RU2104987C1 - Method of preparing concrete mix - Google Patents

Abstract

FIELD: building materials industry, more particularly manufacture of prefabricated concrete components and structures. SUBSTANCE: the claimed method comprises stirring concrete, molding mixture waste and metallurgical slag for 55 minutes at mechanical effect of 120 W/kg at wt ratio of components of (50-70):(20-35) (10-15) and subsequently mixing with filler and water. As compared with prior art method, the claimed method increases compression strength by 30-50% and make higher, the binder usage coefficient. EFFECT: more efficient preparation method. 2 tbl

Description

 The invention relates to the technology of construction production, and in particular to the technology of manufacturing concrete mixtures on fine and coarse aggregate, can be used to obtain monolithic and prefabricated products from concrete and reinforced concrete.

 A known method of preparing a concrete mixture by repeated grinding or by mixing pre-milled Portland cement and various additives (sand, blast furnace slag, limestone, granite) in ball mills with a ratio of components (70... 30)% - (25 ... 75)% in for one to two hours, followed by mixing with aggregates and water [1]. It was established that the highest physicomechanical characteristics of heavy concrete were obtained with additives in the form of sand and blast furnace slag [1, p. 38].

 There is also a method of preparing a concrete mixture by mixing cement with a silica-containing component and subsequent mixing with aggregate and water [2].

The disadvantages of the known methods of preparing a concrete mixture include:
significant time for processing cement with additives 1 ... 2 hours [1, p. 18];
increased rigidity of concrete mixtures (30 sec or more) and the complexity of the technology as a result of the use of weights;
increased consumption of the clinker part of the binder and low strength characteristics;
use of high grade cements (M500);
the need to use building quartz sand;
lack of an integrated approach to the processing of secondary material resources.

 The aim of the invention is to reduce the consumption of cement, increase the strength of concrete, increase the utilization of binder.

 This goal is achieved by the fact that before preparing the concrete mix, preliminary mixing of cement, a siliceous component is carried out, followed by mixing with aggregates, as well as water.

 As additives, wastes of molding sand (OFS) were used - black fine-grained substance and metallurgical slag - cupola, blast furnace, ferrochrome, the chemical composition of which is given in table. one.

 The simultaneous introduction of metallurgical slag, which is mainly calcium silicates, contributes to the formation of an optimal pH-environment of interaction and an increase in the amount of active binder.

 The increase in the strength characteristics of concrete with a decrease in the share of the clinker part of the binder is also due to the effect of "alloying", i.e. the influence of small amounts of rare oxides contained in the OFS and slag on the type of low-basic calcium hydrosilicates formed, providing high physical and mechanical properties of concrete.

The modified OFS quartz grains coated with a thin film of organosilicon compounds and crushed slag, due to their vitrified surface, exhibit plasticizing properties in the concrete mixture, while reducing the amount of mixing water introduced. Thus, the combined use of OFS and slag according to the proposed technology reduces the water demand of the binder with an equal specific surface area S _beats = 4700 ... 4800 cm ² / g [1, p. 25] and provides an additional increase in strength.

 Joint processing of cement, OFS and slag of metallurgical production can be carried out in any grinding device - a ball mill, a rod mixer, a vibration mill, a jet mill, an evaporator, etc.

 The concrete mixture is prepared in the following sequence: first, a joint grinding of Portland cement, OFS and slag is carried out, after which the resulting binder is mixed with small and large aggregate, as well as water.

 In the table. 2 shows examples of the preparation of concrete mixtures at various ratios of cement, OFS and slag and strength characteristics of concrete obtained by the proposed technology. Concrete hardening was carried out in natural air-humidity conditions.

 The method of preparing the concrete mixture according to the invention allows to obtain heavy concrete with increased strength (classes B25-B35) using ordinary grade cements, reduce cement consumption in the binder, and involves the integrated utilization of metallurgical waste. This method can be implemented at metallurgical enterprises, cement plants, or in the form of independent production.

 An example embodiment of the invention.

Materials:
Portland cement of the Pikalevo plant with an activity of 41.2 MPa;
OSF, slags - waste from foundries of the metal and Izhora plant in St. Petersburg;
granite washed gravel fractions of 5 ... 10 mm;
silica sand with M _cr = 2.3;
drinking water tap.

Claims (1)

 A method of preparing a concrete mixture, including pre-mixing cement with a silica-containing component and subsequent mixing of the obtained binder with aggregates and water, characterized in that the cement, the spent molding mixture, the waste from the foundry and the slag of metallurgical production are subjected to preliminary mixing at a ratio of components, respectively, wt. (50 70) (20 35) (10 - 15), while stirring is carried out for 55 min at a mechanical power of 120 W / kg.

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