EP1866262A1

EP1866262A1 - Hardening and setting accelerator additive, use of the latter and method for producing said additive

Info

Publication number: EP1866262A1
Application number: EP06723481A
Authority: EP
Inventors: Christophe Kurz; Heinz Schürch; Benedikt Lindlar; Franz Wombacher; Urs Mäder
Original assignee: Sika Technology AG
Current assignee: Sika Technology AG
Priority date: 2005-03-16
Filing date: 2006-03-16
Publication date: 2007-12-19
Also published as: JP5037485B2; JP2012121804A; WO2006097316A1; AU2006224732A1; JP2008532909A; AU2006224732B2; US20090120329A1

Abstract

The invention relates to a hardening and setting accelerator additive consisting of two components. The first component contains agents for developing the rigidity of the binding agent and the second component is an activating component and/or a texturing component.

Description

Solidification and hardening accelerator for hydraulic binders and its use and process for its preparation

Technical area

The invention is based on a solidification and hardening accelerator for hydraulic binders according to the preamble of the first claim. The invention is also based on a use and a method for producing a solidification and hardening accelerator for hydraulic binders according to the preamble of the respective independent claims.

State of the art

Many substances are known which accelerate the setting and hardening of concrete. For example, strongly alkaline substances such as alkali metal hydroxides, alkali metal carbonates, alkali silicates, alkali aluminates and alkaline earth chlorides are commonly used. For the strongly alkaline reacting However, fabrics can cause undesirable nuisance to the fabricator such as burns and reduce the final strength and durability of the concrete.

EP 0 076 927 B1 discloses alkali-free setting accelerators for hydraulic binders which are intended to avoid these disadvantages. To accelerate the setting and hardening of a hydraulic binder such as cement, lime, hydraulic lime and gypsum and mortar and concrete made therefrom, the mixture containing said binder is from 0.5 to 10% by weight based on the weight of this binder , an alkali-free setting and hardening accelerator added, said accelerator containing aluminum hydroxide. Such mortars and concretes are due to the accelerated setting and hardening particularly well suited as sprayed mortar and concrete.

EP 0 946 451 B1 discloses solidification and hardening accelerators in dissolved form for hydraulic binders, which can be mixed more easily with the concrete when spraying the concrete. Such a solidification and hardening accelerator consists, inter alia, of aluminum hydroxide, aluminum salts and organic carboxylic acids.

Such known accelerators contain relatively high levels of aluminum salts, and amorphous aluminum hydroxide is needed to make it, which is very expensive. To enable the production of such accelerators must the water for the reaction to 60 - 7O ⁰ C are heated. Other disadvantages of such solidification and hardening accelerators are also a relatively low early strength in the first few hours and days and the insufficient stability of the solution. Presentation of the invention

The invention is based on the object in a solidification and

Hardening accelerator for hydraulic binders of the aforementioned type to achieve the highest possible strength with the longest possible stability of the accelerator.

According to the invention this is achieved by the features of the first claim.

The advantages of the invention can be seen, inter alia, in the fact that the use of two separately supplied components makes the accelerator significantly more reactive as a first component. So far, namely, the accelerator was added to the concrete by wet spraying during spraying as a component at the nozzle. Such accelerators consist of several effective components, which also act individually. If these ingredients were presented individually in fresh concrete, this would lead to stiffening.

According to the invention it has now been found that the fresh concrete, a second component can be added, which does not lead to a stiffening of the concrete, but the accelerator can be much more reactive. Any conventional accelerator may be used. These second components can be added to the fresh concrete even during its production, without the processability is significantly limited. The concrete prepared with a second component according to the invention is significantly more reactive with respect to the accelerator, so that improved early strength and a better further

Strength development is achieved until at least 24h. The second component can also be added parallel to the actual accelerator at the spray nozzle. The addition of the second component can However, at any place, for example, during transport, on site in a concrete mixer, the pump, etc. .. The addition in the fresh concrete is particularly advantageous because this can be done in the concrete plant and on site no other components are processed have to. Since in particular the strength development in the period of a few hours often represents a problem with the present alkali-free accelerators, this can be improved by the addition of the second component according to the invention.

Although in WO 9211892 A1, in principle, the method of

However, this patent essentially relates to the combination with the liquefier and its liquefaction effect or their elimination.

Further advantageous embodiments of the invention will become apparent from the description and the dependent claims.

Short description of the drawing

In the following embodiments of the invention will be explained in more detail with reference to the drawings.

Show it:

Fig. 1 shows the early strength values of Examples 1 to 3; Fig. 2 shows the 4h compressive strength values of Examples 1 to 3;

Fig. 3 shows the early strength values of Examples 4 to 8;

Fig. 4 shows the 4h compressive strength values of Examples 4 to 8;

Fig. 5 shows the early strength values of Examples 9 to 11; Fig. 6 shows the 4h compressive strength values of Examples 9 to 11;

Rg.7 the early strength values of Examples 12 to 16;

Fig. 8 shows the 4h and 5h compressive strengths of Examples 12-16;

Ways to carry out the invention

accelerator component

Solidification and hardening accelerators for hydraulic binders are well known, and any solidification and hardening accelerators may be used per se for the present invention. Particularly advantageous are aluminum-containing accelerators, which lead to ettringite formation in the concrete.

Advantageous setting and hardening accelerators which can be used according to the present invention comprise (in% by weight):

0-30% aluminum hydroxide

0 - 50% aluminum sulphate

0-40% formic acid, 85% (or an equivalent mojare amount of another carboxylic acid) 0-15% other metal oxides / hydroxides

0 - 20% inorganic acids

0 - 25% alkali hydroxide

0 - 25% alkali carbonate

0 - 10% other special additives Advantageous alkali-free solidification and hardening accelerators which can be used according to the present invention comprise (in% by weight):

0-30% aluminum hydroxide 0-50% aluminum sulphate

0 - 40% formic acid, 85% (or an equivalent molar amount of another carboxylic acid) 0 - 15% other metal oxides / hydroxides 0 - 20% inorganic acids 0 - 10% other special additives

In these accelerators, it is particularly advantageous if a molar ratio of aluminum to organic acid greater than 0.3 and a molar ratio of aluminum to sulfate greater than 0.50.

In this case, accelerators are particularly advantageous, which have an aluminum content of up to 10%.

A particularly advantageous water-based solidification and hardening accelerator for hydraulic binders has a molar ratio of aluminum to organic acid of less than or equal to 0.65 and is referred to as L53AF S in the examples below.

Water-based accelerator refers to an accelerator that can occur as a solution, as a solution with partially finely dispersed particles or as a dispersion.

Such a water-based solidification and hardening accelerator advantageously comprises (in% by weight): - 14.4 to 24.9% sulphate, - 4 to 9.7% aluminum (or 7.6 to 18.3% Al ₂ O) ₃ ) - 12 - 30% organic acid, - 0 - 10% alkaline earth metal - 0 - 10% alkanolamine, - 0 - 5.0% flow agent,

- 0 - 20% stabilizer,

- And water, wherein a molar ratio of aluminum to the organic acid is less than or equal to 0.65. The aluminum content given as Al ₂ O ₃ is preferably less than 14%, more preferably less than 13% and in particular less than 12% Al ₂ O ₃ .

The abovementioned substances are advantageously to be found as ions in solution, but may also occur in complexed form or undissolved in the accelerator. This is particularly the case when the accelerator occurs as a solution with partially finely dispersed particles or as a dispersion.

A water-based solidification and hardening accelerator for hydraulic binders can be prepared, for example, from Al ₂ (SO ₄ ) ₃ aluminum sulfate, Al (OH) ₃ aluminum hydroxide and organic acid in aqueous solution, wherein a molar ratio of aluminum to organic acid is less than or equal to 0.65.

For the preparation of a preferred water-based solidification and hardening accelerator are advantageously used (in wt .-%):

- 30 - 50% Al ₂ (SO ₄ ) ₃ aluminum sulfate, - 5 - 20% Al (OH) ₃ aluminum hydroxide,

- 12 - 30% organic acid,

- 0 - 10% alkaline earth hydroxide - 0 - 10% alkaline earth oxide - 0 - 10% alkanolamine, - 0 - 5.0% flow agent,

- 0 - 20% stabilizer,

- Remainder water, wherein a molar ratio of aluminum to the organic acid is less than or equal to 0.65. In this case, an aluminum sulfate with about 17% Al ₂ O ₃ is preferably used, but it can also be used other contents, in which case at most the amounts to be added must be adjusted accordingly. The aluminum sulfate can also be produced by a reaction of aluminum hydroxide with sulfuric acid in the preparation of the accelerator, forming corresponding sulfate ions in the aqueous solution. In general, aluminum sulfate can be produced by a reaction of a basic aluminum compound with sulfuric acid.

As aluminum hydroxide, amorphous aluminum hydroxide is advantageously used. The aluminum hydroxide may also be used in the form of ammonium hydroxide carbonate, aluminum hydroxysulfate or the like. As the organic acid, it is preferable to use a carboxylic acid, more preferably a formic acid, but other equivalent organic acids such as acetic acid may be used. In general, however, all mono- or polyprotic carboxylic acids can be used. Since sulfate is used in the accelerator, magnesium hydroxide Mg (OH) ₂ is preferably used as the alkaline earth hydroxide. The same goes for the

Alkaline earth oxide so that then preferably magnesium oxide MgO is used.

As the alkanolamine, diethanolamine DEA is advantageously used. As a flow agent advantageously polycarboxylates and particularly advantageous Sika ViscoCrete® is used. As a stabilizer silica sol is advantageously used.

For the production of particularly advantageous solidification and

Hardening accelerators are used essentially (in wt .-%): - 30 - 50% Al ₂ (SO-O ₃ aluminum sulfate, preferably 35- 45%, in particular 35-38%, and / or - 5 - 20% Al (OH) ₃ aluminum hydroxide, in particular 7 - 15%, and / or - 15 - 23% organic acid and / or

- 1 - 10% alkaline earth metal hydroxide, in particular 2 - 6%, and / or - 1 - 5% alkaline earth oxide and / or - 1 - 3% alkanolamine and / or

- 0.1 - 3.0% flow agent, in particular 0.1 to 1.0% and / or - 0 - 10% stabilizer

- Remainder water, wherein a molar ratio of aluminum to the organic acid is less than or equal to 0.65, preferably less than 0.60, more preferably less than 0.55 and in particular less than 0.50.

The molar ratio of aluminum to the organic acid is preferably in a range from 0.38 to 0.65, particularly preferably in a range from 0.38 to 0.60, in particular between 0.50 and 0.60. Below a value of 0.38, the pH value becomes relatively low and a very high proportion of acid must be used, and in some cases stability is no longer guaranteed.

Compared to conventional setting accelerators, both the amount of aluminum sulfate used in the production and in particular of the aluminum hydroxide is reduced by up to 10% and 38%, respectively. Preferably, up to 10% of magnesium hydroxide and / or a corresponding amount of magnesium oxide are used in the preparation of the accelerator. The pure amount of Mg, based on the total amount of accelerator, is from 0 to 4.2%, preferably from 0.8 to 2.9%, particularly preferably from 1.3 to 2.1%.

The ratio of aluminum to the organic acid is adjusted to a value of less than 0.65, preferably less than 0.60, by the increased organic acid content compared with known accelerators and the pH is adjusted to pH 3-4 by up to 5% alkanolamine. The reduced by up to 25% of the amount of aluminum used in the production, the sulfate resistance is promoted. This is an advantage over conventional accelerators in which the sulfate resistance is drastically degraded by the accelerator. The reduction of sulfate resistance by aluminum entry is particularly caused by the fact that the aluminate phases have a particular affinity for sulfate. The additional aluminum increases the proportion of aluminate phases in the concrete, which then cause a not insignificant crystallization pressure by Ettringitbildung in external Sulfateinwirkung on the cured concrete and thus lead to damage. The aluminum content given as Al ₂ O ₃ is therefore preferably chosen to be less than 14%, more preferably less than 13% and in particular less than 12% Al ₂ O ₃ .

If magnesium hydroxide and / or oxide are used in the preparation of the accelerator, the temperature of the mixture increases so much due to the strong reaction of the magnesium hydroxide and / or oxide with the organic acid that the water does not have to be heated for these mixtures. The other components are then added to this heated mixture. The components can also be added in any other order. This simplifies the process and requires less energy. An additional advantage of the use of magnesium is the significantly higher storage stability of the accelerators caused by the magnesium ions. Already at a content of 1 wt .-% of magnesium hydroxide in the production of a good storage stability is achieved. At higher levels, storage stability is at least four months. Through the use of magnesium hydroxide and / or oxide, the accelerator can also be made significantly cheaper, since expensive aluminum hydroxide can be replaced. In addition, the stability of the accelerator is reduced by the

Aluminum quantity positively influenced. The reduced amount of aluminum also increases the sulfate resistance. The development of the pressure resistance of the sprayed concrete in the first few hours and days is also influenced very positively and is better than with conventionally used accelerators.

Second component

The second component serves to significantly improve the effect of the accelerator, but without the second component itself leading to earlier setting of the binder.

The second accelerator component may include either one of the following two variants or a combination of the two:

Option A)

A chemically active second component, which does not accelerate the setting of the binder but ideally even delayed, this activates for the actual accelerator so that after feeding this accelerator significantly better early strength and further strength development is achieved during the first hours to days.

This additional component is a complexing agent, preferably a complexing agent for calcium, preferably a hydroxydicarboxylic acid, more preferably a dicarboxylic acid, especially oxalic acid, or a mixture of the aforementioned substances.

The abovementioned substances, but in particular oxalic acid, are used in an amount of 0.1-2.0%, preferably 0.3-1.5%, particularly preferably 0.5-1.0%, in particular 0.7-0.9%, based on added hydraulic binders.

In addition, 0 - 20% silica fume, eg SikaFume-HR / -TU, can be added for better meterability and better concrete properties. Variant b)

A structurally acting second component, which in itself has no significant effect on the binding of the binder, but especially in the early phase and consolidates until the first days of the resulting mineral phases in this time.

Such an additional component is a thixotropic agent, preferably an anisotropically charged aluminosilicate, preferably a magnesium aluminosilicate (clay minerals, attapulgites), preferably a non-swelling magnesium aluminosilicate, more preferably an attapulgite, especially Acti-Gel® 208, or a mixture of the foregoing substances. Acti-Gel® 208 is a product of Active Minerals and is a specially prepared atapulgite. The abovementioned substances, but in particular attapulgite or Acti-Gel® 208, are added in an amount of 0.01-5.0%, preferably 0.1-2.0%, particularly preferably 0.15-1.0%, based on the hydraulic binder ,

Of course, a mixture of the second component mentioned under a) and b) can also be added. In this case, the second components can be used according to the above-mentioned areas in the mixture, since the second components according to variant a) and b) do not compete, but complement each other. Particularly preferred is a mixture of 0.25 - 2.0% oxalic acid with 0.05 - 1.5% Acti-Gel® 208, in particular 0.8 oxalic acid with 0.25% Acti-Gel® 208 shown.

The addition of the second accelerator component can be carried out in various ways. The second component is a liquid (solution or dispersion), or a powder, or a mixture thereof. The second component is mixed into the concrete already in the concrete plant separately or as a combination with the flow agent or other additives or can be added only at the spray nozzle, as an additional component. In particular, liquid second components are suitable for this purpose. Of course it is also possible to have the second component on one to add it to another location before the actual processing, or to add only parts of the second component at different locations.

embodiments

In the present experiments, the binding agent used was Portland cement and a typical alkali-free setting accelerator for shotcrete, Sigunit L53 AFS, i. used as the first component. The Sigunit L53AF S used here had a composition of (in% by weight):

37.0% Al ₂ (SO ₄ ) ₃ aluminum sulphate,

10.0% Al (OH) ₃ aluminum hydroxide, 18.3% formic acid,

4.5% magnesium hydroxide - 3.0% alkanolamine,

- balance water, wherein a molar ratio of aluminum to the organic acid is 0.65.

The second components according to Table 1 were all added to the dry mix and thus already present in the fresh mortar. In the case of the chemically activating second component, depending on its appearance (free-flowing, hygroscopic), it can be mixed with a flow aid, preferably finely divided silica, for example up to 3% Sipernat 22 S (Degussa) or up to 3% Cab-O-Sil TS 720. many others would be possible too. Alternatively, the second chemically activating component may be combined with silica, using a special shotcrete powdered silica. The use of silica fume can reduce the amount of Portland cement used.

Table 1

injection trials

All dosages are based on the amount of cement, i. the amount of hydraulic binder used.

The tests were carried out in the spray laboratory with a mortar with a grain size of 0 - 4 mm and a water / cement factor w / z = 0.48. All mixtures were liquefied and delayed with 1.1% ViscoCrete® SC 305. The Sigunit L53 AF S liquid accelerator component used here was added as usual to the spray nozzle at 6% (based on the binder). The early strength was measured in each case by means of a Proctor penetrometer during the first hour after spraying. The further strength development was after 4 - 6 h by means of Hilti bolt and after 24 h, the compressive strength was determined on 5 x 5 cm cores.

results

The results are shown graphically in FIGS. 1 to 10. In order to ensure the best possible comparability, the results are always presented as a comparison within the respective spray series and with the respective reference measurement. Even though the spraying tests are relatively easy to control in the laboratory, there are fluctuations that are caused by parameters that can not be controlled or are difficult to control.

Series 1, 2, (4) with oxalic acid

The addition of oxalic acid improves the accelerator effect of the conventional alkali-free accelerator, without itself significantly altering the workability of the concrete and in particular without shortening the open time of the concrete. From the results of experiments with a second component according to Examples 1 to 3, which are apparent from Figures 1 and 2, the greatly improved early strength and 4h compressive strength is evident, with increasing content of oxalic acid, these values increase continuously Results of the experiments with a second component according to Examples 4 to 8, which are apparent from Figures 3 and 4, the greatly improved early strength and 4h compressive strength is evident, the addition of silica has no influence on the accelerator effect.

Series 2, 3 with silica fume

The combination with Silicafume is very good. possible and useful and represents a good addition variant of oxalic acid. From the results of experiments with a second component according to Examples 4 to 8, which are apparent from Figures 3 and 4, the greatly improved early strength and the 4h compressive strength is evident, the addition of silica has no influence on the accelerator effect. This is also apparent from Examples 9 to 11, Figures 5 and 6, where pure silica is used and no improvement in the acceleration effect is apparent. In this series, the amount of Portland cement was reduced by the amount of silica fume.

Series 4 with attapulgite

By adding attapulgite, Acti-Gel® 208, in fresh concrete, a significant increase in performance of the accelerator can be seen. From the results of experiments with a second component according to Examples 12 to 15, which are apparent from Figures 7 and 8, the greatly improved early strength and 4h compressive strength is evident, with increasing content of Acti-Gel® 208 these values continuously increase.

The combination with oxalic acid according to Example 16 shows that the performance can be improved even further (0.25% Acti-Gel® 208, 0.80% oxalic acid), the effects of the two alternative components thus complement each other.

Of course, the invention is not limited to the embodiment shown and described. In addition to cement, mixed cement, lime, hydraulic lime and gypsum and mortar and concrete made therefrom can be used as hydraulic binders.

Claims

claims

1. A solidification and hardening accelerator for hydraulic binders, characterized in that it consists of two components, that the first component contains means for stiffening the binder and that the second component is an activating component and / or a structuring component.

2. solidification and hardening accelerator according to claim 1, characterized in that the second activating component is a complexing agent, and / or a complexing agent for calcium, and / or a

Hydroxydicarboxylic acid, and / or a dicarboxylic acid, and / or oxalic acid.

3. solidification and hardening accelerator according to claim 2, characterized in that the second activating component is a proportion of 0.1 to 2.0%, preferably 0.3 to 1.5%, particularly preferably 0.5 to 1, 0%, in particular 0, 7 - has 0,9% based on the hydraulic binder.

4. solidification and hardening accelerator according to one of the preceding claims, characterized in that the second structuring component is a thixotropic

Means, and / or an anisotropically charged aluminosilicate, and / or a magnesium aluminosilicate, and / or a non-swelling magnesium

Aluminosilicate, and / or an attapulgite, and / or Acti-Gel® 208.

5. solidification and hardening accelerator according to claim 4, characterized in that the second structuring component has a content of 0.01-5.0%, preferably 0.1-2.0%, particularly preferably 0.15-1.0%, based on the hydraulic binder.

6. solidification and hardening accelerator according to any one of the preceding claims, characterized in that the second component is a complexing agent, and / or a complexing agent for calcium, and / or a Hydroxidikarbonsäure, and / or a dicarboxylic acid, and / or oxalic acid, and / or a thixotropic agent, and / or an anisotropically charged aluminosilicate, and / or a magnesium aluminosilicate, and / or a non-swelling magnesium aluminosilicate, and / or an attapulgite, and / or Acti-Gel® 208.

7. solidification and hardening accelerator according to one of the preceding claims, characterized in that the first component comprises an aluminum content of up to 10%.

8. solidification and hardening accelerator according to one of the preceding claims, characterized in that the first component comprises sulfate, aluminum and organic acid.

9. solidification and hardening accelerator according to claim 8, characterized in that the first component has a molar ratio of aluminum to organic acid from 0.38 to 13.3, preferably from 0.38 to 0.60, in particular less than 0.55.

10. solidification and hardening accelerator according to claim 8 or 9, characterized in that the first component comprises (in wt .-%): 14.4 to 24.9% sulfate, 4 to 9.7% aluminum and 12 - 30% organic acid.

11. Use of the solidification and hardening accelerator according to claim 1 to 10 in a shotcrete or sprayed mortar, which are applied by means of a spray nozzle, characterized in that the first component is supplied to the shotcrete or sprayed mortar in the region of the spray nozzle and that the second component at a any place the shotcrete or sprayed mortar production, - transport, and / or -refining is supplied.

12. Use of the solidification and hardening accelerator according to claim 11, characterized in that the second component is added before the first component.

13. Use of the solidification and hardening accelerator according to claim 11 or 12, characterized in that the second component is supplied to the fresh concrete or mortar.

14. A process for producing a solidification and

Hardening accelerator according to one of claims 1 to 10, characterized the first component and the second component are produced separately from each other so that they can be added to the hydraulic binder separately from one another at different locations.