EA030349B1 - Method for manufacturing a protective negative buoyancy concrete coating for a pipeline - Google Patents

Abstract

The invention relates to pipeline engineering, in particular, to materials for application to outer surfaces of pipes as a protective negative buoyancy coating. The method according to the invention allows highly precise provision of a preset density of a protective concrete material within a range of 2600 to 3400 kg/m. The method for manufacturing a protective concrete weight coating for pipelines includes mixing cement, a filler, a plasticizing additive and water, pumping the resultant mixture into an annular space formed by the outer surface of a pipeline and a permanent formwork mounted thereon with a clearance, and setting the resultant coating. The method is characterized by that Portland cement is supplied for mixing in an amount such that the mixture contains from 8.8 to 20.0 wt.% of Portland cement, and water is added in an amount such that the ratio of water to cement is from 0.31 to 0.63, the plasticizing additive, in the form of a plasticizer and a defoamer, is supplied for mixing in an amount of 1.0 to 3.0 kg/m, the filler supplied for mixing has a grain size not exceeding 10 mm and is selected from barium ore or an iron-bearing ore, or gabbro-diabase, or granite, in a mixture or separately, wherein mixing of the components is performed so that the resultant concrete mixture has a flow behaviour index measured by the slump of a cone which is from 55 to 75 cm, and has an air content of 1 to 4% of the volume.

Description

The invention relates to pipeline engineering, in particular to materials applied to the outer surface of the pipes as a protective weight coating. The claimed method allows with high accuracy to ensure the desired density of the protective concrete material in the range from 2600 to 3400 kg / m ³ . The claimed method of manufacturing a pipeline, protective, weighting, includes mixing the concrete coating cement, aggregate, plasticizer and water, forcing the mixture into the annular space formed by the outer surface of the pipeline and installed on it with a gap fixed formwork, hardening of the resulting coating. The method differs in that Portland cement is supplied for mixing at the rate of its content in the mixture from 8.8 to 20.0 wt.%, Water is introduced at the ratio of water to cement from 0.31 to 0.63, as a plasticizing additive for mixing serves plasticizer and defoamer in an amount of from 1.0 to 3.0 kg / m ³ , the aggregate supplied for mixing with a grain size not exceeding 10 mm, is selected from barite or iron-containing ore, or gabrodiabaza, or granite in a mixture or separately, at the same time, the components are mixed at the rate of obtaining a mixture and having a flow index measured by the spreading of a cone, equal to from 55 to 75 cm, and an indicator of air content from 1 to 4% by volume.

030349

The invention relates to pipeline engineering, in particular to materials applied to the outer surface of the pipes as a protective weighting concrete pavement.

A known method of preparation of the ballast material for the underwater pipeline, which includes mixing cement, aggregate, water and plasticizer, in which coarse aggregate from the group of barite, or iron-containing ore, or their mixture is used as the aggregate, and the mixing is carried out in two stages: the first stage in the mixer serves from 10 to 20 wt.% specified coarse aggregate from its total amount, cement, water and plasticizing additive and carry out the mixing for 10 to 15 s, and in the second stage carry out the supply of the remaining specified coarse aggregate in equal portions with an interval of from 10 to 15 s with stirring and the components are mixed to obtain a homogeneous mixture (KI 2412393, 02.20.2011).

Known ballast material containing cement, barite ore, water and plasticizer. Polycarboacetyl is used as a plasticizer. In the manufacture of ballast material using the following fractional composition of barite ore:

coarse fraction from 5 to 25 mm - from 8 to 16 wt.%, small fraction from 0.16 to 5 mm - from 70 to 84 wt.%,

very fine fraction from 0.01 to 160 cm - from 8 to 14 wt.% (KI 2399828, 09/20/2010).

A ballast material containing cement, aggregate, plasticizer and water is also known. Sulfate-resistant Portland cement was used as a cement, RFE polycarboxylate as a plasticizer, and barite product, barite ore and ferromanganese concentrate as a filler. The material has the following ratio of components:

Portland cement - from 8.2 to 10.5 wt.%, water - from 5.2 to 6.7 wt.%, plasticizer - from 0.1 to 0.15 wt.%,

barite product - from 18 to 28 wt.% with a density of 3.78 kg / cm ³ , to 3.82 kg / cm ³ and humidity from 0.9 to 2.1%,

barite ore - from 18 to 28 wt.% with density from 3.9 to 4.1 kg / cm ³ and humidity of 2%, ferromanganese concentrate - from 25 to 45 wt.% with density from 4.2 to 4.5 kg / cm ³ and humidity

four%.

The ratio of water to portland cement is from 0.35 to 0.5.

The aggregate components have the following granulometric composition: up to 0.16 cm - up to 5%, from 0.16 to 1.0 cm - up to 25%, from 1.0 to 2.5 cm - up to 35%,

from 2.5 to 5.0 cm - the rest (CI 2437020, 12/20/2011).

The disadvantages of the above-mentioned technical solutions are not sufficiently high viscosity of the solution and time to maintain the mobility of the concrete mix, which makes it difficult to fill the annular space of the pipe-in-tube structure and makes it necessary to control the moisture content of the raw material in order to prevent the outer shell from breaking and splitting the concrete solution inside the filled structure.

The closest to the proposed technical solution is a method of manufacturing a ballast coating on the pipeline, which includes mixing the starting components, namely sulfate-resistant portland cement, barite ore, plasticizing additive based on polycarboxylate ether and water. For mixing, take the components in the following quantities:

sulphate-resistant portland cement from 12 to 17 wt.%, water from 4 to 10 wt.%,

plasticizing additive based on polycarboxylate ether from 0.1 to 0.25 wt.%, barite ore - the rest.

Moreover, the mixture serves different fractions of barite ore with their following content:

coarse from 3 to 25 mm - 18 wt.%,

fine from 0.16 to 3 mm - from 70 to 85 wt.%,

very fine from 0.01 to -0.16 mm - from 7 to 16 wt.%.

Water for a concrete mix is subjected to pretreatment, passing it through a magnetic field, in which tension of 120,000 to 140,000 A / m is maintained, at a speed of from 0.5 to 3.0 m / s, while the water treatment time is at least 2 h (CI 2453515, 20.06.2012).

However, the known method is rather difficult to apply to the production of mixtures that are prone to self-compacting, since the water treated in a magnetic field has a relatively short period of effective action, which imposes significant restrictions on the transportation time of the solution, as well as the behavior of such concrete mixtures when external forces are applied (for example, the mixture is pumped by a concrete pump) is subject to drastic changes.

The technical problem to be solved by the proposed invention is to create a method for manufacturing a protective weighting concrete coating of a pipeline with a high predetermined density,

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having after hardening and holding high compressive strength, which, in turn, allows to obtain a technical result, namely to reduce the outer diameter of pipes with a protective ballast coating for underwater, underground and surface laying.

The claimed technical result is achieved by the claimed method of manufacturing a protective weighting concrete piping of the pipeline, which includes mixing cement, aggregate, plasticizer and water. The resulting mixture is injected into the annular space formed by the external surface of the pipeline and fixed non-removable formwork installed on it with a gap. The resulting coating is left to harden. According to the proposed method, Portland cement is supplied for mixing at the rate of its content in the mixture from 8.8 to 20.0 wt.%, Water is introduced at the rate of water to cement ratio, equal to 0.31 to 0.63. As a plasticizing agent, a plasticizer with an antifoam agent is supplied for mixing. The amount of plasticizing agent used in the mixture is from 1 to 3 kg / m ³ . The aggregate supplied for mixing must contain a grain size not exceeding 10 mm. The filler is selected from barite or iron ore, or gabrodiabase, or granite. In this case, the mixing of the components together or separately is carried out at the rate of obtaining a mixture having a flow index, measured by the spreading of a cone, equal to 55 to 75 cm, and the air content is from 1 to 4% of the mixture volume.

Preferably, in order to obtain a better indicator of the density of the protective weighting concrete pavement, the filler supplied for mixing has the following particle size distribution:

up to 0.16 mm - up to 8%, from 0.16 to 1.25 mm - up to 35%, from 1.25 to 2.5 mm - up to 37%, from 2.5 to 10.0 mm - the rest.

It is preferable to use lignosulfonates, melamine sulfonates, naphthalenesulfonates, as a plasticizer of the mixture, each individually or their mixture in any combination. The amount of plasticizer should be up to 1% of dry matter by weight of cement.

Preferably, in the plasticizer defoaming agent was not more than 50% of the applied plasticizer.

To obtain a mixture of necessary mobility and sufficient viscosity, as well as to exclude its stratification, the amount of plasticizer is chosen so that the material obtained on the one hand is fluid enough, namely, the spreading of the cone should be from 55 to 75 cm, and on the other hand the air content should be in the range of 1 to 4% by volume. Thus, in the proposed method, the plasticizing additive supplied to the mixture, consisting of a plasticizer and an antifoam in an amount of from 1.0 to 3.0 kg / m ^{3 of the} mixture at the same time, allows to obtain a plastic concrete mass that will fill all the space between the pipes, and At the same time, after solidification, the concrete coating will have a high density. In this case, in the plasticizer, the content of the antifoam agent should not exceed 50%. The increase in the content of the defoamer leads to a sharp decrease in the fluidity of the concrete mix and the appearance of voids in the concrete coating, which reduces the compressive strength characteristics of the concrete coating. The low content of antifoam less than 1% leads to an increase in the air content in the concrete mix and as a result, the density of the concrete coating decreases.

The ratio of water to cement, selected in the range from 0.31 to 0.63, is necessary to achieve the required mobility and strength of the concrete material. The use of water in smaller quantities leads to a decrease in the mobility of concrete and the appearance of air voids after solidification, and an increase in water leads to delamination and loss of compressive strength of the concrete coating.

The following is an example of the implementation of the claimed method of manufacturing a protective weighting concrete coating of the pipeline on the example of using barite ore as a filler, which does not limit the scope of the present invention.

An example of the method

First, prepare the initial components of the mixture. The process of preparing the components of the concrete mix includes grinding inert aggregate, for example barite ore, to sizes not exceeding 10 mm. The use of larger aggregate fractions leads to a decrease in the density of the resulting coating. If necessary, barite ore is heated to 5 ° C (maximum), especially following the melting of stuck together (frozen) pieces of rock to prevent delamination of the ballast mixture during transportation. Then measure the moisture content of barite ore. According to the results of moisture measurement, the amount of barite ore in the composition of the ballast material is specified according to the formula

w ₁ = w ₂ / (1 - ^ / 100),

where W1 is the mass of barite ore with regard to humidity, t ₂ is the mass of barite ore in the nominal recipe,

- humidity, expressed as a percentage.

Barite ore is sifted through a burate to isolate impurities of a large fraction. Then barite ore and Portland cement in the amount of its content in the mixture from 8.8 to 20.0% through the system trans- 2 030349

Porters are fed to the scales, where the components are weighed according to the adjusted composition. The granulometric composition of the aggregate is given in table. 1, the choice of ratios is due to obtaining a ballast coating with a given density.

To ensure the fluidity of the concrete mix, a plasticizing agent is added in the amount of 1.0 to 3.0 kg / m ³ when pouring into it. Plasticizing additive is a mixture of plasticizer and defoamer. Moreover, the amount of defoamer in the plasticizer should not exceed 50%. Tributyl phosphate or anhydrous silicone self-dispersing Penta-4604 antifoam can be used as a defoamer. As a plasticizer can be any known plasticizers, such as lignosulfonates, melamine sulfonates and naphthalenesulfonates. These plasticizers can be used both individually and in any combination, which does not affect the receipt of the claimed technical result. The amount of plasticizer should be no more than 1% of the dry matter by weight of cement.

Water is added to the mixture at the rate of a ratio of water to cement equal to 0.31 to 0.63, and mixed thoroughly. Stirring is continued until a homogeneous homogeneous mixture is obtained with a cone spreading from 55 to 75 cm.

The concrete mixture obtained is injected by a concrete pump into the space between the conductive tube and the permanent formwork installed on it. In this case, the assembled tubular structure is located on a stand installed at a certain angle. The injection of the solution is made through a special removable plugs at the end of the pipe. At the same time, the poured structure is located obliquely (one end is lower than the other) and the filling is performed from the end below. The concrete mix is pumped by a concrete pump until the structure is completely filled - until the mixture leaves the branch pipe of the structure cover above. After completion of the procedure of filling the structure, it is on the stand for a time of exposure to a curing of at least 5 MPa, after which it is stored to a set of transport durability of at least 22 MPa.

Depending on the technological needs, various types of external fixed formwork can be used when pouring a pipe structure, for example, steel spiral formwork can be made with locks to the outside and inside of the structure and can be painted or coated with various polymeric materials, which allows to obtain various characteristics of products.

To reinforce the structure in the space between the pipe and the permanent formwork, it is possible to arrange the reinforcement (steel or polymer) in the form of rods or mesh, connected by welding or tied, and also to increase the strength of concrete, it is possible to use fiber (steel or polymer).

The claimed method allows with high accuracy to ensure the specified density of the protective concrete weighting coating of the pipeline in the range from 2600 to 3400 kg / m ³ . The determination of the average density of the mixtures was carried out in accordance with GOST 12730.1-78. The compressive strength of concrete was determined in accordance with GOST 10180-90.

To obtain a coating with different characteristics of density and strength, not only barite, but also iron-containing ores, gabrodiabases, and granite can be used as aggregates. These fillers can be used both separately from each other, and in various combinations. Examples of the compositions used in the protected method, and the obtained indicators of the density and compressive strength of the coating obtained are given in table. 2

When used as part of a combination of different aggregates, the fractional series is crushed (prepared) for each component separately. The fine and coarse fractions of the aggregate consist of the same component and in the ratios given in table. one.

The stated amounts of the supplied initial components and the main characteristics of the mixture obtained were determined in the course of numerous field experiments, the results of which are given in table. 1 and 2. In table. 1 shows the particle size distribution of the aggregates. The presence of a fine fraction of the aggregate allows you to create conditions that reduce the separation of the protective weighting concrete material in the process of pouring.

In tab. 2 shows examples of different compositions of the protective weighting coating of the pipeline using components of different densities and shows the compressive strength of the obtained ballast material for each composition, as well as data on the coating obtained in accordance with the prototype.

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Table 1

Component Name Density kg / cm ³ Grading, mm Barite ore from 3.7 to 4.1 Up to 0.16 - up to 8%; from 0.16 to 1.25 to 35% from 1.25 to 2.5 to 37% from 2.5 to 10.0, the rest Iron ore from 3.8 to 4.5 Up to 0.16- up to 8%; from 0.16 to 1.25 to 35% from 1.25 to 2.5 - to 37% from 2.5 to 10.0 - the rest Gabrodiabaz from 3.01 to 3.06 Up to 0.16- up to 8%; from 0.16 to 1.25 to 35% from 1.25 to 2.5 to 37% from 2.5 to 10.0 the rest G wounds from 2.56 to 2.62 Up to 0.16- up to 8%; from 0.16 to 1.25 to 35% from 1.25 to 2.5 to 37% from 2.5 to 10.0 the rest

Components №1 №2 Number 3 №4 №5 №6 №7 №88 Cement, kg / m ³ 470 480 450 450 340 350 480 350 Water, kg / m ³ 210 172.8 194 210 150 150 210 210 Plasticizing additive, kg / m ³ 1.2 1.92 1.2 1,3 2.6 2.6 1.24 1.2 Gravel* - - - - - - - - Barite ore, kg / m ³ * - - - 700 800 600 - 2560 Iron ore, kg / m ’* - - - 750 2060 2100 - Gabrodiabaz, kg / m ³ * 650 - 2230 950 2300 - - Granite, kg / m ³ * 990 1979 - - Sand * - - - - - - Water cement ratio 0.45 0.36 0.43 0.47 0.44 0.43 0.44 0.6 Air content before construction casting,% 2.8 1.7 2.7 2.0 1.9 1.8 1.8 2.5 Blurring cone, cm 57 68 58 60 62 64 55 62 Density, kg / m ³ 2600 2450 2800 .3000 3350 3400 2800 3150 Compressive strength MPa 48 74 48 51 49 48 42 47

table 2

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Components №9 №10 № 11 № 12 № 13 №14 №15 Composition by POTOTIPUUS Cement, kg / m ³ * 430 430 430 450 460 460 420 420 Water, kg / m ³ 210 210 200 200 210 210 210 190 Plasticizing additive, kg / m ³ * Gz 2.1 1.8 1.9 2.1 1.4 2.6 Gravel * 1140 Barite ore, kg / m ³ * 600 500 500 500 - Iron ore, kg / m ’* 2050 2000 900 900 1500 - Gabrodiabaz, kg / m ³ * 560 650 1230 500 Granite, kg / m ³ * 1300 520 300 800 300 370 Sand * - 710 Water cement ratio 0.49 0.45 Air content before pouring the structure,% 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Spread out cone, cm 55 56 54 65 60 56 55 Density. kg / m ³ 2540 3250 3250 3000 2870 2700 3000 2480 Compressive strength, MPa 47 47 48 60 55 56 46 45

^ The data presented in the table are based on dry matter.

Claims (4)

CLAIM 1. A method of manufacturing a protective weighting concrete piping of the pipeline, including mixing cement, aggregate, plasticizing component and water, forcing the resulting mixture into the space formed by the external surface of the pipeline and fixed non-removable formwork installed on it with a gap, hardening of the coating obtained, characterized in that the mixing Portland cement is supplied at the rate of its content in the mixture from 8.8 to 20.0 wt.%, water is introduced at the rate of water to cement ratio equal to 0.31 to 0.63, as plasticizer ruyuschey additive in an amount of 1 to 3 kg / m ³ mix on mixing fed plasticizer defoamer supplied to mixing the filler with a grain size not exceeding 10 mm, is selected from barite, or iron-containing ore or gabrodiabaza or granite, with mixing of the components together or separately carry out at the rate of obtaining a mixture having a flow index, measured by the spreading of a cone, equal to from 55 to 75 cm, and an air content indicator from 1 to 4% of the mixture volume, while the aggregate supplied to the mixture has the following particle size distribution: up to 0.16 mm - up to 8%, from 0.16 to 1.25 mm - up to 35%, from 1.25 to 2.5 mm - up to 37%, from 2.5 to 10.0 mm - the rest. 2. The method according to claim 1, characterized in that lignosulfonates, melamine sulfonates and naphthalenesulfonates are used either individually or in a mixture as a plasticizer of the mixture. 3. The method according to claim 1, characterized in that the plasticizer is used in an amount up to 1% of the dry matter by weight of cement. 4. The method according to claim 1, characterized in that in the plasticizing additive antifoam agent is not more than 50%.