CH650482A5 - Process for the manufacture of concrete or mortar - Google Patents

Abstract

The invention relates to a process for the manufacture of concrete or mortar for building components and surfacings, which are insensitive to impact stresses, wear and alternating frost and thaw, in which at least one inorganic hydraulic binder, at least one plastic and, if appropriate, further additives are mixed with aggregates and water, characterised in that at least one plastic having a T lambda max value, determined by DIN 53445, of less than -8 DEG C is used. The binder used is in particular portland cement of conventional composition, iron portland cement, blast-furnace cement, alumina cement, modified portland cement based on 11 CaO.7Al2O3.CaF2, grenoble cement and/or roman cement. If appropriate, a content of bitumen and/or tar and/or further additives can be provided, the bitumen and/or tar which may additionally be present being in a ground, dry-dispersed, liquid-dispersed and/or dissolved form. The concretes or mortars manufactured according to the invention are virtually insensitive to impact stress, wear and especially frequent alternating frost and thaw stress and are additionally distinguished by a high low-temperature resistance and resistance to grit and thawing salt.

Description

650482

2nd

PATENT CLAIMS

1) Process for the production of concrete or mortar, which contains at least one inorganic hydraulic binder and at least one plastic, for the production of components and coverings which are insensitive to impact stress, abrasion and freeze-thaw, in which the aggregates are first dissolved in part of the and / or the dispersed form of the plastic present, then admixing the total amount of inorganic binder and finally adding the remaining part of the plastic and water, characterized in that a plastic with a Twx value, determined in accordance with DIN 53445, of less than -8 ° C used.

2) Method according to claim 1, characterized in that the concrete or mortar contains further additives.

3) Method according to claim 1 or 2, characterized in that lime or cement, in particular Portland cement, iron Portland cement, blast furnace cement, alumina cement, modified Portland cement based on 1 lCaO.7Al2O3.CaF2, grenoble cement and / or roman cement is used as the binder.

4) Method according to one of claims 1 to 3, characterized in that a plastic is used which has a T / .mM value of less than -15 ° C, in particular less than -36eC.

5) Method according to one of claims 1 to 4, characterized in that the plastic is used in amounts of 3 to 35 wt .-%, preferably from 5 to 20 wt .-%, based on the amount of the binder.

6) Method according to one of claims 2 to 5, characterized in that additionally bitumen and / or tar in finely divided form, preferably in amounts of 0.5 to 25 wt .-%, in particular from 0.5 to 10 wt .-% , particularly preferably from 1 to 6% by weight, based on the amount of the binder, is used.

7) Method according to one of claims 2 to 6, characterized in that additives which regulate the concrete properties are additionally used, preferably a) the amount of mixing water, in particular with the same processability of the mortar and concrete mixture, reducing substances, for example cationic, anionic or nonionic wetting agents or sulfite liquor , and / or b) the setting speed and / or the hardening of the mixture substances, for example gluconates, phosphates, citrates, tartaric acid, succinic acid, succinates, alkali carbonates, silicofluorides, aluminates, alkali or alkaline earth halides, and / or c) introducing micro-air pores Substances, for example conifer resins or synthetic pore formers, for example synthetic soaps or carboxylates, and / or d) pores containing, preferably having a closed surface, shaped bodies with sizes of 5 pm and above, in particular from 5 [m to 4 mm, preferably from 10 to 60 (xm, esp other hollow microspheres, for example hollow microspheres, made of expanded silicate substances, e.g. Pearlites, vermiculites and / or expanded clay, or of plastics, such as made of expanded polystyrenes (EPS), polyurethanes, foamed polyethylene and / or foam rubber.

8) Method according to claim 7, characterized in that component (s) d) in amounts of 1 to 10 vol .-%, preferably from 2.5 to 5 vol .-%, based on the volume of the finished concrete and / or mortar.

9) Method according to one of claims 1 to 8, characterized in that the additives are mixed with 30 to 70%, in particular 50%, of the plastic.

10) Method according to one of claims 6 to 8, characterized in that the aggregates are mixed, in particular coated, with at least part, preferably 30 to 100%, in particular 70 to 100%, of the bitumen and / or tar and part of the plastic, are then mixed in, and then the remaining rest of the plastic and optionally the remaining part of bitumen and / or tar and the desired amount of water are added.

The invention relates to a method for producing concrete or mortar for components and coverings which are insensitive to impact stress, abrasion and frost-thaw changes, in which at least one inorganic, hydraulic binder, at least one plastic and, if appropriate, further additives are mixed with additives and water.

It is known to use mixtures of cement and plastic dispersions and, if appropriate, bitumen emulsions, for example for producing or repairing surface-damaged concrete. Their use in closed rooms, under indoor climate conditions, shows quite satisfactory results. The experience is completely different in all those sectors of the construction industry where coverings, plasters, components or the like are exposed to major temperature fluctuations and in particular temperatures below 0 ° C. This also applies in particular to horizontally laid coverings, such as concrete pavements, which are often exposed to very low temperatures due to salt scattering, but should still maintain their full performance. Regardless of temperature fluctuations and low temperatures, concretes based on cement and plastics, which have been used up to now, show only low elasticity and toughness and, due to their brittleness, relatively high sensitivity to impact loads, e.g. due to heavy traffic, even when bitumen is used in the binder mixture , and relatively high abrasion, such as through spikes.

These properties of previously known binders based on cement and plastics made themselves unpleasantly noticeable both in the case of newly applied coverings or newly manufactured components, and in particular in the case of repairs, for example on road surfaces, bridges or the like, where interfaces between old concrete and new concrete occur.

The aim of the invention is to provide a method for producing concretes or mortars which do not have the disadvantages mentioned within a wide temperature range, are significantly less sensitive to impact stress, abrasion and frequent frost-thaw changes than previously known concretes or mortars and in particular also have a much better elastic behavior at temperatures below 0 ° C than previously used concretes or mortar, using a binder additive based on cement, plastic and possibly bitumen.

It should be stated that the principle - to mix cement with plastics and possibly bitumen or tar - is widely known in this general form in the patent literature. This is also evident from a wide variety of publications. For example, DE-OS 2 116 372 describes a process for producing high-strength cement, in which a possibly early high-strength cement with a macromolecular material that is formed from very specific monomers is used to build up very specific homopolymers.

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mer are capable, is mixed. The macromolecular material is in dispersed form. After mixing, heat or steam treatment at 50-150 ° C is mandatory. There the hardening of the plastic is achieved during the setting of the cement. s

DE-OS 2 449 211 describes a cement-bound building material which contains cement and a polymer plastic, e.g. Polyacrylate, as well as a defoaming agent, which should be present in amounts of up to 4.0% by weight, based on the amount of cement. At no point does the io DE-OS describe the problem to be solved according to the invention of producing components and coverings that are insensitive to impact stress, abrasion and in particular to frost-thawing stress.

DE-OS 1 671 078 describes a method for improving concrete, in which polyvinyl acetate, that is to say a very specific and customary plastic as an aqueous emulsion, as an emulsifiable powder or in the form of a plasticized copolymer, is added in the course of the production of the concrete. 20th

DE-OS 1 935 507 describes, without having the aim and the problem of the present invention, to create an impact-resistant and frost-thaw-resistant concrete and / or mortar, an addition to concrete or mortar, which necessarily a certain Cement, namely 25 Portland cement, contains as the main component. This additive must also contain a "sulfitic liquid" in combination with certain poly (ethylene-propylene) glycols.

In all of the previously mentioned publications, any addition of bitumen and / or tar to the plastic-containing concrete or mortar mixture is not mentioned.

This also applies to CH-PS 485 612, which describes a cement and aggregates as well as a building material mixture containing plastic, which is supposed to contain gluconic acid and / or its derivatives as an additive. A number of possible plastics are enumerated in the subclaims.

DD-PS 49 228 relates to a process for the production of a building material in which the binders are mixed with an emulsion of bituminous substances; here the addition of a plastic is not provided at all. The aim of the DD-PS process is also different from that according to the invention. 45

DD-PS 47 324 describes a method for shortening the drying times and lowering the processing temperatures to -3 ° C. for concrete screeds, in which a mixture of a bitumen emulsion, polyvinyl acetate and necessarily calcium chloride is added to the fresh concrete mixture. As is known, the addition of CaCk is even prohibited in almost all countries with regard to the corrosive effect on the steel inserts for steel and prestressed concrete.

Although a combination of cement, bitumen and 55 plastic is provided here, the aim of the process according to the DD-PS is only to lower the processing temperature, but not to achieve high flexibility at low temperatures and freeze-thaw conditions.

It should therefore be emphasized again that the object to be achieved according to the invention was to create building material mixtures for components and coverings which are exposed to temperatures below 0 ° C. and / or, more importantly, by alternating between freezing and thawing under the action of de-icing and de-icing salt at very low temperatures, the properties according to the invention, ie the elastoplasticity, are always retained at all temperatures. Under these,

As is known, very extreme conditions are said to have the impact resistance and abrasion resistance of the components and coverings to be produced, essentially those values which are otherwise the case at conventional temperature for compositions of the concrete or mortar, as are known from the prior art. Now none of the building material mixtures according to the previously known publications is able to achieve the effect which is sought according to the invention. The desired effect could only be achieved by the building material mixtures specifically described below for the solution to the problem and adapted to the extreme conditions that occur after installation. It was found that the building material mixture did not have to contain any plastic from the large number of commonly available and used polymers, and that it was not sufficient to select and use an elastic or plastic plastic, if necessary, but rather plastics had to be used here brought, which were until recently practically unavailable, and have new, unknown and unusual properties.

The invention thus relates to a process for the production of concrete or mortar, which contains at least one inorganic hydraulic binder and at least one plastic, for the production of components and coverings which are insensitive to impact stress, abrasion and freeze-thaw, in which the additions are first made with a part of the plastic present in dissolved and / or dispersed form is mixed, then the total amount of inorganic binder is mixed in and finally the remaining part of the plastic and water are added, characterized in that a plastic with a T \ max value, determined according to DIN 53445, used below -8 ° C.

In the method according to the invention, a binder batch is used which contains at least one hydraulic binder, e.g. Lime or cement, at least one, preferably in finely divided form, plastic, and optionally in finely divided form, bituminous substances and optionally further additives. Portland cement of conventional composition, iron Portland cement, blast furnace cement, alumina cement, modified Portland cement based on 1 lCa0.7Ah03..CaF2, grenoble cement and / or roman cement are used in particular as inorganic hydraulic binders. The bitumen and / or tar optionally additionally present is in ground, dry-dispersed, liquid-dispersed and / or dissolved form.

As an explanation, it should be stated that T / .max is the temperature at which the logarithmic decrement of the torsional vibration damping runs through a maximum in the test according to DIN 53445. This determination of the Twx value is described, for example, in the company publication "Acrylharzdispersionen", Röhm, pt. 5 p. 9.10.

It should be emphasized that the binder formulation used according to the invention contains a very specifically selected, “finished” plastic that no longer needs to harden during the setting of the cement. Steam treatment or treatment of the mixed concrete or mortar with heat for the polymerization is therefore not provided according to the invention and is not necessary.

In contrast to, for example, plasticized PVA used in building material mixtures (DE-OS 1 671 078), it is not possible for the plasticizer to escape in the plastics to be used according to the invention, which have low-temperature tackiness, since it is not present.

650482

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This "exudation" or leakage would lead to embrittlement, the low T?, Max value, however, is an inherent property of the plastic itself, so that changes due to aging after installation are practically excluded and the properties of the concrete according to the invention are different do not change over a wide range regardless of temperature and age.

The use of plastics according to the invention with a low Txmax value furthermore generally makes one for the durability of concretes or mortars, even in thin layers, each corresponding to the thickness of the largest grain of the aggregates, more than 0.5 mm, for example from about 1 to 40 mm, can be decisive elasticity achieved, which shows a strong damping effect when impact and shock. Hess was also able to ascertain that during repairs, significantly lower stresses occur in the interfaces between old and new concrete, which are caused, for example, by the shrinking of the hydraulic binder during hydration and by the change in length when the temperature changes.

While the previously used binder batches based on cement, plastic and possibly bitumen were still reasonably portable at room temperature or above, the binder batches processed according to the invention enable the production of coverings and components that can also be used at temperatures below 0 ° C and, depending on the choice of plastic, to a large extent including their elasticity and are therefore insensitive to impact, impact and abrasion as well as freeze-thaw cycles.

The additives or their combination according to the invention can on the one hand keep the concrete or mortar properties practically constant over a wide temperature range (-36 to + 80 ° C), on the other hand the elastic modulus and thus the desired concrete or mortar properties can be precisely adjusted in advance - according to the requirements.

The T / .max value of the plastic contained in the binder batch is selected according to the respective intended use and also the elasticity desired at room temperature. For the production of coverings in closed but unheated rooms, e.g. For coverings in garages, halls or the like, all plastics with a Txmax value of less than -8 ° C are suitable, although this value can only be slightly below -8 ° C.

If concretes are required for components and coverings that are not exposed to salt as a result of scattering at low temperatures, i.e. that do not have to endure extreme low temperatures, the addition of a plastic with a Txmax value of -15 ° C or below has proven to be advantageous .

For coverings and components that are exposed to extremely low temperatures as a result of salt scattering and the resulting lowering of the freezing point, the use of a plastic whose Txmax value is below -36 ° C has proven itself.

The concretes or mortars produced according to the invention, which contain the plastics mentioned with a low Txmax value, do not show the defects observed to date, such as splintering in the event of impact stress and embrittlement in the cold, since the plastic, depending on the Txmax value chosen, exceeds the original elasticity the entire desired operating temperature range is maintained without any noteworthy changes.

In addition, studies showed the surprising effect that at normal temperatures, when using plastics with Txmax values of in particular below -15 ° C., the required or respectively desired elasticity can be achieved by adding significantly smaller amounts of plastic, than for mixtures containing plastics whose T / .max value is higher.

The savings are, for example, at a tax value of -15 ° C, as was shown, about 40% and can be increased significantly if the Txmax value of the plastic used in the binder mixture drops.

The most diverse classes of plastics, that is to say pure polymers, but also mixed and co-polymers, can be used in the binders according to the invention if they meet only the criterion of a Txmax value which is below the Txmax value corresponding to the respective intended use. Value is enough. The following may be mentioned by way of example only: pure acrylic resins, olyacrylates, acrylic acid esters, styrene-butadiene resins, butadiene resins, polyvinyl esters (e.g. acetates or chlorides) and copolymers of the resins mentioned.

The low T / .max value can be achieved in particular by stopping the polymerization at a certain chain length. This has the advantage that these resins are essentially no more expensive than those previously used in binder mixtures. It is also possible to lower the Txmax value by adding plasticizers, but since the plasticizer is eliminated over the course of time, such plastics cannot be used for the purposes described above.

As far as the amounts of plastic in the binder batches used according to the invention are concerned, mixtures have proven to be advantageous in which the plastic in amounts of 3-35% by weight, preferably 5-20% by weight, based on the amount of the inorganic Binder is included.

The amount of bitumen and / or tar in the binder batch is advantageously from 0.5 to 25% by weight, in particular from 0.5 to 10% by weight, and preferably from 1 to 6% by weight, based on the amount of inorganic binder. It can also be favorable if the binder preparation contains, in addition to cement, plastic and optionally bitumen and / or tar, additives which regulate the concrete properties, preferably a) the amount of mixing water, in particular with the same processability of the mortar and concrete mixture, substances which reduce, for example cationic, anionic or nonionic wetting agents or sulfite liquors and / or b) substances which change the setting speed and / or the hardening of the mixture, for example gluconates, phosphates, citrates, tartaric acid, succinic acid, succinates, alkali metal carbonates, silicofluorides, aluminates, alkali metal or alkaline earth metal halides c) Substances such as, for example, natural coniferous resins or synthetic pore formers, for example synthetic soaps or carboxylates and / or d) containing pores, preferably having a closed surface, shaped bodies with sizes of approximately 5 μm and above, in particular of 5 μm to 4 mm , preferably from 10 to 60 Jim, in particular micro hollow bodies, for example hollow micro spheres, made of expanded silicate substances, such as e.g. Pearlites, vermiculites and / or expanded clay or made of plastics, such as e.g. made of expanded polystyrenes (EPS), polyurethanes, foamed polyethylene and / or foam rubber.

The amount of additive d) is preferably 1 to 10% by volume, in particular 2.5 to 5% by volume, based on the volume of the finished concrete and / or mortar.

A particularly favorable behavior of the finished mortar or concrete is achieved if the aggregates first with 30 - 70%, in particular about 50%, of the plastic in dissolved and /

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or dispersed form are mixed, in particular coated, then the total amount of inorganic binder is added, and finally the remaining part of the plastic and optionally the desired amount of water is added.

If the binder formulation also contains bitumen, it is advantageous if the aggregates contain at least part, preferably 30-100%, in particular 70-100%, of the bitumen and / or tar and preferably 30-70%, in particular approximately 50%, of the plastic are mixed, in particular coated, then the total amount of inorganic binder is mixed in and finally the remaining part or the total amount of the plastic and optionally the remaining part of the bitumen and / or tar and optionally the desired amount of water are added.

The invention is explained on the basis of the following experimental examples, which are summarized in table form:

Examples 1-14

Cement, dissolved and / or dispersed plastic (s) and optionally bitumen emulsion (s) were mixed in the amounts shown in the following table with those in dry form and with a grain composition according to ÖNorm B

3304 aggregates present in the compulsory mixer are mixed with the water required to achieve the required processing consistency in the order given above and installed in the test specimens.

s Storage up to the test took place under standard climate. To determine the mechanical properties (modulus of elasticity) at low temperatures, the test specimens were frosted 4 hours before the test.

The freeze-thaw cycle with simultaneous impact was achieved in the following way:

All of the cement and plastic mixtures listed in the table with or without bitumen emulsions were applied to a normal concrete, which corresponded to mixture 1), in a layer thickness of 4 cm and, after hardening, were exposed to freezing in the freezer, after a freezing time of 4 hours the test specimens were temporarily stored in water at 50 ° C for one hour. Every half hour, by removing the test specimens, the impact was caused by bouncing with the Schmidt device. This cycle of treatment continued until the new concrete broke loose or splintered. If the durability of the mixture exceeded 70 freeze-thaw cycles with simultaneous impact, the test was stopped.

table

No. Cement plastics kg / m3 FB calculated on the dry weight

Type kg / m3 FB

W / Z value

Density kg / m3

TX max. Value ° C DIN 53445

fresh

7 "

28d

1

400

_

_

-

0.45

2448

2440

2435

2nd

400

pure acrylic resin

40

+56

0.45

2443

2441

2438

3rd

400

Styrene

40

+21

0.45

2441

2436

2430

Butadiene

4th

400

Acrylic acid ethyl ester

40

+ 18

0.45

2440

2430

2425

5

400

Acrylic acid ethyl ester

40

-18

0.45

2438

2431

2428

6

400

Acrylic acid butyl ester

40

-46

0.45

2442

2432

2424

7

400

Styrene

40

-70

0.45

2390

2380

2374

Butadiene

8th

400 *

Acrylic acid butyl ester

30th

+ 18

0.47

2320

2300

2280

9

400 *

Acrylic acid butyl ester

30th

-40

0.47

2310

2302

2284

10th

400

Acrylic butyl ester

25th

-46

0.49

2445

2450

2443

11

400

-

-

-

0.45

2450

2445

2438

12

400

Vinyl acetate

40

-42

0.45

2220

2212

2198

Ethylene, viryl chloride

13

400

Acrylic acid butyl ester

100

-25

0.31

2305

2300

2286

14

400 **

Acrylic propyl ester

20th

-40

0.30

2198

2140

2100

* additionally 1.5% of a 60% bitumen emulsion based on the weight of the fresh room.

** additionally 10% of a 60% bitumen emulsion based on the weight of the fresh room.

Table 1. Continued

No. Compressive strength kp / cm2

Test temperature after storage at + 20 ° C

+ 20 ° C - 15 ° C -36 ° C

2h 7d 28d 2h 7d 28 "2h 7d 28d

1 112 390 425 -

2 118 412 500 -

3 74 240 304 -

4 84 260 330 -

5 72 224 312 -

6 69 200 300 -

381 424 - 396 444

450 548-481 561

285 321-318 378

305 366-350 420

248 364-311 382

201 298-220 312

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b

Table I (continued)

No. Compressive strength kp / cm2

Test temperature after storage at + 20 ° C

+ 20 ° C - 15 ° C -36 ° C

2h

7d

28d 2h

7d

28d 2h

7d

28d

7

44

112

138 -

117

141 -

121

136

8th

55

201

280 -

244

312 -

340

430

9

54

177

244 -

188

260 -

198

271

10th

90

220

315 -

246

338 -

260

350

11

-

300

406 -

312

404 -

340

412

12

-

116

121 -

198

212 -

248

260

13

-

180

190 -

185

200 -

196

204

14

-

100

112 -

160

174 -

240

268

Table 2. Continued

No. Elastic modulus (static) kp / cm2 according to ÖNorm B 3303 test temperature after storage at + 20 ° C

+ 20 ° C - 15 ° C

7d 28d 7d 28d

1

245,000

320,000

248,000

324,000

2nd

212,000

318,000

242,000

358,000

3rd

140,000

160,000

205,000

212,000

4th

152,000

206,000

230,000

321,000

5

112,000

118,000

120,000

127,000

6

98,000

100,000

100,000

102,000

7

60,000

64,000

61,000

64,000

8th

100,000

120,000

205,000

291,000

9

50,000

52,000

50,000

51,000

10th

125,000

140,000

134,000

160,000

11

232,000

310,000

230,000

314,000

12

112,000

122,000

146,000

160,000

13

68,000

69,000

69,000

70,000

14

12,000

13,000

48,000

49,000

Table 3. Continued

No. Elastic modulus (static) kp / cm2 according to ÖNorm B 3303 test temperature after storage at + 20 ° C

-36 ° C

Number of frost-de-icing salt periods and additional impact

Cement type

-15 ° C

-36 ° C

7d

28d

1

252,000

333,000

-

-

modified

2nd

271,000

364,000

4th

2nd

Portland cement

3rd

248,000

280,000

4th

3rd

based on

4th

265,000

357,000

4th

3rd

llCa.07Ah03.CaF2

5

164,000

204,000

> 70

4th

6

112,000

116,000

> 70

> 70

7

78,000

80,000

> 70

> 70

8th

288,000

364,000

4th

1

9

60,000

64,000

> 70

> 70

10th

180,000

200,000

> 70

28

11

242,000

324,000

-

-

Portland cement

12

242,000

228,000

> 70

> 70

PZ375

13

71,000

72,000

> 70

> 70

14

81,000

82,000

> 70

> 70

7

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The attempts, sorted by the number of the table, essentially show the following:

1) shows the mechanical values of a cement-bound concrete without additives and the elasticity behavior under the temperature conditions at 20 ° C, -15 ° C and -36 ° C.

2) When adding a dispersion consisting of pure acrylic resin, whose Txmax value is + 56 ° C, the elasticity at + 20 ° C is almost the same as that of the substrate; in the cold, i.e. already at -15 ° C, the plastic content and thus the covering become brittle, the frost-thaw periods are 2-4.

3) + 4) show essentially similar results, although the T / .max value is reduced compared to 2).

5) The use of plastics with a Ttax value of -18 ° C does not disadvantageously change the elasticity of the concrete even in the cold (at -15 ° C).

6) + 7) show that due to the significantly lower Txmax values, elasticity changes in the cold do not occur to a significant extent.

8) The cement / plastic system was additionally mixed with bitumen emulsion, which improves the elasticity at normal temperatures, but nevertheless embrittles the covering due to the thermoplastic character of the bitumen at lower temperatures.

9) By using plastics with a Txmax value of -40 ° C, the good elastic properties remain

5 shafts to the lowest test temperature fully preserved despite the otherwise common embrittlement of the bitumen.

10) This example demonstrates the possibility of saving plastic in an amount of around 40% by using plastics with low Txmax values to achieve the same elasticity values compared to those with high Txmax values (see comparison to Example 4).

11) is a comparative example as 1), but Portland cement 375 has been used as cement instead of modified Portland cement based on Ci i A7CaF2.

is 12) shows that the criterion of cold elasticity is given by the TW value, regardless of the type of plastic.

13) Higher or plasto-elastic coverings with excellent low-temperature elasticity result from higher proportions of plastics.

20 14) Through the interaction of plastics with low Txmax values and a higher bitumen content, the cold elasticity is guaranteed despite the embrittlement of the bitumen.

B