RU2528330C2 - Complex additive for concretes - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to the field of construction materials, in particular to compositions of additives, used in the production of precast reinforced concrete and commercial concrete. A complex additive for concretes contains a superplasticiser based on naphthalenesulphonates, a setting retarder based on hydroxycarboxylic acids and a nitrogen-containing component based on alkanolamines with the following ratio (wt %): naphthalenesulphonates - 75-95, setting retarder - 2-10, nitrogen-containing component - 3-15. The invention developed in dependent items of the invention formula.

EFFECT: invention provides a possibility of regulating kinetics of concrete structure-formation and hardening.

4 cl, 3 tbl, 6 ex

Description

The invention relates to the field of building materials, in particular to the compositions of additives used in the production of precast concrete and ready-mixed concrete.

In the industrial production of precast and ready-mixed concrete, various additives are widely used. The rheological characteristics of concrete mixtures are regulated using plasticizing additives, and the setting time of concrete mixtures can be accelerated or slowed down, using plasticizers together with other additives. The ratio of the components and the dosage of the additive determine the degree of retarding or accelerating effect. It is advisable to have a comprehensive additive that allows you to purposefully control the kinetics of structure formation and hardening in the production of both precast and ready-mixed concrete. In the first case, the main factor is the quick set of concrete strength after laying, in the second - the preservation of mobility, and therefore the workability of the concrete mixture over a long period of time.

To increase the workability of concrete mixtures, additives based on naphthalenesulfonates are widely used. The use of naphthalenesulfonates makes it possible to obtain concrete mixtures with high workability and ease of laying, however, the disadvantage of such additives is the insignificant period of maintaining the mobility of the concrete mixture [Additives in concrete: Reference manual. / B.C. Ramachandran, R.F. Feldman, M. Kollapardi et al. Edited by B.C. Ramachandrana. Per. from English T.I. Rosenberg and S.A. Boldyreva. M: Stroyizdat, 1988 - 575 s]. These disadvantages are largely eliminated in the complex additive [Patent CN No. 102145985 of 08/10/2011, Preparation method of high-efficiency water reducing agent and early strength agent for concrete], which includes a superplasticizer and retarder — citric acid or gluconate sodium.

The disadvantage of this additive is the impossibility of its use for precast concrete in connection with the extended setting time and slowed down set of strength during the temperature rise during TVO.

A complex additive is known [US 8167998, May 01, 2012], which contains a superplasticizer based on naphthalenesulfonates, a retarder and a nitrogen-containing component alkanolamine. Moreover, as a setting retarder, it may contain one acid from the group of gluconic, citric, heptonic acids or their water-soluble salts. The disadvantage of this additive is the inability to control the kinetics of structure formation and hardening of concrete due to changes in dosage.

The technical task of the present invention is the creation of a complex additive with wide possibilities for regulating the kinetics of structure formation and hardening of concrete by changing the dosage and applicable both in commodity and precast concrete.

The solution of the technical problem in the present invention is achieved by the fact that a complex additive for concrete containing a superplasticizer based on naphthalenesulfonates, a retarder based on hydroxycarboxylic acids and a nitrogen-containing component based on alkanolamines, contains these components in the following ratio (wt.%):

superplasticizer based on naphthalenesulfonates - 75-95

setting retarder - 2-10

nitrogen-containing component - 3-15.

Pure polymethylene naphthalene sulfonates (PNS), a mixture of PNS with lignosulfonates or copolymers based on PNS are used as a superplasticizer based on naphthalenesulfonates, glycolic, malic, tartaric, citric, gluconic, heptonic acids or their heptonic acids are used as retarders. any of these compounds. As the nitrogen-containing component based on alkanolamines, individual alkanolamines, a mixture of alkanolamines, or a mixture of alkanolamine with sulfamic acid, amino sulfonic acids, glycine or tetramethylammonium salts are used.

The claimed range of ratios of the components of the complex additives is established experimentally and is optimal.

The combined use of these components in the composition of the complex additive leads to the manifestation of a synergistic effect that allows you to effectively apply the proposed additive to obtain various effects (increase the persistence of mobility for ready-mixed concrete and accelerate the set of strength for precast concrete) with appropriate optimal dosages of the complex additive and, accordingly, deliberately adjust the kinetics of initial structural formation and the subsequent set of strength.

At a dosage of more than 0.6%, an increase in the persistence of mobility of the concrete mixture prevails without a decrease in strength characteristics (including in the early stages). In such dosages, it is advisable to use the complex additive in ready-mixed concrete.

At a dosage of 0.6% or less, acceleration of the set of strength is observed, which allows the use of the proposed complex additive in precast concrete.

In more detail, the technical nature of the invention and the effects achieved can be illustrated by the following examples.

To prepare a complex prototype additive, use the superplasticizer Polyplast SP-1 according to TU 5870-005-58042865-05, sodium gluconate and triethanolamine in the following ratio of components wt.%: Superplasticizer 60, sodium gluconate 15, triethanolamine 25.

To prepare the complex additive according to the invention, additives based on naphthalene sulfonates are used as a plasticizing component, glycolic, malic, tartaric, citric, gluconic, heptonic acids, their soluble salts or a mixture of any of these compounds are used as a retarder, and as a nitrogen-containing component based alkanolamines use individual alkanolamines, a mixture of alkanolamines or a mixture of alkanolamines with sulfamic acid, aminosulfonic acids, glycine or salts tetramethylammonium.

The given examples do not exhaust all possible variants of a complex additive for concrete, but help to demonstrate its properties more clearly.

Compositions of complex additives according to the invention:

composition 1: superplasticizer based on naphthalenesulfonates - Polyplast SP-1 according to TU 5870-005-58042865-05, setting retarder - glycolic acid, nitrogen-containing component - diethanolamine;

composition 2: superplasticizer based on naphthalenesulfonates - Polyplast SP-1 according to TU 5870-005-58042865-05, setting retarder - tartaric acid, nitrogen-containing component - 2: 1 mixture of triethanolamine and diethanolamine;

composition 3: superplasticizer based on naphthalenesulfonates - Polyplast SP-1 according to TU 5870-005-58042865-05, setting retarder - heptonic acid, nitrogen-containing component - 1: 1 mixture of triethanolamine and sulfamic acid;

composition 4: superplasticizer based on naphthalenesulfonates - a mixture of Polyplast SP-1 and technical lignosulfonates 80:20, retarder - a mixture of malic and citric acids 1: 1, a nitrogen-containing component - a mixture of triethanolamine and glycine 1: 1;

composition 5: superplasticizer based on naphthalenesulfonates - Polyplast SP-1 according to TU 5870-005-58042865-05, setting retarder - gluconic acid, nitrogen-containing component - 1: 1 mixture of monoethanolamine and teramethylammonium sulfate;

composition 6: superplasticizer based on a copolymer of naphthalenesulfonates - Polyplast Premium according to TU 5745-036-58042865-2008, setting retarder - sodium gluconate, nitrogen-containing component - triethanolamine;

composition 7: a superplasticizer based on naphthalenesulfonates — a mixture of Polyplast SP-1 and technical lignosulfonates 85:15, a retarder — a mixture of sodium gluconate and citric acid 1: 2, a nitrogen-containing component — a mixture of triethanolamine and sulfanilic acid 1: 1.

The ratio of the components of the tested complex additives are given in table 1.

Table 1 No. Additive The ratio of the components of the additive, wt.% superplasticizer moderator nitrogen soda. component one prototype 60 fifteen 25 2 composition 1 85 6 9 3 composition 2 95 2 3 four composition 3 75 10 fifteen 5 composition 3 70 10 twenty 6 composition 3 70 fifteen fifteen 7 composition 4 80 8 12 8 composition 5 85 four eleven 9 composition 6 90 5 5 10 composition 7 90 5 5 Examples No. 5, 6 - transcendental compositions

To assess the effect of complex additives on the properties of concrete mix and concrete, in comparison with the prototype, tests, in accordance with GOST 30459-2008, were carried out on a concrete mixture of the composition (kg / m ³ ): cement - 350, sand - 850, crushed stone - 990. Additive dosed on dry matter as a percentage of the mass of cement. Compressive strength was determined according to GOST 10180. Portland cement GGC 500 D0 of the Novorossiysk cement plant was used in the experiments.

The test results are given in table.2, 3.

table 2 The test results of the additive according to the invention and the additive prototype in ready-mixed concrete Additive (no. According to table 1) Dosage% W / C Ok see Compressive strength. MPa source after 1 h after 2 hours after 3 hours 1 s 28 s 1 ∗ 0.6 0.49 22 eighteen 13 7 8.5 37.6 2 0.6 0.49 22 19 16 eleven 11,2 39.7 3 0.8 0.48 21 19 17 fifteen 12.3 38.8 four 0.7 0.49 22 21 19 16 12.5 38.1 5 0.7 0.49 22 eighteen fourteen 9 12.9 38,4 6 0.7 0.49 23 22 twenty eighteen 8.8 37.9 7 0.7 0.49 23 22 21 21 10.5 38.7 8 0.7 0.49 22 21 19 17 11.9 40.1 9 0.7 0.49 24 22 twenty 19 12.3 40.9 10 0.7 0.49 24 23 21 twenty 10.8 39.7 Table 3 The test results of the additive according to the invention and additive prototype in precast Additive (no. According to table 1) Dosage% W / C Ok see Compressive strength, MPa source after 1 h after TVO 28 s one 0.6 0.43 17 7 27.7 36.1 0.5 0.43 fourteen 7 30.3 38,2 2 0.6 0.43 16 four 35.1 44.7 0.5 0.43 13 3 36.1 45,2 3 0.6 0.43 17 5 36.0 43.8 0.5 0.43 13 3 36.7 45.3 four 0.5 0.43 16 6 36.1 43.1 0.4 0.43 eleven 3 36.9 45.6 8 0.6 0.43 17 6 37.3 43.9 0.5 0.43 13 four 37.0 44,4 10 0.5 0.43 16 6 35.7 44.8 0.4 0.43 12 four 36,2 45.3 control staff - 0.43 3 - 33,4 40,2

Table 2 shows the test results of additives in ready-mixed concrete. Analysis of the results of the tests showed the following.

The use of the complex additive according to the invention compared to the prototype additive when they are administered in the same dosage of 0.6%, as well as the introduction of the additive according to the invention in a dosage of more than 0.6% (0.7 and 0.8%, examples 3 and 4 ) allows you to significantly increase the period of maintaining the mobility of the concrete mixture. So with the same dosage component of 0.6% (examples 1 and 2) and the same initial mobility, the mobility retention is significantly higher for the composition with the additive according to the invention. After three hours, the precipitation of the concrete cone with the complex additive according to the invention is 11 cm, and with the prototype additive 7 cm. The use of the additive according to the invention allows for higher strength characteristics of ready-mixed concrete in the early stages. So for the application of the additive according to the invention (example 2), the compressive strength of concrete at the age of 1 day is 11.2 MPa, which is 30% higher than the corresponding value for the application of the additive prototype (example 1). In the future, the difference in strength characteristics decreases, but even at the age of 28 days it is 6%. It is important to note that such an increase is achieved not due to the B / C ratio, which remains constant (examples 1, 2, 4), but rather due to the synergistic effect of the use of the complex additive. When increasing the dosage of additives to 0.8% at the lower limit of the content of the moderator (example 3) or when using a composition with a maximum content of moderator (example 4), there is a noticeable increase in the persistence of mobility (15 and 16 cm after 3 hours, respectively) without reducing the strength characteristics concrete at the daily age.

Examples 5 and 6, presented in table 2, show the impossibility of obtaining an effective additive when going beyond the boundary values of the content of the components. So, with the same dosage equal to 0.7%, the use of a complex additive containing less than 75% PNS and more than 15% nitrogen-containing component (example 5) leads to a decrease in the persistence of mobility of the concrete mixture compared to the application of the additive according to the invention (example 4 ) When the content of the complex additive contains more than 10% moderator (example 6), a decrease in the early strength of concrete is observed compared with the application of the additive according to the invention (example 4). Thus, when going beyond the optimal ratios, there is no synergistic effect, although the mobility and strength are still higher than that of the prototype.

Examples 2, 3, 4, 7, 8, 9, 10 confirm the possibility of obtaining the claimed technical result with various combinations of the claimed alternative components of the complex additives. In all cases, there is a significant increase in the shelf life of the concrete mix while providing higher strength characteristics of ready-mixed concrete in the early stages compared to the use of the prototype additive.

The test results of some of the compositions of the additive according to the invention and the additive prototype in precast concrete are presented in table 3. In all the examples, the W / C ratio remained the same, equal to 0.43.

With the introduction of additives in a dosage of 0.6% or less, the use of additives according to the invention compared with the additive prototype can significantly accelerate the setting of the concrete mixture. So at a dosage of additives of 0.6% for the application of the additive prototype (example 1), the initial draft of the cone was 17 cm, and after an hour - 7 cm; when using the additive according to the invention (example 2), the cone precipitation values were 16 cm and 4 cm, respectively. Moreover, the difference in the strength of concrete compositions at different times is 7.4-8.5 MPa, i.e. the lack of strength of the composition with the additive prototype during TVO is not compensated in the future. With a decrease in the dosage of additives to 0.5%, the difference in strength indicators also slightly decreases, however, it remains quite high (> 6 MPa).

At the boundary values of the content of the components of the complex additive (example 3: the maximum content of PNS (95%), the minimum content of retarder (2%) and nitrogen-containing component (3%); example 4: the minimum content of PNS (75%) and the maximum content of retarder (10%) and nitrogen-containing component (15%)) there are no significant changes in the kinetics of loss of mobility and strength gain, i.e. a synergistic effect is manifested in the entire claimed range of complex additives.

Presented in table 3, examples 2, 3, 4, 8, 10 do not exhaust all possible variants of the additive proposed in the invention, but clearly demonstrate the possibility of obtaining the claimed technical result with various combinations of alternative components of the additive. In all cases, there is a significant acceleration of the setting of the concrete mixture in comparison with the use of the prototype additive.

When comparing the effects of the complex additive according to the invention and the prototype additive in precast concrete with respect to the control composition, it can be concluded that the additives have a comparable plasticizing ability and provide one mobility class with a constant W / C. The use of the additive according to the invention increases the early strength of concrete, while the additive prototype in the opposite way affects this parameter.

Thus, the proposed complex additive has wide possibilities for regulating the kinetics of structure formation and hardening in both commercial and precast concrete due to a simple change in dosage.

Claims (4)

1. A complex additive for concrete, containing a superplasticizer based on naphthalenesulfonates, a retarder based on hydroxycarboxylic acids and a nitrogen-containing component based on alkanolamines, characterized in that these components are part of a complex additive for concrete in the following ratio, wt.%:
naphthalenesulfonates 75-95 setting retarder 2-10 nitrogen-containing component 3-15 2. The complex admixture for concrete according to claim 1, characterized in that pure polymethylene anaphthalene sulfonates, a mixture of polymethylene anaphthalene sulfonates and lignosulfonates or copolymers based on polymethylene anthylene sulfonates are used as a superplasticizer based on naphthalenesulfonates. 3. The complex additive for concrete according to claim 1, characterized in that as the nitrogen-containing component based on alkanolamines, individual alkanolamines, a mixture of alkanolamines or a mixture of alkanolamines with sulfamic acid, aminosulfonic acids, glycine or tetramethylammonium salts are used. 4. The complex additive for concrete according to claim 1, characterized in that glycolic, malic, tartaric, citric, gluconic, heptonic acids, their soluble salts or a mixture of any of these compounds are used as a retarder based on hydroxycarboxylic acids.