CS198401B1 - Process for preparing thermal hardened moulded objects bonded by hydrated silicates - Google Patents

Abstract

Prodn. of thermally hardened (without use of any autoclave) silicate hydrate-bound shaped bodies opt. contg. reinforcing elements from mixt. of lime components and SiO2- or silicate-contg. materials with addition of water-soluble substances increasing the b. pt. of the compsn. and enhancing its reactivity, is improved in that a mixt. of lime components and the silica- or slicate-contg. material (5-100% of this material has a specific surface area >500 cm2/g; the remainder being a coarse-grain material having a particle size 5 mm) is mixed with more than 1 wt. % of reactive lime (calculated as CaO), less than 50 wt. % of water (w.r.t. the dry components), a b.pt. increasing, water-soluble cpd(s). of alkali(ne earth) metals (e.g. >0.05% of an alkali hydroxide and/or 0.5-10% of a salt(s) of alkali(ne earth) metals), and reaction-promoting additives (e.g. > 0.05% of an alkal hydroxide and/or 0.5-10% of a partly or wholly amorphous silica- or silicate-contg. material having a specific surface area >1 m2g); a part or the whole of the compsn. is tribomechanically activated by grinding; the total compsn. is intensively mixed and densified; allowed to mature; heated to 100-300 degrees C within 20 H; kept at this temp. for 20 h. and cooled. This material can be used for the prodn. of building elements, building stones, composites with natural or synthetic materials, etc. Its bulk density exceeds 1.7 g /cm3; the compressive strength >300 kg/cm2 (or even >400 kg/cm2); the porosity is less than 25%.

Description

The invention relates to a process for the autoclave-free production of thermally cured moldings bonded with hydrated silicates, high strength, with or without reinforcement, of any shape and size, starting from mixtures consisting of lime components and materials containing silicon dioxide or silicates. These shaped bodies can be used as building blocks, building elements or artificial stones. The method can also be used to test natural or industrial valuable and waste substances to bring them to a workable state.

It is known that mixtures consisting of lime and silica sand, separated by water, provide solid moldings after hydrothermal curing in an autoclave at 8 to 10 at and 170 to 200 ° C. By adding finely ground silica sand, products with higher compressive strengths, known as silicate concretes, can be produced. After the grinding of lime and sand together or separately and the addition of unground sand, the homogeneous mixture, divided by water, is compressed in molds and cured by water vapor in an autoclave. The curing process consists of a warm-up period of about 1 to 4 hours, an isothermal lag time of about 6 to 12 hours, and a cooling period of about 2 to 4 hours.

The disadvantages of this method are discontinuous operation of the autoclave, insufficient utilization of the autoclave volume due to the cylindrical shape of the autoclave and mold curing, the dimensions of the autoclave limited size of the moldings, high heat steam consumption required for hydrothermal curing and mold heating autoclave and long cycle times of curing and forming.

Attempts have been made to cure lime sand moldings without the use of autoclaves. Carbonization of lime concrete and the use of cement as a binder were tested, and the "mechanochemical activation" of cement by finest grinding leads to rapid hardening.

In addition, a method is known in which the finest dispersed or colloidal oxides, hydroxides or hydrated oxides of metals such as magnesium, aluminum, zinc, iron, chromium or titanium or silicon are mixed with water additives and cured at temperatures below 100 ° C. .

At these low processing temperatures and the composition of the system mixture, as compared to a lime sand lime brick, with a very high lime content, there is no reaction with the new, strengthening phases, but the bonding or adhesion forces produced are only physical or colloidal-chemical in nature. Due to these bonding conditions, the strength of the shaped bodies is only small and their use as building elements is not possible.

It is also known to produce silicate bodies by adding aluminum, nickel or zirconium ions to the reaction mixture consisting of lime, a silicon-containing material and water, as well as heating to a temperature below 100 ° C and drying the expanded mass.

The components required to carry out this process are special compounds, such as alum, which cause relatively high costs. In addition, the manufacturing process is very time-consuming and is insufficiently suited only for the production of the smallest bodies, but not for the production of large-dimension building components. The moldings produced are porous material of low density and low strength.

Also disclosed is a process for the production of self-curable compositions consisting of mixtures of fly ash, lime waste sludge and alkaline lye additive.

In spite of the influence of hydraulic components in the summer. melt ash, a technically unfavorable compression molding is necessary to obtain sufficient strengths. For the course of the curing reaction, it is necessary to store it in air for 14 days, but thereby to lose the advantages of the autoclave curing process for lime-sand compositions, to obtain high-strength moldings within a few hours. When these molded bodies are cured by superheated steam, shorter curing times occur, but only strengths are obtained which are not sufficient for the production of large-dimensional structural members.

Further, it is known to produce molded moldings from unground quartz sand with an alkali metal hydroxide, either alone or with the addition of masses containing calcium hydroxide or iron oxide, without additional steam heating, heating to 180-200 ° C.

Due to the necessary compacting and low strengths achieved, this method is not an option for the production of large-dimension building components.

It is also known in the autoclave-free process to use finely divided silicon dioxide-containing raw materials as well as the addition of water-soluble substances. These are either non-alkaline reacting salts such as calcium chloride or types of sugars, or alkaline substances such as sodium hydroxide, sodium carbonate and water glass.

All these experiments or processes have resulted in products whose properties do not reach the properties of autoclave molded bodies.

Therefore, the literature considers autoclave curing as essential for the production of silicate concrete.

The purpose of the invention is to produce thermosetted moldings bonded with hydrated silicates of high strength, with or without reinforcement of any shape and size, from mixtures of lime components and materials containing silicon dioxide or silicate.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a process for the autoclave-free production of these moldings in which modified solid-liquid mixtures are used even at temperatures above 100 ° C, i.e. is present during the longest cure sections.

According to the invention, this problem is solved by a process for the autoclave-free production of thermally cured hydrosilicate-bonded moldings of any shape and size starting from mixtures consisting of lime constituents and silicon dioxide-containing materials or silicates with well water-soluble additives The invention relates to the preparation of mixtures comprising from 1 to 40% of lime component, calculated on calcium oxide, from 4 to 98% of materials containing silica or silicates, calculated as silica, 5 to 100% of these siliceous materials have a specific surface area greater than 500 cm ² / g and the remainder are coarse-grained and have a grain size below 5 mm, of well-soluble boiling point-increasing bases or alkali metal salts, and / or alkaline earth metal salts, for example 0.05 to 18% alkali metal hydroxides and / or 0.5 to 10% alkali metal or alkaline earth metal salts or mixtures of reaction promoting agents, 0.05 to 18% alkali metal hydroxide and / or 0.5 to 10% of surface-active, partially or totally amorphous materials containing silicon dioxide or silicates, with specific surfaces above 1 m2 / g and 0 to 50% water, based on dry components, whereupon all or a mixture thereof The parts are subjected to tribomechanical activation and all the mixture is heated for 20 hours to between 100 and 300 [deg.] C. for 20 hours after intensive mixing and compacting and for a period of maturation, whereupon it is cooled.

Tribomechanical activation is a co-grinding of the components in comminution aggregates such as ball mills, vibratory mills, disintegrators. This tribomechanical activation results in intensive mixing and nucleation of the new reaction phases.

According to a further development of the invention, it has been found that when using an alkali metal hydroxide as a boiling point additive and at the same time promoting the reaction, it is advantageous to set the ratio of calcium oxide to alkali metal hydroxide in a ratio of 1: 1 to 50: 1 The reaction mixture preferably comprises 3 to 25% reactive lime, calculated as calcium oxide and 0.5 to 10% reactive alkali, calculated as hydroxide.

In addition, it is preferred to use quicklime, quicklime and gypsum, calcium hydroxide and gypsum as the lime components, natural or synthetically produced lime, cement or mixtures thereof.

It has been found that sand, natural and synthetically produced silicas, silicates or mixtures thereof are particularly well suited as components containing silicon dioxide or silicates. It has been shown that the lime or silicate components may be partially replaced by minerals or substances containing iron oxide and / or manganese oxide and / or magnesium oxide and / or alumina.

It has been found that alkali metal or alkaline earth metal nitrates, nitrites, chlorides, formates and / or acetates or mixtures thereof can be used as boiling point compounds.

It has further been found that substances containing silicon dioxide and / or silicates with a large specific surface area, which fall off as by-products, for example in the decomposition of clay, can be used as reaction-promoting additives.

In further preferred embodiments of the invention, it has been found that substances which produce an alkali hydroxide by reaction with the other components of the mixture can be used as boiling point enhancers while promoting reaction.

The preparation of the mixture is preferably carried out by mixing the components as well as the insoluble reaction promoting additives with dry or low water content first with the granulated material and then adding the well-soluble additives with the residual water and mixing until sufficient homogeneity is achieved. of the reaction mixture.

It has been shown that the reaction mixture can be concentrated by casting, vibrating, shaking, concentrating in vacuo or by other means such as vibrating rollers. In this case, it is optionally advantageous to add additives as plasticizers to the reaction mixture. The forming of the reaction mixture can be carried out in pellet making plants, briquetting plants or extruders.

It has further been found that the hardening of the formed reaction mixture can also be carried out by post-drying after pre-cooling without intermediate storage or with intermediate storage.

The formed reaction mixture is cured in drying aggregates, such as continuous dryers, in an atmosphere of hot gases of any water vapor content under atmospheric pressure. The gases contained in the curing atmosphere, such as carbon dioxide, can also promote the reaction of the reaction mixture. Drying units can be heated directly - or. indirectly by electrically infrared radiation or by hot gases or vapors or mixtures thereof. The curing of the reaction mixture can be carried out by applying an electrical voltage by means of electrodes arranged above or in the shaped bodies, and steel reinforcements in the shaped bodies can also serve as electrodes.

The insertion, reinforcement or fabric of inorganic or organic material or metal into the reaction mixture has proved to be advantageous. In addition, particularly solid shaped bodies are produced by admixing a metallic material or inorganic or organic fibers.

In a further development of the invention, it has furthermore been found that by the addition of surfactants such as stearates, polyols or silicones to the reaction mixture, optionally before or during grinding, the hardened moldings are hydrophobized. At the same time, these additives, when added before, or during grinding, act to improve the grinding process. .

Hydrophobization is also achieved by post-treating the cured moldings with hydrophobic substances such as dimethylchlorosilane. The post-treatment can also be carried out in the form of polymer impregnation.

The autoclave-curing of the reaction mixture can be carried out in open molds in a tunnel dryer by heating to temperatures between 100 and 300 ° C. The use of autoclaves or hermetically sealed forms is not necessary. Molded bodies produced directly in this manner have a strength above 300 kp / cm ² , which is sufficient for the manufacture of structural building elements. All previously known methods of autoclaveless hardening of lime-sand masses without hydraulic fractions provided only strengths of up to 200 kp / cm ² , which are not sufficient for structural building elements.

The advantages of the invention are, therefore, that - thermally cured moldings bonded with - hydrated silicates, which have a compressive strength of above 300 kp / cm ² , preferably above 400 kp / at a density of more than 1.7 g / cm ³ , cm ² and a low porosity below 25%.

The method itself provides the following economic and technical advantages:

Reducing investment and process costs, simplifying the manufacturing process by eliminating autoclaves and high pressure water vapor production equipment, shortening the forming cycle times, shortening curing times or reducing cure temperatures, and dropping thickening devices using casting technology.

Increase work productivity by the possibility of fully automating the entire production process of the moldings by continuously mixing the starting materials, continuously filling the molds and the continuous curing process, while ensuring maximum utilization of the aggregate.

Production of arbitrarily large and arbitrarily shaped bodies with qualities that correspond to the qualities of hydrothermally cured silicate concrete.

In view of the properties of the molded bodies obtained in this way, the following economic and technical advantages exist:

shaped bodies with properties corresponding to conventional silicate concrete can be produced, while lime is saved.

Compared to conventional silicate concrete, the fluctuations in the active calcium oxide content of quicklime used in the manufacture of the shaped bodies according to the invention have little effect on the properties of these bodies.

For the manufacture of shaped bodies, unused natural and man-made silicate materials can be used, such as fine sands.

In the molded articles produced, the alkali metal caustic can be retained by the alkali metal caustic, which prevents corrosion by passivation of the steel reinforcement, thereby saving on the cost of protecting the reinforcement against corrosion.

Addition of sodium hydroxide to the reaction mixture greatly improves its consistency so that more thickening and complete wrapping of the reinforcement is achieved.

The moldings produced according to the invention can be used in a wide variety of fields - building, such as in housing and industrial construction, as well as in road construction as building blocks and building elements and in addition as artificial stones for a variety of applications such as cladding - walls and artistic building elements. Pelletized shaped bodies can be used as artificial sand in the production of cement-concrete elements.

According to said method,. they can also piece natural and industrial valuable substances and waste products using conventional equipment to convert them into a workable state. As an example, pelletizing and curing of iron ore concentrates for metallurgical processing may be mentioned.

The method is explained in more detail by means of several exemplary embodiments.

Example 1

Crushed quicklime of less than 10 mm in size with an effective calcium oxide content of 88,5%; sodium hydroxide dissolved in the distribution water; quartz sand with a silica content of 90%.

Composition of the reaction mixture:

7.3% ^18.0 quicklime ^armchair emenn it ^é p ^ u joint grinding in a ball mill to a specific ^P ovrc ^{h PI to} near ²⁸²⁰ cm ² / ^g

2.0% sodium hydroxide

72.7% of quartz sand with a grain size below mm

The addition of water is 12%. based on dry ingredients.

The dry ingredients are first mixed beforehand, then the distribution solution is added, and after sufficient homogenization, the reaction mixture is cast into molds. After a maturation period of 1 h, the molds filled with the reaction mixture without cover sheet are heated in a box drier at 160 ° C for 6.5 h and cooled to room temperature over 4 h.

Cured. Prisms - dimensions - 4x4x 16 cm have a compressive strength of 476 kp / cm2 and a bending strength of 97 kp / cm2 at a density of 1.87 g / cm ³

Composition of reaction mixture:

7.0% quicklime

1.0% sodium hydroxide 92.0% quartz sand

The water additive is 13.9% based on dry ingredients.

The joint grinding and mixing of the raw materials - is carried out in the activation aggregate, the disintegrator, at the speed of both rotors 3000 rpm, while the sand reaches a specific surface of 930 cm ² / g. The addition of the raw materials to the disintegrator is carried out simultaneously; the fresh concrete mixture is filled into molds within 15 minutes and vibrated on a vibrating table at 50 Hz and 0.5 mm amplitude for 3 minutes.

The curing process corresponds to Example 1.

Cured cube samples have a compressive strength of 301 kp / cm 2 at a bulk density of 2.02 g / cm ³ . The prisms have a compressive strength of 304 kp / cm 2 and a flexural strength of 43 kp / cm 2 at a bulk density of 2.04 g / cm ³ .

Example 3

Raw materials:.

Lump lime with an effective calcium oxide content of 88%; sodium hydroxide dissolved in the distribution water; quartz sand with 88.7% silica.

Composition of the reaction mixture:

19.5% binder

0.8% sodium hydroxide.

79.7% additional sand

The water addition is 7.4% based on dry components.

The binder is produced by co-activation in a ball mill with 4.5% quicklime - (crushed lime with a grain size below 10 mm), 10% quartz sand below 5 mm, and 5% quartz sand previously mechanically activated in a vibratory mill with a specific surface 7700 cm ² / g.

The additional sand consists of quartz sand with a grain size below 5 mm. The molar ratio of calcium oxide to sodium hydroxide in the reaction mixture was 3.5: 1.

The reaction mixture, after vigorously mixing the ingredients in a forced mix mixer, is placed in molds and subjected to vibration concentration at a frequency of 50 Hz.

After a maturation period of 1 h, the reaction mixture present in the molds is heated in a drying unit for a period of time

6.5 h at 160 ^° C and cooled to room temperature.

Cured test bars with an edge length of 10 cm have a compressive strength of 405 kp / cm 2 at a bulk density of 2.09 g / cm ² .

Example 4

Raw materials: ₅

Ground quicklime - with an effective calcium oxide content of 88.5%; ground iron-iron oxide (Fe3O4); sodium hydroxide,

Example 2

Raw materials:

Ground quicklime with an active calcium oxide content of 88,5%; sodium hydroxide dissolved in the distribution water; quartz sand with a silica content of 88,7% and a grain size of less than 5 mm.

dissolved in the distribution water; quartz sand with a silica content of 93%, consisting of 70,5% coarse - grained sand of a size. grains below 5 mm and 29.5% ground sand with a specific surface area of 4800 cm ² / g.

Composition of the reaction mixture:

7.3% quicklime

7.3% ferric iron oxide (Fe 3 O 4) 4.0% sodium hydroxide

81.4% of quartz sand

The water addition is 18.5% based on dry components.

After vigorous stirring, the reaction mixture was poured into molds without subsequent concentration.

After a maturation period of 3 h, the reaction mixture-filled molds were coated with sheets and heated in a box oven at 160 ° C for 4 hours, further heated at this temperature for 5 hours and cooled to room temperature over 4 hours. The cured 4x4x16-cm prisms have a compressive strength of 448 kp / cm ² and a bending tensile strength of 42 kp / cm 2 at a bulk density of 1.89 g / cm ³ .

Example 5

Raw materials:

Ground quicklime with an effective calcium oxide content of 88,5%; aluminum hydroxide, dry; sodium hydroxide dissolved in the distribution water; quartz sand containing silica

88.5%; Consisting of 67,9% coarse-grained sand with a grain size below 5 mm and 32,1% ground sand with a specific surface area of 3000 cm ² / g.

Composition of the reaction mixture:

10.9% quicklime 2.0% aluminum hydroxide 3.0% sodium hydroxide

84.1% quartz sand

The addition of water is 16.0%, based on dry components.

The mixing and curing process corresponds to Example 4. Cured roller samples of 5 cm height, 5 cm diameter have a compressive strength of 316 kp / cm ² at a bulk density of 1.85 g / cm ³ .

Example 6

Raw materials:

Ground quicklime with an effective calcium oxide content of .88.5%; sodium hydroxide dissolved in the distribution water; ground water glass, solid with a sodium content of 10,8% and a silica content of 66,6%; quartz sand with a silica content of 88.5%, consisting of 67.3% coarse-grained sand of less than 5 mm · and 32.7% of ground sand with a specific surface area of 3000 cm ² / g.

Composition of the reaction mixture:

10.9% quicklime

2.5% sodium hydroxide

4.0% water glass, solid §2.6% quartz sand

The addition of water is 16.0% by dry weight.

The mixing and curing process corresponds to Example 4.

The cured roller samples have a compressive strength of 391 kp / cm 2 at a bulk density of 1.85 g / cm ³ .

Example 7

Raw materials:

Ground. quicklime with an effective 'calcium oxide content of 77%'; sodium hydroxide dissolved in the distribution water; quartz sand with 96% silica, consisting of 55.7% coarse-grained sand with a grain size below 5 mm and 44.3% ground sand with a specific surface area of 4800 cm ² / g.

Composition of the reaction mixture:

14.6% quicklime

4.0% sodium hydroxide

81.4% quartz sand

The addition of water is 18.5% based on dry. folders. The molar ratio of calcium oxide to sodium hydroxide in the reaction mixture is 2: 1.

The reaction mixture was stirred vigorously after stirring. poured into the molds without subsequent concentration.

After a maturation period of 3 h, the molds filled with the reaction mixture are covered with metal sheets and heated in a box dryer at 160 DEG C. for 4 hours, further heated at this temperature for 2 hours and then heated. cooled to room temperature over 4 hours.

The sample bodies are placed in water for a short time and then dried at 105 ° C for 15 hours.

Cured sample cubes have a compressive strength of 820 kp / cm ² at a bulk density of 1.82 g / cm ³ .

Example 8

Raw materials:

Ground quicklime containing effective calcium oxide. 77%; reactive calcium hydroxide; sodium hydroxide dissolved in the distribution water; quartz sand with 96% silica, consisting of 77,8% coarse-grained sand with a grain size below 5 mm and 22,2% ground sand with a specific surface area of 4800 cm ² / g.

Composition of the reaction mixture:

11.0. % of quicklime

3.6% calcium hydroxide

4.0% sodium hydroxide

81.4% quartz sand

The water addition was 17.0% based on dry components.

The molar ratio of calcium oxide to sodium hydroxide in the reaction mixture. is 2: 1.

The curing process corresponds to Example 1.

Cured cubes - samples have compressive strength

510 kp / cm ² at a bulk density of 1.86 g / cm ³ .

Example 9 parts by weight of sand with 5.5 parts by weight of quicklime are subjected to a tribomechanical stress in a ball mill for 5 hours. Subsequently, 3 parts by weight, parts remaining in the acidic decomposition of the earth, containing 50% amorphous silica and a specific surface area of 55 m ² / g, as well as 74.5 parts by weight, parts of sand having a maximum grain size of 3.5 mm, are added. a solution consisting of 3.1 parts by weight of calcium nitrate and 9 parts by weight of water. After 5 minutes of vigorous stirring and 10 minutes of residence time, 4 * 4 * 16 cm shaped bodies are produced by vibration compaction, which are then cured for 6.5 hours at room temperature. continuously at 180 ° C with increasing temperature in a closed heating box in molds. The cooled and demolded bodies have a density

2.15 g / cm 3 and a compressive strength of 360 kp / cm 2.

Example 10

78.5% by weight of sand parts are mixed with 20.5 parts by weight of quick lime and subjected to a disintegrator at a relative peripheral speed of 250 m / s to tribomechanical stresses. 1 part by weight of vibratory ground sand with a specific surface area of 3.5 m2 / g and a solution consisting of 14.5 parts by weight, parts by weight of water and 6 parts by weight, parts by weight of calcium nitrate and 0.5 parts by weight are added. parts of sodium nitrate. After 10 minutes of vigorous stirring and 2 hours of residence time, cylindrical shaped bodies having a diameter of 4 cm and the same height are produced by compaction. The bodies removed from the mold are heated to 140 ° C for 1.5 hours and then further processed at the same temperature in flowing water vapor at a pressure of 1 t for 3 hours. The cooled moldings have a bulk density of 2.00 g / cm 3 and compressive strength 980 kp / cm ² .

Example 11

Ground quicklime with an effective calcium oxide content of 88,5%; Portland cement PZ 350; reactive sodium hydroxide dissolved in the distribution water; quartz sand with a silica content of 88,5%, consisting of 67,9% coarse-grained sand below 5 mm and 32,1% ground sand with a specific surface area of 3000 cm ² / g. Composition of the reaction mixture:

10.9% quicklime

2.0% Portland cement

3.0% sodium hydroxide

84.1% quartz sand

The water additive is 16% based on dry ingredients.

The mixing and curing process corresponds to Example 4. The cured cylindrical samples have a compressive strength of 428 kp / cm 2 at a bulk density of 1.89 g / cm ³ .

Example 12

Calcium hydrate with a total lime content% calculated as calcium oxide; sodium hydroxide dissolved in the distribution water; quartz sand with 90% silica, consisting of 83.8% coarse-grained sand with a grain size below 5 mm and 16.2% ground sand with a specific surface area of 4100 cm2 / g.

Composition of the reaction mixture:

5.9% lime hydrate

1.5% sodium hydroxide

92.6% quartz sand

The water additive is 7.0% based on dry ingredients.

After vigorously mixing the components in a forced mixer, the reaction mixture is placed in molds and subjected to a vibration densification at a frequency of 50 Hz and a load of 20 p / cm 2. The reaction mixture present in the molds is heated in a drying unit for a period of time

6.5 hours at 160 ° C and then cooled to room temperature.

Cured test bars with an edge length of 10 cm have a compressive strength of 450 kp / cm 2 at a density of 2.06 g / cm ³ . .

Example · 13

Lump lime with an effective calcium oxide content of 88%; sodium hydroxide dissolved in the distribution water; quartz sand with 88.7% silica; Surfactants:

(a) barium acid, solid;

b) Piazep, technical tetramethylmelamine with a reactive group R-NH-CH ₂ OH; hard paste with 50% water content;

c) Piamide, a low-condensation partially methanol-etherified melamine-formaldehyde resin with a reactive group R-NH-Si-O-CH 3; 50% aqueous solution;

d) hydrtsinčitantvá resin, a sulphonated melamine resin with the reactive group ^R -N ^H - _^CH2 - ^{SO3 Na; 22, 7%} aqueous solution

Composition of the reaction mixture:

19.5% binder

1.0% sodium hydroxide

79.5% sand admixture

The water additive is 7.5% based on dry ingredients.

The mixture was added to one of the following surfactants; added quantities on dry ingredients:

(a) 0,005% stearic acid is added to the dry mixture;

(b) 0,1% Piazepu;

c) 0.1% Piamide; ·

d) 0.5% bisulfite resin.

The ingredients listed under b) to d) were always added to the distribution solution.

The binder is produced by co-grinding 4.5% quicklime (pre-crushed lump grain size below 10 mm) and 15% quartz sand grain size below 5 mm in a ball mill.

The admixture of sand consists of quartz sand with a grain size below 5 mm.

The mixing and curing process corresponds to Example 3.

Cured 10 cm edge test cubes have the following characteristics:

Ingredient Compressive strength 1 kp / cm2 | Bulk density g / cm ⁸ stearic acid 415 2.09 Piazep 453 2.15 Piamid 424 2.09 hydrosulfite resin 463 2.11 The test specimens are hydrophobic

Example 14

The cured test specimens were hydrophobized by briefly soaking in an aqueous solution of potassium methyl silicone containing 20% silicone or a solution of dimethylchlorosilane in toluene followed by air drying.

Example 15 parts by weight of sand are mixed with 5.5 parts by weight of slaked lime and 4.5 parts by weight of the residue falling off under the acid decomposition of 50% amorphous silica having a specific surface area of 55 ma / g and then tribochemically stressed in a disintegrator at relative circumferential speed 125 m / s. Then 80 parts by weight of sand and a solution consisting of 1.5 parts by weight of calcium chloride and 8 parts by weight of water are added. After. By means of intensive mixing with vibration densification, the shaped bodies are made from the dimensions 4χ4χ 16 cm, which are then cured

6.5 hours at continuously up to 180 ° C with increasing temperature in a closed heat box in molds. The cooled and molded bodies have a bulk density of 2.07 g / cm ³ and a compressive strength of 290 kp / cm ^{1 2} .

EXAMPLE 16 parts by weight of sand are mixed with 5.5 parts by weight of slaked lime and 4.5 parts by weight of the residue remaining at. acid decomposition of clay containing 50% amorphous silica and a specific surface area of 55 · m2 / g and then tribochemically stressed in the disintegrator at a relative peripheral speed of 125 m / s. 80 parts by weight of sand are then added and a solution consisting of 1 part by weight of sodium chloride and 8 parts by weight of water is added. After intensive mixing, moldings having dimensions of 4x4x16 cm are produced by vibration densification, which are then cured for 6.5 hours in a closed heat cabinet at continuously up to 180 ° C with increasing mold temperatures. . The cooled and molded bodies have a bulk density of 2.10 g / cm 3 and a compressive strength. 270 kp / cm 2.

SUBJECT

Claims (11)

SUBJECT A process for the autoclave-free production of thermosetting molded bodies bonded with hydrated silicates of any shape and size, starting from mixtures consisting of lime components and materials containing silicon dioxide or silicates, with additives well in water. water-soluble boiling point-increasing and reaction-promoting substances, characterized in that mixtures comprising 1 to 40% of lime component, calculated on calcium oxide, 4 to 98% of materials containing silica or silicates, are produced; 5 to 100% of these siliceous materials have a specific surface area greater than 500 cm 2 / g and the remainder are coarse-grained and have a grain size below 5 mm of well-soluble, boiling point-increasing bases or alkali metal salts, and and / or alkaline earth metal salts, for example 0.05 to 18% alkali metal hydroxide and / or 0.5 to 10% alkali metal or alkaline earth metal salts or mixtures of additives supporting the reaction of 0.05 to 18% alkali metal hydroxide and / or from 0.5% to 10% of surfactant, partially or totally amorphous materials, comprising % of silicas or silicates with specific surfaces above 1 m2 / g and 0 to 50% water, based on dry components, whereupon all or part of the mixture OF THE INVENTION the parts are subjected to tribomechanical activation and all the mixture is heated to a temperature between 100 ° C to 300 ° C for 20 hours after intensive mixing and compacting and after maturation, held at this temperature for up to 20 hours and then cooled. 2. Process according to claim 1, characterized in that, when alkali metal hydroxide is used as a boiling point additive while promoting the reaction, it is adjusted. The ratio of calcium oxide to alkali hydroxide 1: 1 to 50: 1, in each case based on dry components, the reaction mixture preferably comprising 3 to 25% reactive lime, calculated as calcium oxide and 0.5 to 10% reactive. alkali, calculated as hydroxide. 3. A process according to claim 1, wherein the process is lime. · Or replace silicate components in part with minerals or substances containing iron oxide and / or manganese oxide and / or magnesium oxide and / or alumina. 4. The process according to claim 1, wherein the alkali metal or alkaline earth metal nitrate, chloride, formate and / or acetate is used as the boiling point. 5. Process according to claim 1, characterized in that by-products of other processes, such as from the decomposition of clay, in the form of silicon dioxide or silicates are used as reaction-promoting additives. 6. Process according to claim 1, characterized in that substances which raise the alkali hydroxide by reaction with the other components of the mixture are used as boiling point additives while promoting the reaction. 7. Process according to claim 1, characterized in that the components and the insoluble reaction-promoting substances are first mixed with the coarse-grained material in the dry state or in the presence of a low water content, and then water is added with the other components. and stirring until sufficient homogeneity of the reaction mixture is obtained. 8. The process of claim 1, wherein the formed reaction mixture is heated in an atmosphere of hot gases of any water vapor content at atmospheric pressure. 9. The process of claim 1 wherein surfactants such as stearates, polyols or silicones are added to the reaction mixture, optionally before or during grinding. 10. The method of claim 1, wherein the cured and cooled moldings are temporarily stored in water and then dried. 11. Method according to claims 1 to 10, characterized in that the cured shaped bodies. are subsequently treated with hydrophobizing substances, for example dimethylchlorosilane or subjected to polymerisation impregnation. Printing 51/82