CH618668A5 - Hydraulic mortar composition - Google Patents

Abstract

The mortar compositions comprise, mixed, a hydraulic binder, fibrils of a synthetic polymer and a wetting agent for the fibrils. The mortar compositions are particularly suitable for the application of wall coverings, such as adhesive mortars for the application or grouting of tiling and as casting material.

Description

The present invention relates to hydraulic mortar compositions which may be suitable in particular as a wall coating for outdoor or indoor use, for laying or grouting tiles such as wall covering tiles, and as molding material.

The wall coatings and mortars used for laying or grouting tiles are generally prepared by mixing with water a composition comprising a hydraulic binder such as Portland cement or plaster, for example, optionally mixed with a filler such as sand, for example, and one or more additional additives intended to give them specific properties.

It is also known to make molded objects, for example statuettes or ornamental moldings, from plaster or other hydraulic binders.

To improve the mechanical properties of mortars, in particular their resistance to cracking and impact, as well as the rheological properties of fresh mortars, it has already been proposed to mix asbestos fibers with the hydraulic binder.

However, the incorporation of asbestos into mortar compositions has various drawbacks. This results in particular in a serious danger to the health of the manufacturer and of the user of the mortar composition in powder form, because of the toxic nature of the asbestos fibers.

Furthermore, when a white mortar is desired, for example in order to produce a white wall coating or white joints between ceramic tiles, it is necessary to incorporate into the mortar constituents a white pigment of superior quality,

for example titanium dioxide, so as to compensate for the gray tint of asbestos. The addition of this pigment obviously puts a strain on the cost price of the mortar, without however helping to improve its mechanical characteristics.

The licensee has now found that it is possible to remedy these drawbacks of the known compositions for mortars, by replacing asbestos with fibrils of a synthetic polymer.

Consequently, the invention relates to hydraulic mortar compositions suitable in particular as a wall coating, for laying and / or grouting tiles and as molding material, said compositions comprising a hydraulic binder and optionally a filler and additives, the improvement consisting in that the compositions contain between 0.05 and 3% by weight of fibrils of a synthetic polymer and between 0.05 and 0.5% by weight of a wetting agent of the polymer. The balance is normally made up of the binder, the filler material and any additives, in proportions known per se for hydraulic mortars.

The fibrils referred to in the mortar compositions according to the invention are a specific structure of the polymeric material. They consist of an aggregate of a multitude of very fine filaments, of dandruff appearance, connected together so as to form a three-dimensional network. With fibrous appearance, the fibrils have an oblong shape; their length varies from 0.5 to 50 mm approximately and their diameter from a few microns to approximately 5 mm. They are characterized by a high specific surface, greater than 1 m2 / g and even, in many cases, 10 m2 / g.

The fibrils used in the mortar composition according to the invention preferably have a length substantially between 0.5 and 15 mm and a diameter less than 0.5 mm.

In general, all the polymers capable of being spun are suitable for the manufacture of the fibrils used in the mortar compositions according to the invention. By way of example, mention may be made of polyolefins, polyamides, thermoplastic polyesters, polyurethanes, vinyl polymers and acrylic polymers. Advantageously, fibrils made of polyethylene, polypropylene or polyvinylidene fluoride can be used.

The fibrils used in the mortar compositions according to the invention can, for example, be produced by subjecting a two-phase mixture of a polymer in the molten state and of a solvent, to sudden expansion through an appropriate orifice, such as described in particular in French patents N05 1596107 of December 13, 1968, 2148449 and 2148450 of August 1, 1972, and in Belgian patents N ° s 811778 of March 1, 1974 and 824844 of January 17, 1975, all in the name of the owner.

As a variant, the fibrils used in the mortar compositions according to the invention can obviously be manufactured by other methods, for example by one or the other of the methods described in French patents No. 1214157 of June 10, 1958 and 1472989 of September 24, 1965, in the name of EI du Pont de Nemours and Co. In these manufacturing processes, however, continuous fibrillated wicks are obtained, which must then be shredded, for example by grinding, to obtain fibrils which can be used in mortar compositions according to the invention.

The function of the wetting agent used according to the invention is to ensure a homogeneous distribution of the fibrils, when the mortar compositions are mixed with water, at the time of their use. It can for example be chosen from cellulose ethers, polyvinyl acetate, polyvinyl alcohol and casein.

The hydraulic binder can comprise any binder usually used in hydraulic mortars, for example hydraulic lime, plaster, cements such as portland cement, blast furnace cements, clinkers.

Depending on the type of binder used, it may be necessary or advantageous to incorporate a filler material in the mortar composition, in variable amounts depending on the nature of the binder, its

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particle size as well as the variety and particle size of the filler. In a manner known per se, the filler material can for example comprise sand, veriniculite, perlite, glass particles.

The sand optionally used in the mortar compositions according to the invention can be a natural sand (for example sand pits) or an artificial sand such as a dust resulting from the crushing of hard rocks or from the granulation of a slag of blast furnace.

In the mortar compositions according to the invention, the content of fibrils is adjusted as a function of the properties sought for the mortar.

According to the invention, the content of fibrils is substantially between 0.05 and 3% by weight of the mortar composition. The lower limit content corresponds to that for which the action of the fibrils on the properties of the mortar becomes perceptible, while the upper limit content is that beyond which the fibrils have an unfavorable action on the mechanical performance of the mortar.

According to the invention, the content of wetting agent in the mortar compositions is substantially between 0.05 and 0.5% by weight of the mortar composition. The content of wetting agent depends on the nature of the wetting agent, as well as on the nature of the fibrils, their dimensions and their quantity in the mortar composition. It must be sufficient to ensure effective wetting of the fibrils and their substantially homogeneous dispersion in water.

The mortar compositions according to the invention may optionally include additives commonly used to impart specific properties to hydraulic coatings or mortars, for example fluidizers, setting accelerators or retarders, thickeners, plasticizers, water repellents, quantities known per se in hydraulic mortar compositions.

The mortar compositions according to the invention find application in the preparation of hydraulic mortars intended in particular for the application of interior or exterior wall plasters, for laying or grouting tiles, as well as for molding objects such as statuettes or ornamental moldings.

The mortar compositions according to the invention have the appreciable advantage of making it possible to obtain mortars having high mechanical properties, at least equal to those obtained from known mortar compositions containing asbestos, while eliminating the drawbacks inherent in asbestos.

All other things being equal, the mortars obtained from the compositions according to the invention have the additional advantage of being less prone to cracking than known mortars or plasters.

Furthermore, thanks to the use of white polymer fibrils, the mortar compositions according to the invention have the advantage of lending themselves to the production of wall plasters or mortar joints between tiles whose degree of whiteness is greater. to that of known plasters or mortars containing simultaneously asbestos and a white pigment such as titanium dioxide. The invention also makes it possible, in this case, to overcome the presence of white pigment in the mortar composition, which reduces the cost price.

It is however very obvious that the mortar compositions according to the invention also lend themselves to the production of colored wall coatings, colored joints between ceramic tiles and colored molded objects. It suffices, in this case, to incorporate a pigment into the mortar composition according to the invention, such as, for example, depending on the desired shade, particles of chromic oxide, lead oxide, lead chromate or carbon black.

Alternatively, the fibrils can be impregnated with a pigment.

In a particular embodiment of the mortar compositions according to the invention, a filler material is incorporated into the polymer used for the manufacture of the fibrils, so as to confer on them one or the other particular property. As filler, it is possible, for example, to incorporate kaolin, silica, crushed chalk or a pigment into the polymer.

In another particular embodiment of the mortar compositions according to the invention, intended more particularly for the manufacture of white mortars, the hydraulic binder comprises white cement or plaster, and the filler material possibly present comprises white sand.

In an advantageous embodiment of the mortar compositions according to the invention, the content of polymer fibrils is substantially between 0.2 and 1% by weight of the composition.

In a preferred embodiment of the mortar compositions according to the invention, the wetting agent is a cellulose ether, such as methylcellulose, which has the advantage of constituting, at the same time, a thickener for the mortar.

The composition according to the invention finds particular application in the covering of building facades with a protective and decorative coating, white or colored.

The composition according to the invention can also be used to apply a coating of ceramic tiles to a vertical masonry partition of a building.

In the use according to the invention, the amount of mixing water for the paste or the malleable mortar depends on the nature and the particle size of the binder, the nature and the particle size of the filler material possibly used, as well as weight proportions of binder and filler material.

The purpose of the few application examples which follow is to illustrate the invention without, however, limiting its scope.

First series of tests

Three wall plasters were prepared from three different mortar compositions, based on white cement and white sand.

Example 1 relates to a mortar composition prior to the invention, containing asbestos, while Examples 2 and 3 relate to two particular embodiments of the mortar composition according to the invention, free of asbestos.

In each test, the flexural strength and the modulus of elasticity of the coating were measured 28 days after its application, and the ratio of these two quantities was calculated, which is a measure of the resistance of the coated with cracking. We also noted the degree of whiteness of the coating, expressed by the ratio, in percent of the diffuse reflection factor of the coating to the diffuse reflection factor of pure magnesium oxide, these two reflection factors being measured in the purple and blue portion of the spectrum.

Example 1 (comparative):

A coating was applied to a vertical masonry wall from a mortar composition prior to the invention, containing:

white cement: 460 g white sand: 460 g insulating filler: 40 g methylcellulose: 5.5 g asbestos: 27.5 g titanium dioxide: 7.5 g mixing water: 40%

by weight of the composition

28 days after its application, the coating exhibited the following characteristics:

flexural strength (Rf): 36.5 kg / cm2

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modulus of elasticity (E): 525 kg / cm2

Rf / E ratio: 6.9%

degree of whiteness: 69%

Example 2:

A coating was applied to a vertical masonry support, using the following mortar composition, in accordance with the invention:

white cement:

460 g white sand:

460 g insulating charge:

40g methylcellulose:

5.5 g polyethylene fibrils:

10 g mixing water:

42%

28 days after its application, the coating exhibited the following characteristics:

flexural strength (Rf): 34 kg / cm2 elastic modulus (E): 450 kg / cm2

Rf / E ratio: 7.6%

whiteness: 72.5%

Example 3:

The test of Example 2 was repeated with a mortar composition in accordance with the invention, containing:

white cement:

460 g white sand:

460 g insulating charge:

20 g methylcellulose:

5.5 g polyethylene fibrils:

10 g mixing water:

40%

28 days after its application, the coating exhibited the following characteristics:

15 flexural strength (Rf): 38 kg / cm2

elastic modulus (E): 530 kg / cm2

RF / E ratio: 7.2%

degree of whiteness: 72%

The results obtained with the coatings of Examples 1 to 3 are reported in Table 1.

Table I

Example

Resistance

Module

Report

Degree

No.

to elastic flexion

Rf: E

whiteness

(kg / cm2)

(kg / cm2)

(%)

(%)

1

36.5

525

6.9

69

2

34

450

7.6

72.5

3

38

530

7.2

72

It is observed that the coatings obtained from the mortar compositions in accordance with the invention (Examples 2 and 3) have a resistance to cracking (expressed by the ratio Rf / E) greater than that of the coating obtained from the mortar composition of Example 1, prior to the invention.

Furthermore, the coatings of Examples 2 and 3 (in accordance with the invention) have a higher degree of whiteness than that of the coating of Example 1 (prior to the invention), containing asbestos and dioxide titanium.

Second series of tests

This series of tests focused on adhesive mortars based on cement, intended for the installation of tiles. In each test, the following mechanical characteristics of the mortar were noted:

1. the aptitude of the mortar for crushing, a property which conditions the ease of application of tiles on a wall; to measure the ability of the mortar to be crushed, parallel strips of mortar 6 mm wide by 4 mm high, spaced 6 mm apart, were placed on a support covered with a sheet of paper. crushed these strips against a 5 x 5 cm glass plate and we noted the effort required for the entire glass plate to be covered with mortar;

2. linear shrinkage of the mortar during a 28 day drying;

3. the adhesion of the mortar to the tiles, expressed by the shearing force necessary to break a layer of mortar 20 cm2 in area and 3 mm thick, bonding two 5 x 5 cm tiles together. In each test, two adhesion measurements of the mortar were carried out after 28 days of drying, respectively with earthenware tiles and with sandstone tiles.

Among the examples which follow, example 4 relates to a mortar composition prior to the invention, containing asbestos, while examples 5, 6 and 7 relate to three

35 mortar compositions according to the invention, free of asbestos.

Example 4 (comparative):

An adhesive mortar was prepared from the following composition, prior to the invention, containing asbestos:

cement: 400 g sand: 600 g methylcellulose: 6 g asbestos: 6.6 g mixing water: 23%

The adhesive mortar obtained from this composition exhibited the following properties, as defined above:

n / a 1. crushability:

- after 5 minutes of drying:

- after 15 minutes of drying:

- after 30 minutes of drying:

5S 2. linear withdrawal after 28 days:

3. adhesion after 28 days:

- on earthenware:

- on sandstone:

60 Example 5:

An adhesive mortar was prepared from the following mortar composition, in accordance with the invention:

cement: 400 g

“Sand: 600 g methylcellulose: 6 g polyethylene fibrils: 2.2 g mixing water: 25%

1.6 kg 2.5 kg 3.2 kg

0.78 mm / m

13 kg / cm2 3.4 kg / cm2

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The mortar exhibited the following mechanical properties:

1. crushability:

- after 5 minutes of drying:

1.5 kg

- after 15 minutes of drying:

2.5 kg

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- after 30 minutes of drying:

3.4 kg

2. linear withdrawal after 28 days:

0.92 mm / m

3. adhesion after 28 days:

- on earthenware:

13 kg / cm2

10

- on sandstone:

3.4 kg / cm2

Example 6:

The test of Example 5 was repeated, with the composition of

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following mortar, according to the invention:

cement:

400 g

sand:

600 g

methylcellulose:

6g

20

polyethylene fibrils:

4.4 g mixing water:

29%

The mortar obtained with this composition presented the

following properties:

1. crushability:

25

- after 5 min:

1.5 kg

- after 15 min:

2.4 kg

2. linear shrinkage after 28 days: 0.75 mm / m

3. adhesion after 28 days:

- on earthenware: 21 kg / cm2

- on stoneware: 3.1 kg / cm2

Example 7:

The tests of Examples 5 and 6 were repeated with the following mortar composition, in accordance with the invention:

cement:

400g sand:

600 g methylcellulose:

6g polyethylene fibrils:

6.6 g mixing water:

33%

The mortar prepared from this composition had the following mechanical characteristics:

1. crushability:

- after 5 minutes of drying:

- after 15 minutes of drying:

- after 30 minutes of drying:

2. linear withdrawal after 28 days:

3. adhesion after 28 days:

- on earthenware:

- on sandstone:

1.6 kg

2.7 kg 3.3 kg

0.70 mm / m

18 kg / cm2 3.3 kg / cm2

after 30 min:

3.8 kg

The results obtained with the adhesive mortars of Examples 4 to 7 are recorded in Table 2.

Table II

Examples Crushability (kg) Removal Adhesion after linear drying after 28 days after 28 days (kg / cm2)

No.

5 mins

15 mins

30 mins

(mm / m)

Earthenware

Sandstone

4

1.6

2.5

3.2

0.78

13

3.4

5

1.5

2.5

3.4

0.92

13

3.4

6

1.5

2.4

3.8

0.75

21

3.1

7

1.6

2.7

3.3

0.70

18

3.3

It is observed that the adhesive mortars of Examples 5, 6 and 7, Of course, various modifications can be made to

in accordance with the invention, have properties comparable to the above description, given by way of nonlimiting example,

those of the adhesive mortar of Example 4, prior to the invention, without departing from the scope of the invention.

while avoiding the presence of asbestos. 50 - -

R

Claims (12)

618,668 1. Composition of hydraulic mortar suitable in particular as a wall coating, comprising a hydraulic binder, characterized in that it contains between 0.05 and 3% by weight of fibrils of a synthetic polymer and between 0.05 and 0.5% by weight of a polymer wetting agent. 2. Composition according to claim 1, characterized in that it contains between 0.2 and 1% by weight of fibrils. 2 3. Composition according to one of claims 1 or 2, characterized in that the fibrils are made of polyethylene. 4. Composition according to any one of claims 1 to 3, characterized in that the fibrils contain a filler. 5. Composition according to any one of claims 1 to 4, characterized in that the wetting agent comprises a cellulosic ether. 6. Composition according to claim 5, characterized in that the wetting agent comprises methylcellulose. 7. Composition according to any one of claims 1 to 7, characterized in that the fibrils have a length between 0.5 and 50 mm, a diameter at most equal to 5 mm and a specific surface greater than 1 m2 / g . 8. Composition according to claim 7, characterized in that the fibrils have a length between 0.5 and 15 mm and a diameter less than 0.5 mm. 9. Use of a composition according to claim 1 as a mortar, characterized in that water is added to the composition. 10. Use according to claim 9 for laying and grouting tiles. 11. Use according to claim 9 for the preparation of a wall coating. 12. Use according to claim 9 as a molding material.