CS272246B2 - Admixture to building materials with anhydride content - Google Patents

Description

(57) The solution consists of adding anhydrite as a binder and sand as a sanding material to mixtures for cement-free building materials, consisting of aluminum-containing fluoride or aluminum hydroxide sulphate complex.

CS 272263 B2

The present invention relates to an additive to anhydrite-containing building materials.

Anhydrite has recently become increasingly important as a binder for building materials. Its use is particularly important in the field of screed and plaster mortars. For example, European Patent No. 63232 discloses the use of a mortar which, when applied in a floor area, itself creates a horizontal surface and contains synthetic anhydrite and cement as hydraulic binders, furthermore contains other additives and natural anhydrite with normal grain size distribution and maximum particle size in range from 0.8 to 1.1 mm as a grit.

In Austrian patent no. 280 873 it is proposed to treat anhydrite-based building materials as binders and other additives, for example sand, by adding modified sulfite or sulfone resins based on amino-s-triazine to give the materials water resistance.

The screed has hitherto been processed using cement as a binder. The disadvantage of this process is the fact that the cement has a relatively high shrinkage rate, so that the screed needs to be treated with the least amount of water and in a relatively solid etave to avoid strong shrinkage, which is very labor intensive.

If lime and cement are used as binders for the plaster mortar, the problem of high shrinkage of both binders also arises in this case. If gypsum is used instead, it is possible to overcome the disadvantage of high shrinkage and thus the risk of cracking. Gypsum, however, is relatively very sensitive to the presence of water and mortar, which contains gypsum as a binder, is therefore only suitable for those indoor areas where there is no high humidity.

As an adhesive, anhydrite has the advantage over lime and cement that its shrinkage rate is very low, compared to gypsum it has the advantage of being much more resistant to water.

Of particular importance is anhydrite as a binder in the preparation of screeds. In this case, it is necessary to lay as large surfaces as possible without separating joints and regardless of the geometric dimensions of these surfaces, without the risk of cracking during screed shrinkage. In addition, screed laying should be as laborious as possible and very fast. For the production of screeds, therefore, well-flowable compositions are desirable, especially those which, as far as possible, themselves create a horizontal surface. To date, screeds of this type can only be obtained using anhydrite as a binder. In order to achieve good flowability, liquefying additives such as water-soluble melamine resins are added to the screed composition. In addition, in order to avoid the deposition of additives in the liquid screed composition, substances which prevent this deposition, in particular cellulose ethers, the use of which has long been known in the construction industry, are added. However, these additives thicken the resulting mixture, which again increases the amount of water to be used in the preparation of the mixture. In addition, the cellulose ethers retain a high amount of water, which slows the drying time and negatively affects the water resistance of the building material.

An accelerator is required to solidify the anhydrite. However, the solidification process cannot be precisely controlled, which means that the solidification time range cannot be accurately predicted, so that the process can proceed at very different speeds. In addition, the setting process depends largely on ambient conditions, in particular on temperature and air humidity.

The solidification of the anhydrite-containing compositions is also largely influenced by the mineralogical composition of the sand used for screed production. It is therefore necessary to test the sand used before its actual use and it is usually necessary to discard a wide variety of sand types as unsuitable for that use. In particular, anhydrides of natural origin are very sensitive to mineralogical sand compositions.

OS 272247 B2

It has now been shown that by using certain inorganic compounds as additives to mixtures for the production of building materials containing anhydrite as a binder, it is possible to obtain mortar and various screeds which evenly solidify independently of the environmental conditions and the mineralogical composition of the sand used, and even with very thin, liquid screeds which themselves create a horizontal surface, there is no deposition of individual additives. In addition, these additives increase the strength of the material and its resistance to water.

Accordingly, the present invention provides an additive to anhydrite as a hydraulic binder and sand as a grinder to mixtures for the production of cement-free building materials, the additive being an aluminum or silicon containing fluoride or an aluminum hydroxide sulfate complex.

In the case where a mixture for building materials is made of sand, anhydrite, accelerator and water and the salt of the above compounds is added in an amount of 0.05 to 4, preferably 0.05 to 3.0%, based on the anhydrite, very precisely control the solidification. During screed formation, it was verified that, despite the good flowability of the mixture, there was no deposition of sand in the mixture. The strength of the mixture increases, as can be seen in the following tables, while the water resistance also increases. Preferred additives according to the invention are, for example, pachnolite, magnesium silicofluoride, cryolite or a water-insoluble, acid-soluble and alkali-soluble aluminum hydroxide sulfate complex.

By using these additives, either the amount of water used in screed formation can be reduced, thereby increasing the material's strength and drying time, or by increasing the flowability of the mixture with the same amount of water without increasing the settling of the additives in the mixture. This latter effect is of particular importance in the production of liquid screeds.

The following examples illustrate the practice of the present invention.

Example 1

Mix the following components thoroughly for the parts by weight:

component anhydrite potassium sulphate lignin sulphonate pachnolite (NaCaAlFg)

At the destination, the mixture has a particle size of 0-4 mm water parts by weight

100 ALIGN!

1.0

0.6

0.5 adds sand,

150-170 28

The mixture is mixed in a mixer and then pumped through a conventional pump onto the surfaces to which the screed is to be applied. The mixture is so fluid that it flows itself over the entire surface.

The same mixture without the addition of pachnolite is less liquid, so it does not flow itself and needs to be distributed over the whole area with rakes or other tools. The strength of these mixtures is summarized in the following table:

CS 272246 s2 with pachnolite without pachnolite

Compressive strength normal climate after 28 days

Normal climate 28 days and then 7 days in water

Bending tensile strength

Normal climate after 28 days

Normal climate 28 days and then 7 days in water

N / mm ² 50 N / mm ²

N / mm ² 25 N / mm ²

N / mm ² 7 N / mm ²

5.5 N / mm ² 3.5 N / mm ²

Example 2

Ke

100 parts by weight of anhydrite; and

180.0 parts by weight of dolomitic sand with a grain size of 0 to 3 mm, the mixture is added at the construction site

1.2 parts by weight of potassium sulphate,

0.7 parts by weight of melamine resin,

3.0 parts by weight of a basic aluminum sulfate complex with a very simplified formula of Alg (0H) ggSO0.5 HgO; and

27.0 parts by weight. water.

This mixture is mixed, preferably in a mortar pump, and then applied to the respective areas. The following table shows the values for the strength of this material.

with an aluminum-free aluminum sulfate sulfate complex complex

Compressive strength normal climate 28 days 52 N / mm ² 39 N / mm ² normal climate 28 days and then 7 days in water 38 N / mm ² 22 N / mm ²

Tensile bending strength of aluminum sulfate complex without aluminum sulfate complex

normal climate 28 days 7.5 N / mm ² 5 N / mm ² normal climate 28 days and then 7 days in water 5.0 N / mm ² 3 N / mm ²

Example 3

The following mixture is mixed in the mortar pump:

100.0 parts by weight of anhydrite

0.05 parts by weight of magnesium silicofluoride

1.40 parts by weight of potassium sulfate

0.50 parts by weight of melamine resin

0.20 parts by weight of lignin sulfate

120.0 parts by weight of quartz sand with a grain size of 0 - 3 mm by weight of water.

The resulting mixture is then applied as a screed. Material strength data are given in the following table:

with magnesium- without magnesium silicofluoride silicofluoride

Compressive strength normal climate 28 days normal climate days and then days in water

Bending strength normal climate 28 days normal climate 28 days and then 7 days in water

N / mm ² 54 N / mm ²

N / mm ² 20 N / mm ²

9.5 N / mm ² 7.0 N / mm ²

5.5 N / ram ² 3.0 N / mm ²

Example 4

Mix the following mixture thoroughly in the mortar mixer:

100.0 parts by weight of anhydrite

160.0 parts by weight of quartz sand with grain size 0 - 4 mm *

1.0 part by weight of potassium sulfate

0.7 parts by weight of zinc sulphate

0.1 parts by weight of cryolite (Na 2 AlPg) and parts by weight of water.

The resulting mixture is pumped through a conventional mortar pump and used as a screed. The following table shows the strength of the resulting material.

with cryolite without cryolite

Compressive strength normal climate days 59 N / mm ² 45 N / mm ² normal climate 28 days and then days in water 38 N / mm ² 22 N / mm ²

Bending strength normal climate days 8.5 N / mm ² 7.0 N / mm ² normal climate 28 days and then days in water 4.5 N / mm ² 2.3 N / mm ²

Example 5

180.0 parts by weight of anhydrite 100.0 parts by weight of slaked lime

720.0 parts by weight of dolomitic sand with a grain size of 0.3 - 1 mm 1.0 parts by weight of potassium sulfate

1.5 parts by weight of methylcellulose

0.2 parts by weight of a pore-forming substance (aliphatic alcohol sulphonate)

1.5 parts by weight of magnesium silicofluoride are thoroughly mixed. The mixture is mixed with water and then applied to a brick harvest.

* p

The material flow rate is 17.5 cnr. After 28 days the material strength is 1.8 N / mm and the bending tensile strength is 0.65 N / mm.

Other mortar compositions suitable for plaster applications are given in the following examples:

Example 6

200.0 parts by weight of anhydrite 9.0 parts by weight of slaked lime

700.0 parts by weight of dolomitic sand with a grain size of 0 - 0.8 mm 4.0 parts by weight of zinc sulphate

1.8 parts by weight of methylcellulose

0.25 parts by weight of a pore-forming compound 0.12 parts by weight of cryolite (Na 2 AlPg).

Example 7

250.0 parts by weight of anhydrite 50.0 parts by weight of slaked lime

710.0 pbw of dolomitic sand 2.0 pbw of potassium bisulfate 1.0 pbw of zinc sulfate 2.0 pbw of methylcellulose

0.2 pbw of air pore compound

7.4 parts by weight of a basic aluminum sulfate complex.

Example 8

250.0 parts by weight of anhydrite 50.0 parts by weight of slaked lime

710.0 pbw of dolomitic sand 2.0 pbw of potassium sulfate 1.0 pbw of zinc sulfate 2.0 pbw of methylcellulose

0.2 pbw of air pore compound; and

0.18 parts by weight of pachnolite (NaCaAlPg).

Claims (5)

SUBJECT OF THE INVENTION 1. An additive to anhydrite as a hydraulic binder and sand as a grinder for mixtures for the production of oement-free building materials, characterized in that the additive is an aluminum or silicon-containing fluoride or an aluminum hydroxide sulfate complex. In an amount of 0.05 to 4 parts by weight based on 100 parts by weight of anhydrite. 2. · ‘ Additive according to claim 1, characterized in that it is composed of pachnolite (NaCaAlPg). 3. Additive according to claim 1, characterized in that it is composed of magnesium silicofluoride. 4. Additive according to claim 1, characterized in that it is composed of cyolite (Na 2 AlPg). 5. An additive according to claim 1, characterized in that it is a water-insoluble, acid-soluble and alkali-soluble aluminum hydroxide complex.