RU2524698C1 - Binder - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: binder, which contains portland cement, a ground silica-containing component and an alkaline activator with metal cations, contains as the ground silica-containing component quartz sand with specific surface area of 300 m²/kg, as said activator Humate +7 with pH 12-13, added in form of a 2% aqueous solution by mixing with said sand and holding for 10 minutes, with the following ratio of components, wt %: portland cement 70-85, said sand 15-30, said Humate +7 0.1-0.2 per dry substance over 100.

EFFECT: high compression strength after 28 days, wider range of use of an alkaline activator for a silicon-containing component, simple production technique.

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Description

The invention relates to compositions of binders and may find application for the production of concrete.

Known hydraulic binder (PC-D0) - Portland cement without additives M400 with compressive strength (activity) of 41 MPa.

Along with great advantages (high strength), there are also disadvantages, i.e. relatively expensive (4000 rubles per 1 ton) and not corrosion resistant enough.

A second cement binder is also known, in which corrosion resistance is increased due to the partial replacement of PC-D0 with an active mineral additive - silica fume (dusty waste from the production of ferrosilicon) in combination with alkaline plasticizer lime and SDB and given in the mortar (see Auth. USSR No. 637357, MKI C04B 13/02, publ. 1977) and including components in the following ratio, wt.%:

Portland cement "PC-D0" 59.1-61.1 Silica fume 12.3-16.93 Lime 23.87-25.7 SDB rest Ground slag 12.3-16.93

The advantages of the invention is the disposal of slag. The disadvantages include:

- low compressive strength 25.8-26 MPa;

- silica fume and lime are expensive additives.

The closest in composition and technical solution astringent given in ed. testimonial. USSR No. 1203051, MKI C04B 7/14, publ. 01/07/86 and including components in the following ratio, wt.%:

Amorphous silica (diatomite) 12.0-19.5 Portland cement 15.0-20.0 Yarozit KFe ₃ (SO ₄ ) · (OH) ₆ 1.0-2.5 Ground Marten Slag rest

Along with the advantages of the known binder - strength increases in the early stages of hardening due to the activation of amorphous silica and slag by sulfate-alkali and metal-containing cations (K ⁺ , Fe ⁺⁺ ) with jarosite, corrosion resistance is increased due to the binding of Ca (OH) ₂ - with amorphous silica Portland cement clinker mineral product in calcium silicate hydrate, there are also disadvantages, i.e.:

- low compressive strength after 28 days (11.0-14.1 MPa);

- amorphous silica is not only a sought-after natural raw material as an active mineral additive in binders, but it is also the main raw material for the production of heat-insulating materials.

The objective of the invention is to increase the compressive strength at the age of 28 days and expand the field of application of the alkaline activator for the silica-containing component and simplify the production technology.

To implement the invention, an astringent including Portland cement, ground silica-containing component and an alkaline activator with cations of metals, characterized in that it contains silica sand with a specific surface of 300 m ² / kg as a ground silica-containing component, “Humate +7” is introduced as said activator - a product for fertilizing and deoxidizing the soil with a pH of 12-13, introduced in the form of a 2% solution by mixing with the specified sand and subsequent exposure for 10 minutes, with the following ratio of components, wt.%:

Portland cement 70-85 Indicated sand 15-30 The specified "Humate +7" 0.1-0.2 dry over 100

Table 1 shows the experimental mixture of the proposed and known binders.

Table 1 Mixtures Binder Components The numbers of mixtures and composition, wt.% one 2 3 four 5 6 (prototype) 1. Portland cement M400 “PC-D0” one hundred 85 85 70 70 twenty 2. Quartz sand with a specific surface of 300 m ² / kg ^* , including substandard for concrete - fifteen fifteen thirty thirty - 3. Ground amorphous silica (diatomite) ^* - - - - - 13.5 4. Jarozite (KFe ₃ (SO ₄ ) · (OH) ₆ ) ^* - - - - - 1,5 5. "Humate + 7", on dry over 100 - 0.2 0.15 0.1 0.05 - 6. Ground open-hearth slag (dump) ^* - - - - - 65 7. The pH level of a 2% aqueous solution "Humate + 7" - 13.0 12.5 12.0 11.9 - ^* - materials are subject to fine grinding

Table 2 shows the test results of the properties of the proposed and known binders.

table 2 Property Test Results The properties Units rev. Mixture numbers and property indicators one 2 3 four 5 6 (prototype) Compressive strength (after 28 days. Hardening in NU) MPa 41.0 45.0 34.9 30.06 14.5 14.1

CHARACTERISTICS OF COMPONENTS:

In the experiments for the implementation of the tasks accepted:

1. Portland cement grade M400 (GOST 10178-85; GOST 30515-97) of OJSC Mikhailovcement.

Mineralogical composition of clinker (%):

Table 3 Mineralogical composition of clinker C ₃ S (tricalcium silicate) 59% C ₂ S (dicalcium silicate) 16% C ₃ A (tricalcium aluminate) 9% C ₄ AF (tetracalcium allumoferrite) 12%

2. "Humate +7" - a fine powder of brown color. Completely (without sediment) is dissolved in water. It is used in agriculture as a fertilizer and deoxidizer, the pH of the solution is from 12 to 13.

Obtained on the basis of humic acids by extraction of brown and other types of coal, followed by neutralization to an alkaline medium with a two percent solution of caustic alkali (potassium or sodium). Information on obtaining humic preparations is given in L.N. Ekaterina, L.V. Motovilina et al. “Humic preparations from coal to increase crop yields. M .: Publishing House: Central Board of the All-Union Scientific and Technical Society. P.87, 1989

In the experiments “Humate +7”, Brands - C. In the experiments, it was introduced into the binder in the form of a true aqueous solution with a concentration of 20 g / l with a pH of 12-13, and in combination with ground quartz sand.

It should be noted that the composition of humic acids contains a high carbon content (* more than 60-65%) (see the same source by L.N. Ekaterina and others). Therefore, this activator can be attributed to carbon-containing additives.

“Gumat + 7” is freely sold in agricultural stores or departments, and is also sold at wholesale prices by suppliers.

The experiments used "Gumat + 7" produced by LLC "Agricultural Technologies".

Composition, wt.%: Humate - 40.0, nitrogen - 1.5, K ⁺ - 5.0, Cu ⁺⁺ - 0.2, Mn ⁺⁺ - 0.17, Zn ⁺⁺ - 0.2, Mo ⁺⁺ - 0.018, Co ⁺⁺ - 0.02, B - 0.2, Fe ⁺⁺ - 0.4, the rest is alkali salts.

Quartz sand with a specific surface area of 300 m ² / kg obtained by grinding in a ball mill. For grinding, in order to expand the resources of natural raw materials, substandard sand has been adopted (as a fine aggregate for concrete), i.e. in the form of screening fractions less than 0.14-0.16 mm Pulverized quartz sands, as well as other quartz-containing rocks, such as seeding from crushed quartzite, rock crystal, containing at least 80% silica, are recommended.

The components for the binder are prepared, wt.%: Portland cement M400 70-85, quartz sand with a specific surface of 300 m ² / kg 15-30, "Humat +7", on dry over 100 0.05-0.2 (compositions 2- 5, Table 1), respectively.

At the same time, components are prepared for the control non-additive composition (composition 1, table 1).

Molding mixtures for compositions 2-5 (Table 1) are prepared as follows: ground quartz sand is pre-treated with a 2% aqueous solution of Humate +7 and kept for 10 minutes to achieve the activation effect. Portland cement is added to the activated mixture, mixed thoroughly and an astringent is obtained. The resulting binder is mixed with standard quartz sand of the Volsky deposit at a ratio of 1: 3, mixed and shut with water in the amount necessary to obtain equal-moving mixtures, and with a water-binding ratio of 0.4. The resulting mixture is thoroughly mixed and molded beam samples measuring 40 × 40 × 160 mm.

Samples for control composition 1 (table 1) were made in accordance with GOST 310.4-81.

All samples were left to harden under normal conditions at t = 20 ± 2 ° C and humidity 95-98% in a bath with a hydraulic shutter and tested for compressive strength after 28 days.

The tests were carried out according to standard methods, and the samples were made in accordance with the requirements of GOST 310.4-81 “Cements. Methods for determining the tensile strength in bending and compression. "

Examples of the implementation of the task.

Example 1. Binder: quartz sand with a specific surface area of 300 m ² / kg is treated with a 2% aqueous solution "Humate +7" and incubated for 10 minutes Portland cement M400 was added to the mixture and mixed.

The content of components in the mixture, wt.%:

Portland cement 85 Specified Quartz Sand fifteen The specified "Humate +7" 0.1 dry over 100

The binder is mixed with standard quartz sand in a ratio of 1: 3, mixed and mixed with water at a water binder ratio of 0.4. Then, beam samples measuring 40 × 40 × 160 mm are formed from the resulting mixture. Samples harden under normal conditions at t = 20 ± 2 ° C and a humidity of 95%.

The pH level of a 2% aqueous solution of "Humate +7" is 13.

The compressive strength at the age of 28 days is 45 MPa.

Example 2. Carried out analogously to example 1 in the following ratio of components, wt.%:

Portland cement 85 Specified Quartz Sand fifteen The specified "Humate +7" 0.15 dry over 100

The pH level of a 2% aqueous solution of "Humate +7" is 12.5.

The compressive strength at the age of 28 days is 34.9 MPa.

Example 3. Carried out analogously to example 1 in the following ratio of components, wt.%:

Portland cement 70 Specified Quartz Sand thirty The specified "Humate +7" 0.1 dry over 100

The pH of a 2% aqueous solution of Humate +7 is 12.

The compressive strength at the age of 28 days is 30.06 MPa.

Example 4. Carried out analogously to example 1 in the following ratio of components, wt.%:

Portland cement 70 Specified Quartz Sand thirty The specified "Humate +7" 0.05 dry over 100

The pH of a 2% aqueous solution of "Humate +7" is 11.9.

The compressive strength at the age of 28 days is 14.5 MPa.

Analysis of the test results of the properties shown in table 2, the proposed binder in relation to the known (prototype) shows the following:

- the proposed optimal composition of binder No. 2 has a strength of not less than composition No. 1 (analogue), i.e. no less than the strength of PC-D0 grade M400, adopted for the implementation of the task, and even higher by 9.75%, and the cement consumption of PC-D0 per 1 m ^{3 is} saved with ground sand and the introduction of additives (0.2% by weight of the binder) - 15%, and in relation to the prototype - by 15-30%;

- the strength relative to the strength of the prototype increased 2.17-3.19 times;

- composition No. 5 is transcendental due to the lack of evidence of an increase in strength with respect to the strength of the prototype, because the introduced amount of “Humate +7” 0.05% of the mass of dry components does not ensure the full activation of ground quartz sand, taken in place of cement in an amount of 30%;

- significantly simplified the technology of preparation of the proposed binder in relation to the prototype, because only quartz sand is subject to fine grinding, and the latter can also be taken substandard for concrete, for example, sowing with a particle size of less than 0.14-0.16 mm or dusty natural sands, which reduces energy consumption by 40-60%. “Humate +7” as well as “ПЦ-Д0” can be used in finished form, the latter being dissolved in water in 1-2 minutes with almost no effort in mixing. The solution has high stability (at least 7 days);

- it is shown that "Humat +7" finds a new field of application, i.e. in the composition of the binder, and therefore concrete, which will allow to dispose of finely dispersed fossil fuels formed during transportation in wagons.

The physicochemical nature of the increase in strength of the proposed binder is explained by the complex composition of the Humate +7 activator, which in a dry (almost dusty) state is a mixture of an organic carbon component, i.e. huminate (40% wt.) and 60% water-soluble alkali metal bases (K ⁺ or Na ⁺ ) and salts of other metal cations in an amount of seven types of Fe ⁺⁺ , Co ⁺⁺ , Mn ⁺⁺ , etc. (see chemical composition above), i.e. the supplement is organomineral.

Currently, many scientists have proved that carbon-containing additives such as “Soot” or “Taunit”, the latter contributes to an increase in the strength of fine-grained concrete after 28 days of hardening with respect to the strength of the PC by 20%, with a dose of “Taunit” 0.1% by weight of the PC (see A. G. Tkachev, Z. A. Mikhaleva et al. “Modification of building composites with carbon nanomaterials”, International scientific journal “Alternative Energy and Ecology” No. 9, (53), 2007, Scientific and Technical Center “ Tata ").

Thus, the organic part of "Humate +7" has a positive effect on strength, because belongs to the modifier of the structure of binders and concrete, i.e. contributes to the compaction of the system, and therefore, strength. A more accurate reason for increasing the strength of carbon-containing additives at the nanoparticle level is under study and has not been precisely established.

The main reason for the increase in strength lies in the alkaline environment of the aqueous solution of "Humate +7" with a pH of 12-13, which contributes to the hydration of SiO ₂ microparticles, because uncompensated valencies of SiO ₂ attach OH ^- chemisorption ions from the humate aqueous solution "Humate +7", and the solution is enriched with H ⁺ ions, i.e. pH of the medium decreases. This mechanism has been proved experimentally by geologists (N. A. Kozyrin, M. I. Gorbacheva. On one of the possible causes of changes in the pH of ore-forming solutions (experimental data). M: “Geology of ore deposits”, Volume XVIII, 1976, p. 92 -95). It was shown that the pH of the alkaline solution at t = 25 ° C from 10.65 over a 30 day stay of quartz microparticles in it decreases to 6.83, i.e. by 2.7%. Thus, microparticles of silica flour are coated with gel-like SiO ₂ · nOH films and become reactive active additives, i.e. react with Ca (OH) ₂ , which is formed during hydration of cement of clinker minerals, binding them to insoluble hydrates of calcium silicate, i.e. an increase in calcium hydrate silicate yield increases strength.

2Ca (OH) ₂ + SiO ₂ · nH ₂ O = 2CaO · SiO ₂ · nH ₂ O

In addition, the authors of the present invention found that pre-mixed ground quartz flour, with a specific surface of 300 mg / kg, when mixed with a solution of "Humate +7" is able to set and harden, which is consistent with the work of Japanese scientists who found that when mixing silica fume - waste production of ferrosilicon with a solution of caustic alkali - a binder is formed, which is used for refractory concrete (see Japan application No. 49-36812, MKU CO413 19/04 or NKI 22 (3) C3, publ. No. 18, 1975).

Thus, the introduction of a binder, not quartz flour, but a preliminary test of this flour, capable of setting and hardening on its own, accordingly helps to increase the strength of the proposed binder.

The presence in the structure of "Humate +7", i.e. organomineral carbon-containing additive of cations K ⁺ , Fe ⁺⁺ , Mn ⁺⁺ , etc., also contributes to the compaction of the structure of the knitting sand mixture with its use, which also helps to increase strength (see L.F. on the strength properties of concrete composites. Nanotechnology in construction, No. 6/2010. Nanobuild, ru).

ECONOMIC EXPEDIENCY.

1. The consumption of PC-D0 is saved by 15-30%.

2. Saves energy consumption for grinding additives by 40-60% relative to the prototype, because 90% of additives are crushed in the prototype, and 15-30% in the proposed one.

3. The consumption of materials is reduced by 1 MPa of strength:

3.1. in the prototype (100% of the material: 14.1 MPa) = 7.1,

3.2. in the proposed (100% material: 34.9 MPa) = 2.86,

those. 7.1: 2.86 = 2.5 times.

4. Substandard quartz sands are disposed of, career costs are lower than diatomite by 30-40%.

5. Jarozit ground and "Humate +7" have approximately the same selling price.

Based on these factors, the cost of 1 ton of binder is reduced by 10-12%.

Claims (1)

A binder comprising Portland cement, a ground silica component and an alkaline activator with cations of metals, characterized in that it contains silica sand with a specific surface of 300 m ² / kg as a ground silica component, as the specified activator "Humate +7" with pH 12- 13, introduced in the form of a 2% aqueous solution by mixing with the specified sand and subsequent exposure for 10 minutes, with the following ratio of components, wt.%:
Portland cement 70-85 Indicated sand 15-30 The specified "Humate +7" 0.1-0.2 dry over 100