RU2738882C1 - High-strength fine-grained concrete based on composite binder using technogenic material - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention relates to construction materials, in particular to a crude mixture for preparing high-strength fine-grained concrete using man-made material - concrete scrap of destroyed buildings, and can be used for production of frame elements of buildings and structures, both in civil and industrial construction. High-strength fine-grained concrete based on composite binder using technogenic material includes portland cement, active (multifunctional) additive, aggregate and water. Active mineral additive used is a powder modifier consisting of a mixture of alumina cement, microsilica, finely ground concrete scrap with specific surface area of 500 m²/kg, crystalline quartz with specific surface area of 500 m²/kg, limestone with specific surface area of 500 m²/kg and plasticizing additive Melflux 2651F. As filler there used are man-made materials: concrete scrap of fraction of 0.315-2.5 mm and screening of crushing of quartzite sand of fraction of 0.315-1.25 mm at specified ratio of components.

EFFECT: increased durability and reliability of structures due to provision of resistance to operational and climatic effects.

1 cl, 1 tbl

Description

The invention relates to building materials, in particular to a raw mix for the preparation of high-strength fine-grained concrete using man-made material of concrete scrap from destroyed buildings in Iraq, and can be used for the manufacture of elements of the frame of buildings and structures from high-strength fine-grained concrete, both in civil and industrial construction.

Known raw mix for the manufacture of high-strength concrete containing Portland cement, silica-containing component, sand, crushed stone, silicate flour, plasticizing additive and water [Yu.M. Bazhenov. Concrete technology. Textbook. / Yu.M. Bazhenov. - M .: Publishing house ASV, 2002, p. 376-377].

The main disadvantages of the raw mix for high-strength concrete with a plasticizing additive include a high consumption of Portland cement and high water absorption, since the aggregates used have a larger fraction, because of this, the resulting material has increased porosity.

The closest in technical essence to the claimed invention is High-strength fine-grained concrete based on a composite binder with the use of man-made material [RU 2625410, published on July 13, 2017, bulletin No. 20], which contains Portland cement, an active additive, filler, aggregate, plasticizing additive and water; Alumina cement and microsilica is used as an active additive (Multifunctional additive); as a filler - man-made chamotte material with a specific surface area of 450-500 m ² / kg; as a filler - quartz sand of fraction 0.63-1.25 mm and screening of crushing of quartzite sandstone of fraction 1.25 mm; as a plasticizing additive - Melflux 2651 F hyperplasticizer and water with the following ratio of components, wt. %: Portland cement - 20.0-21.0, alumina cement - 2.0-2.1, microsilica - 2.0, man-made chamotte material - 0.7-1.7, quartz sand - 20.5-21, 5, screening of quartzite sandstone crushing - 46.5-47.5, Melflux 2651 F hyperplasticizer - 0.2, water - the rest.

The main disadvantage of this raw material mixture is high water absorption and low strength, since the aggregates used have a larger fraction, the resulting material has a low density.

The invention is aimed at obtaining high-strength fine-grained concrete based on a composite binder with high strength and low water absorption, using man-made materials - concrete scrap and screening of crushing quartzite sandstone. As a result, there is an increase in the durability and reliability of structures due to the provision of resistance to operational and climatic influences.

This is achieved by the fact that high-strength fine-grained concrete based on a composite binder with the use of man-made material, includes Portland cement, an active (multifunctional) additive, aggregate and water, as an active additive, a powder modifier is used, consisting of a mixture of alumina cement, microsilica, finely ground concrete scrap with a specific surface area of 500 m ² / kg, crystalline quartz with a specific surface area of 500 m ² / kg, limestone with a specific surface area of 500 m ² / kg, and Melflux 2651F plasticizing additive; As a filler, man-made materials are used: concrete scrap of 0.315-2.5 mm fraction and screening of crushing of quartzite sandstone of 0.315-1.25 mm fraction with the following ratio of components, wt. %:

-portland cement - 27.0-29.8

- alumina cement - 2.5 -2.7

- microsilica - 7 - 7.2

- finely ground concrete scrap - 14 - 16.0

- finely ground crystalline quartz 1.6 -1.8

- finely ground limestone - 2.6 - 2.8

- hyperplasticizer Melflux 2651F - 0.7 - 0.9

- screening of crushing of quartzite sandstone - 20.2 - 20.2

- crushed concrete scrap - 13.6 - 13.9

- water - the rest

Characteristics of components of high-strength fine-grained concrete.

Composite binder:

- Portland cement grade CEM I 42.5 N corresponds to GOST 10178-85;

- powder modifier and plasticizing additive - hyperplasticizer Melflux 2651 F (Manufacturer: Degussa Constraction Polymers (SKW Trostberg, Germany)) - powder product obtained by spray drying on the basis of modified polyether carboxylate, [http: //www.slimstone .ru / color.html from 22.03.2017 (13:35:18)].

Powder modifier includes:

- alumina cement grade GC 40 in accordance with GOST 969-91,

-microsilica that meets the requirements of TU 5743-048-02495332-96,

- crystalline quartz with a specific surface area Ssp = 500 m ² / kg complies with GOST 2138-91,

- limestone with a specific surface area Ssp = 500 m ² / kg complies with GOST 9179-2018,

- finely ground concrete scrap with a specific surface area Ssp = 500 m ² / kg, the raw material of which is the fragments of various destroyed buildings and structures, for example, the Republic of Iraq, the city of Er-Ramadi, and the Anbar province.

Aggregate:

- screening out of crushing of quartzite sandstone GOST 8267-93, for example Lebedinsky GOK, fraction 0.315-1.25 mm;

- crushed concrete scrap of fraction, the raw material of which are fragments of various destroyed buildings and structures, for example, the Republic of Iraq, the city of Er-Ramadi, the province of Anbar.

Water for concrete and mortar meets the requirements of GOST 23732-79.

Several compositions of the proposed high-strength fine-grained concrete were made.

An example of the implementation of the invention is shown in the composition No. 3 presented in table 1.

Crystalline quartz, limestone, and part of the concrete scrap were ground in a ball mill to a specific surface area Ssp = 500 m ² / kg. All dry components were dosed by gravimetric method.

1st stage of the technological process - preparation of a composite binder (CB) in dry form, for this:

- dosed by weighing the components of the powder modifier: alumina cement - 58.9 kg (2.7%); microsilica - 157 kg (7.2%), finely ground concrete scrap - 348.8 kg (16.0%); finely ground crystalline quartz - 39.2 kg (1.8%); finely ground limestone - 61 kg (2.8%) was ground separately in a vibration mill to a powdery state with a specific surface area S _beats = 500 m ² / kg each. Portland cement was used with the factory fineness of grinding S _beats = 280 m ² / kg. After that, 588.6 kg (27%) Portland cement was separately mixed in a ball mill with 19.6 kg (0.9%) Melflux 2651F hyperplasticizer.

Then, all the components of the composite binder were placed in a forced concrete mixer and mixed to homogenize the mixture for 2 minutes.

2nd stage of the technological process - preparation of a concrete mixture of high-strength fine-grained concrete, for this:

- dosed by weighing the amount of fine aggregate, consisting of screening of crushing quartzite sandstone - 440.4 kg (20.2%) and crushed concrete scrap - 303 kg (13.9%) was placed in a concrete mixer and mixed for 1 minute. After that, a thoroughly mixed and homogeneous mixture of KB was added there, and the mixture was mixed for another 3 minutes. To the obtained dry homogeneous mixture, 163.5 (7.5%) l of water (W / C = 0.28) was added to the concrete mixer and mixed for another 3 minutes to obtain a homogeneous concrete mixture.

3rd stage of the technological process - production of experimental concrete samples of high-strength fine-grained concrete, for this:

- molded cube samples of 100x100x100 mm by filling in standard forms 2FK-100 in accordance with GOST 10181-2014. The samples in the molds were kept for 12 hours, after which they were stripped, and the samples were placed in a normal hardening chamber with a temperature of 20 ± 2 ° C and a relative humidity of 95 ± 5% for 28 days. After the expiration of the standard period, the samples were tested for strength in accordance with GOST 10180 and water absorption was determined in accordance with GOST 12730.3-78. The test results are presented in table 1.

P / p No. Content of components, wt. % Compressive strength at the age of 28 days, MPa Water absorption,% Composite binder Aggregate Filler Water Portland cement Multifunctional additive Powder modifier Plasticizing additive Alumina cement Microsilicon-earth Finely ground concrete scrap Finely milled crystalline quartz Finely ground limestone Hyperplasticizer Melflux 2651 F Quartz sand Screening of crushing of quartzite sandstone Crushed concrete scrap Technogenic material chamotte one 2 3 4 5 6 7 8 nine ten eleven 12 13 Prototype 20-21 2-2.1 2.0 - - - 0.2 20.5-21.5 46.5 -47.5 - 0.7-1.7 rest 80-81.5 0.80 one 29.8 2.5 7.0 14.0 1.6 2.6 0.7 - 20.0 13,7 - rest 81.6 0.67 2 28.5 2.6 7.1 15.0 1.7 2.7 0.8 - 20.1 13.6 - rest 82.0 0.64 3 27.0 2.7 7.2 16.0 1.8 2.8 0.9 - 20.2 13.9 - rest 83.1 0.61

Table 1

Composition and properties of fine-grained concrete based on a composite binder using a technogenic material

All samples showed high results in strength (strength class B80) and low water absorption (0.61-0.67%). Therefore, these compositions are selected as optimal for the production of high-strength fine-grained concrete based on a composite binder with the use of technogenic material.

Fine grinding of concrete scrap contributes to the destruction of the cement stone contained in it and reduces the intergranular void in the concrete structure.

Fine-grained concrete on a composite binder using a technogenic material has characteristics that exceed the properties of the prototype, which indicates additional mineral formation processes (crystallization of new formations - hydrosilicates and calcium hydroaluminates). Such concrete has minimal porosity, high density and frost resistance.

The obtained fine-grained concrete with the use of man-made material satisfies all the tasks, the strength was increased and the water absorption was reduced. The main advantage of the obtained concrete is the use of man-made material, which reduces the consumption of natural resources and fulfills an important modern task - the transformation of construction waste into high-quality construction materials.

The invention is aimed at obtaining high-strength fine-grained concrete based on a composite binder with high strength and low water absorption, using man-made materials - concrete scrap from various destroyed buildings and structures and screening out crushing of quartzite sandstone. As a result, there is an increase in the durability and reliability of structures due to the provision of resistance to operational and climatic influences.

Claims (2)

High-strength fine-grained concrete based on a composite binder using a technogenic material, including Portland cement, an active additive, a plasticizing additive, a filler and water, characterized in that a powder modifier is used as an active additive, consisting of a mixture of alumina cement, microsilica, finely ground concrete scrap with specific surface area of 500 m ² / kg, crystalline quartz with a specific surface area of 500 m ² / kg, limestone with a specific surface area of 500 m ² / kg and Melflux 2651F plasticizer; Technogenic materials are used as a filler - concrete scrap of 0.315-2.5 mm fraction and screening of crushing of quartzite sandstone of 0.315-1.25 mm fraction with the following ratio of components, wt. %: Portland cement 27.0-29.8 alumina cement 2.5-2.7 microsilica 7-7.2 finely ground concrete scrap 14-16.0 finely ground crystalline quartz 1.6-1.8 finely ground limestone 2.6-2.8 hyperplasticizer Melflux 2651F 0.7-0.9 screening of crushing of quartzite sandstone 20.2-20.2 crushed concrete scrap 13.6-13.9 water rest