RU1778097C - Method of producing binder for concrete mix - Google Patents

Abstract

The invention relates to building materials, to methods for preparing cementitious concrete mixes used in the production of concrete and reinforced concrete products. The purpose of the invention is to reduce shrinkage and prevent the formation of efflorescences on the surface of concrete hardening at a temperature of from -5 to -30 C. Summary of the invention: cementitious concrete mixture is prepared in two stages: in the first stage, cement is grinded with superplasticizer and 1/10 -1/5 of the compounds from the group: salts of nitric or nitrous acid, urea or a mixture thereof, to a specific surface of 4500-5000 cm / (, and the remaining part of the specified compound is introduced into the second and the resulting mixture is ground to a specific surface 5500- 6500 cm2 / g 1 tab.

Description

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The invention relates to building materials, in particular to methods for the preparation of cementitious cementitious materials and additives used in the manufacture of concrete and reinforced concrete products.

A known method of preparing cementitious concrete is by mixing cement, a siliceous component and a superplasticizer with a mass ratio of components, max: cement 100, silica admixture 10-160, superplasticizer 0.25-1.5.

A disadvantage of the known solution is the relatively low strength of concrete hardening at low temperatures.

The closest in technical essence and the achieved result is a method of preparing a cementitious concrete mixture, comprising mixing cement and 2-10% of an additive containing parts by weight: superplasticizer 1, nitrate, nitrite or urea 1-20.

A disadvantage of the known solution is the relatively high shrinkage and efflorescence on the surface of the runner, hardening at a temperature of from -5 to -30 ° C.

The purpose of the invention is to reduce shrinkage and prevent the formation of efflorescence on the surface of concrete hardening at temperatures from -5 to -30 ° C.

This is achieved by the fact that the method of preparing cement for concrete mix by mixing with grinding cement, a superplasticizer and a compound from the group: salts of nitric or nitrous acid, urea or a mixture thereof in a weight ratio of cement and said compounds of 85: 5: 10 - 98, 5: 1 0.5, respectively, cement is mixed with grinding in two stages, and in the first stage, cement is mixed with superplast stiffie

4 00 O O VI

boat and 1/10 to 1/5 of the specified compound and crushed to a specific surface area of 4500-5000. and on the second, the remainder of said compound is introduced and the resulting mixture is milled to a specific surface of 5500-6500 cm2 / g.

The following superplasticizers were used in the work: S-3 TU 6-14-625-80, 10-03 TU 44-3-505-81. 40-03 TU 38-402-58- 82, and as building materials - Portland cement M-350, crushed stone granite FR 5-10, quartz sand with MKR 2.2. A concrete mixture is prepared by mixing in cement, sand, crushed stone and mixing water at a ratio of B: P: U 1.2.1: 2.9 and cement: water equal to 0.33.

As follows from the data in the table, the use of the proposed method of preparation of cement (examples 4-7) can reduce shrinkage and prevent the formation of efflorescence on the surface of concrete hardening at temperatures from -5 to -30 ° C compared with the known solution (examples 2-3). Application of the proposed solution beyond

Composition in the burning, May. %

Portland cement

superplasticizer

S-3

10-03

40-03 sodium nitrite calcium nitrate urea Cooking conditions:

specific surface area in the first stage of grinding,

specific surface area of cement in the second grinding stage, smv / t

Electrolyte consumption in the first grinding stage

Shrinkage of concrete,%

The compressive strength of concrete, Upa.hvt res.28 solid-temperature. nor .C

ABOUT

-fifteen

-thirty

The presence of efflorescence on the surface of concrete

100 85.0 98.5 85.0 92.0 92.0 98.5 83.0 99.1

6.0 0.5 5.0

4.0

4.0

0.5 6.0 0.7

3.0

2.5-2.51, 0 --4.00.5

2.6-2.5 4.0-0.5 3.0. 0.3

4500500050004750 4300 5700

5500600060006500 5300 7000

100 98

95

1/10 1/7 40 35

1/7

thirty

1/5 30

1/11 1/4 85 90

27.0. 32.2 29.5 70.3 80.1 81.4 83.274,677.1

O18.6 4.5 51.2 35.0 10.5 16.257.219.1

O0.5 012.6 0.7 0.6 0.713.50.5

 .not-no-no-no-no-eat is yes

 . t

0

Cooking conditions do not allow to reach the set goal (examples 8-9).

Claims (1)

SUMMARY OF THE INVENTION A method for preparing a cementitious cementitious concrete mixture by mixing with grinding cement, a superplasticizer and a compound from the group: nitric or nitrous acid salt, urea or a mixture thereof in a weight ratio of cementitious and said compounds (85: 5: 10) - (98.5: 1: 0.5), respectively, characterized in that, in order to reduce shrinkage and prevent the formation of efflorescence on the surface 5 of concrete hardening at a temperature of (-5) to (-30) ° C, the cement is mixed with grinding in two stages, moreover, in the first stage carry out the mixing a portion with a superplasticizer and 1 / 10-1 / 5 part of the specified compound and crushed to a specific surface area of 4500-5000 cm2 / g, and the second part of the specified compound is introduced and grinding the resulting mixture to a specific surface 5 in binder 5500-6500 cm2 / g. 0 6.0 0.5 5.0 4.0 4.0 0.5 6.0 0.7 2.5-2.51, 0 --4.00.5 2.6-2.5 4.0-0.5 4500500050004750 5500600060006500 1/10 1/7 40 35 1/7 thirty 1/5 30 1/11 1/4 85 90