DE2125248A1 - Binders for concrete, in particular refractory concrete - Google Patents

Description

SociSte "ä responsabilitS Sol / Pi, Dr.R.

limitSe dite: ECOTEC La Soliniore

Figanidres (France) Binders for concrete, in particular refractory concrete.

The invention relates to a binder for concrete which has improved properties with respect to the concrete on mechanical strength, fire resistance and insulation properties, regardless of whether dense or porous aggregate materials are used in this concrete. The medium with the binder according to the invention The concrete produced is easy to process and is in terms of heat resistance, insulation properties and Strength at least equal to or superior to molded refractory products and generally superior conventional refractory concrete.

It is known to use a binder made of cement, clay and in the manufacture of concrete There are additives that play the role of a wetting agent and flocculant. In all concrete, the Presence of calcium oxide a decrease in heat resistance, while the water of hydration of the cement and that required for the processing of the concrete Water will increase the porosity of the concrete.

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With the binder according to the invention, thanks to a careful selection of the materials to be used, it is achieved that the amount of cement can be reduced within certain limits so that the loss of fire resistance is mitigated and this is still always sufficiently high. When processing the concrete, considerable amounts of water can be saved; for example, 6 to 10 % water can be used instead of 12 to 16 % in the production of a concrete that has an apparent density of more than 2.00 ·

The binder according to the invention can nissen thanks to the selection of its components and their proportions fulfill the following two essential tasks:

a) on the one hand, it ensures sufficient cohesion of the aggregates with the formation of a solid, resilient body, and

b) on the other hand, it accelerates the formation of mullite and corindon under the influence of lime of the cement and the constituents known as impurities in the cement on the aggregates containing alumina exercise.

The cement ensures the necessary cohesion. Clay is used to lower the cement content. Such mixtures are already known and have been described in connection with flocculants and wetting agents. For example, a mixture is known which contains 5 to 25 % calcium aluminate cement and 1 to 15 % clay.

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In order to increase the level of heat resistance, it is best to check the content of lime in the product to be produced Decrease concrete.

If the strength is to be improved, the formation of mullite must be promoted or accelerated or the Conversion or formation of Corindon are promoted.

The aim of the invention is to achieve optimal results with the binder in the following respects: {

1) Ensuring a constant and perfect connection between the units;

2) Reduction of the lime content within reasonable limits to maintain heat resistance ;

3) Maintaining such a level of lime and cement impurities that the conversion or the formation of corindone or the formation of mullite can be accelerated.

This aim is achieved according to the invention with a binding agent, the components of which are given in the following
Weight ratios are mixed together:

cement 39.5 until 53 volume k3 until 60 additions 0.5 until k

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With this binder, if it is for the manufacture of a fire-resistant concrete according to the invention is used, the following weight ratios result:

Refractory aggregates 92, ifO to 77.36 cement 3 to 12

Tone k,% to 9.73

Additions 0.04 to 0.91.

Even if the proportions of the constituents of the binder are chosen within this framework, it is additionally indispensable to use the constituents of the binder in order to achieve the objectives according to the invention to be carefully selected with reference to their nature

The cement used is essentially a cement based on calcium aluminates. His choice is decisive for the degree of heat resistance.

The mineral clay from the class of phylites must be chosen very carefully, preferably from kaolinites will. It must not contain any significant impurities, it must not be faded, and it must must have an exchange capacity for weak Bc.sen, so that the flocculation of the Binder paste is not disturbed or made impossible. Because of this requirement, the montmorillonites, for example, separate which have water skins and have alkali and alkaline earth ions in their lattice, as well like the bentonites.

Furthermore, when choosing the tone, its theological properties must be taken into account require good workability of the concrete.

Clays that can be used also include ultra-fine solids with colloidal properties that support the have desired properties. The additives that play the role of a flocculant and a wetting agent play must be electrolytes that prevent flocculation of clay and cement. To this end, they are preferred among the following Material classes, individually or in combination, selected:

1) alkali salts of phosphoric acid in their various forms,

2) alkali salts of silicic acid in its various forms, and

3) Salts of certain organic and inorganic acids (sodium hexametaphosphate, sodium tannate, Sodium humate)

So that this binder promotes the formation of mullite or accelerated, the aggregates that are processed with this binding agent should be among the silicic acid clays or containing alumina. Examples are chromite and silicon carbide. In these cases, the fiction, contemporary guarantees Because of its low lime content and its dispersibility, the binder is, on the one hand, a sufficient one Cohesion and on the other hand fire resistance and

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an insulation capacity that is superior to conventional concrete.

- The aggregates can be dense, insulating or expanded and lie within the above-mentioned limits with regard to their composition. A binder according to this invention enables the production of concrete in which the aggregates 80 to 92% account for a concrete%, the effects of the binder used in the composition best suited for carrying. Among other things, it is no longer necessary when using such a binder to moisten the concrete after bringing it a. In certain applications it may be useful to add an _s means of accelerating the set without deteriorating the properties of the concrete Bindsmittels and preserved.

The following examples illustrate the invention: Example Ii heat-resistant concrete;

Aggregates: Fired, expanded clay (German) from 0 to 12 mm with a content of more than 35 % alumina, of which 550 kg as granules from 1 to 12 mm and 280 kg as granules from 0 to 1 mm;

Binder: cement (Rollandshütte

Standard) 100 kg

Kaolitic clay 70 kg

Additions: a) Sodium hexametaphosphate 620 g

b) sodium pyrophosphate 620 g

Required water for preparation: 18-22 1 per 100 kg.

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A concrete made with such a binder has the following properties:

Apparent density: 1.10 to 1.20; Compressive strength (cold): 50 - 70 kg / cm ² .

(These two properties apply to a raw, dry concrete).

After firing at 1300 you get for the same concrete has the following values:

Apparent density: 1.10 to 1.20 Compressive strength: 50 - 70 kg / cm

Dimensional stability -1 % to -2 %

The raw concrete was tamped in. Example 2: Concrete based on Corindon:

Aggregates: Corindon from 1 to 7 mm 750 kg G Corindon from 0 to 1 mm 100 kg G Binder: Cement ( ; Secar 250 Lafarge) 100 kg kaolin clay 50 kg Additions: 500 500 : a) Sodium hexameta-
phosphate b) sodium pyrophosphate
phat

Water to prepare: 6-8 1/100 kg.

This binder provides a concrete with the following properties:

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1) Raw, dry: Apparent density: 3 to 3 »10

Compressive strength: 600 to 800 kg / porosity: 12 to 15 %

2) After firing at 160 ° y

Apparent density: 3.10 to 3.20 Compressive strength: 14OO to 1800 kg / cm ² Porosity: 12 to 15 %

Dimensional stability: -1 to - 2 #.

This concrete was poured raw by means of a vibrator

According to another embodiment of the invention can be a binder with the proportions mentioned above in which, however, an calcium-containing cement instead of a calcium aluminate-containing one is used. This binder, containing silicic acid or silica / calcareous and / or processed cellular aggregates, allows the production of a building concrete

The concretes produced with the binders of the preceding examples show improvements the following areas: strength, soundproofing, thermal insulation, tightness,

The selection of the aggregates is influenced to a considerable extent by the properties that are sought will. The use of such binders enables the production of concrete for walls and facades

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den, dense concrete layers, for the insulation of smoke ducts, for systems that generate strong thermal shocks exposed, etc.

It is possible to change the proportions of the constituents of the binder within the possible Limits to vary. The binder can accordingly contain the constituents in the following weight ratios contain;

cement ZZ until ΊΖ volume 28 until % additions O, 1 to 10.

Within the above-mentioned limits, the following criteria should apply to each component:

a) The total of the measurement numbers for each component should be 100;

b) the binder thus created should be 8 to

Make up 22 % of the concrete by weight, and \ each component of the binder, based on the concrete, should be within the following limits:

Cement 3 to 12

Ton k>% to 9173

Additions 0.0if to 0.91

c) the choice depends on the nature of the clays and the desired results for the concrete. Yet

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clays of the same nature can react very differently depending on their deposit. That's why the selection of the tones within the limits shown above should be explained again as follows:

1) The selected clay must lose its viscosity in the presence of cement and liquefy completely, so that the whole penetrate in an optimal way into the gaps and a complete enclosure of the Can cause aggregates;

H) the choice should fall on a clay that has the required liquefaction with a minimal addition reached by water, so that the density of the concrete increases significantly and the amount of cement in the lightweight concrete decreased.

The choice is based on the manual or instrumental examination of material samples.

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Claims (1)

- li - Claims; 1. · Binder for concrete, which improves the properties of the concrete due to its composition and enables the production of refractory concrete which is superior to the fired refractory molded articles are characterized by the following composition in parts by weight: cement 39.5 to 53 volume 2f3 to 60 additions 0.5 to if. 2. Binder according to claim 1, characterized in that it is a calcium aluminate-containing cement Cement and a clay from the group of mineral Philites, preferably a kaolin clay Clay, of high purity, non-fuzzy, with an exchange capacity for weak bases, excluding the Contains montmorillonite and bentonite, this clay also being made up of ultra-fine solids with colloidal properties can exist that produce the desired effects 3. Binder according to claim 1 or 2, characterized in that it is used as additives, alone or in combination 1098453/17 6 nation, which includes: Alkali salts of phosphoric acid in their various forms, Alkali salts of silicic acid in their various forms, Salts of certain organic acids if · Binder according to claim 1 or 2, characterized characterized in that it contains a calcium oxide-containing cement instead of a calcium aluminate cement Binder, characterized in that it contains the following components in percent by weight: cement 22nd until 72 volume 28 until 76 additions 0.3 until 10. 5. Use of the binding agent according to claims 1 to if for the production of a concrete from pebble acid / alumina-containing or alumina-containing aggregates 6 · Use of the binder according to claim 1 to if for the production of a concrete in an amount of up to 20 Qew.-Ji, based on the concrete 7. Use of the binder according to claim 1 to if for the production of a concrete from dense, insulating or expanded aggregates 109840 / 8. Use of the binder according to claim 1 to k for the production of a concrete from silica and / or silica-containing calcium oxide and / or cellular aggregates 9 · Use of the binding agent according to claim 1 to if for the production of a concrete with the addition of up to 50 % less water than is conventionally used · 10 · Use of the binder according to claim 1 to k for the production of a concrete without moistening after the concrete has been poured. 11 · Use of the binding agent according to claims 1 to k for the production of concrete from aggregates under 10 am for dense concrete and aggregates under 20 mn for cellular or expanded concrete « 109849/1764