RU2228264C2 - Method for manufacture of cellular concrete articles - Google Patents

Abstract

FIELD: building materials, applicable for manufacture of cellular concrete articles and structures. SUBSTANCE: the method consists in delivery of the components of raw material without heating, their batching and agitation, delivery of the molding sand to a non-heated mould and simultaneous, without any cure, formation of a porous structure and heating at an atmospheric or gauge pressure. The mix is delivered to the mould and heated by electrodes at a voltage of 220 or 380 V up to swelling of the mix three and more times and filling of the mould with it during 5 to 15 min at an ambient temperature up to minus 10 deg C. EFFECT: reduced mean density of cellular concrete, simplified condition of production. 1 dwg, 2 tbl, 1 ex

Description

The invention relates to the field of building materials and can be used in the manufacture of cellular concrete products and structures.

The known manufacturing technology of cellular concrete products using certain methods of forming a porous structure (see Yu.P. Gorlov et al. Technology of heat-insulating materials. M: Stroyizdat, 1980 - 399 p.) - analogue.

The disadvantages of the known technology are the complexity and strict adherence to technological production modes, which is not feasible at the construction site.

The closest analogue is a method of manufacturing aerated concrete products, including feeding, dosing and mixing the raw components without heating, dispensing the molding mixture into an unheated form and without holding it, combining the formation of a porous structure and heat-moisture treatment at atmospheric or overpressure (RF patent No. 2153483, IPC ⁶ 7 C 04 B 38/00, 1998).

The disadvantage of this method is the inability to use it in adverse conditions of a construction site.

With traditional methods of manufacturing aerated concrete products, the process of expansion and gradual cooling of a pre-heated mixture occurs spontaneously. This process is uncontrollable and depends on the size of the array or structure, their open surface and ambient temperature, which negatively affects the swelling, its uniformity.

The objective of the invention is to develop a method that allows you to build structures of aerated concrete in adverse building conditions, in particular at low positive temperatures up to 0 ° C and negative, up to -10 ° C.

The problem is solved in that in a method for manufacturing aerated concrete products, including supplying raw materials without heating, dosing and mixing them, dispensing the moldable mixture into an unheated mold and without soaking, the formation of the porous structure and its heating at atmospheric pressure are combined according to the proposed solution, the molding sand is heated with the help of electric energy at a voltage of 220 or 380 V until it acquires the optimum temperature for expansion of 35 ... 50 ° C.

It is known that for the formation of the porous structure of an aerated concrete mixture it is necessary that it has a temperature of 35 ... 45 ° C, which must be maintained strictly constant during the expansion period, which cannot be ensured under construction conditions. During the erection of monolithic structures, especially in the autumn-spring and winter periods, the ambient temperature is usually low positive or negative and changing. Therefore, it is impossible in such an environment to create the conditions necessary for expanding the molding material. For this reason, the construction of structures from aerated concrete in the conditions of the construction site is not currently being carried out, since it is technically not feasible. In the proposed solution, this technical problem is solved by creating the required conditions for the expansion of a cold aerated concrete mixture at low positive or negative ambient temperatures. This is achieved by combining the formation of a porous structure and heating the mixture with any initial temperature to a temperature of 35 ... 50 ° C with electric current using electrodes at a voltage of 220 or 380 V, which is the technical novelty of the proposed solution.

This will allow the construction of monolithic aerated concrete structures in adverse conditions and thus expand the scope of its application in construction.

As experiments have shown, heating aerated concrete mixture with any initial temperature by electric current using electrodes at a voltage of 220 or 380 V not only ensures its expansion in adverse climatic conditions (low positive temperatures up to 0 ° C and negative temperatures up to -10 ° C), but also uniform mass heating consistent with the setting process throughout the volume, which eliminates its settling after expansion and provides a more uniform material structure with better performance. The method allows you to create any desired mode of heating the mixture, regardless of external conditions, to intensify the expansion of the mixture, increase its height by 3 or more times, which means that up to 70% of the structure is self-reconstructed due to the expansion of the mixture, which reduces the complexity and cost of products.

Thus, for the first time, a causal relationship was found between heating the molding sand at low positive temperatures up to 0 ° C and negative temperatures down to -10 ° C with electrodes at a voltage of 220 or 380 V and the formation of a homogeneous porous structure without settling after expansion, which makes it possible to produce aerated concrete products in adverse building conditions with high physical and mechanical characteristics. Known methods today to achieve such an effect is not possible. This confirms the conformity of the claimed technical solution to the criterion of "inventive step".

An example of a specific implementation.

In the experiments we used Portland cement M500 D0 of the Belgorod cement plant, lime with an activity of 70% of Belgorodstroymaterialy OJSC, local river sand with M _cr = 1.3, and aluminum powder PAP-2. The mixture was prepared in the traditional way. The mass was mixed in a laboratory mixer for two minutes, and then an aluminum suspension was added to it, with which the mixture was stirred for another minute, after which it was fed into molds of size 100 × 250 × 120.

The water-solid ratio of the mixture, the amount of aluminum powder and the ratio of the mass of sand to the mass of cement were varied. The compositions of the molding mixtures are presented in table. 1.

The strength of aerated concrete was determined in accordance with GOST 10180-90. The experiment was conducted in the open air at low positive temperatures up to 0 ° C and negative temperatures up to -10 ° C. The mixture was exposed to electricity with a voltage of 220 or 380 V. As a result of exposure to electricity, the molding mixture was heated and expanded, filling the form.

The drawing shows a heating circuit of the molding sand with two electrodes installed at the ends of the mold, where 1 is the mold; 2 - electrodes; 3 - molding sand.

A mold with a size of 250 × 120 mm was filled with a mixture to a height of 30 ... 45 mm, after which it was exposed to electric current without exposure until it reached a temperature of 35 ... 50 ° C.

The process of heating the mixture with a volume of up to 1.5 liters lasted from 5 to 15 minutes, depending on the initial temperature of the mixture, the environment and the voltage in the network.

The experimental data are presented in table. 2.

Conclusions:

As can be seen from the table. 2, the proposed method for the manufacture of cellular concrete products through the use of electrodes allows for uniform heating throughout the whole volume and expansion of the molding material at any low positive and negative temperatures up to -10 ° C, which cannot be achieved in a building site by known methods. In this case, up to 70% of the volume of the walls is self-erected only due to expansion by the proposed method of the molding mixture, which reduces their complexity and cost.

Claims (1)

A method of manufacturing aerated concrete products, including supplying raw materials without heating, dosing and mixing them, feeding the molding mixture into an unheated mold and without holding it, combining the formation of a porous structure and heating at atmospheric or overpressure, characterized in that the mixture is fed into the mold and is heated by electrodes under a voltage of 220 or 380 V until the mixture swells three or more times and forms are filled with it for 5-15 minutes at ambient temperature up to minus 10 ° С.