SU1252173A1 - Method of manufacturing concrete and reinforced concrete articles - Google Patents

Description

one

The invention relates to the production of thin-walled concrete and reinforced concrete products and can be used in the manufacture of products with increased demands on the density and strength of concrete, floor covering slabs, tiles, and paving slabs.

The chain of the invention is to increase the strength, density, durability and quality of the face of the products.

The method is carried out as follows.

Before preparing the dry concrete mix, the mixture is heated to 105-110 ° C, then mixed with other components of the dry mixture — aggregates, having a natural storage temperature (positive (10 ° C) or also heated). Up to this temperature can be heated and completely dry concrete mix.

The dry concrete mix is placed in an airtight shape in which the piston moves with a gasket sealing the cavity. The surface of the piston forms the front face of the product. The opposite part of the mold is perforated and through it vacuuming of the dry concrete mix and water supply are carried out. The loose concrete mix is evacuated for 0.5-5.0 minutes at a pressure of 0.0001-0.01 MPa. The vacuum time is determined by the vacuum depth and the amount of the dry concrete mix. The evacuation of a dry concrete mix at a pressure of 0.0001-0.01 MPa in combination with the heating of a concrete up to 105-110 ° C allows you to quickly remove it from the bottom 1 (the concrete mix is not only air found in the mixture pores, but also gases adsorbed on the surface in the carrier and aggregates. This removes the water molecules adsorbed on the surface in the carrier and aggregates. The adsorbed water is easily removed at 105-110 ° C.

At high temperatures, the process is intensified, but is associated with high energy costs. Further, in the process of vacuuming, the dry concrete mixture is compacted by vibrating or pressing, or vibrating HVTOM followed by pressing, or 52173J

bo vibrating with simultaneous pressing.

Next, in a dry concrete mix, flowing under static pressure equal to the compaction pressure, and

free from air, hot water is fed at 90. Saturation of the dry concrete mix with water can be done at atmospheric pressure,

10 and redundant. The water pressure is determined depending on the thickness of the impregnated product and the desired duration of impregnation.

Water used to saturate

 5 dry concrete mix, pre-boil at atmospheric pressure. This removes air from the water, dissolved in a liquid, and which could prevent it from seizing.

20 dry concrete mix with water.

The use of hot water and impregnant accelerates the saturation of the dry concrete mix due to the decrease in the viscosity of the water, and this eliminates

25 temperature deformations of freshly mixed concrete.

At the end of the water treatment, the product is removed from the mold and the dp is then further solidified into the container

30 with hot water. Intensive hardening of the concrete allows to obtain finished products after 2-6 hours of curing in hot water.

Example. Concrete samples of 10 x 10 x 10 cm are made of concrete with a consumption of cement 360, sand 810 and crushed stone 1200 kg per m of concrete. Cement activity is up. 49.0 MPa. Initial tech dry

0 concrete mix (cement, sand, crushed stone is 20 C, water 17 C.

Samples of the proposed method are made in the following sequence. Portland cement is heated 5 to 105 C, then mixed with rubble and sand. The dry concrete mix is placed in a mold with hermetic side edges. In the lower part of the mold there is a sprout, having a hermetic mat that slides over the side edges. The surface of the piston (matrix) is carefully ground. A chamber is placed on the 4th mold, the lower part of which, in contact with the dry blend, is perforated. Perforation is required for the removal of air from the dry concrete mix and the subsequent supply of water. The loose dry concrete mix in the hermetic volume of the mold is evacuated for 3 minutes. Then, with continued evacuation, the concrete mix for 30s is compacted by vibrating at standard parameters (frequency 50 Hz, amplitude 0.5 mm with simultaneous pressing at a pressure of 0.5 hOla, acting on the piston. Further, when the pressing pressure is maintained (fixing the water supplied to the chamber is supplied. The dry mixture is heated at atmospheric pressure with water. The water intended for saturating the dry concrete mix is boiled at atmospheric pressure for 10 minutes before using it. and the samples are removed from the forges and immediately placed in a container with hot water having a temperature of 80 ° C. The samples harden for A h in the container, then they are stored in normal-humidity conditions.

By a known method, the samples are made in the following sequence. The mixed dry blend is placed in a mold (the mold device is similar to that described above), then compacted (compaction mode is similar to that described above) while vacuuming at a pressure of 0.02 MPa. Then, while maintaining the pressing pressure of 0.5 MPa, saturated steam is fed into the mold at a pressure of 0.8 MPa for 15 minutes. Samples harden for 190 s, then they are stored in normal-humid conditions.

Production parameters and properties of concrete are given in the table. In variants 1-19, boiled water was used to fill the dry retone mixture; In versions 20-21, the water used to saturate the dry concrete mix was not subjected to preliminary boiling. In variants 18-19, loose dry concrete mix is not evacuated, but evacuated only during the compaction process and compacted for a total duration of 3 minutes.

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Claims (1)

METHOD FOR PRODUCING CONCRETE AND REINFORCED CONCRETE PRODUCTS, mainly thin-walled, including the preparation of a dry concrete mixture by mixing a binder with aggregate, laying it in a mold, compaction by vibration and vacuum followed by wetting in a compressed state and heat treatment, characterized in that it durability and quality of the face of the product, the binder is preheated to 105 - I10 ° C, before sealing, vacuum is additionally carried out at 0.0001-0.01 MPa in t 0.5-5 min, and moisturizing is carried out with boiled water with a temperature of 90-100 ° C from the side opposite to the front face of the product.