UA72703A - A method for making concrete and reinforced concrete articles - Google Patents

Abstract

A method for making concrete and reinforced concrete articles involving preparation of plastic concrete bulk by mixing cement, liquid, coarse and fine fillers, placing the mixture in the mold or shaping the first layer of plastic concrete, vibrocompaction of the mixture and form stripping the shaped article, preparing rigid or dry concrete mixture being delivered to the shape by second layer after vibrocompaction of plastic concrete mixture, thereafter the shaped layers of plastic or dry concrete are compacted.

Description

The invention relates to the construction industry and can be used in the production of concrete and reinforced concrete products, namely various structures and blocks, general and special purpose parts, panels, columns, crossbars, facing plates, including plates with subsequent grinding and polishing, road elements bridging, etc.

There is a known method of obtaining concrete products from a concrete mixture | Patent of the Russian Federation, VI 2103234 dated 27.01.98, IPC 6 сСо04 in 28/00, B 28 B 1/08, 11/00, 5/00, 15/00), which includes mixing the components of the concrete mixture, laying the mixture in forms, its vibro-compaction, exposure of the formed products in the forms with their subsequent dismantling, and vibro-compaction leads to the appearance of cement slurry on the surface of the mixture.

The disadvantages of this method are the high cost of the products obtained due to the rather large consumption of the most expensive concrete-forming component - cement, as well as limited indicators of the physical and mechanical characteristics of concrete products.

The method of production of concrete and reinforced concrete products is the closest in terms of features to the claimed method (Patent of Ukraine, Sha 59103 A dated 15.08.2003, IPC 7 C04840/00, 40/02, C04828/00,

В28С5/00, В298 11/00), which provides for mixing the components of the concrete mixture, its formation, vibration compaction, exposure of the formed product in the form followed by its formwork, and according to the method, vibration compaction of the concrete mixture is continued after the beginning of its delamination and is stopped at the stage of clear stratification of the mixture into light and heavy fractions, after which the light fraction, saturated with cement, is removed and reused for the preparation of concrete mixture, which makes it possible to achieve significant savings on the most expensive component of concrete - cement. At the same time, the upper light fraction mostly consists of cement and liquid aggregate (water, alkali), that is, a gel-like cement mass, and the lower heavy fraction, that is, the product itself, in addition to cement, contains heavier components, for example, crushed stone, gravel (coarse aggregate) and sand (fine aggregate), which leads to an increase in the density of the material and an increase in the physical and mechanical characteristics of concrete products obtained by this method.

But the disadvantage of the above-described method is the relatively low manufacturability inherent in it due to the presence of the necessary operations to remove the light fraction (gel-like cement mass) from the surface of the product and transport it to the concrete mixer for reuse and preparation of the concrete mixture, as well as due to the need to use a large number of molds for production concrete structures, as plastic concrete products used in the method need to be kept in such forms for a sufficiently long time.

The technical problem, the solution of which is aimed at the invention, is the creation of a more technological method of manufacturing concrete and reinforced concrete products with a reduced number of working elements and reduced time costs for the production of a unit of products.

The task is solved by the fact that the proposed method, which includes the preparation of a plastic concrete mixture by mixing at least cement, liquid, coarse and fine aggregates, placing the mixture in a mold or forming the first layer of plastic concrete, vibration compaction of the mixture and demoulding of the formed product, and vibration compaction continues after the start of stratification of the mixture and stop at the stage of its clear stratification into a light fraction, the basis of which is cement and liquid aggregate, and a heavy fraction, the basis of which is formed by coarse and fine aggregates with cement and liquid aggregate, according to the invention, additionally includes the preparation of hard (or dry ) of the concrete mixture, which is fed into the form with the second layer after the termination of the vibration compaction of the plastic concrete mixture, after which the formed layers of plastic and rigid concrete are compacted.

That is, the formation of the product takes place in two stages: 1) the laying of the first layer of plastic concrete mixture in the form, followed by its stratification into light and heavy fractions, and 2) the laying of the second layer of hard (or dry) concrete mixture, followed by the compaction of two layers of plastic and hard concrete.

The product is compacted by vibropressing under vacuum or by any other method. In order to remove air pores, the first layer of plastic concrete is also vacuumed before its vibration compaction.

Stratification during vibration of a plastic concrete mixture occurs, as in the closest analogue, due to the difference in the masses of the concrete-forming components. At the same time, the upper light fraction mostly consists of cement and liquid aggregate (water, alkali), that is, a gel-like cement mass, and the lower heavy fraction, in addition to cement, contains heavier components, for example, crushed stone, gravel (coarse aggregate) and sand (fine aggregate) .

And after feeding the hard (or dry) concrete mixture into the mold, during vibropressing, that is, compaction, it is saturated with a gel-like cement mass, which is on the surface of the layer of plastic concrete laid in the first stage. The content of cement in a mixture of rigid concrete is reduced by its corresponding amount, which penetrates during vibro-pressing from plastic concrete.

The above makes it possible to obtain a product made of hard concrete with reduced cement consumption and improved physical and mechanical characteristics, which does not require further aging in the form and to exclude operations for removal, transportation and reuse of excess cement (gel-like cement mass).

Since in general, and including in the method adopted as the closest analogue, laying of concrete is carried out layer by layer in order to remove excess air, in the proposed method, laying is also carried out in two layers, but at the same time operations on removal, transportation are excluded and reuse of excess cement due to its use during one technological cycle by penetrating the hard concrete layer during vibro-pressing. This leads to a significant reduction in the time for the manufacture of concrete products, as well as the elimination of inconveniences associated with the need for urgent removal and use of excess cement before it hardens.

At the same time, one stationary form is used instead of a large number of forms for long-term aging of products made of plastic concrete, which makes it possible to reduce the error of product dimensions and significantly reduce the working area required for placing forms for aging concrete structures, as well as eliminate the necessary labor costs for assembly, lubrication and cleaning forms This allows you to reduce the cost of products obtained by the presented method.

Thus, the technical result consists in achieving savings in time costs for manufacturing a unit of products and in reducing the number of working elements, while maintaining high indicators of physical and mechanical characteristics of concrete and reinforced concrete products, such as strength, wear resistance, heat and frost resistance, waterproofness, etc., according to due to obtaining denser material in relation to classic technologies.

In fig. 1 presents a technological scheme for the production of concrete and reinforced concrete products.

An example of the method.

According to this method, the components of the plastic concrete mixture, such as cement, crushed stone, sand, water, thinner, retarder, superplasticizer, from the appropriate tanks (containers 1, 2, 3, 4, 5, 6) (Fig. 1) are fed into the concrete mixer forced action 7, where their mechanical mixing takes place. 1 - cement capacity; 2 - crushed stone capacity;

C - sand capacity; 4 - water capacity; - thinner capacity; b - clutch retarder capacity.

The mixture from the concrete mixer is fed into the stationary form for the production of concrete or reinforced concrete products 8, which is located on the pallet 9, that is, the first layer of the plastic concrete mixture is formed. Next, the mixture is vibrated, for which vibrators 10 are used. At the same time, the plastic concrete mixture is vibrated until its complete delamination or the termination of delamination into light and heavy fractions, that is, the vibration time of the concrete mixture is chosen longer than the vibration time adopted in known processes of manufacturing concrete products. where delamination is unacceptable. Thus, a mixture of two fractions is obtained: the upper light fraction 12 and the lower heavy fraction 11. The upper fraction mostly consists of cement and water, and the base of the lower, denser fraction is formed by heavy components - crushed stone and sand.

After vacuuming and stratification of the first layer of plastic concrete mixture into fractions, the second layer of hard (or dry) concrete mixture 13 is fed into the mold from the appropriate concrete mixer.

Then, vibropressing of the two stacked layers is carried out under vacuum, using a vibropress 14 and a vacuum device 15. At the same time, as shown in Fig. 1, the penetration of the second layer of rigid concrete mixture into the first and the saturation of the second layer with a gel-like cement mass, that is, excess cement from the surface, occurs first layer

In this way, a solid concrete product is obtained.

Concrete products enter the steaming chamber 16, after which the formwork of the finished products is carried out.

All types of cements can be used to prepare the above-mentioned concrete mixtures: Portland cement, Portland slag cement, alumina cement, gypsum-alumina cement, magnesium, slag-alkaline cement, and others. Crushed stone is taken in fractions of 5-10 mm, 10-20 mm, 20-40 mm and 40-70 mm, while sand is used with a coarseness modulus of up to 2.7.

Comparative table 1 shows the quantitative composition and physico-mechanical characteristics of concrete products obtained by classical technology (without layering of the concrete mixture), by the method accepted as the closest analogue and by means of the claimed method.

Table 1

Name Manufacturing method - plastic. iy B, material of products cement crushed stone sand (kg) | water (l) | Rare | density | strength (kg) (kg) (ko) (kg/m (kg/cm?) TECHNOLOGY according to the method of sewing ASSISTANCE WITH ZY

O. K. 12-15 - I am the closest analogue of the claim

It can be seen from the table that when using the proposed method, improved indicators of the physical and mechanical characteristics of concrete products are preserved in relation to such indicators of products obtained by the method that is accepted as the closest analogue, and also the consumption of cement remains reduced to 5095. At the same time, the method is more technological and allows to reduce the cost of production.

To implement the described method, the necessary standard equipment is used, that is, the method does not require specific devices and equipment and can be implemented at any profiled enterprise.

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Claims (3)

1. The method of manufacturing concrete and reinforced concrete products, which includes the preparation of a plastic concrete mixture by mixing at least liquid cement, coarse and fine aggregates, laying the mixture in a mold or forming the first layer of plastic concrete, vibration compaction of the mixture and formwork of the formed product, and vibration compaction is continued after the start stratification of the mixture and is stopped at the stage of its clear stratification into a light fraction, the basis of which is cement and liquid aggregate, and a heavy fraction, the basis of which is formed by coarse and fine aggregates with cement and liquid aggregate, which is distinguished by the fact that it additionally includes the preparation of a hard or dry concrete mixture , which is fed into the mold as a second layer after vibration compaction of the plastic concrete mixture, then the formed layers of plastic and hard or dry concrete are compacted. 2. The method according to claim 1, which differs in that the first layer of plastic concrete is subjected to vacuum before its vibration compaction. 3. The method according to claim 1 or 2, which differs in that the layers are sealed by vibropressing under vacuum.