Process for producing and processing a setting and hardening accelerator
TECHNICAL FIELD
The invention relates to a process for producing a setting and hardening accelerator in accordance with the preamble of the first claim.
BACKGROUND OF THE INVENTION
Many substances which accelerate the setting and hardening of hydraulic binders
such as concrete are known. Customarily used substances are, for example,
strongly alkaline substances such as alkali metal hydroxides, alkali metal carbon-
ates, alkali metal silicates, alkali metal aluminates and alkaline earth metal chlo-
rides, alkali free accelerators. Accelerators for hydraulic binders are mostly used
for sprayed concrete. Sprayed concrete and the spraying machines used for this
purpose, e.g. Sika® Aliva® spraying machines, are generally known. The accelera-
tors, which are added in the region of the spray nozzle are always introduced in
liquid form. These accelerators are usually brought in containers to the spraying
apparatus or to the spraying machine. However, a problem with these liquid addi-
tives is the storage stability which is frequently unsatisfactory, as a result of which
the additives can become unusable on prolonged storage. In addition, these liquid
concrete additives have a relatively large volume, which can present supply prob-
lems and high transport costs.
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SUMMARY OF THE INVENTION
Accordingly, one object of the invention is to provide an accelerator which over-
comes the afore mentioned problems.
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 in the
present method according to the invention, the liquid accelerator is not prepared
beforehand. Due to the fact that in each case only the necessary amounts of com-
ponents A, B and water are mixed, no problems with the stability of the individual
components occur in the present method. The individual components A and B are
very stable and have no stability problems. Furthermore, the volume of the pow-
dery component A is at least a factor of two smaller than when liquefied compo-
nent A would be used, as a result of which lower transport costs are incurred and
environmental pollution is reduced.
Further advantageous embodiments of the invention emerge from the sub claims.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A setting and hardening accelerator according to the invention is advantageously
produced by using three components. One of the components is in a powdery
form, the other component is in liquid form, the other component is water.
The powdry component A comprises (in % by weight) from:
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- 0 to 100% of aluminum sulfate (containing 17% of Al2O3),
- 0 to 40% of aluminum hydroxide,
- 0-10% magnesium hydroxide (Mg(OH)2)
- 0-5%o manganese sulfate (MnS04 x H20),
- 0-12% ferric sulfate (Fe2(S04)3 x H20),
- 0-1 % of sodium gluconate,
- 0-30% of silica,
- the aluminum content is at least 1%.
The liquid component B comprises (in % by weight) from:
- 0 to 100% of organic acid,
- 0-100% of alkanolamine,
- 0-100%o phosphoric acid (75%)
- 0-50%o hydrofluoric acid (40%),
- 0-5% other mineral acid such as boric acid,
- 0-100% of silica sol (30% solid content),
- the acid content is at least 1%,
- remainder water.
The three components A, B and water are mixed in a ratio of 10-80% of compo-
nent A, 1-35% of component B, remainder water. A preferred range is 50-65%
component A, 4-20% component B, remainder water, a most preferred range is
55-60% component A, 5-15% component B, remainder water.
Preferably, an aluminum sulfate containing about 17% of Al203 is used, but it is
also possible to use other contents, although the amounts to be added then may
have to be adapted accordingly. The aluminum sulfate can also be produced by
reaction of aluminum hydroxide with sulfuric acid in the production of the accelera-
tor, with sulfate ions correspondingly being formed in the aqueous solution. In
general, aluminum sulfate can be produced by reaction of a basic aluminum com-
pound with sulfuric acid.
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Amorphous aluminum hydroxide is advantageously used as aluminum hydroxide.
The aluminum hydroxide can also be used in the form of aluminum hydroxide car-
bonate, aluminum hydroxysulfate or the like.
Since sulfate is used in the accelerator, magnesium hydroxide Mg(OH)2 is prefer-
ably used as alkaline earth metal hydroxide. The same applies to the alkaline
earth metal oxide, so that magnesium oxide MgO is then preferably used.
As organic acid, preference is given to using a carboxylic acid, particularly prefer-
ably formic acid HCOOH, but it is also possible to use other organic acids having
an equivalent effect, e.g. acetic acid CH3COOH, oxalic acid, etc. In general, it is
possible to use all monoprotic or multiprotic carboxylic acids.
Diethanolamine DEA is advantageously used as alkanolamine.
Silica sol is advantageously used as stabilizer.
It is also possible to use a thickened component A or moist powder instead of the
dry powdery component A. However, attention may have to be paid to stability
problems. The component A to be used for the purposes of the invention should
have a certain solids content of at least above 50%, preferably above 80%, most
preferably above 90%.
To produce the inventive accelerator, the powdery component A, the liquid com-
ponent B and water were given into a container and stirred until the reaction has
abated. Optionally the components can also be mixed in an apparatus as de-
scribed in WO 2005/065906 A1, the teaching of which is incorporated herein. As
described in WO 2005/065906 A1 the accelerator is preferably used in sprayed
concrete.
Advantageous ranges of the component A are:
- aluminum sulfate (containing 17% of Al203): 65-90%, preferred 70-85%;
- aluminum hydroxide: 0-35%, preferred 0-30%, most preferred 10-30%, in
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particular 20-25%;
- magnesium hydroxide (Mg(OH)2): 3-6%, preferred 4-5%;
- manganese sulfate (MnS04 x H20): 0-3%, preferred 1-3%;
- ferric sulfate (Fe2(S04)3 x H20): 0-6%, preferred 2-6%
- sodium gluconate: 0-0.7%. preferred 0.2-0.5%)
- silica: 5-30%, preferred 15-25%
Advantageous ranges of the component B are:
- organic acid: 10-80%, preferred 20-75%, most preferred 50-75%;
- alkanolamine: 10-90%;
- phosphoric acid (75%): 0-90%, preferred, 0-75%, most preferred 5-50%, in
particular 10-35%;
- hydrofluoric acid (40%): 0-20%, preferred 15-20%;
- silica sol (30% solid content): 0-80%, preferred 20-80%), most preferred 40-
60%.
In an advantageous composition component A comprises 65-90% of aluminum
sulfate, component B comprises 10-90% alkanolamine and 20-75% organic acid
and component A and B are mixed in a ratio of 50-65% component A, 4-20%
component B, remainder water.
In another advantageous composition component A consists of aluminum sulfate,
component B consist of 45-50% diethanolamine, 28 to 35% acetic acid, remainder
water and component A and B are mixed in a ratio of 57-63% component A, 4-8%
component B, remainder water.
In contrary to other accelerators the inventive accelerator is not prepared before-
hand and thus no far transport is needed for the liquid accelerator. Due to the fact
that in each case only the necessary amounts of components A, B and water are
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mixed, no problems with the stability of the individual components occur in the
present method.
The accelerator prepared according to the invention is processed after mixing
within 7 days, preferred within 5 days, most preferred within 3 days, in particular
within 1 day.
Examples
A number of samples of accelerators according to the invention were produced in
accordance with the values indicated in Table 1, using aluminum sulfate contain-
ing 17% of Al2O3. The remainder to sum up to 100% was water.

Example Component A
(powder) Component B
(liquid)
A1 60%(AI-Sulfate17%) 6.25 % (15.7%H20 / 52.3% DEA
(90%) / 32% CH3COOH)
A2 55%(AI-Sulfate17%) 6.25 % (15.7%H20 / 52.3% DEA
(90%) / 32% CH3COOH)
A3 60%(AI-Sulfate17%) 6.25 % (15.7%H20 / 52.3% DEA
(90%) / 28.5% HCOOH)
A4 55%(AI-Sulfate17%) 6.25 % (15.7%H20 / 52.3% DEA
(90%) / 32% HCOOH)
A5 51%(AI-Sulfate17%)/
1.5% Mn-Sulfate 12.5 % (16%H20 / 24% DEA(90%) /
40% HCOOH / 20% Glycerin)
A6 51%(AI-Sulfate17%)/
3.7%Mg(OH)2 /1.5% Mn-
Sulfate 12.5 % (16%H20 / 24% DEA(90%) /
40% HCOOH / 20% Glycerin)
A7 51%(AI-Sulfate17%)/5%
Mg(OH)2 12.5 % (16%H20 /24% DEA(90%) /
40% HCOOH / 20% Glycerin)
A8 52% (Al-Sulfate 17%) 6.25 % (15.7%H20 / 52.3% DEA
(90%) / 32% CH3COOH)
A9 52% (Al-Sulfate 17%) / 5%
Mg(OH)2 6.25 % (15.7%H20 / 52.3% DEA
(90%) / 32% CH3COOH)
A10 37% (Al-Sulfate 17%) /10%
AHA/4.9%Mg(OH)2 30% (20.33%H2O /52.3% DEA(90%) /
69.67% HCOOH)
A11 52% (Al-Sulfate 17%) / 5%
Mg(OH)2 12.5 % (16%Silcasol / 24% DEA(90%) /
40% HCOOH / 20% Glycerin)
Table 1: Sample composition in % by weight, remainder water
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To produce the accelerators A1 to A11 the powdery component A, the liquid com-
ponent B and water were given into a container and stirred until the reaction has
abated and the temperature has dropped to about 40°C. This results in a solution
which, depending on the composition, can also contain finely dispersed particles.
Depending on the mixture used, the water can also be used in preheated form, to
accelerate the reaction.
From 0.1 to 10% by weight of the accelerator according to the invention can be
added to hydraulic binders.
To determine the effectiveness of the accelerator according to the invention of Ex-
amples A1 to A11 a conventional concrete mixture for use as sprayed concrete
was in each case admixed with 7% of the accelerator, based on the content of the
hydraulic binder. Portland cement was used as hydraulic binder.
The accelerator was in each case introduced in the region of the spray nozzle dur-
ing processing of the sprayed concrete. Optional other admixtures such as a plas-
ticizercan be used, advantageously a polycarboxylate, particularly advantageous-
ly Sika ViscoCrete®.
For the examples presented a cement with the following characteristics was used:
CEM I 42.5, W/C = 0.48, 1% ViscoCrete® SC305, grout 0-2 mm.
After application of sprayed concrete, the properties of the sprayed concrete was
determined.
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Example Penetrometer [min]

220g 600g 2200g
A1 17 30 55
A2 20 31 52
A3 18 28 57
A4 17 30 72
A5 20 38 90
A6 11 24 58
A7 14 24 48
A8 12 28 50
A9 14.0 27.0 58.0
A10 7.0 13.0 38.0
A11 7.0 16.0 39.0
Table 2: Penetrometer results

Example Mean value compression strength

6h 24 h 7d
A1 2.0 19.6 37.8
A2 2.0 19.5 35.9
A3 1.9 21.0 38.7
A4 1.8 20.3 35.9
A5 1.3 21.3 44.2
A6 1.4 18.6 39.9
A7 2.0 19.9 38.9
A8 2.1 20.2 38.1
A9 2.2 19.5 36.8
A10 2.6 16.1 34.4
A11 2.0 19.6 38.9
Table 3: Compression strength in N/mm2
All the tested cements with the accelerators A1 to A11 show good values in the
penetrometer test and good values in compressive strength.
The accelerators of the invention can also be used for hydraulic binders other than
cement, for example mixed cements, lime, hydraulic lime, and gypsum, and also
mortar and concrete produced there from.
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The invention is of course not restricted to the exemplary embodiment shown and
described. Obviously, numerous modifications and variations of the present inven-
tion are possible in light of the above teachings. It is therefore to be understood
that within the scope of the appended claims, the invention may be practiced oth-
erwise than as specifically described herein.
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WE CLAIM:
1. A process for producing and processing a setting and hardening accelera-
tor,
wherein a powdery component A comprising aluminum, a liquid component
B comprising an acid are mixed in a ratio of 10-80% of component A, 1-
35% of component B, remainder water, and that the so received accelera-
tor is processed after mixing within 7 days.
2. A process for producing and processing a setting and hardening accelera-
tor as claimed in claim 1,
wherein component A comprises (in % by weight):
- 0 to 100% of aluminum sulfate (containing 17% of Al203),
- 0 to 40%o of aluminum hydroxide,
- 0-10% magnesium hydroxide (Mg(OH)2)
- 0-5% manganese sulfate (MnS04 x H20),
- 0-12% ferric sulfate (Fe2(S04)3 x H20),
- 0-1% of sodium gluconate,
- 0-30% of silica,
- the aluminum content is at least 1%.
3. A process for producing and processing a setting and hardening accelera-
tor as claimed in claim 1 or 2,
wherein component B comprises (in %> by weight):
- 0 to 100%> of organic acid,
- 0-100% of alkanolamine,
- 0-100%) phosphoric acid (75%)
- 0-50% hydrofluoric acid (40%),
- 0-5%) other mineral acid such as boric acid,
- 0-100% of silica sol (30% solid content),
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- the acid content is at least 1%.
- remainder water.
4. A process for producing and processing a setting and hardening accelera-
tor as claimed in one of the preceding claims,
wherein component A comprises (in % by weight):
- aluminum sulfate (containing 17% of Al2O3): 65-90%, preferred 70-85%;
- aluminum hydroxide: 0-35%, preferred 0-30%, most preferred 10-30%,
in particular 20-25%;
- magnesium hydroxide (Mg(OH)2): 3-6%, preferred 4-5%;
- manganese sulfate (MnS04 x H20): 0-3%, preferred 1-3%;
- ferric sulfate (Fe2(S04)3 x H20): 0-6%, preferred 2-6%
- sodium gluconate: 0-0.7%. preferred 0.2-0.5%)
- silica: 5-30%, preferred 15-25%
5. A process for producing and processing a setting and hardening accelera-
tor as claimed in one of the preceding claims,
wherein component B comprises (in % by weight)
- organic acid: 10-80%, preferred 20-75%, most preferred 50-75%;
- alkanolamine: 10-90%;
- phosphoric acid (75%): 0-90%, preferred, 0-75%, most preferred 5-50%,
in particular 10-35%;
- hydrofluoric acid (40%): 0-20%, preferred 15-20%;
- silica sol (30% solid content): 0-80%, preferred 20-80%, most preferred
40-60%.
6. A process for producing and processing a setting and hardening accelera-
tor as claimed in one of the preceding claims,
wherein the components are mixed in a ratio of 50-65% component A, 4-
20% component B, remainder water.
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7. A process for producing and processing a setting and hardening accelera-
tor as claimed in one of the preceding claims,
wherein the components are mixed in a ratio of 55-60% component A, 5-
15% component B, remainder water.
8. A process for producing and processing a setting and hardening accelera-
tor as claimed in one of the preceding claims,
wherein the organic acid is carboxylic acid, preferably formic acid, acetic
acid and / or oxalic acid
9. A process for producing and processing a setting and hardening accelera-
tor as claimed in one of the preceding claims,
wherein the alkanolamine is Diethanolamine DEA.
10. A process for producing and processing a setting and hardening accelera-
tor as claimed in one of the preceding claims,
wherein accelerator is processed within 5 days, preferred within 3 days,
most preferred within 1 day.
11. A process for producing and processing a setting and hardening accelera-
tor as claimed in claim 10,
wherein the accelerator is used in sprayed concrete.
Dated 15th Day of October 2007
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Disclosed is a process for producing and processing a setting and hardening accelerator, wherein a powdery component A comprising aluminum, a liquid component B comprising an acid and water are mixed in a ratio of 10-80% of component 10A, 1-35% of component B, remainder water, and that the so received accelerator is processed after mixing within 7 days.