RU2473492C1 - Fine-grain concrete - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to construction materials and can be used for manufacturing products from fine-grain concrete, both in civil and in industrial construction. Fine-grain concrete is obtained from mixture, which contains Portland cement, fractioned quartz sand with content of fractions in the following ratio, %: fraction 5-1.25 mm - 57-63; fraction 1.25-0.315 mm - 17-23; fraction 0.315-0.14 mm - 17-23, ground quartz sand with specific surface S_sp=120-170 m²/kg, product, based on modified polycarboxylate hyperplasticiser "Melflux 265IF" and water, with the following component ratio, wt %: Portland cement 15.0-23.0, fractioned sand 68.1-78.1, ground quartz sand 1.5-2.3, hyperplasticiser "Melflux 265IF" 0.075-0.115, water the remaining part.

EFFECT: increased compression resistance and flexural strength at early and design age, reduction of water absorption.

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Description

The invention relates to building materials and can be used for the manufacture of concrete products in civil and industrial construction. Known raw mix for the preparation of concrete, including Portland cement, screening crushing quartzite sandstone, mechanically activated screening quartzite sandstone and water, with the following ratios of components, kg / m ³ :

Portland cement 300-350 Quartzite sandstone crushing screening 1100-1300 The specified screening quartzite sandstone mechanically activated 90-140 Water rest

(Patent RU 2389703 IPC С04В 28/04, С04В 111/20, 05/20/2010).

The disadvantage of this mixture is its low compressive strength and bending. The closest in technical essence to the claimed invention is fine-grained concrete containing Portland cement, glauconite sand, filler - glauconite sand with a specific surface S _beats = 350 m ² / kg, C-3 superplasticizer and water, in the following ratio, wt.%:

Portland cement 18.0-19.0 Glauconite sand 68.1-68.9 Filler 1.0-2.0 Superplasticizer S-3 0.1-0.2 Water 11.0-11.7

(patent RU 2358938 IPC С04В 28/04, 2010).

The disadvantage of this technical solution is the low compressive strength and bending at an early and design age, as well as increased water absorption.

The problem to which the invention is directed, is the creation of fine-grained concrete with increased compressive strength and bending at an early and design age with low water absorption.

The solution to the problem is achieved in that the fine-grained concrete obtained from a mixture containing Portland cement, aggregate, silica-containing component, plasticizer and water, according to the invention contains fractionated sand with fractions in the following ratio,%: fraction 5-1.25 mm - 57-63; 1.25-0.315 mm - 17-23; 0.315-0.14 mm - 17-23; as a silica-containing component - ground quartz sand with a specific surface S _beats = 120-170 m ² / kg, and as a plasticizer - a product based on modified polycarboxylate - Melflux 2651 F hyperplasticizer, in the following ratio, wt.%:

Portland cement 15.0-23.0 quartz sand 68.1-78.1 specified silica-containing component 1.5-2.3 Melflux 2651 F hyperplasticizer 0.075-0.115 water rest

The characteristics of the substances used to produce fine-grained concrete Portland cement are in accordance with GOST 31108-2003 “Cement for general construction. Technical conditions. "

Quartz sand - in accordance with GOST 8736-93 "Sand for construction work. Technical conditions. "

Melflux 2651 F hyperplasticizer is a product obtained by spray drying based on a modified polyester carboxylate manufactured by Degussa Constraction Polymers (SKW Trostberg, Germany).

Quartz sand, used as a filler, is pre-fractionated by selecting the optimal ratio of fractions. The content of each fraction in the aggregate has the following ratio,%:

fraction 5-1.25 mm - 57-63;

fraction 1.25-0.315 mm - 17-23;

fraction 0.315-0.14 mm - 17-23.

In this case, the minimum voidness of quartz sand is ensured, which allows to obtain fine-grained concrete with a dense structure and low porosity.

A silica-containing component, ground quartz sand with a specific surface area S _beats = 120-170 m ² / kg, is also introduced into the composition, which allows to compact the structure of fine-grained concrete, since it fills the free space between small particles of fractionated quartz sand. In addition, it chemically binds portlandite formed during cement hydration into low-basic calcium hydrosilicates, which strengthens the structure of the cement stone.

Thus, fine-grained concrete obtained from a concrete mixture consisting of Portland cement, quartz sand of a selected fractional composition, a silica-containing component in the form of ground quartz sand with a specific surface S _beats = 120-170 m ² / kg, and Melflux 2651 F hyperplasticizer leads to increase the compressive strength and bending at an early and design age and to reduce water absorption. The claimed invention is applicable and can be used in industrial and civil engineering.

The order of preparation of the concrete mixture is as follows:

1. Prepare fractionated sand. Quartz sand is pre-screened into three fractions of 5-1.25 mm, 1.25-0.315 mm and 0.315-0.14 mm, then these fractions are mixed in the following ratio,%:

fraction 5-1.25 mm - 57-63;

fraction 1.25-0.315 mm - 17-23;

fraction 0.315-0.14 mm - 17-23.

2. Dose Portland cement, prepared fractionated quartz sand, a silica-containing component, which is ground quartz sand with a specific surface S _beats = 120-170 m ² / kg.

3. Dose water.

4. Dose the Melflux 2651 F hyperplasticizer and add it to the prepared water.

5. Dosed components: Portland cement, fractionated quartz sand, silica-containing component and water containing a dosed additive - Melflux 2651 F hyperplasticizer, are placed in a concrete mixer, where components are mixed to prepare the concrete mixture from which the necessary concrete products and samples are made for quality control according to GOST 10180. One part of the samples hardens under normal conditions, the other during heat-moisture treatment (TVO) in a steaming chamber according to the 2 + 3 + 5 + 4 hours regime.

The compositions of the concrete mixture of fine-grained concrete are presented in table 1, the test results of fine-grained concrete in table 2.

table 2 Indicators Compositions prototype one 2 3 four 5 The limit of compressive strength, MPa - at the age of 3 days
- after TVO - 15.1 30.1 37,4 41.2 58.8 18.9 20,4 37.3 52,4 68.5 81.4 Bending Strength, MPa - at the age of 3 days
- after TVO - 3.8 4.1 5.3 6.4 7.9 4.1 4,5 5.1 6.4 7.7 9.1 Water absorption,% 2.9 2.9 2.7 2.6 2,4 2,3

Analysis of the data presented in tables 1, 2 shows that the proposed fine-grained concrete according to this invention, in comparison with the prototype, has an increased compressive strength of 4.3 times, when bending - 2.2 times, while reduced by 20% water absorption.

Claims (1)

Fine-grained concrete obtained from a mixture containing Portland cement, aggregate, silica-containing component, plasticizer and water, characterized in that it contains fractionated quartz sand with fractions in the following ratio,%: fraction 5-1.25 mm - 57-63 ; 1.25-0.315 mm - 17-23; 0.315-0.14 mm - 17-23; as a silica-containing component - ground quartz sand with a specific surface S _beats = 120-150 m ² / kg; as a plasticizer - a product based on modified polycarboxylate - Melflux 2651 F hyperplasticizer, in the following ratio, wt.%:
Portland cement 15.0-23.0 quartz sand 68.1-78.1 specified silica-containing component 1.5-2.3 Melflux 2651 F hyperplasticizer 0.075-0.115 water rest