DE102014003104A1 - Alkali aluminosilicate foam or slurry compositions or bodies and process for their preparation and their use - Google Patents

Abstract

The invention is directed to a process for the production of foam or expanding materials or bodies from a raw material mixture with a solid with aluminosilicates which, after alkaline activation, form and thereby harden polymeric structures and / or spatial networks, the alkaline activation of the solid during the production the curable raw material mixture is first introduced by mixing the solid containing aluminosilicates together with at least one alkaline activator and homogenizing them well, but a swelling process takes place before the geopolymer matrix has completely hardened; furthermore to a foam or blowing material produced by this process or to a foam or blowing material produced according to it, which has a pore volume of preferably 30% by volume or more, and finally to the use of such a foam or blowing material or such Foam or inflatable body for the production of any construction products and / or construction elements such as plates or stones.

Description

The invention is directed to a process for the production of foam or blowing masses or bodies from a raw material mixture with a solid with aluminosilicates, which after alkaline activation form polymeric structures and / or spatial networks and thereby harden; furthermore, a foaming or blowing mass produced according to this process or foam or inflatable body produced therefrom; and finally to the use of such a foaming or blowing mass or such foam or inflatable body.

Geopolymers are materials that are artificially produced from predominantly inorganic raw materials in a multi-stage process. They resemble strongly naturally occurring rocks in their properties. Hence the term geopolymers. Due to their physical properties and their environmentally friendly production geopolymers represent an interesting alternative to conventional building materials. Since geopolymers u. a. can be produced from thermally activated waste / secondary raw materials and no fire is necessary to form their ceramic structure (cold-hardening), geopolymers are particularly interesting in terms of a resource-saving and low-energy production.

• – Hohe Resistenz gegenüber chemischen, thermischen und biologischen Angriffen;
• – niedrige Wärmeleitfähigkeit gegenüber anderen Produkten mit vergleichbarer Stabilität;
• – geringe Emission von CO₂ durch eine Aushärtung ohne Brand;
• – keine oder nur geringe Schwindung beim Trockenvorgang;
• – einfache und schnelle Formgebung;
• – Verwendung von Abfallprodukten/Sekundärprodukte z. B. Flugasche, Ziegelmehl und Schmelzkammersand;
• – kostengünstige Produktion;
• – gießfähige Masse, Aushärtung erfolgt rasch;
• – gute Bindeeigenschaften;
• – Produkteigenschaften lassen sich durch Zuschlagstoffe beliebig beeinflussen.

Compared to other building materials, geopolymers have the following advantages:

• - High resistance to chemical, thermal and biological attacks;
• - low thermal conductivity compared to other products with comparable stability;
• - low emission of CO ₂ by curing without fire;
• - no or only slight shrinkage during the drying process;
• - easy and fast forming;
• - Use of waste products / secondary products z. B. fly ash, clay and slag sand;
• - cost-effective production;
• - pourable mass, curing is rapid;
• - good binding properties;
• - Product properties can be arbitrarily influenced by aggregates.

Geopolymerbinder or aluminosilicate polymer binder consist of interconnected [SiO ₄ ] and [AlO ₄ ] tetrahedra, the Si and Al atoms are not directly, but always indirectly connected via O atoms. Since in the coordination of four [AlO ₄ ] tetrahedra Al ³⁺ ion causes a negative charge, additional positive ions must be present, for example Na ⁺ , K ⁺ , Ca ²⁺ , Ba ²⁺ , NH ₄ ⁺ , H ₃ O ⁺ . Preference is given to incorporating monovalent cations such as K ⁺ or Na ⁺ . Thus, an empirical formula of a geopolymer or aluminosilicate polymer is: M _n [- (Si-O ₂ ) _z -Al -O ₂ -] _n wH ₂ O.

Where M is a cation such as K ⁺ or Na ⁺ ; n is the degree of polymerization; z can assume the values 1, 2 or 3 and determines the proportion in which the [SiO ₄ ] and [AlO ₄ ] tetrahedra are in relation to one another.

Aluminosilicate polymer binders or so-called geopolymers are inorganic polymers which are formed at high pH values by polycondensation. In their formation, aluminum and silicon oxides are activated alkaline, usually with sodium or potassium hydroxide. The cleavage of the Si-O bonds can form a new three-dimensional structure. The stability of the geopolymers is strongly dependent on the molar ratios of silicon to aluminum ions, the temperature during the later curing and the composition of the activator solution. In order to improve the ratio between aluminum and silicon ions, it is advisable to add an additional silicon source - mostly sodium silicates (water glass). Basically, a geopolymer consists of an aluminosilicate and an activator solution.

Krivenko ^[1] and Davidovits ^[2] noted that many aluminosilicates can undergo alkaline activation. Frequently, natural clays such. As kaolin, metakaolin and waste products / secondary products such as blast furnace slag and fly ash used.

In principle, aluminum and silicon-containing substances are suitable, from which the required aluminum and silicon ions can be dissolved out. Naturally occurring, suitable raw materials are, for example, 1-1-layer silicates. In many other natural substances, however, dissolution of the required ions is often impossible due to the crystalline nature of the substances. On the other hand, amorphous materials do not have a uniform surface charge due to their structure and can therefore be attacked well with acids or bases, whereby the required aluminum and silicon ions can be dissolved. Amorphous substances are therefore suitable as starting materials for the geopolymerization (eg thermally activated substances such as fly ash, etc.).

For his dissertation entitled "Inorganic-Organic Hybrid Foams" from 2004, Andree Barg has made several attempts with the alkaline activation of metakaolin to form an aluminosilicate polymer binder. It showed that, among other things, the ambient temperature has a decisive influence on the setting time has. In this case, 26 g of metakaolin (0.23 mol of SiO ₂ , 0.1 mol of Al ₂ O ₃ ) were mixed with 33 g of water glass AOS (0.05 mol of K ₂ O, 0.06 mol of Na ₂ O) and 18 ml of water. First, the mixture was stored for 3 days at room temperature - eventually curing - and then post-dried at 80 ° C for one day. On the other hand, the same mixture was heated for 4 minutes in a microwave oven, curing it after a total of 2 minutes. Here, too, a drying took place at 80 ° C for two days. This shows that despite the use of an alkaline activator - here water glass - the setting time at room temperature is comparatively long (several days) against an - additional - thermal activation, for example in a microwave oven.

For example, the following materials may be used as aluminosilicate solid components: natural aluminosilicates, synthetic aluminosilicates, metakaolin, granulated blastfurnace, microsilica, trass flour, oil shale, fly ash, wood fired slag, siliceous fumed silica, pozzolans, basalt, clays; Marl, andesite, diatomaceous earth, kieselguhr, zeolites, clay, slag sand or mixtures thereof.

As alkaline activator, for example, the following materials can be used: sodium water glass, potassium water glass, lithium water glass, ammonium water glass, sodium hydroxide, caustic soda, potassium hydroxide, sodium carbonate, potassium carbonate, alkali metal sulfate, sodium metasilicate, potassium metasilicate, milk of lime or mixtures thereof. The respective materials are preferably present in an aqueous solution or suspension.

Before the alkaline activation of the polycondensation reaction, the aluminosilicate solid component may be contained in a proportion of 20% by weight or more, for example, in a proportion of 40% by weight or more, preferably in a proportion of 60% by weight or more, especially in an amount of 70% by weight or more.

The alkaline activator or its aqueous solution or suspension, however, should be contained in a proportion of 2 wt .-% or more, for example in a proportion of 5 wt .-% or more, preferably in a proportion of 10 wt .-% or more, in particular in a proportion of 20 wt .-% or more. The larger this proportion, the faster the polycondensation reaction proceeds.

Accordingly, the invention provides for firstly mixing the aluminosilicate-containing solid together with at least one liquid activating component and homogenizing it well. By mixing a mass of a solid aluminosilicate content and a liquid, alkaline activator content and homogenizing this mass, a settable, low-viscosity to mushy substance is produced and at the same time the polycondensation of the alkali aluminosilicate building blocks is initiated. For this reaction to be favored, the most homogeneous possible composition of the settable substance is important. For this purpose, the mixing process must continue at least until at least 70% of the surface area of the solid component (s) is wetted with the liquid component (s), preferably at least 80% of the surface area of the solid component (s), in particular at least 90% of the surface of the solid component (s). As a result, the formation of lumps is avoided, and the thus mixed substance has sufficient homogeneity for the further setting process. The term "well-homogenized" contained in the main claim therefore means wetting of the solid component (s) by the liquid component (s) to at least 70% of the surface, preferably to at least 80% of the surface, in particular to at least 90% of the surface Surface.

The polycondensation of the individual alkali aluminosilicate (geopolymer) is started to alumosilicate polymer chains, the reaction rate can be increased by the addition of exothermic substances such. As CaO, MgO, Na ₂ O and Na ₂ CO _{3 are} accelerated. In particular, substances that react exothermically with water and thereby energy z. B. in the form of heat to the surroundings.

In addition, the mass fraction of water is important for the later stability of the geopolymers. Excess water is counterproductive, the strength decreases sharply, the monomer chains / oligomer chains are interrupted and prevent chaining of the polymers. In contrast, can be significantly increased by an increased water content of the pore content within a geopolymer matrix. The reason for this is the evaporation of the excess water.

Additives / additives with extremely high water requirements, which are able to store a lot of water chemically and / or physically, can additionally increase the water content within the geopolymer matrix. As a result, the amount of water can be increased significantly, without this counterproductive acts with respect to the concatenation of the individual monomer / oligomer chains of the geopolymers. Examples of such additives are zeolites, fumed silica, glycerine, gelatin, cat litter, vermiculite, superabsorbent, sodium acrylate, polyacrylamide, celluloses, starches, carboxymethylcelluloses, polyethylene oxide, polyethylene glycol, quicklime, lime, lignin sulfonate, polyvinyl alcohol and polycarboxylate ethers, etc.

According to the invention, highly porous geopolymer products can be produced. For this purpose, by shock-heating and expanding of finely sprayed, liquid Geopolymertropfen at temperatures, for example, more than 150 ° C, optionally more than 400 ° C, preferably more than 700 ° C, in particular more than 900 ° C, or even greater than 1000 ° C, a blowing geopolymer made. In this case, the water contained in the geopolymer expands preferably by the transition into the vapor phase and inflates this extremely. Grain size and bulk density are influenced by the expansion process.

One way to produce such a bulking geopolymer, z. B. the use of a vertical and / or rotary kiln. Due to the temperature-induced increase in pressure inside the grain, the water vapor escapes. The geopolymer mixture puffs up and forms a porous structure inside. The surfaces, however, consist of a solid shell.

In addition, the pore content and / or other parameters, such as. B. the thermal conductivity, etc. during the expansion process by further admixed substances, if necessary, burn-off materials, such as. As various organic and inorganic substances are strongly influenced. Suitable substances are, for example, additives such as mineral fibers, glass fibers, organic fibers, carbon fibers, cellulose fibers, graphite, carbon nanotubes, carbon black, carbon black, expandable graphite, carbon modifications, sand, silicate particles, talc, kaolin, chalk, mica, wollastonite, barite, zeolite, Slate, rock quarry u. flour, glass flour, hollow glass spheres, perlite, vermiculite, expanded glass, clay, ceramics and the like flour, phyllosilicates, flame retardants, metal sulphides, boron nitride, colored pigments, titanium oxide, iron oxide, zinc oxide, iron, manganese, chromium, lead, zinc, molybdenum, nanowhiskers, organophilic phyllosilicates, dendrisch polymers, liquid crystalline polymers, foaming agents, air entraining agents, addition of extremely hydrophilic Substances, addition of hydrophobic substances, peroxides, naphthalene, polyvinyl alcohol, polyethylene oxide, metal powder, carbide powder, ammonium carbonate, lime, dolimite powder, magnesium carbonate, pumice, tuff, lava foam, aerogels, latent heat storage, glycerol, porosity agents such as polystyrene or the like, with water exothermic reacting substances such. As fire lime to support the setting reaction, etc.

The term "bulking geopolymer" thus means an expanded geopolymer, preferably a geopolymer expanded by high-temperature flash heating.

Another possibility for producing highly porous geopolymer products is the production of geopolymer foams. The geopolymer foams are produced by chemical and / or physical foaming with the aid of foaming agents and / or mechanical processing. Suitable foaming agents are for. As aluminum powder, hydrogen peroxide, air entraining agents and / or the addition of surfactants such as sodium lauryl sulfate, Kokosfettsäureamidopropylbetain, lauramine oxide and N, N-dimethyldodecylamine N-oxides.

Likewise, a pneumatically assisted foaming is possible.

In addition, an additional heating during the foaming process - as this is carried out - conceivable. The aim is to achieve rapid curing of the geopolymer matrix in order to stabilize the fragile foam structure. In addition, by a sudden heating, the foaming by outgassing processes such. B. of water vapor, additionally reinforced.

A drying, evaporation and / or evaporation process should therefore be rapid or even shock-like, so that on the one hand, the swelling occurs and on the other hand, the setting process as evenly as possible and fast, for example - depending on the reaction rate - within a period of a quarter of an hour or less, preferably within a Period 10 minutes or less, in particular within a period of 5 minutes or less, or even within a period of 2 minutes or less. The drying, evaporation and / or evaporation process is generally better the shorter this period is. For example, while a rapid process should occur within fifteen minutes, a shocking course of the drying, evaporation, and / or evaporation process may be even faster, for example within minutes, for example within 5 minutes or less, preferably within 2 minutes or so less, especially within 1 minute or less. In an evaporation process, this period means the time until the boiling point of water (about 100 ° C, taking into account that the boiling point is increased in the presence of dissolved substances compared to the value of the pure solvent) is completely exceeded. In a drying or evaporation process can be included that period after which the residual moisture has fallen below 20% of the original value, for example below 10% of the original value, in particular below 5% of the original value, or even below 2% of the original value ,

Further advantages result from the fact that the drying, evaporation and / or evaporation process for activating the introduced Curing process is imposed on the system, preferably by an imposed, in particular rapid or shock-like temperature change and / or by an imposed, in particular rapid or shock-like drying is effected. A shock-like heating, for example by a flame, very highly heated additives / additives, extremely hot surface, highly heated form, confocal radiation drying or microwaves, a shock-like evaporation, for example by shock-like lowering of the ambient pressure, for example, to 0.1 bar or less, preferably 0.01 bar or less, in particular to 0.001 bar or even to an even lower vacuum, so that the boiling point is lowered. This could be realized, for example, within a vacuum chamber.

Furthermore, it is possible to remove the water thermo-hydraulically. For this purpose, in particular the use of excess pressure and elevated temperature into consideration, for. B. by pressing the substance by means of extruder. Due to the sudden transition from very high pressures to ambient pressure exiting the extruder, a sudden expansion of the mixture takes place. It is thus due to the rapid drop in temperature and pressure to foam the mass. Likewise, intensive shearing, mixing, kneading and, in some cases, relaxation processes take place during production. By cooling or heating the housing sections, different treatment zones (intensity of the shear, dwell time, pressure and temperature level) can be realized over the length of the extruder. In addition, the thermal-hydraulic process could be assisted by the addition of aggregates that have a so-called "popcorn effect". Such additives are z. B. Starches from vegetable raw materials such as corn or potato.

In order to accelerate the drying process, as it is carried out, the surface of the mixed and homogenized mass can first be increased after the initiation of the initial curing, for example by spraying or atomizing the mass. Due to their large surface on the one hand and small distances within the mass to their surface on the other hand, the moisture contained can easily diffuse to the surface and leave the mass there or transfer into local, hydrophilic substances, which can then be removed, for example.

In addition, the resulting product of the spraying process is a granulate and / or powder which is particularly suitable for (immediate) further processing (see Bläh geopolymer).

Furthermore, it is possible to hydrophobize the cured or still curing foam or Blähmassen by selectively used additives / additives. In this case, the hydrophobization can then take place after the curing process, such as. B. by dipping and / or spraying method or directly in the production of pourable geopolymer composition by adding a hydrophobing agent. Suitable water repellents would be z. As resins, natural resins, silicones, silanes, siloxanes, waxes, paraffins, oils, bitumen and etc.

In the context of the present invention, it is of particular importance that the swelling or shaming process take place only after the activation of the setting process of the aluminosilicate, but before its complete curing. In this partially set state, the swelling or foaming process is most effective because, on the one hand, the matrix is already in a plastic state and thus a swelling process is no longer reversible, such as in a muddy or even dry state, with most of the matrix remaining does not exist or has not yet solidified and therefore could easily collapse from the foamed state; On the other hand, however, the material is still malleable, in contrast to the finished cured product.

Bibliography:

• [1] PV Krivenko, C. Shi, D. Roy, Alkali-Activated Cements and Concerets 1st Ed. Taylor & Francis, New York, NY, 2006
• [2] J. Davidovits, Geopolymer Chemistry and Applications 2nd Ed., Institute of Geopolymers, St. Quentin France, 2008

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited non-patent literature

• Krivenko [0007]
• Davidovits [0007]

Claims (28)

A process for producing foam or Blähmassen or bodies from a raw material mixture with a solid with aluminosilicates, which form after alkaline activation polymeric structures and / or spatial networks and harden, characterized in that the alkaline activation of the solid in the preparation of the curable raw material mixture is initially introduced by mixing the alumosilicates having solid together with at least one alkaline activator and well homogenized, but before the complete curing of the geopolymer matrix, a swelling and / or foaming process takes place. A method according to claim 1, characterized in that the foam or Blähmasse or the foam or inflatable body has a pore volume of preferably 30 vol .-% or more, for example, a pore volume of 50 vol .-% or more, preferably a pore volume of 70 Vol .-% or more, in particular a pore volume of 90 vol .-% or more. A method according to claim 1 or 2, characterized in that the expansion process is caused by the fact that at least one liquid component passes into a gaseous or vaporous state. Method according to one of the preceding claims, characterized in that the expansion process is caused by the fact that at least one component required for the reaction, for example water, in particular liquid water, is reduced in quantity, preferably by physical and / or chemical methods such as drying or evaporation and / or transfer to another state of aggregation, in particular in steam, for example by evaporation. A method according to claim 3 or 4, characterized in that the drying, evaporation and / or evaporation or other dehydration is rapid or even shock-like, for example within a period of 30 minutes or less, optionally within a period of 20 minutes or less , preferably within a period of 10 minutes or less, in particular within a period of 5 minutes or less, or even within a period of 2 minutes or less, or even within a period of 1 minute or less, or even within a period of a few seconds. Method according to one of the preceding claims, characterized in that for heating or firing of the geopolymer raw material mixture, for example, dryers, ovens, rotary kilns, extremely hot surfaces, highly heated molds, open flames, confocal radiation drying and / or microwaves are used. Method according to one of the preceding claims, characterized in that additives are heated before their addition in order to additionally support the heating of the geopolymer raw material mixture. Method according to one of the preceding claims, characterized in that a thermohydraulisches manufacturing method is applied, in particular under application of pressure at elevated temperature and subsequent relaxation, z. B. by pressure build-up in an extruder with heating, wherein upon exiting the extruder by spontaneous pressure loss occurs a sudden expansion of the mixture. Method according to one of the preceding claims, characterized in that mechanically and / or pneumatically foamed before setting the geopolymer mixture, z. Example, by a device for carrying out such a method by means of pressure gradients, compressed air, mixing unit, kneader and / or pump device. Method according to one of the preceding claims, characterized in that additives are added to support the blowing effect, which cause a Blähffekt, such as starches from vegetable raw materials such as corn or potato. Method according to one of the preceding claims, characterized in that the geopolymer raw material mixture heated additives are added, which cause spontaneous vapor evolution due to the high temperature. Method according to one of the preceding claims, characterized in that the water is converted by heating, in particular by shock heating, in the state of aggregation steam, which additionally inflates the raw material mixture during outgassing. Method according to one of the preceding claims, characterized in that the water requirement and thus the blowing effect are enhanced by the addition of hydrophilic substances with high water demand, possibly with Vorquellen the said hydrophilic substances. Method according to one of the preceding claims, characterized in that it is shock-heated and / or spray-dried, so that the drying and / or evaporation process starts abruptly, for example. By the fact that the largest possible surface of the raw material mixture is exposed to a high temperature the temperature should preferably exceed 150 ° C. A method according to claim 14, characterized in that the enlargement of the surface is effected by spraying the geopolymer composition, preferably by means of a sputtering device, in particular by means of a sputtering nozzle. Method according to one of the preceding claims, characterized in that the cured geopolymer is further processed into a powder or granules, optionally ground and / or sieved, for example, to a particle size of 10 mm or below, preferably to a particle size of 5 mm or less , in particular to a grain size of 2 mm or less, or even to a grain size of 1 mm or less, possibly even to a grain size of 0.5 mm or less, or even to a grain size of 0.2 mm or less. Method according to one of the preceding claims, characterized in that the cured geopolymer is hydrophobicized, for example by adding at least one hydrophobing agent to the pourable geopolymer mass, and / or by spraying or dipping method after the curing process of the geopolymer. A method according to claim 17, characterized in that waxes, resins, silicones, silanes and / or siloxanes are used as water repellents. Method according to one of the preceding claims, characterized in that the liquid geopolymer mixture further additives for process and / or product optimization are admixed, for example, porosity such. B. Styrofoam and / or exothermic reacting with water substances such. As quicklime and / or air entrainment such. As protein acids, proteins and / or foaming agents such. As aluminum powder, hydrogen peroxide and / or surfactants. Method according to one of the preceding claims, characterized in that during the foaming process, an additional heating takes place in order to achieve the fastest possible curing of the geopolymer matrix and thereby stabilize the fragile foam structure, and / or by a sudden heating the foaming by Ausgasungsprozesse , such as B. of water vapor, in addition to reinforce. Method according to one of the preceding claims, characterized in that the shaping takes place according to the desired shape during the curing process. Foam or Blähmasse or body of a raw material mixture with a solid with aluminosilicates, which form after alkaline activation polymeric structures and / or spatial networks and harden, whereby the alkaline activation of the solid in the preparation of the curable raw material mixture is first initiated by the aluminosilicates having solid is mixed together with at least one alkaline activator and well homogenized, but before the complete curing of the geopolymer matrix, a swelling and / or foaming process takes place, so that the foam or Blähmasse or the foam or inflatable body, a pore volume of preferably 30% by volume or more, for example, a pore volume of 50% by volume or more, preferably a pore volume of 70% by volume or more, in particular, a pore volume of 90% by volume or more. Foaming or blowing mass or body according to claim 22 in the form of granules, powder, a bed or any shaped body. Foaming or blowing mass or body according to one of claims 22 or 23 in the form of a refractory and / or acid-resistant product. Use of a foaming or blowing mass or foam or inflatable bodies according to one of claims 22 to 24 for the production of any construction products and / or structural elements, such as, for example, slabs or bricks. Use of a foam or blown or foam or inflatable bodies according to any one of claims 22 to 24 for the production of insulating or insulating bodies, insulating molds, insulating fillings, insulating granules, and / or insulating powders in particular for thermal insulation. Use of a foaming or blowing mass according to one of Claims 22 to 24 for the production of sound-damping and / or impact-sound-damping products, bodies and / or bulk materials. Use of a foaming or blowing mass according to any one of claims 22 to 24 as Leveling pad, absorbent and / or lightweight aggregate for mortar, plasters, etc.