility of organic materials in the construction industry include wraps. For example, there are approximately 150 million wooden utility poles in North America, many are in areas prone to forest fires. Pole wraps including fiberglass mesh with intumescent coatings can be effective in protecting wooden poles against fire. However, the cost of current fire resistant materials and difficulty in its application have limited their use. In another example, most commercial and residential constructions in North America use OSB for partition, roofing, and floor, etc. In order to achieve required fire rating, FR panels must be used to isolate the OSB board from potential fire source, resulting in additional cost, weight, and installation time.

[0005] Accordingly, a continuing need exists for an effective, economical, and operationally viable process to improve fire resistance of construction materials including utility poles.SUMMARY OF THE DISCLOSURE

[0006] Advantages of the present disclosure include geopolymer sheets that can be used to improve the flame resistance of a variety of substrates. Advantageously, the geopolymer sheets of the present disclosure can be flexible and can be bonded, adhered, or otherwise fastened to, or wrapped around, a variety of substrates.

[0007] In certain implementations, the geopolymer sheet includes a sheet with a geopolymer thereon and / or therein. Such geopolymer sheets can be formed by applying a geopolymer composition on a sheet. In some aspects, the sheet is a porous sheet in which geopolymer sheets can be formed by impregnating the porous sheet with the geopolymer composition. In other aspects, the sheet is a non-porous sheet, e.g., impervious sheet, in which a geopolymer composition is applied directly on such a sheet. To improve flexibility, the geopolymer sheet advantageously can be a thin sheet. In addition, the geopolymer composition can be partially cured after applying a geopolymer composition on the sheet and more fully cured after the geopolymer sheet is applied to an underlying substrate.

[0008] In certain aspects, the geopolymer composition comprises an aqueous formulation based on geopolymer matrix forming components of a metal silicate, a metal oxide, a water-soluble caustic agent, and water. It is understood that a metal hydroxide (i.e., a hydrated form of the metal oxide) can be used in place of a metal oxide in the present disclosure. An advantage of the aqueous formulation of the present disclosure is that it generally can have a low solids content and / or it generally can be free of, or substantially free of large solid particles. For example, the aqueous formulation can have a low solids content of the metal silicate, metal oxide and water-soluble caustic agent; and / or the aqueous formulation can be free of, or substantially free of, large solid particles comprised of the metal silicate, metal oxide and water-soluble caustic agent. Limiting the amount of solids in the formulation and / or limiting the size of solid particles in the aqueous formulation allows for the geopolymer composition to be applied as one or more thin layers and / or applied by a liquid atomizer or liquid aerosol spray. Further, the aqueous formulation of the present disclosure advantageously can have all of the components that react to form a geopolymer matrix (e.g., metal silicate, metal oxide, water-soluble caustic agent, and other reactive components) dissolved or substantially dissolved in the formulation. Limiting the amount of solids in the formulation and limiting the size of solid particles in the aqueous formulation further allowsformation of a more uniform geopolymer matrix from the geopolymer forming components with a substantial lack of aggregated material on the geopolymer sheet.

[0009] In other aspects, the geopolymer composition can further comprise optional components such as one or more catalysts or activators, one or more pigments, one or more rheology modifiers, one or more ceramic particles, one or more fibers, one or more surfactants, or any combination thereof. Certain of these components may or may not be soluble in the composition and may be solid components of the coating composition.

[0010] In some implementations, the metal silicate comprises one or more of: an alkali metal silicate, sodium silicate, neosilicates, sorosilicates, cyclosilicates, inosilicates, phyllosilicates, tectosilcates, mullite, kaolinite, muscovite, or any combination thereof. In other implementations, the metal oxide comprises one or more of aluminum trihydrate (ATH), zinc oxide (ZnO), iron oxide, titanium dioxide (TiCh), copper oxide, zirconium oxide, manganese oxide, nickel oxide, silver oxide, vanadium oxide, bismuth oxide, tin oxide, lead oxide, aluminum oxide, chromium oxide, cobalt oxide, or any combination thereof. Further, the metal oxide can be used as the hydrated (hydroxy) form of itself. In still further implementations, the water-soluble caustic agent comprises one or more of an alkali metal hydroxide, Na2O(SiO2), or ammonium hydroxide.

[0011] Advantageously, a variety of sheets can be used in the present disclosure. In some aspects, the sheet is a porous sheet that can be impregnated by the geopolymer composition. Such porous sheets include, for example, a woven, non-woven, or knit fabric, felt, paper, veil, scrim, a cellulosic material, or any combinations thereof. In certain aspects, the cellulosic material can include corrugated paper board, fiber board, kraft paper, or any combination thereof. In some aspects, the porous sheet can include a plurality of fibers. For example, the porous sheet can include a plurality of fibers composed of cellulosics and cellulosic derivatives, polyamide, aramid, polyethylene terephthalate, polyvinyl alcohol, polyvinylbutyral, acrylic, glass, basalt, carbon, or any combination thereof. In other aspects, the sheet can be a non-porous sheets and coated, on at least one major surface thereof, with geopolymer composition. Such non-porous sheets include, for example, a metallic foil, plastic film, or otherwise thin material.

[0012] In certain implementations of the present disclosure, the geopolymer sheet can be prepared by applying the geopolymer composition onto a major surface, and / or on an opposing major surface of the sheet and drying the applied composition to at least partially cure the geopolymer composition to form the geopolymer sheet. Advantageously, the geopolymer composition can be applied by spraying the composition onto a sheet as an aerosol. Alternatively,or in addition thereto, the geopolymer composition can be applied by dip coating, rolling, brushing, etc. In some implementations, the applied geopolymer composition can be dried in air at a temperature of from about 5 °C to about 50 °C or can be dried by exposing the applied composition to heat at a temperature of from about 50 °C to about 500 °C.

[0013] In other implementations, the geopolymer sheets of the present disclosure can be applied to a substrate. Advantageously, the geopolymer sheets of the present disclosure can act as a fire resistant barrier to the underlying substrate. For example, geopolymer sheets of the present disclosure can be applied to substrates such as metallic and inorganic surfaces (barriers)- gypsum, cementitious, mortar, and drywall panels (barriers), etc., construction panels, with or without a core including foamed cores, construction boards, wooden poles, structural insulated panels (i.e. SIPs), etc.

[0014] Additional advantages of the present disclosure will become readily apparent to those skilled in this art from the following detailed description, wherein only certain embodiments are shown and described, simply by way of illustration of carrying out certain subject matter. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modifications in various respects, all without departing from the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Reference is made to the attached drawings, wherein elements having the same reference numeral designations represent similar elements throughout and wherein:

[0016] FIG. 1A illustrates a porous sheet having a geopolymer composition impregnated therein according to one or more aspects disclosed herein;

[0017] FIG. IB illustrates a non-porous sheet having a geopolymer composition thereon according to one or more aspects disclosed herein;

[0018] FIG. 2 illustrates a perspective view of a composite board including a core and geopolymer sheet layers adhered to the first and second major surfaces of the core according to one or more aspects disclosed herein;

[0019] FIG. 3 illustrates a perspective view of a composite board including a core having a layer of unidirectional tape adhered to the first and second major surfaces of the core and geopolymer sheet layers adhered to the unidirectional tape according to one or more aspects disclosed herein;

[0020] FIG. 4 illustrates a geopolymer sheet wrapped around a utility pole according to one or more aspects disclosed herein;

[0021] FIG. 5A is a photograph of a porous sheet composed of woven yarns;

[0022] FIG. 5B is a photograph of the porous sheet of FIG. 5A that has been impregnated with a geopolymer composition according to one or more aspects disclosed herein;

[0023] FIG. 5C is a photograph of the geopolymer sheet of FIG. 5B that has been adhered to a wooden panel according to one or more aspects disclosed herein;

[0024] FIG. 6A is a photograph of a non-porous sheet comprised of aluminum;

[0025] FIG. 6B is a photograph of the non-porous sheet of FIG. 6A that has been coated with a geopolymer composition according to one or more aspects disclosed herein; and

[0026] FIG. 6C is a photograph of the geopolymer sheet of FIG. 6B that has been adhered to the surface of a composite thermoplastic sandwich panel according to one or more aspects disclosed herein.DETAILED DESCRIPTION

[0027] The disclosure may be more fully appreciated by reference to the following description, including the following definitions and examples. Certain features of the disclosed compositions and methods which are described herein in the context of separate aspects, may also be provided in combination in a single aspect. Alternatively, various features of the disclosed compositions and methods that are, for brevity, described in the context of a single aspect, may also be provided separately or in any sub-combination.

[0028] Unless otherwise defined herein, scientific and technical terms used in connection with the present application shall have the meanings that are commonly understood by those of ordinary skill in the art. Further, unless otherwise required by context, singular terms shall include pluralities and plural terms shall include the singular.

[0029] As employed above and throughout the disclosure, the following terms and abbreviations, unless otherwise indicated, shall be understood to have the following meanings.

[0030] As used in the specification including the appended claims, the singular forms “a,” “an,” and “the” include the plural, and reference to a particular numerical value includes at least that particular value, unless the context clearly dictates otherwise.

[0031] As used in the specification including the appended claims, when a range of values is expressed, such range includes from the one particular value and / or to the other particular value. All ranges are inclusive and combinable. Further, reference to values stated in ranges includes each and every value within that range. The term “about” as used herein when referring to a measurable value such as an amount, a temporal duration, and the like, is meant to encompass reasonable variations of the value.

[0032] The present disclosure is directed to geopolymer sheets. Such sheets can have a total thickness of no more than about 0.125 inches. For example, geopolymer sheets of the present disclosure can have a thickness in the range of from about 0.001 inches to about 0.1 inches. Further the width of the geopolymer sheet can be one or more orders of magnitude greater than the thickness. For example, the geopolymer sheets of the present disclosure can have a width of from about 4 inches (0.333 feet) to about 120 inches (10 feet). Similarly, the length of the geopolymer sheet can be one or more orders of magnitude greater than the thickness or the width. For example, the geopolymer sheets can have a length from about 4 inches (0.333 feet) to about 300 feet.

[0033] Once the geopolymer composition on the geopolymer sheet is fully cured (e.g., substantially all water removed), the cured geopolymer can be in a range of about 15 wt% to about 95 wt%, based on the total weight of the geopolymer sheet. In addition, the sheet, e.g., porous sheet or non-porous sheet, can comprise about 5 wt% to about 85 wt% of the geopolymer sheet based on a total weight of the geopolymer sheet.

[0034] FIGS. 1A and IB illustrate a geopolymer sheet according to certain implementations of the present disclosure. In particular, FIG. 1A illustrates a porous sheet 102a having a geopolymer composition 104a impregnated therein to form a geopolymer sheet 100 A. As illustrated in this example, the porous sheet can absorb the geopolymer composition and have the composition within and on the porous sheet. Advantageously, a variety of porous sheets can be impregnated by the geopolymer composition and include, for example, a woven fabric, a nonwoven fabric, a knit fabric, a cellulosic material, a felt, a paper, a veil, a scrim or any combinationthereof. In certain aspects, the cellulosic material can include corrugated paper board, fiber board, kraft paper, or any combination thereof. In some aspects, the porous sheet can include a plurality of fibers. Such plurality of fibers can be configured in a tow, yarn, end, pic, roving, compound yam (core-sheath yam), folded yarns, or cabled yams. The plurality of fibers can be composed of a variety of materials. For example, the porous sheet can include a plurality of fibers composed of cellulosics and cellulosic derivatives, such as cotton, rayon, linen, jute, coir, hemp, or cellulose acetate, wool, silk, polymeric fibers such as polyamide, aramid, polyethylene terephthalate (PET), polyvinyl alcohol, polyvinyl butyral, polyethylene, polypropylene, polyphenylene sulfide, polyacrylonitrile (PAN), acrylic fibers, glass fibers, basalt fibers, carbon fibers, metallic fibers or any combination thereof. In some aspects, the porous sheet includes a plurality of glass fibers such as a plurality of fibers comprising E-glass, A-glass, C-glass, D-glass, S-glass, ECR-glass, AR glass, R-glass, or any combination thereof.

[0035] FIG. IB illustrates a geopolymer sheet 100B composed of a non-porous sheet 102b having a geopolymer composition 104b deposited directly on the non-porous sheet. In this example, the geopolymer composition coats one major surface of the non-porous, impervious sheet. Advantageously, the geopolymer composition of the present disclosure can be applied on a variety of non-porous sheets including, for example, a non-porous metallic sheet such as a foil of aluminum, steel, copper, zinc, or other metal alloy, a polymeric sheet such as a thermoplastic film comprising polyethylene terephthalate (PET), polyvinyl acetate (PVAc), polyamide, polyketoneethylene (PKE), polyvinylbutyral (PVB), ethyleneacrylic copolymers, ethyleneacrylate salt copolymers, polyvinyl alcohol film (PVA), maleated polyethylene, polyphenylene sulfide (PPS), polyvinylchloride (PVC), styrene acrylonitrile copolymer (SAN), cellulose acetate, or any combinations thereof.GEOPOLYMER COMPOSITIONS

[0036] Tthe geopolymer compositions can be composed of relatively low cost components and can be used to impregnate porous sheets. The geopolymer composition can be at least partially cured on the sheet to form geopolymer sheets. Such geopolymer sheets then can readily be used to impart a geopolymer coating onto an underlying substrate by applying one or more geopolymer sheets to the underlying substrate. Geopolymer sheets of the present disclosure on or wrapped around an underlying substrate advantageously can improve fire resistance, weather-resistance, moisture loss or gain of the underlying substrate.

[0037] In certain aspects, a geopolymer composition of the present disclosure can comprise an aqueous formulation prepared from a metal silicate, a metal oxide, a water-soluble caustic agent, and water. The metal silicate, metal oxide, water-soluble caustic agent components of the aqueous formulation can react to form a geopolymer matrix. As discussed further below, the geopolymer matrix forming components of the formulation advantageously can be dissolved or substantially dissolved in the formulation. Moreover, the aqueous formulation can be included in the geopolymer composition which can include components other than the geopolymer matrix forming components which may or may not be dissolved or substantially dissolved in the geopolymer composition.

[0038] The aqueous formulation of the present disclosure generally can have a low solids content and / or it generally can be free of, or substantially free of large solid particles. For example, the aqueous formulation can have a low solids content comprised of the metal silicate, metal oxide and water-soluble caustic agent. Additionally or alternatively, the aqueous formulation can be free of, or substantially free of, large solid particles comprised of the metal silicate, metal oxide and water-soluble caustic agent. Limiting the solids content and / or size of solid particles in the aqueous formulation allows a geopolymer composition to be applied as one or more thin layers and / or applied by a liquid atomizer or liquid aerosol spray on to the porous sheet. Further, the aqueous formulation of the present disclosure can have all of the components that react to form a geopolymer matrix (e.g., metal silicate, metal oxide, water-soluble caustic agent, and other reactive components) dissolved or substantially dissolved in the aqueous formulation to allow a more uniform geopolymer matrix with a substantial lack of aggregated material on the geopolymer sheet.

[0039] In addition, the aqueous formulation can be included in a geopolymer composition which can include components other than the geopolymer matrix forming components which may or may not be dissolved or substantially dissolved in the composition. However, it can be advantageous to limit the solids content and / or particle size of the entire geopolymer composition.

[0040] In certain aspects, the geopolymer composition, and / or the aqueous formulation, of the present disclosure has a solids content of no more than 10 weight percent (wt%) based on the total weight of the geopolymer composition and / or the aqueous formulation. The solids content and particle size is determined when the composition or formulation, as the case may be, is at a temperature of 25 °C. For example, a geopolymer composition, and / or the aqueous formulation, of the present disclosure can include no more than 8 wt%, 6 wt% 4 wt%, 2 wt%, 1 wt%, and evenless than 1 wt%, of solids in the geopolymer composition and / or aqueous formulation, based on the total weight of the composition and / or formulation at a temperature of 25 °C.

[0041] In other aspects, the geopolymer composition and / or aqueous formulation is free of, or substantially free of, solid particles comprised of the metal silicate, metal oxide and water-soluble caustic agent having no more than 10 wt% of such solid particles based on the total weight of the composition or formulation at a temperature of 25 °C, e.g., no more than 8 wt%, 6 wt% 4 wt%, 2 wt%, 1 wt% or less of solid particles. In other implementations, the composition or formulation is free of, or substantially free of, any type of solid particles in such amounts.

[0042] In another aspect of the present disclosure, the geopolymer composition and / or aqueous formulation can exclude solid particles (e.g., the metal silicate, metal oxide and water-soluble caustic agent; or any type of solid particles) having an average diameter of greater than 10 pm, e.g., having an average diameter of no more than 5 pm, 3 pm, 2 pm, or no greater than 1 pm, when the composition or aqueous formulation is at a temperature of 25 °C. The average diameter of the solid particles may be determined by particle Dynamic Light Scattering (DLS). In cured coating compositions, the average particle size may be determined by Scanning Electron Microscopy (SEM). In some implementations, the geopolymer composition of the present disclosure can be a solution of its components at a temperature of 25 °C with no detectible solid particles as determined by filtering the solution through a 0.5 pm filter at a temperature of 25 °C or by an equivalent determination.

[0043] In other implementations, the geopolymer composition of the present disclosure can include optional components such as one or more catalysts or activators, e.g., carbonates or bicarbonates, phosphate acids and partial acids, or organic carboxylic acids to modify time of cure and / or reactivity of the formulation components; one or more pigments, e.g., to adjust color; one or more rheology modifiers; one or more ceramic particles such as ceramic spheres (e.g., ZEEO SPHERES™), carborundum (SiC), AI2O3, etc.; one or more fibers such as those composed of cellulose or cellulose derivatives, jute, coir, a polyamide, polyethylene terephthalate, acrylic, modacrylic, polyacrylonitrile, polyvinyl alcohol, basalt, glass, quartz, carbon, etc.; one or more surfactants; or any combination thereof. Certain of these components may or may not be soluble in the composition and may be solid components of the geopolymer composition. However, in some implementations, the geopolymer composition or aqueous formulation is free of, or substantially free of, solid particles comprised of the metal silicate, metal oxide and water-soluble caustic agent.

[0044] The amounts of the components used to form the aqueous formulation can be adjusted for ease of application of the formulation to the sheet, e.g., porous or non-porous sheet, and the desired characteristics of the formed geopolymer sheet. For example, the geopolymer composition can have a weight ratio of the metal silicate to metal oxide ranging from about 5: 1 to 1 :5, e.g., from about4.5:l, 4: 1, 3.5: 1, 3: 1, 2.5: 1, 2: 1, 1.5: 1, 1:1 to 1: 1, 1 :1.5, 1 :2, 1 :2.5, 1 :3, 1 :3.5, 1 :4, 1 :4.5, and any value thereof or therebetween. For example, the geopolymer composition can have a weight ratio of the metal silicate to metal oxide ranging from about 1 : 1 to about 1 :3 for rapid curing formulations and from about 3 : 1 to about 1.5: 1. In some implementations the aqueous formulation includes, based on the total weight of the aqueous formulation, 10 wt% to 45 wt% of the metal silicate, 5 wt% to 65 wt% of the metal oxide, 5 wt% to 30 wt% of the water-soluble caustic agent. In addition, the aqueous formulation can include, based on the total weight of the aqueous formulation, 25 wt% to 80 wt% of the water. For example, when used for dip-coating, the aqueous formulation can be formed from, on a weight basis, 10 wt% to 30 wt% of the metal silicate, 30 wt% to 40 wt% of the metal oxide, 5 wt% to 10 wt% of the water-soluble caustic agent, and 20 wt% to 50 wt% of the water, based on the total weight of the formulation. When used as an atomized spray application, the geopolymer composition can be formed from, on a weight basis, 15 wt% to 35 wt% of the metal silicate, 5 wt% to 30 wt% of the metal oxide, 10 wt% to 25 wt% of the water-soluble caustic agent, and 35 wt% to 70 wt% of the water, based on a total weight of the composition. Although, the metal silicate and the metal oxide components are sometimes listed separately in the present disclosure, these components can be included in the aqueous formulation from a source that has both of these components together, such a kaolin, etc. and forming the aqueous formulation is not limited to using the metal silicate and the metal oxide as separate components.

[0045] Useful metal silicates that can be used to form the compositions of the present disclosure include one or more of: an alkali metal silicate, neosilicates, sorosilicates, cyclosilicates, inosilicates, phyllosilicates, tectosilcates, mullite, kaolinite, muscovite, etc. or any combination thereof. The alkali metal silicate can include a sodium silicate, e.g., sodium metasilicate, Na2.vSirO2r .v or (Na2O).v (SiO2)r, such as sodium metasilicate (Na2SiOs), sodium orthosilicate (Na4SiO4), sodium pyrosilicate (NaeSi?©?), etc. These sodium silicate compounds are generally colorless transparent solids or white powders, and soluble in water in various concentrations. In some aspects of the present disclosure, the compositions and / or formulations comprise sodium metasilicate as the majority of the metal silicate, e.g. the metal silicate comprises at least 50 wt% sodium metasilicate such as at least 60 wt% of sodium metasilicate.

[0046] Metal oxides and metal hydroxides that can be used to form the compositions and aqueous formulations of the present disclosure include one or more of aluminum trihydrate (ATH) (A1(OH)3), zinc oxide (ZnO), iron oxide, titanium dioxide (TiCh), copper oxide, zirconium oxide, manganese oxide, nickel oxide, silver oxide, vanadium oxide, bismuth oxide, tin oxide, lead oxide, aluminum oxide, chromium oxide, cobalt oxide, or combinations thereof. Further, it is understood that metal oxides in aqueous solutions convert to their equivalent hydroxide, and thus the use of metal hydroxide is equivalent to use of the metal oxide (e.g., ZnO is equivalent to Zn(OH)2). Hence, a metal oxide in the present disclosure is understood to include or be substituted for its metal hydroxide. In some aspects of the present disclosure, the compositions and / or formulations are formed from aluminum trihydrate as the metal oxide in percent of the metal oxide of at least 20 wt% of the total metal oxide, e.g., 20 wt% to 100 wt%, 10 wt% to 50 wt%, or 75 wt% to 100 wt% of the total metal oxide.

[0047] The water-soluble caustic agent of the composition and formulation is designed to facilitate dissolution of the alkali metal silicate and metal oxide in water and any other component that can react with the alkali metal silicate and metal oxide in water. Examples of water-soluble caustic agents useful for the present disclosure include, without limitation or more of an alkali metal hydroxide (such as NaOH, KOH), alkali metal carbonates (such as Na2COs, K2CO3), alkali metal phosphates (such as NasPO4, K3PO4), Na2O(SiO2), ammonium hydroxide, or one or more combinations thereof. Sufficient amount of water-soluble caustic agent is combined with the alkali metal silicate and metal oxide to form a composition and / or formulation with the desired level of solids and will increase the pH of the compositions and / or formulation to generate a pH of no less than 8, such as a pH of no less than 8.5, 9, 9.5, 10, 10.5, 11, 12, 12.5, 13, 13.5, 14, etc. Increasing the pH tends to increase the amount of alkali metal silicate and metal oxide dissolved in the formulation.

[0048] In some aspects, the geopolymer compositions and / or formulations of the present disclosure has at least 95 wt% of the alkali silicate content as silicate ions in solution. This state can be determined, for example, when the solution can be passed through a 0.5 pm filter with no remaining visible particulate residue.

[0049] To facilitate spray application of the geopolymer compositions of the present disclosure, the composition can have a viscosity ranging from about 20 cP to about 2,000 cP as determined by cup and bob viscosity measurement at a temperature of 85 °F (29.4 °C). For example, the geopolymer compositions of the present disclosure can have a viscosity ranging fromabout 20 cP to about 200 cP for very thin, uniform application of the composition, and viscosity of about 140 cP to about 700 cP for thicker, rougher application on the sheet. To facilitate dip coating the geopolymer composition on a sheet, the viscosity can be generally from about 300 to 2,000 cP. Viscosity of the system measured by rotational viscometry (cup and bob viscosity measurement) is performed as per ASTM D2196, D2556, D7867.

[0050] The compositions and / or formulations of the present disclosure can be prepared by combining a metal silicate, a metal oxide, a water-soluble caustic agent, and water to form the composition. The metal silicate and the metal oxide can be from the same source material or separate source materials or a combination thereof. Geopolymer compositions can further include combining other components that can react with the metal silicate and the metal oxide dissolved in, or substantially dissolved in, the formulation and combining other optional components.

[0051] Further the components can be in a kit prior to preparing the formulation in which one or more of the components are isolated from another component in the kit. The order of combining the components is not particularly limiting. Some components, however, typically take longer to dissolve in water and are thus more suited to combining as an initial step. For example, the metal silicate can be dissolved in water to form a metal silicate solution and then combined with the other components to form the geopolymer composition. Alternatively or additionally, the water- soluble caustic agent can be dissolved in water to form a caustic agent solution and then combined with the other components. Alternatively or additionally, the metal silicate and caustic agent can be dissolved in water as a metal silicate-caustic agent solution and then combined with the other components to form the geopolymer composition. In some aspects, the initial alkali metal silicate, metal oxide, and / or water-soluble caustic agent initially can be in powder form such as finely divided powders having average powder diameters ranging from about 1 pm to about 40 pm. Such powder forms can facilitate dissolution of the components in a shortened period of time. (Typically when the powders have an average diameter of less than 1 micron, there can be viscosity increases associated with high surface areas to volume ratios.)

[0052] Further the kit can include the metal silicate solution isolated from the other components, or the caustic agent solution isolated from the other components, or the metal silicatecaustic agent solution isolated from the metal oxide and / or other components for forming the coating composition. The kit can further include instructions for preparing the geopolymer composition and / or aqueous formulation according to the present disclosure and can provide instructions on how to apply the formulation to form a geopolymer sheet.

[0053] As explained earlier, in some implementations the prepared geopolymer composition and / or formulation can be free of, or substantially free of, solids comprised of the metal silicate, metal oxide and water-soluble caustic agent and even free of or substantially free of any solid particles. Such compositions and formulations can be prepared by substantially or completely dissolving the reactive components that form the geopolymer matrix in water, including mixing and / or heating the composition until the desired dissolution of the component. Alternatively or additionally, preparing the compositions can include filtering the formed composition to remove solid particles and / or decanting the formed compositions from any solids. Filtering can be carried out by passing the formulation through a 0.5 pm to 50 pm filter or any range therebetween. Blending of the solution can be carried out by shear mixing, agitation, planetary centrifugal mixing, in-line static mixing, or other processes of combining liquid and solid components for dissolution or substantial dissolution. Particulate remnants may also be separated gravitationally or by centrifugal separation.

[0054] In certain implementations, the prepared geopolymer composition and / or formulation can include one or more optional components, e.g., a catalyst, activator, pigment, rheology modifier, ceramic particle, fibers, surfactant, or any combination thereof. For example, the geopolymer composition can include an optional pigment such as an organic pigment, e.g., azo dyes, etc., and / or an inorganic pigment, e.g., ultramarine blue (a complex sulfur-containing sodium-silicate), iron oxide, cobalt blue, Cerulean blue, Egyptian blue, Azurite, chrome green, cadmium yellow, cobalt green, Malachite, Primrose yellow (bismuth vanadate), lamp black, bone black, titanium oxide, manganese dioxide, lithopone, or copper oxide, etc. Certain of these components may or may not be soluble in the composition and may form solid components of the coating composition. However, in some implementations, the geopolymer composition or aqueous formulation is free of, or substantially free of, solid particles comprised of the metal silicate, metal oxide and water-soluble caustic agent. In one aspect, an optionally included pigment can be selected from an inorganic pigment (e.g., iron oxide, titanium oxide, or copper oxide) that can react with and covalently bond to the metal silicate and / or metal oxide upon forming a geopolymer matrix from the composition. In some aspects, such a reactive pigment can be dissolved or substantially dissolved in the formulation to facilitate reaction with other reactive components.PROCESS OF FORMING GEOPOLYMER SHEET

[0055] Geopolymer sheets can be formed from the geopolymer composition by applying the geopolymer composition to a sheet (e.g., a porous or non-porous sheet) and drying the appliedcomposition on the sheet to at least partially cure the composition into a sheet having a geopolymer matrix thereon and / or therebetween. As explained earlier, the components of the geopolymer composition form a geopolymer matrix based on a metal silicate, a metal oxide, a water-soluble caustic agent, and water. In some implementations, the geopolymer composition can have a low solids content and / or can be free, or substantially free, of large solid particles such as solid particles of the metal silicate, metal oxide and water-soluble caustic agent. Limiting the solid particle content and / or size of solid particles in the geopolymer composition and / or aqueous formulation permits forming a geopolymer sheet having a more or less uniform geopolymer matrix and facilitates formation of thin sheets without substantial aggregates. The geopolymer matrix is believed to be formed by a reaction among the metal silicate, metal oxide and water-soluble caustic agent dissolved in the formulation. In certain aspects, the aqueous formulation of the present disclosure advantageously can have all of the components that react to form the geopolymer matrix (e.g., metal silicate, metal oxide, water-soluble caustic agent, and other reactive components) dissolved or substantially dissolved in the formulation to allow formation of thin and uniform geopolymer sheets.

[0056] In some implementations, a geopolymer sheet can be formed by impregnating a porous sheet with a geopolymer composition. In other implementations, a geopolymer sheet can be formed by applying a geopolymer composition on at least one major surface or on both major surfaces of a non-porous sheet. The geopolymer compositions can be applied to a surface of the sheet in a variety of ways including brushing, rolling, spraying, dip coating, etc. In one aspect, the geopolymer composition is applied to the sheet by spraying the geopolymer composition onto one or more major surfaces of the sheet as an aerosol, e.g., a suspension of fine liquid droplets in air or another gas. Aerosol sprays can be generated from aerosol spray dispensers, atomizers, etc.

[0057] In some implementations, one or more geopolymer compositions can be applied to a sheet with the same or different geopolymer compositions. Concurrent with or after applying the one or more geopolymer compositions to the one or more major surfaces of the sheet, the geopolymer composition dries or is dried. Drying the geopolymer composition causes it to cure and bond to the sheet. Upon drying, the geopolymer composition forms long-range, covalently bonded, non-crystalline (amorphous) networks from the reactive components of the composition such as a geopolymeric matrix material.

[0058] Drying can be carried out conveniently in air at ambient conditions. For example, the geopolymer composition applied to the sheet can be dried in air from a temperature range of about5 °C to about 50 °C. Drying can also be carried out by heating at a temperature of from about 50 °C to about 500 °C in air or another gas, such as heating from 50 °C to about 500 °C, 50 °C to about 200 °C, 50 °C to about 150 °C. Heating can be carried out in air or an inert gas such as nitrogen.

[0059] In some implementations, a sheet (e.g., a porous sheet or nonporous sheet) can be pulled through an aqueous bath of the same or different geopolymer compositions to dip-coat and, in the case of a porous sheet, impregnate throughout the sheet. Once dipped, the sheet with the aqueous geopolymer solution can be pulled through an open-air convection oven for drying at about 50 °C to about 500 °C. Advantageously the drying temperature will be kept below the boiling point of water (below 100 °C or 212 °F at sea level) to facilitate an incomplete cure by leaving reactive sites available on the surface of the geopolymer sheet. Once applied to a final substrate for practical use, the sheet can be post-cured at a temperature of about 100 °C to about 500 °C, such as from about 100 °C to about 200 °C.USE OF GEOPOLYMER SHEET ON SUBSTRATE

[0060] Advantageously, geopolymer sheets of the present disclosure can be included on a variety of substrates including utility poles, building materials such as construction panels, construction boards, and SIPs.

[0061] Advantageously, geopolymer sheets of the present disclosure can be applied to substrates in manufacturing facility or in the field. Geopolymer sheets may be applied in the field, for example, by applying the geopolymer sheet to a substrate after a substrate is installed in its final location or prior to installation in the final location. The geopolymer sheets may be applied in the field immediately after installation in the final location or after a period of time after installation such as more than a week, more than four weeks, more than 25 weeks or more than a year after installation.

[0062] For example, the geopolymer sheets of the present disclosure can be applied to a construction board or insulation board having a first major surface and an opposing second major surface. Geopolymer sheets of the present disclosure can be applied (e.g., adhered or fastened) to either or both of the first and / or second major surfaces of such boards. In addition, the geopolymer sheets of the present disclosure can be applied to any or all edge surfaces of such boards connecting the first and second major surfaces of such boards. The construction board can be composed of a cellulose, polymer, cementitious based material, or a combination thereof. Construction boards orpanels that can benefit from having one or more geopolymer sheets thereon can have a length and width of each of up to about 64 feet (19.5 m) and a thickness, including the geopolymer sheet(s) thereon of up to about 16 inches (410 mm), e.g., a length and width from about 4 feet to about 16 feet and a thickness of from about 0.25 inches to about 8 inches. In some aspects, construction board of the present disclosure can have dimensions of length and width of up to 16 feet such as from about 4 feet to 16 feet and includes length and width dimensions, in feet, of standard 4 x 8 board, 4 x 12 board, 4 x 16 board, 4.5 x 12 board, 8 x 12 board, etc. In some aspects, construction board can have a thickness of up to about 12 inches, such as up to about 8 inches, e.g., from about 0.25 inches to about 8 inches. For example, construction boards of the present disclosure can have dimensions of a length and width from about 4 feet to about 16 feet and a thickness of from about 0.25 inches to about 8 inches. In some aspects, the construction board can include engineered wood, engineered cellulosic composite, a wood-plastic composite, a natural fiber plastic composite and includes, for example, plywood, fiberboard, high density fiberboard (HDF), medium-density fiberboard (MDF), oriented strand board (OSB), particle board, Masonite board, Balsa, wood planks, drop ceiling tile (plank), etc. Construction boards of the present disclosure also include boards composed of a plastic and composites thereof, such as fiber reinforced plastic (thermoset and thermoplastic) composite boards and sandwich boards thereof. Such plastic composite boards, also referred to as panels, can be configured to include a core having a first major surface and an opposing second major surface. In addition, one or more layers of a fiber reinforced facing sheet and / or one or more layers of fiber reinforced tape can be adhered to the first and second major surfaces of the core.

[0063] FIGS. 2 and 3 illustrate composite boards according to certain aspects of the present disclosure. In the example of FIG. 2, a composite board 200 includes a core 210 having a first major surface 212 and an opposing second major surface 214. One or more geopolymer sheets can be adhered to the first and second major surfaces of the core. As illustrated in FIG. 2, a geopolymer sheet 230a is adhered to the first major surface 212 and a second geopolymer sheet 230b is adhered to the opposing second major surface 214 of the core 210. In this construct, the geopolymer sheets 230a, 230b act as a skin or facing for the composite board. Although not illustrated, one or more geopolymer sheets also can be adhered to edge surfaces (e.g., 216, 218) of the composite board that connect the first and opposing major surfaces 212, 214 to completely encase the board.

[0064] FIG. 3 illustrates another composite board 300 in which the core 310 has an outer layer on its first and second major surfaces 312, 314. In this example, the outer layer is a unidirectionaltape or a multidirectional laminate 320a, 320b adhered to the first and second major surfaces 312, 314 of the core 310. Geopolymer sheets 330a, 330b are then adhered to the unidirectional tape or multidirectional laminate 320a, 320b on the first and second major surfaces 312, 314 of the core 310. In this construct, the geopolymer sheets 330a, 330b act as a skin or facing for the composite board.

[0065] In each of FIGS. 2 and 3, the thickness of the geopolymer sheet (shown in the Y direction) is significantly less than the length and width of the board (shown in the Z and X direction, respectively). In a non-limiting example, the geopolymer sheet can have a thickness of from about 1 mil to about 25 mil. The composite board thickness, including the geopolymer sheet(s) thereon and any outer layers between the geopolymer sheet and core, can have a length and width from about 4 feet to about 16 feet and a thickness of from about 0.25 inches to about 8 inches.

[0066] In some aspects, the core can have a foam, or honeycomb configuration. The core can be composed of a cellulosic material such as balsa wood and / or a polymer including a polymer configured as a foam or honeycomb configuration. Polymers that can be used for a core include, for example, a thermoset, such as a polyurethane and a foam thereof, a polyisocyanurate, and a foam thereof, etc. A thermoplastic and thermoplastic foams can also be used for the core such as a polyethylene terephthalate (PET), such as a fire retardant polyethylene terephthalate (FR PET), polyvinylchloride (PVC), styrene acrylonitrile (SAN) copolymer, a polyether imide (PEI), etc. and foams thereof. Inorganic materials can also be used for a core, for example, an inorganic and inorganic foam can be used for the core such as calcium silicate, and a foam thereof.

[0067] In addition to construction board, the geopolymer sheets of the present disclosure can be used to protect wooden utility poles. Advantageously, the geopolymer sheets of the present disclosure can be used to protect such utility poles already in the field by simply wrapping the pole with the geopolymer sheet and / or adhering the sheet to the pole. For example, and as shown in FIG. 4, a geopolymer sheet 430 can be wrapped around a utility pole 410. As described in more detail below, the geopolymer sheet can be adhered to the pole by treating a surface of the sheet and / or pole with an aqueous fluid, e.g., wetting with water, and allowing the sheet to dry on the pole with or without the application of pressure. Alternatively, a pre-cured geopolymer sheet can be mechanically fastened to a utility pole by means of common fasteners e.g., bands, clamps, staples, nails, or screws.

[0068] Advantageously, the geopolymer sheets of the present disclosure can be used to protect such construction panels already in the field by simply attaching the panel with the geopolymer sheet and / or adhering the sheet to the panel. The geopolymer sheet can be adhered to the pole by treating a surface of the sheet and / or pole with an aqueous fluid, e.g., wetting with water, and allowing the sheet to dry on the pole with or without the application of pressure. Alternatively, a pre-cured geopolymer sheet can be mechanically fastened to a utility pole by means of common fasteners e.g., staples, nails, or screws.PROCESS OF APPLYING GEOPOLYMER SHEET TO SUBSTRATE

[0069] In some implementations, the present disclosure includes applying one or more geopolymer sheets of the present disclosure to an underlying substrate. For example, a process for forming a geopolymer layer on a substrate can include: contacting a surface of the geopolymer sheet to a surface of a substrate. In such a process, the surface of the geopolymer sheet or the surface of the substrate or both surfaces can be treated, e.g., wetted, with an aqueous fluid prior to contacting the surfaces. The geopolymer sheet can be adhered to the contacted surface of the substrate by drying with optional application of pressure and optional heat. Further, treating the surface or surfaces can include spraying, rolling, brushing, or wiping the aqueous fluid on the surface(s). The treating aqueous fluid can comprise tap water, ground water, water having a pH of greater than 7, or 9, or 11, for example.

[0070] In some implementations, water or an aqueous solution is not required to facilitate the bond between the geopolymer sheet and the substrate. In these instances externally applied pressure with or without additional heat can be used to facilitate the bond between surfaces.

[0071] Further, if the geopolymer sheet is partially cured prior to contacting with the underlying substrate, the geopolymer sheet can be further cured on the substrate by drying with optional heating. For example, curing the geopolymer composition can include exposing the impregnated sheet in air to a temperature of from about 5 °C to about 500 °C. The upper limit of the cure temperature is dependent on the safe working temperature of the substrate.

[0072] Alternatively, or in addition, the geopolymer sheets can be adhered to the materials by applying an adhesive such as an adhesive thermoplastic film, glue, or any combination thereof.

[0073] In certain aspects, geopolymer sheets can be applied over one another to form a multilayer of geopolymer sheets.EXAMPLES

[0074] The following examples are intended to further illustrate certain aspects of the subject technology and are not limiting in nature. Those skilled in the art will recognize, or be able to ascertain, using no more than routine experimentation, numerous equivalents to the specific substances and procedures described herein.

[0075] A geopolymer composition was prepared by mixing 6 lbs. (2.72 kg) of aluminum hydroxide, 6 lbs. (2.72 kg) of zinc oxide, and 0.5 lbs. (0.23 kg) iron oxide in a plastic container to which was added 18 lbs. (8.16 kg) of 40% sodium silicate in water, 1 lb. (0.45 kg) of 50% sodium hydroxide in water, and 2 lbs. (0.91 kg) of water. The mixture was then shear mixed for 3 minutes, allowed to settle for 2 minutes, and then shear mixed an additional 2 minutes.

[0076] A geopolymer sheet was prepared by impregnating a woven fabric comprised of staple fiber yarns of blended materials including cotton and acrylic fiber (FIG. 5 A) by dip-coating and squeezing through pinch rollers with the aforementioned geopolymer composition. The geopolymer sheet was then partially cured by curing the geopolymer impregnated sheet for 12 hours at room temperature such that the prepreg sheet was still flexible and could be manipulated to fit on the surface or surfaces of a panel or pole of a desired geometry. FIG 5B shows an image of the geopolymer sheet having a partially cured geopolymer composition impregnated therein.

[0077] The geopolymer sheet was applied to the surface of a wooden panel by adding a small amount of water to the wooden surface and then pressing the geopolymer sheet on the surface of the wooden panel in a press to 250 psi (17.2 bar) for 1 minute. The resulting panel was then cured in an oven at 200 °F (93.3 °C) for 60 minutes to yield a finished panel with a geopolymer sheet adhered thereon (FIG. 5C).

[0078] In a similar fashion, a geopolymer sheet was prepared by applying the geopolymer composition to the surface of an aluminum sheet 0.010 inches thick (FIG. 6A) and curing at 160 °F (71.1 °C) for 30 minutes such that the sheet was still flexible and could be manipulated to fit on the surface or surfaces of a panel or pole of a desired geometry. The thus prepared geopolymer sheet is shown in FIG. 6B.

[0079] The geopolymer sheet as prepared in the previous paragraph was applied to the surface of a composite thermoplastic sandwich panel by preheating the panel to 200 °F (93.3 °C) and then pressing the geopolymer sheet on to the surface of the panel in a press to 250 psi (17.2 bar) for 1 minute to yield a finished panel with a non-porous geopolymer sheet adhered thereto (FIG. 6C).

[0080] Only certain features and aspects of the present disclosure and examples of their versatility are shown and described in the present disclosure. It is to be understood that the technology disclosed herein is capable of use in various other combinations and environments and is capable of changes or modifications. Thus, for example, those skilled in the art will recognize, or be able to ascertain, using no more than routine experimentation, numerous equivalents to the specific substances, procedures and arrangements described herein. Such equivalents are considered to be within the scope of the invention and are covered by the following claims.

Claims

WHAT IS CLAIMED IS:

1. A geopolymer sheet comprising: a sheet impregnated with a geopolymer composition; wherein the geopolymer composition is formed from an aqueous formulation that comprises geopolymer matrix forming components of: (a) a metal silicate; (b) a metal oxide; (c) a water-soluble caustic agent; and (d) water; and wherein the aqueous formulation has a solids content of less than 10 wt% and / or the aqueous formulation excludes solid particles having an average diameter of greater than 5 pm.

2. The geopolymer sheet of claim 1, wherein the sheet has a thickness in a range of from about 0.001 inches to about 0.125 inches (1 mil to about 125 mil).

3. The geopolymer sheet of any one of the preceding claims, wherein the geopolymer sheet comprises the geopolymer composition in a range of about 15 wt% to 95 wt%, based on the total weight of the geopolymer sheet.

4. The geopolymer sheet of any one of the preceding claims, wherein the sheet comprises about 5 wt% to about 85 wt% of the geopolymer sheet based on a total weight of the geopolymer sheet.

5. The geopolymer sheet of any one of the preceding claims, wherein the sheet comprises a porous sheet.

6. The geopolymer sheet of claim 5, wherein the porous sheet comprises a woven fabric, a non-woven or knit fabric, felt, paper, veil, scrim, a fibrous cellulosic material, or any combination thereof.

7. The geopolymer sheet of claim 5, wherein the porous sheet comprises a woven fabric selected from the group consisting of a plain weave, twill weave, satin weave, basket weave, leno weave, or any combination thereof.

8. The geopolymer sheet of claim 5, wherein the porous sheet comprises a cellulosic material selected from the group consisting of corrugated paper board, fiber board, kraft paper, or any combination thereof.

9. The geopolymer sheet of claim 5, wherein the porous sheet comprises a plurality of fibers comprising cellulosics and cellulosic derivatives, cotton, rayon, polymeric fibers, polyamide, aramid, polyethylene terephthalate, polyvinyl alcohol, polyvinyl butyral, polyethylene, polypropylene, polyphenylene sulfide, acrylic fibers, glass fibers, basalt fibers, carbon fibers, metallic fibers or any combination thereof.

10. The geopolymer sheet of claim 9, wherein the plurality of fibers are configured in a tow, yam, end, pic, roving, compound yarn, folded yarns, or cabled yarns.

11. The geopolymer sheet of any one of claims 1-4, wherein the sheet comprises a non-porous sheet.

12. The geopolymer sheet of claim 11, wherein the non-porous sheet comprises a foil of aluminum, steel, copper, zinc, or other metal alloy, a polymeric nonporous sheet, a thermoplastic film, a polyethylene terephthalate (PET) film, polyvinyl acetate film, polyvinyl alcohol film, or any combinations thereof.

13. The geopolymer sheet of any one of the preceding claims, wherein the aqueous formulation has a solids content of less than 5 wt% and / or the aqueous formulation excludes solid particles having an average diameter of greater than 3 pm when the aqueous formulation is at a temperature of 25 °C.

14. The geopolymer sheet of any one of the preceding claims, wherein the aqueous formulation is a solution of the metal silicate, the metal oxide, the water-soluble caustic agent, and water at 25 °C.

15. The geopolymer sheet of any one of the preceding claims, wherein the ratio of metal silicate to metal oxide ranges from about 5: 1 to 1 :5.

16. The geopolymer sheet of any one of the preceding claims, wherein at least 95 wt% of the silicate content in the fire resistant coating composition are silicate ions in solution.

17. The geopolymer sheet of any one of the preceding claims, wherein the metal silicate comprises at least 50 wt% sodium metasilicate.

18. The geopolymer sheet of any one of the preceding claims, wherein the aqueous formulation includes, based on the total weight of the aqueous formulation, 10% to 45% of the metal silicate, 5% to 65% of the metal oxide, and 5% to 25% of the water-soluble caustic agent.

19. The geopolymer sheet of any one of the preceding claims, wherein the aqueous formulation includes, based on the total weight of the aqueous formulation, 25% to 80% of the water.

20. The geopolymer sheet of any one of the preceding claims, wherein the aqueous formulation has a pH of no less than 9.

21. The geopolymer sheet of any one of the preceding claims, wherein the aqueous formulation has a viscosity ranging from about 25 cP to about 2,000 cP as measured by cup and bob viscosity measurement.

22. The geopolymer sheet of any one of the preceding claims, wherein the metal silicate comprises one or more of an alkali metal silicate, sodium silicate, neosilicates, sorosilicates, cyclosilicates, inosilicates, phyllosilicates, tectosilcates, mullite, kaolinite, muscovite, or any combination thereof.

23. The geopolymer sheet of any one of the preceding claims, wherein the metal oxide comprises one or more of: aluminum trihydrate (ATH), zinc oxide (ZnO), iron oxide, titanium dioxide (TiCh), copper oxide, zirconium oxide, manganese oxide, nickel oxide, silver oxide, vanadium oxide, bismuth oxide, tin oxide, lead oxide, aluminum oxide, chromium oxide, cobalt oxide, or any combination thereof.

24. The geopolymer sheet of any one of the preceding claims, wherein the water-soluble caustic agent comprises one or more of an alkali metal hydroxide, Na2O(SiO2), or ammonium hydroxide.

25. The geopolymer sheet of any one of the preceding claims, wherein the metal silicate comprises one or more of an alkali metal or alkali earth silicate; the metal oxide comprises one or more of aluminum trihydrate (ATH) or zinc oxide (ZnO); and the water-soluble caustic agent comprises one or more of NaOH, KOH, or Na2O(SiO2).

26. A process for forming a geopolymer sheet, the process comprising: applying a geopolymer composition on a sheet; and at least partially curing the geopolymer composition to form the geopolymer sheet; wherein the geopolymer composition is formed from an aqueous formulation that comprises geopolymer matrix forming components of: (a) a metal silicate; (b) a metal oxide; (c) a water-soluble caustic agent; and (d) water; and wherein the aqueous formulation has a solids content of less than 10 wt% and / or the aqueous formulation excludes solid particles having an average diameter of greater than 5 pm.

27. A process for forming a geopolymer layer on a substrate, the process comprising: applying a surface of the geopolymer sheet according to any one of the preceding claims to a surface of the substrate.

28. The process of claim 27, wherein applying the surface comprises: treating the surface of the geopolymer sheet or the surface of the substrate or both surfaces with an aqueous fluid and drying the geopolymer sheet on the substrate to adhere a geopolymer layer on the substrate.

29. The process of claim 28, wherein treating the surface or surfaces comprises spraying, rolling, brushing, or wiping the aqueous fluid on the surface.

30. The process of claim 29, wherein the aqueous fluid comprises tap water, ground water, water having a pH of 7 or greater.

31. The process of claim 27, wherein the geopolymer sheet is fastened or dry bonded to the surface of a substrate.

32. The process of claim 27, wherein a second geopolymer sheet is applied over the geopolymer sheet applied to the underlaying substrate to form a multilayer of geopolymer sheets.

33. The process of claim 27, wherein the substrate is a construction panel, construction board, or pole.

34. The process of claim 27, wherein applying the surface of the geopolymer sheet is performed in the field.

35. A substrate having the geopolymer sheet obtained from any one of claims 27-33.

36. A substrate having the geopolymer sheet of any one of claims 1-25, on the substrate.

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