RU2795636C1 - Complex concrete mixture additive - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: construction of underground concrete and reinforced concrete structures. Complex additive to the concrete mixture contains nitrogen-containing catalyst production waste and polycarboxylate superplasticizer ST 5.0 in the following ratio, in % by weight: nitrate-nitrite-alkaline water 60.0-65.0; superplasticizer ST 5.0 35.0-40.0.

EFFECT: increasing the strength of concrete in the initial stages of its hardening and water resistance when gaining design strength.

1 cl, 1 tbl

Description

The invention relates to the construction of underground concrete and reinforced concrete structures, such as tunnels, protective shelters for manpower and equipment, fuel and lubricants storage facilities, etc.

The specificity of such structures requires a rapid set of concrete strength in the early stages of its hardening, corrosion resistance of concrete and steel reinforcement in the presence of aggressive agents in the soil, as well as increased water resistance at a high level of groundwater.

Known complex additive for concrete containing a superplasticizer based on naphthalenesulfonates, a retarder based on hydroxycarboxylic acids and a nitrogen-containing component based on alkanolamines in the following ratio (wt.%): naphthalenesulfonates - 75-95, retarder - 2-10, nitrogen-containing component - 3 -15 (patent RU No. 2 528 330 C2, C04B24/12, 09/10/2014).

The disadvantage of this complex additive is the need to use in its composition a retarder based on hydroxycarboxylic acids, which does not contribute to the corrosion resistance of steel reinforcement and embedded parts in reinforced concrete structures.

The closest to the claimed is a complex additive (see A.S. No. 402273, C04 B 13/24, 1973 (not subject to publication in the open press). This complex additive includes calcium nitrate, sodium sulfate and sodium abietate as a surfactant ingredient.

The disadvantages of this complex additive are the relatively low strength of concrete in the initial period of hardening and water resistance to achieve the design strength.

The objective of the invention is to increase the strength of concrete in the initial stages of hardening and increase the degree of water resistance after the design strength has been set.

The essence of the invention lies in the fact that the complex additive in the concrete mixture contains as a nitrogen-containing ingredient nitrate-nitrite-alkaline waste of catalyst production, and as a surface-active ingredient polycarboxylate superplasticizer ST 5.0 in the following ratio, wt.%:

catalyst production waste 60.0-65.0 superplasticizer ST 5.0 35.0-40.0

The technical result is an increase in the strength of concrete aged from 1 to 3 days and the water resistance of hardened concrete.

Characteristics of the components

Nitrate-nitrite-alkaline catalyst production waste (NNShchV) at the Novocherkassk plant of synthetic products contains (wt.%) 26-30 sodium nitrate; 6-8% sodium nitrite; 3-5% caustic soda; water - the rest up to 100%.

Polycarboxylate superplasticizer ST 5.0, supplied by SkyTrade LLC in accordance with TU 5745-001-94590966-2011, contains 20±2 dry matter by weight, the density of the additive is 1.045±0.03 g/cm ³ . The additive is a homogeneous light brown liquid with a pH of 7.5±1.5 and a total chloride content of less than 0.1%.

A complex additive to the concrete mixture, including nitrogen-containing and surfactant ingredients, contains as such nitrate-nitrite-alkaline water (NNShchV), which is a waste of catalyst production and polycarboxylate superplasticizer ST 5.0, supplied by SkyTrade LLC in accordance with TU 5745-001 -94590966-2011 with the following ratio between the indicated ingredients, wt.%: (35.0-40.0) ST 5.0 and (60.0-65.0) NNShchV. The complex additive is introduced into the concrete mix with mixing water.

The effectiveness of the proposed complex additive was tested in laboratory conditions by testing the strength of specimens-cubes with an edge of 100 mm at the age of 1, 3 and 28 days of normal hardening, and the water resistance of specimens-cylinders with a diameter and height of 150 mm at the age of 28 days.

The process of manufacturing a complex additive consists in introducing its components into the composition of the concrete mix directly during its mixing. Each of the components of the complex additive is a finished product and is introduced into the concrete mixture with mixing water as a percentage of the accepted cement consumption in the mixture. Nitrate-nitrite-alkaline water NNShchV and polycarboxylate superplasticizer ST 5.0 are introduced at the following ratio between the indicated ingredients, % of the cement consumption in the concrete mix: (1.0-2.0) NNShchV and (0.6-1.2) ST 5.0 .

As a binder, cement JSC "Sebryakovcement" CEM 0 42.5N GOST 31108-2020 was used. The fine filler was quartz sand with fineness modulus Mk = 1.9; coarse aggregate - crushed stone of a fraction of 5-20 mm from dense sandstone. For class B30 concrete, the initial composition of the concrete mixture was adopted with the ratio of components, wt. hours:

C: P: W: \u003d 1: 1.44: 3.42

The mixing water flow rate in each case was selected from the condition of obtaining equally mobile mixtures.

The test results are presented in the table.

As can be seen from the data in the table, a complex additive to the concrete mixture containing waste from the catalyst production of NNShchV and polycarboxylate superplasticizer ST 5.0 in wt.%, respectively, (60.0-65.0) and (35.0-40.0) provides an increase in the strength of concrete at the age of 1-3 days of normal hardening by 2-2.5 times and increases the water resistance grade to W14-W20.

Table

Test results

Compound Composition and consumption of the complex additive Compressive strength during hardening under normal conditions at age, MPa brand
water resistance The content of ingredients in the additive, wt.% Consumption, % of the consumption of cement in the mixture Proposed Catalyst production waste NNShchV Superplasticizer ST 5.0 calcium nitrate calcium sulfate sodium abietate 1 day 3 days 28 days - - - 8.4 12.4 33.4 W6 - - - 16.1 30.6 38.7 W14 - - - 19.3 33.7 42.6 W20 - - - 21.7 31.1 41.3 W18 - - - 20.8 28.3 41.1 W18 A.s.
402273 - - 5.2 9.1 20.6 W4

Claims (2)

A complex additive to the concrete mixture, including nitrogen-containing and surface-active ingredients, characterized in that it contains nitrate-nitrite-alkaline water as a nitrogen-containing ingredient, which is a waste of catalyst production, and as a surface-active ingredient - ST 5.0 polycarboxylate superplasticizer with the following their ratio, wt.%: nitrate-nitrite-alkaline water 60.0-65.0 superplasticizer ST 5.0 35.0-40.0