DE1646716C2 - Setting retardant additive for mortar and concrete compounds - Google Patents

Description

The present invention relates to an additive to mortar or concrete compounds that Contain hydraulic binders, the additive reducing the setting time of these mortar or concrete masses lengthens, regulates the amount of air, improves the consistency, results in a uniform density, the separation between water and aggregate is reduced and the strength of the set material is improved.

The production of mortar and concrete masses with an extended setting time is often expedient. This is especially true for mortar and concrete masses, which in their plastic state take a long journey from the place of manufacture must withstand up to the place of use. In certain areas of use, such as B. at Grouting around a reinforcement, z. B. for a dam construction, bridge arch, building, etc., it is furthermore expedient to lengthen the solidification time to a greater period for the vibration and Treat the surface to get the concrete mass. By increasing the setting time, the will continue avoiding the formation of so-called cold joints that occur when putting fresh concrete on Pour already set concrete, and which reduce the strength of the finished concrete structure. Through By extending the setting time, it is still possible to control the development of heat in mortar and concrete masses delay and expand over a longer period of time, which is particularly important when making heavy concrete structures is expedient, and to counteract the accelerating effect that warm weather, hot Have aggregates and hot water on the hardening process.

The use of certain additives has been known so far to achieve the above purposes. the However, previously known additives can only be used to extend the solidification time of masses that contain hydraulically setting cement of various types, and not for masses that hydraulically hardening lime alone or in combination with cement or non-hydraulic, hydrated Contain lime. Such previously known additives are, for. B. Lignosulfonates and various types of Hydroxycarboxylic acids. However, these materials have certain disadvantages as, if overdosed, they will reduce the

15th

40

50

60 Shorten the setting time instead of lengthening it, which causes a reduction in the strength of the hardening material. So far the use of certain cellulose derivatives, such as hydroxyethyl cellulose, MiHhylcellulose, Äthylhydroxyäthylcellulose, carboxymethyl cellulose (CMC) or salts thereof as additives in concrete was known, whereby a certain extension of the setting time was achieved. In most cases, however, these additives cause reduced strength.

The present invention relates now to an additive to mortar or concrete masses that Contain hydraulic binders, which prolong the setting time of this Mas; n without any need for use an overdose of the additive, the above disadvantages occur. The additive according to the invention consists of 10 to 40 percent by weight, preferably 15 to 35 percent by weight, of a water-soluble one nonionic active cellulose ethers and 60 to 90 percent by weight, preferably 65 to 85 percent by weight, Sodium or potassium gluconate. It was found that such an additional center! not only the The setting time is extended, but a mortar or concrete mass with other advantageous properties, such as good consistency, uniform density, reduced tendency to separate, adjustable air volume and improved strength of the setting material. The additive according to the invention gives a Setting time of at least 6 hours, which is considered to be the time required for an admixture to be classified as a means of delay.

By adding cellulose ethers to mortar and concrete compounds alone, workability is improved and reduced water separation achieved, but the masses are simultaneously compared to one Overdosing is more sensitive because the air content is difficult to control. By adding sodium or Potassium gluconate alone in the mortar and concrete masses will sometimes shorten the setting time and sometimes lengthened, in which case the processability and the water separation are impaired at the same time is increased. It is therefore extremely surprising that it is with an inventive, from a Mixture of water-soluble, nonionic cellulose ethers and the salts of gluconic acid mentioned It is also possible to completely regulate the amount of air in the mortar and concrete masses, and that the Additives can be introduced in large, potentially overdosing amounts without that the strength of the hardening material is reduced, but on the contrary is increased. By varying the Amount of additive it is still possible to adjust the setting time within various limits vary while maintaining an adjustable amount of air.

The additive according to the invention can be used in the production of mortar, the Contains building lime; below this is lime, such as air lime, water lime, hydraulic and highly hydraulic lime understood according to DIN 1060. The additive according to the invention can also be used in concrete masses hydraulic cement according to DIN 1164 in combination with common aggregates such as sand, Contains gravel, macadam, blast furnace slag, etc. It is also particularly suitable for use in so-called "bastard" mortar, which uses a mixture of hydruulia cement and building lime as a binding agent contains.

The kaikar commonly used in Sweden cn are / .. B. hydraulic and highly hydraulic lime, Water hydrated lime and air hydrated lime with and without • Orene-forming agents.

Common hydraulic cements are ortland cement, high alumina cement, slag cement and > ozzolan cement etc. Of these cement materials ind the fast setting types, such as clay cement, icsonders difficult to delay; the inventive-Je Admixture has, however, also shown an exceptionally good effect in these types of cement.

Suitable water-soluble, non-ionic fibers for the additives according to the invention

Methyl cellulose, ethyl cellulose, hydroxy ethyl cellulose,
Hydroxypropyl cellulose,
Äthylh.N droxyäthylcellulose,
Ethyl hydroxypropyl cellulose, propyl hydroxyethyl cellulose, methyl hydroxyethyl cellulose, propyl cellulose, etc.

The cellulose ether used should have a viscosity 100-50 00OcP, measured as a 2% have igc aqueous solution at 2O ⁰ C.

The ionic cellulose ethers, such as carboxymethyl cellulose, are not suitable for use as additives according to the invention because, as stated above, they are in normal pressures and temperatures have little effect. Furthermore, they will be in the presence of a Excess calcium is easily precipitated as insoluble calcium salts, which completely loses its effect and the quality of the product is impaired rather than improved (see US Pat. No. 2,427,683). Furthermore, the bivalent and tetravalent metal ions present in the lime apart from calcium ions can be insoluble Fill in carboxymethyl cellulose salts.

The weight ratio of the water-soluble, nonionic Cellulose ethers and said salts of gluconic acid in the additives according to the invention can between 10 to 40 percent by weight of cellulose ether and 60 to 90 percent by weight of the salt of gluconic acid, preferably 15 to 35 percent by weight cellulose ether and 65 to 85 percent by weight of the salt of gluconic acid. Sodium gluconate is preferred used.

The amount of additive added to a mortar or concrete mass depends on how long the Solidification time should be delayed as well as on the amount and viscosity of the cellulose derivatives used. Suitable amounts of additives are generally between 0.1 and 20.0 g per kilogram of the Hydraulic binder used in the mortar or concrete mass, which reduces the setting time usually extended by 2 to 36 hours. In the production of concrete masses, the addition of 0.8 to 2.5 g of additives per kilogram of cement have been found to be particularly useful; in the preparation of of mortar based on hydraulic lime alone or hydraulic lime and cement is one

s Additive quantity of 1 to 6 g per kilogram of hydraulic binder is particularly advantageous. at the production of mortar based on cement and non-hydraulic, hydrated lime is supposed to Amount of additive is preferably between 1 and 12 g per kilogram of cement.

The additive can be in the form of an aqueous solution or as a dry powder in different Mixing sequences are introduced into the mortar or concrete mass during its manufacture. It is also possible that

ι s additives according to the invention in the preparation of the to mix in hydraulic lime or cement. The result shown in Example 1 is a combination of test results from the National Swedish Institute for Materials Testing.

B e i s ρ i e 1 1

With coarse sand (gravel) with a grain size of 0 to

Four types of concrete were produced in 32 mm as an aggregate. The cement used was a mixed one

: _s material made from equal proportions of standard cement three different manufacturers. The weight ratio between cement and gravel was 1: 6.34. the The additive used consisted of 25 percent by weight ethyl hydroxyethyl cellulose with a viscosity of

, o 2500 cP (measured as a 2% aqueous solution) and 75 Weight percent sodium gluconate. The amount added was 0, 1.0, 2.0 and 2.5 g per kilogram of cement. The fresh concrete was tested in terms of consistency, air content, volume weight and hardness sequence (time).

1.S steadily. A Proctor needle was used in determining solidification and the test was performed in accordance with ASTM Method C-403. The solidification, however, was only followed until a penetration resistance of about 25 kg / cm ^{2 was} reached.

The water and cement content was determined from the mass density and the amount of material obtained calculated.

The consistency was determined by the Mo method. An open cylinder connected to a half cylinder at the bottom was filled with the mortar in question and repeatedly hit against a solid foundation with constant force. The number of knocks and blows that are required to empty the cylinder onto the mortar mass and to transfer the mortar mass into the half-cylinder indicates the Mo number. 16 Mo joints are comparable to a spread of about 46 cm if a vibrating table according to DIN 1164 § 15, but with a larger setting funnel (below ¹ Z 300 mm, above 0 200 mm, height

ss 150 mm) is used.

The test results are shown in Table 1.

Table 1 cement Additive: ratio Consistency; Air content Volume Solidification *) Compressive strength % Components salary Water too Mol-F.in- Weight after 28 days 100 Cement too Grams per cement heitivi 105 Surcharge kilogram 115 material kg / m ³ cement % kg / dm ³ Hours. kg / cm ³ 124 300 0 0.572 15th 1.3 2.41 5 415 1: 6.34 299 1.0 0.565 15th 2.5 2.39 10 436 1: 6.34 299 2.0 0.551 17th 2.8 2.38 19th 476 1: 6.34 300 2.5 0.542 16 2.9 2.40 31 518 1: 6.34

* \ According to ASTM D-403.

As can be seen from Table 1, the setting time of a concrete mass by adding an inventive Additive increased significantly. When adding 2.5 g of admixture per kilogram of cement a 6-fold increase in the setting time compared to a concrete mass without additional garbage. the Compressive strength can be increased by 24% at the same time. In concrete with an inventive Additive, in particular, the air content is kept constant between 2.5 and 2.9%, which shows that the Additive according to the invention has no adverse effect on the air content.

For the following Examples 2 to 8, three different additives were used with the following composition manufactured:

Additive 1

35 weight percent methyl cellulose having a viscosity of 40OcP (in 2% aqueous solution at 20 ⁰ C) and 65 percent by weight of sodium gluconate.

Additive 2

25 percent by weight ethyl hydroxyethyl cellulose with a viscosity of 2500 cP (in 3% aqueous Solution at 20 "C) and 75 percent by weight sodium gluconate.

Additional 3

15 weight percent Hydroxyäthylcelluiose a viscosity of 31 000 cP (in a 2% aqueous solution at 20 ⁰ C) and 85 percent by weight of sodium gluconate.

These additives were made into cement or lime mortar with that given in Examples 2-8 Add composition. To achieve a constant consistency, the amount of water was reduced, when the amount of admixture in the mortar has increased.

The amounts of additives and added water can be seen from the tables of the respective examples. The amount of water is given in relation to the amount of binding agent as the water / cement number and the water / binding agent number. The tables also show the test data for the various cement and lime mortars. The solidification was determined in Examples 2 to 8 in a Vicat device according to DIN ΓΙ64 § 10. The entire test was carried out in accordance with DIN 1164.

Example 2 The cement mortar had the following composition:

1 part by weight portland cement,

3 parts by weight of sand with a grain size of 0 to 4 mm.

Table 2

ratio
Water to cement

Addition: g / kg
hydrl. binder

2 3

Freeze
Hrs. Min.

0.50
0.48
0.45
0.44
0.46

*) Measurement not carried out.
*) Not determined.

3
6th
7th

16
5

30th
50

22 22 22 22 31 346
406

Temperature during strength according to air content of the

28 days of testing fresh

° C kg / cm ^{2 of} mortar

6th
11th
14th

Example 3
The lime mortar had the following composition

1 part by volume of hydraulic lime,
4 parts by volume of sand of one grain size
from 0 to 4 mm.

Table 3 Example 4

The lime-cement mortar had the following composition:

2 parts by volume of hydraulic lime,
1 part by volume Portland cement,
12 parts by volume of sand of one grain size
from 0 to 4 mm.

ratio Addition: g / kg Freeze Min. temperature Table 4 Addition: g / kg Freeze Min. temperature Water too Lime hydrl. binder while Lime hydrl. Bandage while 50 of testing ^fl ° ratio medium 25th of testing 1 2 3 Hours. ⁰ C Water too 2 Hours. 40 ° C 30th 30th 1.30 - 0 - 5 25th 0 3 30th 25th 1.28 A. 10 30th 25th 2 5 25th 1.20 - 14 - 12th 30th 25th (κ 0.95 4th 25th 1.15 20th 21 25th 0.93 6th 10 25th 1.29 4th 12th 30th 0.90 I 98 - - 4 7th 31 0.85

Example 5

The lime-cement mortar had the following composition:

3 parts by volume of hydraulic lime, 1 part by volume of Portland cement, 16 parts by volume of sand of one grain size from 0 to 4 mm.

Table 5

Ratio of addition: g / kg solidification temperature pressure-water to hydrl. Binding while firmness Binder by means of testing

28 days 2 hrs. Min. ⁰ C kg / cm?

Example 6

The lime-cement mortar had the following composition:

1 part by volume of white lime hydrate, 4 parts by volume of Portland cement, 20 parts by volume of sand of one grain size from 0 to 4 mm.

Table 6

1.06 0 1.05 1.6 1.05 2.7 1.03 5.3 1.00 8.0

3-25

5 35 25

8 45 25

10 20 25

12 30 25

20 *) ·)

45

Measurement did not take place.

ratio additive 0 ■: g / kg Freeze Min. Tcmperatui Water too Lime hydrl. 3 Bindc- 10 while medium 9 50 of testing; 2 14th Hours. 45 ⁰ C 1.00 3 _ 25th 0.93 6th 25th 0.82 12th 25th 0.75 21 25th

Example 7 The lime-cement mortar has the following composition:

2 parts by volume dolomite lime hydrate, 1 part by volume Portland cement, 12 parts by volume of sand with a grain size of 0 to 4 mm.

Table 7

Ratio of addition: g / kg

Water to binding hydrl. Medium binder

I 2 3

, 14
, 12
, 09
, 08
, 11
.10

Freeze

Hours.

5 9 16 6 6

Min. 40

30 20

Temperature during Compressive strength air content
of the fresh of testing after 28 days Mortar % "C kg / cm ² 7th 25th 74 **) 25th *) Il 28 *)

28 30 30

") Measurement not done. "") Not k'stgL-Mi-llt,

12 17

Ii e i s ρ i e The Kulk-Zemunt-Müilcl luitlc has the following composition:

1 part by volume of white lime hydrated, I part by volume of Portland cement, 8 volume toilu and a grain size from 0 to 4 mm.

Tubelle 8

ratio
Water too 1IiM (I (MlMtIl ¹ I TIME LIMIT
hyilii.
2 : K / k «
1IiMiIiMMiUi ¹ I r.rsliUTiMi
Style. Min. TcintK'l'iiUir wllhrciid
(U ¹ S 1 (. ¹ SlOMS
¹ X ' Diuckfosligkeil
MiIi ¹ Ii 2H Ta (U ¹ N
kg / cm ' 1.10
1.07
1.05
1.01 0
J
6th 2
7th ^r ) ^r )
40 27
27
27
27 148
IN THE M Muslim ! llil'lll I ¹ I ¹ InI (M.

Jl) Il 111!

It can be seen from the above examples that the desired extension can be achieved with the additives according to the invention the solidification time without the simultaneous occurrence of undesirable acceleration tendencies can be achieved although in some cases quite large amounts of additives are used. In In all examples, the mortar obtained had a good consistency with no tendency to separate between solid particles and the water. Furthermore, the strength could be improved in each case and the Air content can be regulated.

10

Examples 9 to 12

To illustrate the synergistic effect of the additives according to the invention, the following ' Tests carried out in Examples 9 to 12. Example E. shows the effect in a conventional cement mortar Example 10 in a lime-cement mortar which mainly is intended for indoor use, Example 11 in a lime-cement mortar for outdoor use and Example 12 in a quick setting high alumina cement mortar.

Example 9

Composition:

1 part by weight of Portland cement with a high tricalcium aluminate and medium alkali content. 3 parts by weight of sand with a particle size of 0 to 4 mm.

Table 9

cement Additive: cement Binding line Min. Compressive strength Air resounding g / kg Nu-gluconate Ethyl hydroxyethyl _ after 28 days of the fresh cellulose 25th Mortar (Viscosity 2500 cP) Hours. 25th kg / cm- % Hellekis 3 30th 300 0.6 Hellekis 1.5 - _ 30th 335 0.5 Hellekis - 0.5 3 205 7th Hellekis 1.5 0.5 6th 406 10 Cement mix *) - - 4th Cement mix *) 1.5 - 1 _ I.

*) Since an additive / agent on Portland cement !, which are produced in different places, has a different effect can, a mixture of equal parts cement of different origins was made as a comparison.

The above test shows that the addition of sodium gluconate alone in an amount according to the invention d;> s The setting of the Hellekis Portland cement and the above Portland cement mixture is not delayed, but rather greatly accelerated. If sodium gliiconui in Powder form added instead of a solution, so with an addition of 1.5g sodium gluconate per Kilograms of cement get a setting time of only 10 minutes at llellckis / .emcnt. The above tests / own further that the addition of the cellulose derivative «· alone in the amount according to the invention does not noticeably delay solidification. The addition of Nalriumglii coiuil in connection with a non-ionic CdIuIn This derivative produces a synergistic effect with regard to the delay in the production process. Out the values for the compressive strength also show that an addition of the non-ionic cellulose derivative «, For cement mixing alone, the pressure fluid is reduced by about 3) "/ o reduced during an addition of cellulose derivative in combination with Natriuindiiional one ! the compressive strength by about J.j '% orgibl.

table IO Ethyl hydroxy MrM arren Compression wedge Addition: g / kg cement iithylcellulosi- after 2H days (Viscosity 2500 el '] Sodium- - gluconate - I style. Min. kg / cm- ' 2.2 ^r ) 3 40 «2 - 2.25 5 _ " 95 6.75 5 45 - <■) 92 e., 75

Example IO

Composition:

1 dewidilstcil Portland cement mil high

Thculcium aluminate and medium
high alkali diali,

2 Cicwiclitsicilc Lultkalkhydrat,

12 (which is a part of a particle of
0 to 4 mm.

The above test /(.- shows that with calcareous cement mixes for a limcn use a certain lengthening of the cement time (2 hours is achieved by adding sodium gluconate alone, the addition of the niclnionic cdlulose derivative allcii causes a similar lengthening of the hardening / .eit however reduces the time The addition of the nonionic Cdlulose derivative in combination with Nntriuingliiuonni increases synergistic dk solidification time (with an increase of ^r > hours 2t minutes) as well as the compressive strength.

Example Il
Composition:

I volute Portland cement with high

Tricalt, aluminum iminate and medium alcohol
I part by volume of hydrated lime,
H Volumteik: sand of one particle size
from 0 to 4 mm.

Table 11

Addition: g / kg cement

Solidifying compressive strength
after 28 days
Sodium ethyl hydroxygluconate ethyl cellulose c

(Viscosity 2500 cP) hrs. Min. Kg / cm- '

1.5

1.5

55

40
40

149
166
101
161

The above test shows that with calcareous cement mixes for outdoor use Some extension of the solidification time (1 hour 5 minutes) by adding sodium gluconate alone is achieved. Addition of the nonionic cellulose derivative alone results in a similar extension of the Setting time, but noticeably reduces the compressive strength. The addition of the nonionic cellulose derivative in combination with sodium gluconate brings a synergistic increase in the setting time (4 hours and 45 minutes) and an increase in compressive strength.

Example 12

Composition:

I part by weight of high-alumina cement,

3 weight of one particle size sand

from 0 to 4 mm.

Table 12

Addition: g / kg cement

Sodium Ethyl Hydroxy

gluconate ethylcellulose c

(Viscosity 2500 cP)

Freeze

Hours.

0.5
0.5

1 30th 1 30th 1 30th 3

The above test shows that the setting time of a fast setting cement, such as alumina cement not influenced at all by a separate addition of sodium gluconate or nonionic cellulose derivative will. If, on the other hand, sodium gluconate is used together with a nonionic cellulose derivative in accordance with the invention Admittedly, then the setting time is surprisingly doubled.

Claims (4)

Patent claims: 1. Anti-setting additive for mortar and concrete compounds, the hydraulic binding agent included, characterized in that> it consists of 10-40% by weight, preferably 15-35% by weight, of a water-soluble, non-ionic, active cellulose ether in combination with 60-90% by weight, preferably 65-85% by weight, sodium or potassium gluconate. i <> 2. Additive according to claim t, characterized in that the water-soluble, non-ionic see cellulose ether ethyl hydroxyethyl cellulose and the gluconate is sodium gluconate. 3. Additive according to claim 1, characterized is characterized in that it still contains an inorganic filler. 4. Application of the additive according to claims 1 to 3, characterized in that 0.1 up to 20.0 g of the additive per 1 kg of the hydraulic binder added to the mortar or concrete mass will.