RU2189366C2 - Raw mixture for extra strength and heavy concrete preparing - Google Patents

Abstract

FIELD: building materials. SUBSTANCE: raw mixture for preparing extra strength and heavy concrete involving cement of grade M 500, not less, large and small filling agents of fractions 10-20 mm, 5-10 mm, 1.25-5 mm, 0.16-1.25 mm prepared of scale, cast iron or steel shots of number 1.8-3.6, water, superplasticizing agent based on a condensation product of naphthalene sulfoacid sodium salts with formaldehyde and nitrilotrimethylenephosphonic acid as a retardant of the raw mixing. The consumption of components, kg/m³ of concrete is the following: cement of grade M 500, not less, 450-650; large filling agent prepared of scale: fraction 10-20 mm, 650-1000; fraction 5-10 mm, 540-800; small filling agent prepared of scale: fraction 1.25-5 mm, 400-650; fraction 0.16-1.25 mm, 500-700; cast iron or steel shots, 800-1500; water, 120-210; superplasticizing agent, 3.0-9.0; retardant of concrete mixture seizing, 0.4-0.9. The proposed concrete is used for making metal-concrete containers for transport and/or storage of depleted nuclear fuel and providing the enhancement of radiation-protective properties of metal-concrete containers. EFFECT: increased density and strength of concrete, expanded assortment of scale used as a filling agent for concrete. 2 cl

Description

 The invention relates to building materials, in particular to a raw material mixture for the preparation of particularly strong and heavy concrete, mainly for containers for long-term storage and / or transportation of spent nuclear fuel (SNF) and radioactive waste (RAW), as well as for structures for the biological protection of reactors.

 Containers for transportation and storage of spent nuclear fuel are known, the manufacturing method of which includes concreting the tank in the form of a glass (German patent 3331892, class G 21 F 5/02, 1986, patent GDR 235353, class G 21 F 5/00, 1986).

In accordance with radiation safety standards and the requirements of the IAEA, such containers should provide high radiation-protective and strength properties, including in emergency situations, possible during the transportation and storage of spent nuclear fuel. For example, IAEA regulatory requirements for a container include providing
radiation safety of personnel during transportation and storage of the container;
tightness in the event of an accidental fall from a height of 9 m onto a rigid base or onto a pin with a diameter of 150 mm from a height of 1 m;
resistance to shock waves with a front pressure of 30 kPa;
safety when falling onto a container of an airplane weighing 20 tons at an airplane speed of 200 m / s;
resistance to thermal effects in case of fire at 800 ^o C for 30 min;
long-term operation at negative temperatures up to minus 50 ^o C.

 At the same time, based on the technical and economic requirements for reducing the costs of organizing SNF container storage, it becomes necessary to create containers of a relatively large usable volume (with a maximum SNF capacity) under certain (in particular, transport) restrictions on their external dimensions.

 These requirements have identified the need to create and use concrete with the highest possible density with a sufficiently high strength and minimum value.

Known heavy concrete for the manufacture of a container for transportation and storage of spent nuclear fuel, containing in 1 m ³ from 280 to 370 kg of cement, from 2800 to 3400 kg of filler; the water content is determined by the ratio of water-cement in the range of 0.40-0.60. From 650 to 800 kg of barite and from 2000 to 2400 kg of hematite are used as filler. Heavy concrete has a compressive strength of 40 to 60 MPa per 28 days, the density of the concrete mixture is 3800 kg / m ³ , and concrete in the dry state is up to 3500 kg / m ³ (EPO, 0264321, class C 04 V 20/00 1988).

The disadvantages of this heavy concrete are
low strength of concrete due to insufficient strength of barite aggregate and high water-cement ratio of concrete mix;
low fire resistance of concrete due to the low resistance to fire effects of the specified aggregate;
insufficient density and, accordingly, radiation-protective properties of concrete in relation to the design of the container intended for storage of highly active SNF.

Also known is the raw material mixture for the preparation of heavy concrete of class B20 on mill scale, intended for protective shields from radioactive radiation (Construction of nuclear power plants / Edited by V. B. Dubrovsky, M .: Energoatomizdat, 1987, p. 122, table 5.7. ) The composition of the raw mix is as follows, kg per m ^{3 of} concrete:
Coarse aggregate of scale 5-10 mm - 1858
Fine aggregate of scale 0-5 mm - 1380
Cement with an activity of 48 MPa - 401
Water - 248
The density of the raw material (concrete) mixture ρ = 3887 kg / m ³ , the density of concrete at the age of 28 days of natural hardening ρ = 3820 kg / m ³ , the mobility of the concrete mixture is 14 cm of precipitation of a standard cone, the strength at 28 days of age is 23.2 MPa

 The disadvantages of the known raw mix are the low strength of concrete and the presence of significant shrinkage of concrete in the hardening process. In addition, a high water-cement ratio (W / C = 0.62) leads to a large amount of water that is not involved in chemical hydration reactions and, consequently, to a large pore volume and a decrease in the radiation-protective properties of concrete.

Closest to the proposed invention is a raw material mixture for the preparation of particularly strong and heavy concrete of classes B80 - B105 and grades of medium density D4000-D4100 (RF patent 2100304, class C 04 B 28/00, G 21 F 5/00, 1 / 4, 1997) The composition of the raw mix is as follows, kg / m ³ concrete:
Cement grade not lower than M 500 - 610-650
Coarse aggregate from the scale of machine firing:
fractions of 10-20 mm - 800-1000
fractions of 5-10 mm - 900-1200
Fine aggregate from the said scale:
fractions of 1.25-5 mm - 400-500
fractions of 0.63-1.25 mm - 400-500
fractions 0.16-0.63 mm - 500-650
Water - 165-180
Superplasticizer based on Na-salts of the condensation product of naphthalenesulfonic acid with formaldehyde in an amount of 0.5-1% by weight of cement consumption.

However, in the known raw material mixture, only one type of heavy aggregate is used - the scale of machine firing, which virtually eliminates the possibility of producing concrete with a strength class of more than B 105 at a density of more than 4100 kg / m ³ .

The present invention is directed to a highly durable (R _SJ = 600-1400 kg / cm ²⁾ and heavy (D4200-4500) B90 concrete classes - V135 both protective and structural member metalobetonnogo container (IBC) for the transportation and storage of spent nuclear fuel long.

This problem is solved due to the fact that the raw material mixture for the preparation of particularly strong and heavy concrete, including cement of grade not lower than M 500, coarse and fine aggregates of fractions 10-20 mm, 5-10 mm, 1.25-5 mm, 0.16 -1.25 mm from scale, water and a Na-salt-based superplasticizer of the condensation product of naphthalene sulfonic acid with formaldehyde according to the invention additionally contains cast iron or steel shot numbers 1.8-3.6 as filler at the following component consumption in kg per m of concrete :
Cement grade not lower than M 500 - 450-650
Large scale aggregate:
fractions of 10-20 mm - 650-1000
fractions of 5-10 mm - 540-800
Fine scale aggregate:
fractions of 1.25-5 mm - 400-650
fractions 0.16-1.25 mm - 500-700
Fraction pig-iron or steel numbers 1.8-3.6 - 800-1500
Water - 120-210
Superplasticizer based on Na-salts of the condensation product of naphthalene sulfonic acid with formaldehyde - 3.0-9.0
At the same time, in another embodiment, the raw material mixture further comprises nitrilotrimethylene phosphonic acid (NTP) as a retarder for setting the raw material mixture at a flow rate of 0.4-0.9 kg per m ^{3 of} concrete.

The necessary scale is chosen in the metallurgical industry from various technological processes. Suitability criterion is
the true density of the scale of 5.0-5.6 g / cm ³ ;
mark for crushing of large fractions not lower than "1000"
absence in the mass of scale of harmful impurities regulated by GOST 8267-93 "Crushed stone and gravel from dense rocks. Technical conditions" and GOST 8736-93 "Sand for construction work. Technical conditions".

 Dross before application in the case is dispersed into standard fractions 10-20; 5-10; 1.25-2.5; 0.16-1.25 mm, grains larger than 20 mm and foreign inclusions are removed.

 The mass of aggregates is selected according to the required average density of concrete in the range of grades D3300-D4500, workability of concrete mix depending on the geometric dimensions of the volume filled with concrete mix. The consumption of cement and water is prescribed in accordance with the above requirements, as well as for a given class of concrete for strength.

The proposed technical solution allows
increase the average density and strength of concrete by 15-20%, i.e. to achieve class B strength 135 (150 MPa) at a density of up to 4,500 kg / m ³ , which provides an increase in the radiation-protective properties of MBC while increasing the strength of MBC;
expand the range of scale used as aggregate for concrete, which simplifies the organization of the supply of scale.

 Studies on the selection of the composition of the raw mixture were carried out by the method of multivariate experiment with varying the ratio of components and their characteristics indicated in the claims.

 Table 1 shows examples of the composition of the raw material mixture on fillers of scale and steel shot, Portland cement M 600, the main mechanical and physical characteristics of the raw material mixture and concrete (table C-3 - superplasticizer based on Na-salts of the condensation product of naphthalene sulfonic acid with formaldehyde, TU 6 -36-0204229-625-90: W / C - water-cement ratio; OK - cone sediment). In compositions 1 ... 12, the retarder of setting the raw mix of NTF was not used, since it does not affect the properties of concrete and is necessary only in production conditions with prolonged concreting of the product (more than 2 hours).

 In embodiments of the invention, scale was used, which was formed during the processing of steel billets at OAO Izhorskiye Zavody (St. Petersburg). Table 2 presents the characteristics of the scale.

 The strength of concrete was determined by testing standard samples (GOST 10180-78 "Concretes. Methods for determining the strength of control samples"), workability was determined in accordance with the requirements of GOST 10181.1-81 "Concrete mixtures. Methods for determining workability", the average density was determined in accordance with the requirements of GOST 12730.1-78 "Concrete. Methods for determining the density."

 Higher strength and density of concrete than in the well-known solution according to Clause RF 2100304 were obtained due to the introduction of steel or cast iron fractions into the composition of the raw material mixture and its partial replacement of fine aggregate from scale.

The effective role of fine aggregate from steel or cast iron shots became possible due to the use of the mortar part of a very high average density (cement, water, plasticizer and fine scale - 0.16-5 mm) in the liquid state. In an embodiment of the invention, it is 2800-3200 kg / m ³ .

New in the invention in comparison with the prototype is, in particular, the use as a fine aggregate of scale of fractions up to 5 mm in combination with steel or cast iron shots, which makes it possible to increase strength and density, respectively, up to 150 MPa (class B 135) and 4500 kg / m ³ instead of 123.5 MPa (class 110) and 4100 kg / m ³ .

 The high average density of the mortar part provides a uniform distribution of the shot over the height, for example, MBK, and creates the conditions for the widespread use of shot in radiation-protective concrete. Table 3 shows examples of laying and compaction of the raw mix in cylindrical samples with a diameter of 250 and a height of 800 mm The mixture was compacted with a standard deep industrial vibrator. After compaction, the cylindrical shape was disassembled and samples of the raw mix were taken from the lower, middle and upper parts of the sample for 4 samples of 100x100x100 mm in size. In the experiments, the compositions of the raw mix 1, 3, 5, 8, 11 were used (table 1).

 Table 3 shows the average values for the test results of 4 samples. The range of values in the series between the minimum and maximum values did not exceed 7%.

 The average density of concrete of the entire cylindrical sample and the average strength determined by testing 4 samples prepared from concrete mix before laying it in the cylinder were taken as 100%.

 The proposed solution is industrially applicable. All components of the raw mix are produced by industry, including domestic. The following standards and specifications are available for the materials used: GOST 10178-85 "Portland cement, slag Portland cement. Technical conditions", GOST 24211-91 "Additives for concrete. General technical requirements", GOST 11964-81 "Fraction of pig-iron and steel technical. General technical conditions ", GOST 23732-79" Water for concrete and mortars. Technical conditions. " The technology for the preparation of concrete mix is based on serial domestic equipment.

The technical efficiency of the proposed concrete for products and structures of nuclear energy compared with the prototype is that it provides concrete with an average density of up to 4500 kg / m ³ inclusive, increase compressive strength by 15-20% and achieve its value up to 150 MPa, simplification of the technology for the preparation of aggregates from scale and a significant increase in the number of types of used scale.

Claims (1)

1. The raw material mixture for the preparation of particularly strong and heavy concrete, including cement grade not lower than M 500, coarse and fine aggregate fractions 10-20 mm, 5-10 mm, 1.25-5 mm, 0.16-1.25 mm from scale, water and a superplasticizer based on Na salts of the condensation product of naphthalenesulfonic acid with formaldehyde, characterized in that it additionally contains a cast-iron or steel shot number 1.8-3.6 as a filler with the following flow rate of components, kg per m ^{3 of} concrete:
Cement grade not lower than M 500 - 450-650
Large scale aggregate:
fractions of 10-20 mm - 650-1000
fractions of 5-10 mm - 540-800
Fine scale aggregate:
fractions of 1.25-5 mm - 400-650
fractions 0.16-1.25 mm - 500-700
Fraction pig-iron or steel numbers 1.8-3.6 - 800-1500
Water - 120-210
Superplasticizer based on Na-salts of the condensation product of naphthalene sulfonic acid with formaldehyde - 3.0-9.0
2. The raw material mixture according to claim 1, characterized in that it additionally contains nitrilotrimethylene phosphonic acid as a retarder for setting the raw material mixture at a flow rate of 0.4-0.9 kg per m ^{3 of} concrete.

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