DE2643133A1 - LIGHT CONCRETE - Google Patents

Description

DipL-Ing. . Dipl.-Chem. DIpl.-Ing.

E. Prince - Dr. G. Hauser - G. Leiser

Ernsbergerstrasse 19

8 Munich 60

IDET-CEGOS S.A. September 24, 1976

"Technique et Industry"

331 Quai Gallieni

92152 Suresnes / France

Our reference: I 628

Lightweight concrete

The invention relates to a new lightweight concrete.

Various types of lightweight concrete are currently known; this is how one usually differentiates between the poured concrete, the sealed concretes with light aggregates and the cellular concretes.

In the first case, in addition to the binder, coarse aggregates are used without the addition of fines; the Concrete obtained in this way has in its mass a certain number of cavities or pores and thus a lack of homogeneity.

Dr Ha / Ma

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-A -

Use the waterproofing concrete with light aggregates In particular, organic additives with a low density, such as expanded polystyrene, or mineral additives Low density aggregates such as expanded clay or expanded slate. For certain Concrete, the use of light wood pulp, e.g. wood fiber, is recommended as a light aggregate.

With the third type of lightweight concrete, namely cellular concrete, the aggregates become one beforehand subjected to physical or chemical treatment, the purpose of which is the creation of closed pores in the Inside this aggregate is; in certain cases these pores contain a gas, e.g. carbonic acid, oxygen or hydrogen.

Currently the most widely used aggregates are expanded vermiculite, cell clay, expanded perlite.

A recently proposed concrete consists of a mixture of expanded cork, cement and expanded Volume. The compressive strength is good, but the coefficient of thermal conductivity λ is only mediocre because it between 18 and 0.22, which is already a represents a considerable advantage over the usual concretes, the λ of which is about 0.4.

For so-called "lightweight concretes" corresponding densities in the order of magnitude of 0.7 to 1 approximately apply:

- loose concrete:. λ = 0.25

- Cell concrete: λ = 0.22

- Sealed concrete with slight aggregates: λ = 0.25.

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The present invention relates to sealed concrete with lightweight aggregates of the type described above Kind of a mixture of cement, cork and expanded clay. It has now surprisingly been found that certain Types of spheres made of expanded glass at a very low λ with at the same time acceptable compressive strength to lead. These glass spheres have a cell structure with closed cells covered with a non-toxic, odorless Are filled with gas and do not result in an alkaline reaction. Such glass spheres are, for example, under the name "EXPANVER" from the Boussois company on the market brought.

To put it more precisely, the new lightweight concrete, in particular expanded cork and cement, is characterized contains, in that it also contains expanded glass spheres, preferably those of the above described type.

These balls advantageously have a diameter of 3/8 mm or 8/16 mm.

According to one embodiment of the invention, fines, for example sand, are also mixed into this concrete.

Various experiments are described below, but the invention is not limited thereto.

Experiment No. 1

800 liters of the glass balls with a diameter of 8/16 mm are made with 450 liters of expanded cork and 400 kg of cement mixed; this mixture is then made up with about 220 liters of water.

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This leads to a concrete with a density of 0.72, a compressive strength of 31 bar (after 7 days) and from 40 bar (after 28 days).

Experiment No. 2

The "described glass spheres with a diameter of 8/16 mm from the previous experiment are replaced by glass spheres with a diameter of 3/8 mm; the Quantities of the different materials (balls, cork, cement, water) are the same as above and mixing takes place in the same way.

The concrete obtained in this way has the following properties:

- Density: 0.78

- Compressive strength (in bar): 40 (after 7 days)

52 (after 28 days)

These results are surprising insofar as the balls with a diameter of 3/8 mm have a lower compressive strength than the balls with a diameter of 8/16 mm, while the concrete from test No. 2 as a whole however, has better compressive strength.

Experiment No. 3

800 liters of glass spheres with a diameter of 8/16 mm, 450 liters of expanded cork, 380 kg are mixed dry Cement and 100 liters of sand; the mixture obtained is then mixed with 220 liters of water.

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The results are far better than those from experiment no. 1, namely:

- Density: 0.83

- Compressive strength (in bar): 34 (after 7 days)

44 (after 28 days).

Experiment No. 4

Sand is added to a mixture containing glass spheres with a diameter of 3/8 mm. That The method used to achieve the lightweight concrete differs from that of experiments 1 to 3; instead of First, to mix the different components dry, one stirs the mixture water-cement beforehand, after which one the cork and sand are added, which are mixed with the "water and cement, whereupon the glass balls are finally added interferes. This experiment No. 4 is carried out with the following proportions: 800 liters of glass spheres with a diameter of 3/8 mm, 350 liters of expanded cork, 400 kg of cement, 100 liters of sand and 200 liters of water.

The properties of such a concrete are as follows:

- Density: 0.87

- Compressive strength (in bar): '53 (after 7 days)

69 (after 28 days).

Experiment No. 5

A fifth attempt is made using balls with a diameter of 3/8 mm and 8/16 mm accordingly the experiment no. 4 and carried out with the following proportions: 200 liter glass spheres with a

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Diameter of 3/8 mm, 600 liters of glass balls with a diameter of 8/16 mm, 350 liters of expanded cork, 500 kg of cement, 100 liters of sand and 200 liters of water; the properties of the concrete thus obtained are as follows:

- Density: 0.86

- Compressive strength (in bar): 49 (after 7 days)

64 (after 28 days).

These latter results confirm the influence of the dimensions of the glass spheres, being 3/8 mm / 8/16 mm Mixture led to less good results than those obtained with balls with a diameter of 3/8 mm alone (Experiment No. 4).

The following table summarizes the five tests described above in terms of both proportions and on the results achieved together:

Shares and 1 attempt No. 4th 5 properties _ 2 3 800 200 Glass balls 3/8 (liter) 800 800 - - 600 Glass balls 8/16 (liter) 450 - 800 350 350 Cork (liter) 400 450 450 400 400 Cement (kg) 220 400 380 200 200 Water (liter) - 220 220 100 100 Sand (liters) 0.72 - 100 0.87 0.86 density 0.78 0.83 Compressive strength according to 31 53 49 7 days (bear) 40 34 Compressive strength according to 40 69 64 28 days (bar) 52 44

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It can be seen from the table above that the best results were obtained in Experiment No. 4, at which glass balls with a diameter of 3/8 mm and sand were used at the same time. In this case a particularly interesting coefficient of thermal conductivity λ is achieved, as this is 0.09.

For the other experiments, λ is almost constant and lies 'between 0.10 and 0.11.

The concrete of the present invention is thus an excellent one A compromise between good compressive strength (69 bar in test no. 4) and an excellent one Thermal conductivity coefficient λ from about 0.09 to

0.10, as it is for a sealed concrete with light aggregates has never been achieved before. This makes the concrete according to the invention particularly suitable for Construction sector.

Of course, the concrete according to the invention also offers the various advantages inherent in this type of lightweight concrete, in particular very good deformability, as well as the possibility of incorporating common additives or even reinforcing it or changing the proportions of the starting materials, with a change of + _ 10 % hardly affected the physical properties of the concrete obtained.

It is preferable to use the method according to tests 4 and 5, giving the best results achieved when the concrete is vibrated before it dries.

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Claims (12)

Patent "applications 1) Made of sealed concrete with light aggregates Lightweight concrete, containing in particular cement and light aggregates, one of which is expanded cork, characterized in that it contains spheres made of expanded glass as a further light aggregate. 2) lightweight concrete according to claim 1, characterized in that the balls of non-alkaline-reacting expanded glass with closed, with a non-toxic _; odorless gas-filled cells are made. 3) lightweight concrete according to claim 1 and 2, characterized in that that the balls have a diameter of 3/8 mm. 4) lightweight concrete according to claim 1 and 2, characterized in that the balls have a diameter of 8/16 mm own. 5) lightweight concrete according to claim 3 or 4, characterized in that it consists of: 720 to 880 liter glass balls, 400 to 500 liters of expanded cork and 350 to 450 kg of cement consists. 6) Lightweight concrete according to claim 1, characterized in that it also contains fine substances, e.g. sand. 7098H / 0951 ORIGINAL IMSPECTED 7) lightweight concrete according to claim 3 and 6, characterized in that that after drying it out; 720 to 800 liters of glass balls, 310 to 390 liters of expanded cork, 350 to 450 kg of cement and 90 to 110 liters of sand consists. 8) lightweight concrete according to claim 3 and 6, characterized in that after drying it consists of: 800 liters of glass balls, 350 liters of expanded cork, 400 kg of cement and 100 liters of sand consists. 9) lightweight concrete according to claims 4 and 6, characterized in that it consists of: 720 to 880 liters of glass balls, 400 to 500 liters of expanded cork, 340 to 420 kg of cement and 90 to 110 liters of sand consists. 7Q98U / 09S1 10) lightweight concrete according to claims 3, 4 and 6, characterized in that it consists of: 180 to 220 liter glass spheres with a diameter of 3/8 mm, 450 to 660 liter glass balls with a diameter from 8/16 mm, 310 to 390 liters of expanded cork, 350 to 450 kg of cement and
90 to 110 liters of sand consists. 11) method for producing the concrete "according to any one of the preceding claims, characterized in that man - produces a mixture of water and the cement, - adding the cork and optionally the sand to the mixture obtained, and - add the glass spheres to the mixture obtained. 12) Method according to claim 11, characterized in that the mixture obtained last before drying the concrete is vibrated. 7O98U / 0951