RU2439019C1 - Concrete mixture and preparation method thereof - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to construction materials, particularly a concrete mixture and preparation method thereof, and can be used to make concrete and reinforced concrete structures, monolithic and assembled, used in construction. The method of preparing the concrete mixture involves mixing cement and water in amount 75% of its total amount until a homogenous mixture is obtained, adding chips from a crushed scrap concrete and sand while stirring for 3-4 minutes, adding the remaining amount of water and final mixing, with the following ratio of components, wt %: cement 12-17, chips from crushed scrap concrete 39-41, sand 35-39, water 8-9. The concrete mixture is obtained using said method.

EFFECT: high strength-density ratio - reduction of density of the concrete while maintaining strength, and improvement of the environmental situation.

2 cl, 2 ex

Description

The invention relates to a concrete mixture and a method for its preparation, and may find application in the building materials industry for the manufacture of concrete and reinforced concrete structures, both precast and monolithic.

Known concrete mixture, including cement, sand, gravel and water in the following ratio of components, wt.%: Cement - 12, sand - 29, gravel - 52, water - 7 (Yu.M. Bazhenov "Concrete technology" M .: ASV , 2002, p. 219).

The known concrete mixture is characterized by a relatively high coefficient of variation of strength properties and a relatively high consumption of cement, ceteris paribus.

A known method of preparing a concrete mixture, including pre-mixing sand and gravel with 40-60% mixing water for 3-4 minutes and adding 40-45% plasticizer solution in an amount of 5-9% by weight of cement, the subsequent addition of cement and additional mixing with the introduction of the remainder of the mixing water (RU No. 2028279 C1, publ. 09.02.1995).

The disadvantage of this method is that it requires an increased consumption of cement, and also does not provide the required compressive strength and workability of the concrete mixture.

The closest analogue to the proposed concrete mixture and the method of its preparation is a concrete mixture containing cement, crushed stone from concrete scrap, sand and a method for its preparation by mixing these components. (Murtazaev S.A. Yu. Effective concretes and mortars based on technogenic raw materials for repair and construction works, dissertation abstract for the degree of Doctor of Technical Sciences. Grozny 2008, p.22-24).

The technical result achieved by the present invention is to increase the coefficient of structural quality - reducing the density of concrete while maintaining its strength. The technical result is achieved due to the method of preparing a concrete mixture by mixing cement and 75% of the total water content until a homogeneous mixture is obtained, crushed stone from crushed concrete scrap and sand is added to it with mixing for 3-4 minutes, the remaining water is added and the final mixing in the following ratio of components, wt.%: cement 12-17, crushed stone from crushed concrete scrap 39-41, sand 35-39, water 8-9 and concrete mixture obtained by the specified method

To prepare the concrete mix, gravel from concrete scrap of a fraction of 5-20 mm, sand for construction work, which meets the requirements of GOST 8736-93, is used. The cement used is Portland cement CVM I 42.5N, which meets the requirements of GOST 31108-2003.

Examples of the invention:

Example 1

The concrete mixture is prepared by mixing the cement of CVM I 42.5N and 75% of the total water content until a homogeneous mixture is obtained, crushed stone from crushed concrete scrap and quartz sand is added to it with stirring for 4 minutes, the remaining water is added and the final mixing is carried out at the next the ratio of components, wt.%: the specified cement 17, crushed stone from crushed concrete scrap fractions 5-20 41, quartz sand 35, water 7. From the prepared concrete mixture, samples are prepared — cubes 10 × 10 × 10 cm in size, after curing the samples in normal condition Ovia test hardened concrete. The density of concrete is 1900 g / cm ³ , with a strength of 40 MPa.

Example 2

A concrete mixture is prepared by mixing the cement of CVM I 42.5N and 75% of the total water content until a homogeneous mixture is obtained, crushed stone from crushed concrete scrap and limestone sand is added to it with mixing for 3-4 minutes, the remaining water is added and the final mixing in the following ratio of components, wt.%: the specified cement 12, crushed stone from crushed concrete scrap fractions 5-20 40, limestone sand 39, water 9.

Samples are prepared from the prepared concrete mix — cubes 10 × 10 × 10 cm in size; after hardening the samples, hardened concrete is tested under normal conditions. The density of concrete is 1850 g / cm ³ , with a strength of 38 MPa.

Concrete prepared according to the closest analogue has the same strength, but at the same time its density is higher - 2200 g / cm ³ , i.e. the coefficient of constructive quality is lower.

The resulting concrete can be recommended for the manufacture of load-bearing structures of buildings and structures in industrial and civil engineering.

Claims (2)

1. A method of preparing a concrete mixture by mixing cement and 75% water from its total content to obtain a homogeneous mixture, adding crushed stone from crushed concrete scrap and sand to it with stirring for 3-4 minutes, adding the remaining water and final mixing in the following ratio components, wt.%:
cement 12-17 crushed concrete scrap 39-41 sand 35-39 water 8-9 2. The concrete mixture obtained by the method according to claim 1.