WO2015076675A1

WO2015076675A1 - Geopolymer materials comprising alkaline activator and an additive selected from sugar and/or organic acids

Info

Publication number: WO2015076675A1
Application number: PCT/NL2014/050798
Authority: WO
Inventors: Arno Keulen; Pieter Izaak Jan KAKEBEEKE
Original assignee: Pqa B.V.
Priority date: 2013-11-22
Filing date: 2014-11-24
Publication date: 2015-05-28
Also published as: NL2011834C2

Abstract

The present invention relates to geopolymer materials curable within 24 hours at a temperature of at least 40°C comprising an alkaline activator having a molarity of 1.0 to 10 M and an additive selected from sugars and derivatives thereof and/or organic acids and salts thereof having a molarity of 0.001 to 0.2 M. The geopolymer compositions of the present invention have sufficient strength to be used for construction purposes. The present invention further relates to a method for manufacturing a geopolymer product comprising the geopolymer materials of the present invention and to geopolymer products obtained by the method of the present invention.

Description

GEOPOLYMER MATERIALS COMPRISING ALKALINE ACTIVATOR

AND AN ADDITIVE SELECTED FROM SUGAR AND/OR ORGANIC ACIDS

The present invention relates to a geopolymer material having a density of about 500 kg/m³ to about 4500 kg/m³. The present invention further relates to a method of manufacturing a geopolymer product using the geopolymer material of the present invention and geopolymer products obtainable by the method of the present invention.

Geopolymer concrete production, i.e. the making of artificial stone, is a promising and potential sustainable technique for the production of the new construction/building materials. Geopolymer compositions can partially replace the need of currently used conventional construction materials, e.g. glue, cement mortar, cement concrete, ceramics, gypsum, composites, coating, and asphalt. A replacement of the conventional named construction materials has environmental and sustainable advantages, because waste or industrial minerals can be used as secondary raw mineral in the production of geopolymer s.

Geopolymers are typically formed by reacting an alkaline with a geological or mineral based source material. The reaction product from this material can be used to bind aggregates or other suitable filler materials to form concrete, solid material or a shaped product. The geological based source materials, i.e. minerals, preferably contain a high content of aluminum, silicon, calcium, magnesium and iron. In combination with or without additional materials like resins and fibers. Due to relative high alkalinity of the mixture the solid minerals dissolve to form aluminum, silicon, calcium, magnesium and iron monomers. The monomers will start to form a polymerized network when contacted with a geopolymer activator composition and, combined with the fibers and aggregate, a covalently bonded network grows over time resulting in a concrete that may be more stable compared to cement or gypsum, which are based on a crystalline bonded networks. The production of geopolymer compositions is costly and typically has a bad workability. Since elevated temperatures are applied to initiate the geopolymerization process to increase the compressive strength of the geopolymer material, an important drawback is the time needed (28 days) to cure the geopolymer compositions resulting in a costly and environmental unfriendly production process. Furthermore, another drawback is the need for excessive amounts of alkaline components.

The present invention therefore aims to provide a geopolymer material that can be cured in a significantly shorter period of time. The invention thereto provides a geopolymer material at least partially curable within 24 hours at a temperature of at least 40°C, comprising a matrix forming material comprising a mineral binder and optionally an adjuvant selected from an aggregate, a fiber, a polymer, a resin or a combination thereof, a liquid, e.g. water, and, optionally, an alkaline reagent. The geopolymer material of the present invention further comprises an alkaline activator having a molarity in the range of about 1.0 to about 10 M and an additive having a molarity in the range of about 0.001 to about 0.2 M selected from a sugar and derivatives thereof and/or an organic acid and salts thereof and wherein the density of the geopolymer material is about 500 kg/m³ to about 4500 kg/m³.

The term "about" as used herein is intended to include values, particularly within 10% of the stated values.

The most suitable method for determining the density of the geopolymer material depends on the product characteristics of the geopolymer material. For example, the density of materials comprising coarse aggregates may be determined using the NEN- EN 1097-6 standardized method. Whereas the density of bituminous materials using the NEN 3943: 1978 NL standardized method. It was found that the geopolymer material of the present invention can be at least partially cured within 24 hours at a temperature of at least 40°C. Depending on the composition of the geopolymer material, e.g. the density of the geopolymer material, the time for at least partially curing the geopolymer material could be even shorter, e.g. within 18 hours, within 12 hours, within 8 hours and even within 4 hours. It is further noted that by increasing the temperature, the curing time of the geopolymer material of the present invention may be even shorter. Preferably, the geopolymer material of the present invention is at least partially cured at a temperature of at least 50°C, at least 60°C or at least 70°C. Even further preferred the geopolymer material of the present invention is cured at a temperature of about 80°C providing the optimum balance between a resulting at least partially cured geopolymer material having optimum product characteristics, e.g. compressive strength values, and a cost efficient process. For a geopolymer ceramic material the typical curing temperature used is up to 1400°C. The geopolymer material according to the present invention allows the preparation of a geopolymer ceramic material at a significant lower maximum temperature than typically needed. For example, the maximum temperature may be more than 10% lower than the typical maximum temperature of 1400°C, even more than 20% lower than the typical maximum temperature of 1400°C. The terms "cured" or "curable" as used herein, refers to the state of the geopolymer material wherein the strength of the geopolymer material does no longer significantly change, i.e. the strength increment is less than 1% per 12 hours. In other words, the terms "cured" or "curable" refer to the substantially 'end state' of the geopolymer material, i.e. the state wherein the geopolymer material retains its final product characteristics. The time needed to cure geopolymer materials is the time period between forming a 'fresh state' geopolymer material, i.e. the state of the geopolymer material mixture directly after mixing the essential components, and the 'end state' of the geopolymer material, i.e. the geopolymer product. The terms "partially cured" or "partially curable" as used herein, refer to the state of the geopolymer material wherein the strength of the geopolymer material is sufficient solidified and allows further processing of the partially cured geopolymer material. In other words, the terms "partially cured" or "partially curable" refer to a 'stable state' of the geopolymer material, i.e. an intermediate state between the above-defined 'fresh state' and 'end state'.

The present invention further aims to provide a geopolymer material suitable for manufacturing several types of geopolymer products, i.e. construction elements, such as various types of concrete products, prefabricated or non-prefabricated concrete elements like pavement stones, fire resistant coatings, panels, roof tiles, floor tiles, bricks, road barriers, building blocks, utilization and utility construction elements, roads and road top layers, sewerage pips, agrarian building elements, countertops, costal protection elements, heavy construction elements, base layer material, top layer material for roads and other surfaces, heavy weight concrete and ultralight-weight concrete, coating a repairing agent for cement concrete structures, stabilization and immobilization of (non) hazardous or radioactive wastes and soils or the like. The geopolymer material of the present invention is further suitable for manufacturing geopolymer ceramic products.

It was further found that the geopolymer material of the present invention also provides satisfactory levels of strength, in particular compressive strength while allowing curing at ambient temperature, i.e. without the need for additional heating, in a period of time that is common in the art, i.e. curing during a period of 56 days or less, even during a period of 28 days or less. The term "ambient temperature" as used herein, refers to the "temperature of the surroundings". Since the geopolymer compositions of the present invention are used in construction of building materials or the like, the "temperature of the surroundings" is equal to the outside temperature (i.e. atmospheric temperature). Surprisingly, it was found that the geopolymer material of the present invention can be cured at temperatures lower than 5°C. The curing temperature may be even lower than 0°C, e.g. about -5°C, about -10°C or even about -15°C. Geopolymer compositions currently available cannot provide sufficient strength when cured at temperatures below 5°C. Preferably the temperature of curing is equal or higher than about -15°C, -10°C, -5°C, preferably equal or higher than about -2°C, higher than 0°C. More preferably the temperature is in the range of about 5°C to 90°C and even more preferred the temperature is in the range of about 10°C to 40°C.

As already mentioned above, it is noted that by increasing the temperature, a shorter curing time, i.e. hardening time, will be established. Therefore, the geopolymer material of the present invention may well be cured at temperatures higher than 40°C, e.g. by using an autoclave, oven and or a curing chamber wherein curing of the material may be further allowed by using vaporized liquids, e.g. steam, and/or electromagnetic radiation, e.g. microwaves, ultraviolet light or infrared. The use of electromagnetic radiation, such as microwaves, is preferably used since the electromagnetic radiation will cure the inner part of the geopolymer material first before curing the outer part of the geopolymer material. Even further a ceramic oven may be used to cure the geopolymer material of the present invention. Preferably, the geopolymer material of the present invention may be cured at temperatures higher than 100°C, higher than 250°C, higher than 500°C, or even higher than 750°C.

The mineral binder of the present invention comprises a high content (i.e. at least 30% m/m, preferably at least 40% m/m and most preferred at least 50% m/m) of aluminum, silicon, calcium, iron, magnesium or combinations thereof. Preferably the mineral binder is selected from pozzolanic and/or hydraulic and/or non-hydraulic materials. Preferred mineral binders are industrial powders and/or ashes selected from the group of powder coal fly ash, (ground/granulated) blast furnace slag, meta kaolin, calcinated clay, industrial slag, e.g. phosphor slag and/or industrial metal slag, such as steel slag, copper slag, zinc slag, lead slag or the like, industrial incineration ash, cement, e.g. Portland cement, energetically modified cement and/or green cement, soils, e.g. sand, slit and/or clay, natural minerals, waste minerals, sludge, e.g. red mud and combinations thereof.

Preferably the geopolymer material of the present invention comprises a combination industrial powders and/or ashes. In particular the geopolymer material of the present invention comprises a mineral binder comprising a combination of a powder coal fly ash, a meta kaolin and/or a slag selected from ground blast furnace slag, granulated blast furnace slag and combinations thereof.

The matrix forming material of the geopolymer material of the present invention may further comprise an adjuvant selected from an aggregate, a fiber, a polymer, a resin or a combination thereof. Aggregates are preferred adjuvants to increase the strength of the matrix forming material, whereas resins are preferably added to increase the density of the geopolymer material. Fibers are the preferred option in case the sustainability of the geopolymer material needs to be increased.

Aggregates used in the present invention can be selected from any kind of aggregates. Preferably the aggregates are selected from coarse aggregate, fine aggregate and other materials, e.g. fillers, collar pigments and the like, used in construction, including dolomite and limestone powder, other natural mineral powders, industrial mineral powders, sand, gravel, steel, fibers, resin, plastics, organic materials, e.g. wood, natural stones, crushed stone, recycled crushed concrete, waste minerals, industrial minerals and combinations thereof. In an embodiment of the present invention, the geopolymer material comprises an aggregate, which aggregate is an ultralight-weighted aggregate selected from clay, expanded clay aggregate, pumice, perlite, expanded glass, vermiculite and combinations thereof.

The term "coarse aggregate" as used herein is material having a grain diameter size of at least 4 millimeter (mm). The term "fine aggregate" as used herein is material having a grain diameter size of less than 4 mm, e.g. powders, dust or the like. Resins, polymers and fibers used in the present invention may be selected from organic or inorganic resins or fibers. The resins, polymers and fibers used may be biodegradable or non-biodegradable.

Preferably, the resins may be selected from natural and synthetic origin such as epoxy resin. The polymers may be selected from rubbers, e.g. from natural and/or synthetic origin, latex and/or bio-polymers, e.g. (modified) starch, (modified) cellulose, gum, chitin and combinations thereof. Preferably the fibers may be selected from metal, wood, synthetic materials, silicon, carbon, traditional reinforcement fibers and combinations thereof.

It was found that the above adjuvants influence the elasticity, E-modulus, thermal conductivity, porosity, workability, compressive strength and/or flexural strength of the geopolymer material to be formed. The terms "alkaline reagent" and "alkaline activator" as used herein are intended to include an alkaline bicarbonate activator, a sulfate activator, an alkaline silicate activator, e.g. sodium silicate and/or potassium silicate and/or an alkaline hydroxide activator, e.g. sodium hydroxide, potassium hydroxide, calcium hydroxide and/or other earth metal hydroxide or alkaline solutions. Preferably, the alkaline reagent is selected from soluble silicate and/or hydroxide. It is noted that the alkaline activators/reagents suitable for use in the present invention are those alkaline activators/reagents commonly used in the field of geopolymer concrete production. Since the alkaline

activators/reagents are used in building materials one should understand that the use of alkaline activators and alkaline reagents which may harm the environment is preferably avoided.

In an embodiment of the invention, the geopolymer material comprises an alkaline activator having a molarity of more than about 1.0, additives having a molarity in the range of about 0.001 to about 0.2; and an alkaline reagent, e.g. soluble silicate, preferably having a molarity in the range of about 0.01 to about 5.0, wherein the additives are selected from a sugar and derivatives thereof and/or an organic acid and salts thereof.

The additives are selected from complexing agents comprising reactive complexing groups, e.g. hydroxyl-, and/or carboxyl-groups. The reactive groups of the complexing agents are preferably suitable for forming a complex between the complexing agents and minerals comprised in the mineral binder and/or the alkaline reagent/activator, e.g. aluminum, silicon, calcium, potassium, iron and/or magnesium aluminum either present as a monomer, dimer, trimer and/or polymer, used in the geopolymer material of the present invention.

The additives in the geopolymer material are selected from sugars and/or organic acids and salts thereof. Preferred sugars are monosaccharides, e.g. glucose, fructose and galactose, disaccharides, e.g. sucrose, maltose and lactose, oligosaccharides, e.g.

dextrin, maltodextrin and starch, polysaccharides, e.g. cellulose, dextran and sugar like polymer structures. Furthermore, products comprising mixtures of sugars, such as starch or molasses, can be used as well. Additionally, honey, fruit juices and waste materials, such as rotten fruit, can form a potential source for sugars suitable as additives in the geopolymer mixtures of the present invention. The above defined sugar derivatives may be selected from sugar alcohols, natural sugar substitutes, e.g. sorbitol, lactitol, glycerol, isomalt, maltitol, mannitol, stevia and xylitol, and synthetic sugar carbohydrate substitute, i.e. artificial sweeteners, e.g. aspartame, alitame, dulcin, glucin, cyclamate, saccharin, sucralose and lead acetate. Preferably the geopolymer material of the present invention comprises sucrose, fructose and/or lactose, optionally in combination with monosaccharides, disaccharides, polysaccharides and/or oligosaccharides. Preferred organic acids are (vinylogous) carboxylic acids, e.g. oxalic acid, ascorbic acid, lactic acid, citric acid, malonic acid, glutaric acid, adipic acid, uric acid, citric acid and tartaric acid. It was found that a geopolymer material comprising an inorganic acid did not result in a geopolymer material suitable for use in the preparation of geopolymer products. Preferably the geopolymer material of the present invention comprises oxalic acid, citric acid, lactic acid, malonic acid, glutaric acid, adipic acid and/or ascorbic acid. It was found that those organic acids, in particular, provide a geopolymer material having a sufficient strength within a relatively short time of curing. Preferred salts used in the geopolymer material may be calcium citrate, sodium citrate and/or sugar salts, e.g. sodium gluconate. In a further preferred embodiment of the present invention, the geopolymer material may comprise an additive selected from sucrose, fructose, lactose, malonic acid, glutaric acid, lactic acid, adipic acid, oxalic acid, ascorbic acid, sodium gluconate and combinations thereof.

The list of possible additives is not limited to the additives mentioned above, other sugars and derivatives thereof and/or organic acids and salts thereof may be used as well in the geopolymer material of the present invention. The use of additives as defined above reduces the concentration of alkaline activator needed in the geopolymer material of the present invention. Furthermore, the use of additives increases the final material mechanical strengths, e.g. after 56 days or even after 28 days of curing time, and the final material properties of the geopolymer material and/or the geopolymer product. Also the workability of geopolymer material is improved by using the additives compositions of the present invention.

In another aspect of the invention, the geopolymer material may be classified into two classes, i.e. earth-moist geopolymer material and wet geopolymer material. Both classes differ by viscosity of the geopolymer material, e.g. defined by the concrete slump and rheology test. The viscosity of earth-moist geopolymer material cannot be measured.

Earth-moist geopolymer materials have no slump, and therefore have a low workability. Wet geopolymer material, i.e. geopolymer materials having slump and therefore have medium to high workability properties. The viscosity of the wet geopolymer material is preferably more than about 25,000 cP. More preferred the viscosity of the geopolymer material is more than about 75,000 cP. Most preferred the viscosity of the geopolymer material is more than about 150,000 cP.

In a preferred embodiment, the geopolymer material of the present invention comprises a mineral binder mixture comprising industrial powders and/or ashes, such as powder coal fly ash and blast furnace slag. The major constituent of blast furnace slag is calcium, silicon, aluminum and magnesium. It was found that the calcium silicate, calcium aluminate, magnesium silicate present in the blast furnace slag may have a positive effect on the polymerization process. In the preferred embodiment the concentration of blast furnace slag is more than about 5% by weight of the total weight of powder coal fly ash and blast furnace slag. More preferred the concentration is in the range of about 5 to 40% by weight of the total weight of powder coal fly ash and blast furnace slag and even more preferred the concentration of blast furnace slag is in the range of about 10 to 35% by weight of the total weight of powder coal fly ash and blast furnace slag. Most preferred the concentration blast furnace slag is in the range of about 15 to 30% by weight of the total weight of powder coal fly ash and blast furnace slag.

The geopolymer material of the present invention is prepared by mixing or blending the matrix forming material comprising the mineral binder, and optionally the adjuvant selected from an aggregate, a fiber, a polymer, a resin or combinations thereof, followed by the addition of the additive and the alkaline activator, wherein the additive and the alkaline activator are preferably added simultaneously using an additive/alkaline activator solution. A solution comprising additive and alkaline activator is preferred since such solution increases the workability of the geopolymer material. Additionally, but not necessarily, the alkaline reagent, e.g. soluble silicate, can be added in to tuning the curing process, e.g. by increasing the speed of the curing process. Furthermore, liquid, e.g. water, may be additionally added depending on the product characteristics of the final geopolymer product or in case the viscosity of the blended mixture need to be increased.

The term "soluble silicate" as used herein is intended to include silicates, which are soluble in water and/or alkali, in particular silicates include sodium, potassium and lithium silicates which are generally not distinct stoichiometric chemical substances (i.e. with a specific chemical formula and molecular weight), but rather aqueous solutions of glasses, resulting from combinations of alkali metal oxide and silica in varying proportions. The general formula for soluble alkali silicates is:

M₂0 · x S1O2

where M is Na, K, Mg, Ca or Li, and x is the molar ratio, defining the number of moles silica (S1O2), including disilicates, per mole of alkali metal oxide (M₂0).

In another embodiment of the present invention, the geopolymer material of the present invention is prepared by mixing or blending fine and/or coarse aggregate followed by the addition of the mineral binder, additive and alkaline activator, wherein the mineral binder, additive and alkaline activator are preferably added together in the form of a powder and/or liquid. Additionally, but not necessarily, the alkaline reagent, e.g. soluble silicate, can be added in to tuning the curing process. Furthermore, liquid, e.g. water, may be additionally added depending on the product characteristics of the final geopolymer product or in case the viscosity of the blended mixture need to be increased.

The present invention further relates to a method for manufacturing a geopolymer product comprising the steps of:

a) providing a geopolymer material according to any of the preceding claims; and b) curing the geopolymer material at a temperature of at least -5°C, preferably at a temperature of at least 40°C.

As already mentioned above, the geopolymer material of the present invention may be cured at any suitable temperature. However, it was found that by curing the geopolymer at a temperature of at least 40°C, the curing time was reduced from 28 days to less than 24 hours. It is noted that the geopolymer material of the present invention may be cured at temperatures lower than 5°C (for 28 days). Therefore, the curing temperature of step b) may be lower than 0°C, e.g. lower than about -5°C, lower than about -10°C or even lower than about -15°C. The geopolymer material of the present invention may well be cured at temperatures higher than 40°C, e.g. by using an oven, autoclave, a curing chamber wherein curing of the material may be further allowed by using vaporized liquids, e.g. steam, and/or electromagnetic radiation, e.g. microwaves. The use of electromagnetic radiation, such as microwaves, is preferably used since the electromagnetic radiation will cure the inner part of the geopolymer material first before curing the outer part of the geopolymer material. Even further a ceramic oven may be used to cure the geopolymer material of the present invention. Preferably, the geopolymer material of the present invention may be cured at temperatures higher than 100°C, higher than 250°C, higher than 500°C, or even higher than 750°C.

The present invention further relates to a geopolymer product obtainable by the above described method. It was found that the geopolymer product of the present invention has improved product characteristics such as an improved heat/fire resistance, low thermal conductivity and low electrical resistance. It was further found that the geopolymer product of the present invention has a low chloride permeability which makes the geopolymer product of the present invention in particular suitable for use in sea defense constructions and/or materials used in road construction (high road salt resistance). Even further, the geopolymer product of the present invention exhibits an improved acid resistance. The improved acid resistance makes the geopolymer product of the present invention in particular suitable for use in agricultural, industrial and utility applications.

In a preferred embodiment in order to produce a geopolymer product of the present invention the geopolymer material comprises less than about 10 M alkaline activator. It was found that a geopolymer material comprising more than 10 M alkaline activator resulted in a mixture having a too high viscosity which was no longer suitable as an activator composition for use in the preparation of geopolymer compositions. Preferably the geopolymer material comprises less than about 8.0 M alkaline activator, more preferred less than about 6.0 M alkaline activator, even more preferred less than about 5.0 M alkaline activator. Preferably the geopolymer material comprises about 0.001 M to about 10 M alkaline activator, or about 0.01 M to about 8.0 M alkaline activator. More preferred the geopolymer material comprises about 0.1 M to about 7.0 M alkaline activator. Even more preferred the geopolymer material comprises about 1.0 M to about 6.0 M alkaline activator.

In another preferred embodiment the geopolymer material further comprises less than about 5.0 M alkaline reagent, e.g. soluble silicate, preferably the geopolymer material comprises an alkaline reagent, e.g. soluble silicate, in the range of 0 to about 3.0 M. In case soluble silicate is used in the geopolymer material, less amount of alkaline activator is needed to provide a geopolymer product having a sufficient strength after curing for 56 days, even after curing for 28 days. Furthermore, the geopolymer material comprises the additive in the range of about

0.001 to about 0.2 M. Preferably, the additives present in the geopolymer material of the present invention having a cumulative molarity in the range of about 0.002 to about 0.15 M, preferably in the range of about 0.003 to about 0.13 M. More preferred the geopolymer material has a cumulative molarity of additives in the range of about 0.004 to about 0.12 M or in the range of about 0.005 to about 0.10 M. Even more preferred the geopolymer material has a cumulative molarity of additives in the range of about 0.01 to about 0.05 M. Most preferred the geopolymer material has a cumulative molarity of additives in the range of about 0.02 to about 0.04 M. Surprisingly, the geopolymer product of the present invention can be prepared by a geopolymer material comprising alkaline activator and additive without the presence of a soluble silicate. Preferably such geopolymer material is cured at a temperature of at least 5°C, more preferably the geopolymer material is cured at a temperature of at least 20°C, even more preferably the geopolymer material is cured at a temperature of at least 40°C and most preferred the geopolymer material is cured at a temperature of at least 60°C.

In even another embodiment, the geopolymer material of the present invention comprises an amount of a matrix forming material comprising at least a mineral binder of more than about 5% by weight of the total weight of the geopolymer material. More preferably the geopolymer material compositions comprise an amount of a matrix forming material comprising at least a mineral binder of more than about 10% by weight of the total weight of the geopolymer material. Even more preferred the geopolymer material compositions comprise an amount of a matrix forming material comprising at least a mineral binder in the range of about 10 and 35% by weight of the total weight of the geopolymer material. The amount of a matrix forming material comprising at least a mineral binder in ultralight- weight material is in the range of about 40% to about 80% of the total material weight of the geopolymer material, due to the use of ultralight-weight aggregates in the ultralight-weight material products. The amount of a matrix forming material comprising at least a mineral binder in heavyweight materials is in the range of about 10% to about 25% of the total material weight of the geopolymer material. The invention will now be further illustrated with reference to the following examples.

Examples

Geopolymer materials were made by mixing ultralight-weighted aggregates, mineral binder materials, alkaline reagent, alkaline activator, liquids and additives. The mixture of ultralight- weighted aggregates included aggregate material having a size range of 0.25-0.50 mm (540 kg/m³), 1.00-2.00 mm (350 kg/m³), 2.00-4.00 mm (310 kg/m³) and 4.00-8.00mm (300 kg/m³). The mineral binder materials were selected from blast furnace slag (2300 kg/m³) and powder coal fly ash (2500 kg/m³). The alkaline reagent included sodium silicate. The alkaline activator included sodium hydroxide 33% (1300 kg/m³). The liquid included water (1000 kg/m³) and the additive included sucrose

The mixtures were cured for 28 days at ambient temperature (20°C). The composition and results have been summarized in table 1.

Table 1. Ultralight-weighted geopolymer materials

In addition to the above formed ultralight- weighted geopolymer materials, fine aggregate, powder coal fly ash and blast furnace slag were mixed with a solution of sodium hydroxide, sodium silicate and sucrose in a rotating pan mixer for 3 minutes. After mixing the geopolymer mortar was poured in molds, for curing over time at 60°C. Compressive strength was measured on cubic blocks of 40 by 40 by 40 mm.

Table 2 provides an overview of the compressive strengths, after a curing period of 7 and 28 days of the geopolymer mixtures of the present invention prepared by the method given above. The compressive strengths are compared with a geopolymer mixture (hereinafter the "ref '), without comprising additives of the present invention, containing:

1350 gram fine aggregate;

- 270 gram powder coal fly ash;

180 gram blast furnace slag; and

5.6 M sodium hydroxide and 0.25 M sodium silicate and water.

The reference mixture was cured under the same conditions as the geopolymer mixtures of the present invention. The strength of the reference mixture was measured after 7 and 28 days as well.

Table 2. Geopolymer materials

Claims

1. Geopolymer material at least partially curable within 24 hours at a temperature of at least 40°C, comprising:

- A matrix forming material comprising a mineral binder and optionally an adjuvant selected from an aggregate, a fiber, a polymer, a resin or a combination thereof;

a liquid; and

optionally, an alkaline reagent,

wherein the geopolymer material further comprises an alkaline activator having a molarity in the range of about 1.0 to about 10 M and an additive having a molarity in the range of about 0.001 to about 0.2 M selected from a sugar and a derivative thereof and/or an organic acid and a salt thereof and wherein the density of the geopolymer material is about 500 kg/m³ to about 4500 kg/m³.

2. Geopolymer material according to claim 1, wherein the mineral binder comprises at least 30% m/m of aluminum, silicon, calcium, iron, magnesium or combinations thereof.

3. Geopolymer material according to claim 1 or 2, wherein the mineral binder is selected from pozzolanic and/or hydraulic and/or non-hydraulic materials.

4. Geopolymer material according to any of the preceding claims, wherein the mineral binder is an industrial powder and/or ash selected from the group of powder coal fly ash, blast furnace slag, ground granulated blast furnace slag, meta kaolin, industrial slag, calcinated clay, industrial incineration ash, cement, soils, natural minerals, waste minerals, sludge and combinations thereof.

5. Geopolymer material according to any of the preceding claims, wherein the mineral binder comprises a combination of powder coal fly ash and a slag selected from ground blast furnace slag, granulated blast furnace slag and combinations thereof.

6. Geopolymer material according to any of the preceding claims, wherein the aggregate is selected from fine aggregates having a grain diameter size of less than 4 mm, coarse aggregates material having a grain diameter size of at least 4 mm and combinations thereof.

7. Geopolymer material according to any of the preceding claims, wherein the aggregate is selected from dolomite powder, limestone powder, natural mineral powder, industrial mineral powder, sand, gravel, steel, plastic, organic material, natural stone, crushed stone, recycled crushed concrete, waste minerals, industrial minerals and combinations thereof.

8. Geopolymer material according to any of the preceding claims, wherein the aggregate is an ultralight-weighted aggregate selected from clay, expanded clay aggregate, pumice, perlite, expanded glass, vermiculite and combinations thereof.

9. Geopolymer material according to any of the preceding claims, wherein the resins is selected from a natural resin or synthetic resin, preferably an epoxy resin.

10. Geopolymer material according to any of the preceding claims, wherein the fiber is selected from metal, wood, synthetic material, silicon, carbon, traditional

reinforcement fibers and combinations thereof.

11. Geopolymer material according to any of the preceding claims, wherein the polymer is selected from rubbers, latex, biopolymers and combinations thereof, wherein the rubbers are preferably selected from natural and/or synthetic origin and/or the biopolymers are preferably selected from starch, modified starch, cellulose, modified cellulose, gum, chitin and combinations thereof.

12. Geopolymer material according to any of the preceding claims, wherein the alkaline activator is selected from an alkaline bicarbonate activator, an alkaline silicate activator, an alkaline hydroxide activator and combinations thereof.

13. Geopolymer material according to any of the preceding claims, wherein the alkaline activator is an alkali metal hydroxide selected from sodium hydroxide and/or potassium hydroxide.

14. Geopolymer material according to any of the preceding claims, wherein the sugar is selected from monosaccharide, disaccharide, oligosaccharide, polysaccharide and combinations thereof.

15. Geopolymer material according to any of the preceding claims, wherein the sugar is selected from glucose, fructose, galactose, sucrose, maltose, lactose, dextrin, maltodextrin, starch, cellulose, dextran, sugar like polymer structures, starch, molasses and combinations thereof.

16. Geopolymer material according to any of the preceding claims, wherein the sugar derivative is selected from sugar alcohol, natural sugar substitute, synthetic sugar carbohydrate substitute and combinations thereof.

17. Geopolymer material according to any of the preceding claims, wherein the sugar derivative is selected from sorbitol, lactitol, glycerol, isomalt, maltitol, mannitol, stevia, xylitol, aspartame, alitame, dulcin, glucin, cyclamate, saccharin, sucralose, lead acetate and combinations thereof.

18. Geopolymer material according to any of the preceding claims, wherein the organic acid is selected from carboxylic acid, vinylogous carboxylic acid and combinations thereof.

19. Geopolymer material according to any of the preceding claims, wherein the organic acid is selected from oxalic acid, ascorbic acid, lactic acid, malonic acid, glutaric acid, adipic acid, uric acid, citric acid, tartaric acid and combinations thereof.

20. Geopolymer material according to any of the preceding claims, wherein the salt is selected from calcium citrate, sodium citrate, sodium gluconate and combinations thereof.

21. Geopolymer material according to any of the preceding claims, wherein the additive is selected from sucrose, fructose, lactose, malonic acid, glutaric acid, adipic acid, oxalic acid, ascorbic acid, sodium gluconate and combinations thereof.

22. Geopolymer material according to any of the preceding claims, wherein the geopolymer material comprises less than about 10 M alkaline activator.

23. Geopolymer material according to any of the preceding claims, wherein the geopolymer material comprises about 1.0 M to about 6.0 M alkaline activator.

24. Geopolymer material according to any of the preceding claims, wherein the geopolymer material comprises less than about 5.0 M alkaline reagent.

25. Geopolymer material according to any of the preceding claims, wherein the geopolymer material comprises the alkaline reagent in the range of 0 to about 3.0 M.

26. Geopolymer material according to any of the preceding claims, wherein the alkaline reagent is soluble silicate.

27. Geopolymer material according to any of the preceding claims, wherein the amount of a matrix forming material comprising at least a mineral binder is in the range of about 40% to about 80% of the total material weight of the geopolymer material or in the range of about 10% to about 25% of the total material weight of the geopolymer material.

28. Geopolymer material according to any of the preceding claims, wherein the geopolymer material has no slump.

29. Geopolymer material according to any of the preceding claims, wherein the viscosity of the geopolymer material is more than about 25,000 cP.

30. Method for preparing a geopolymer material according to any of the preceding claims, comprising the steps of:

a) mixing or blending matrix forming material comprising the mineral binder and optionally the adjuvant selected from an aggregate, a fiber, a polymer, a resin or combinations thereof;

b) adding the additive and alkaline activator to the mixture and/or blend; and c) optionally, adding alkaline reagent and/or liquid to the mixture and/or blend.

31. Method according to claim 30, wherein the additive and the alkaline activator are added simultaneously to the mixture and/or blend using a solution comprising the additive and the alkaline activator.

32. Method for preparing a geopolymer material of any of claims 1-29, comprising the steps of:

a) mixing or blending the aggregate comprising fine aggregate having a grain diameter size of less than 4 mm and/or coarse aggregate having a grain diameter size of at least 4 mm;

b) adding the mineral binder, additive and alkaline activator to the mixture and/or blend; and

c) optionally, adding alkaline reagent and/or liquid to the mixture and/or blend.

33. Method according to claim 32, wherein the mineral binder, additive and alkaline activator are added simultaneously to the mixture and/or blend in the form of a powder.

34. Method for manufacturing a geopolymer product comprising the steps of:

a) providing a geopolymer material of any of claims 1-29; and

b) curing the geopolymer material at a temperature of at least -5°C, preferably at a temperature of at least 40°C.

35. Method according to claim 34, wherein the temperature of step b) is at least 100°C, preferably at least 250°C, at least 500°C or at least 750°C.

36. Method according to claim 34 or 35, wherein the geopolymer material is cured at a temperature of at least 40°C, preferably at least 60°C, more preferably at a temperature of about 80°C.

37. Method according to any of claims 34-36, wherein the geopolymer material is cured in an autoclave, climate chamber, microwave or ceramic oven.