RU2564705C1 - Method of treatment of concrete structures from ammonia - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: in method of treatment of concrete structures from ammonia the process of hydration in concrete structures is effected by its heating by microwave radiation, the following is pre-determined in concrete structures: percentage of salts, humidity outdoors, humidity indoors, air humidity and temperature, concrete structure thickness, then the microwave radiation of the respective intensity and duration is directed at the processed concrete structure, the process is monitored by the monitoring unit consisting of gas analyzers and pyrometers.

EFFECT: damping and complete elimination of ammonia release, maintenance of temperature at which the material to be dried is not damaged.

3 cl, 1 ex

Description

The invention relates to methods for processing concrete structures, improving its operational properties, in particular weakening negative reactions with the release of ammonia.

In recent years, one of the problems in Russia has been the pollution of the indoor air with ammonia released from concrete structures. Ammonia (NH ₃ ) is hydrogen nitride, a colorless gas with a pungent odor. When in an atmosphere contaminated with ammonia, people experience irritation of the mucous membranes of the eyes, nose and throat. In chronic intoxication with gaseous ammonia, headaches, metabolic disorders, lowering blood pressure, neurasthenia, chronic inflammatory diseases of the upper respiratory tract, inhibition of the immune system and blood formation are noted.

In the formation of concrete structures at the initial stage, concrete works as a reactor in which reactions of hydration of cement components, hydrolysis of urea and other ammonium-containing substances occur, with the formation of a number of compounds, including ammonia. Ammonia is emitted from the pores to the volume of the premises, which creates uncomfortable living conditions and a threat to human health.

A known method of reducing the emission of ammonia from concrete by lowering the porosity of building structures. A method of colmatization is proposed (research report No. State registration 01201065826 SPb GASU, 2011). The process of clogging consists of two stages: priming of concrete with Granite (a mixture of granite dust and liquid glass) and applying a polyurethane composition Elacor-PU. This treatment creates the effect of "conservation" of ammonia in the pores of concrete.

The disadvantage of this method is that gaseous substances (ammonia) have no exit from the pores and, accumulating in the pores of concrete, can cause unforeseen changes in the structure of concrete. In addition, the decomposition of salts continues, and the problem of eliminating the emission of ammonia is not solved.

        There is also a method of cleaning residential premises from ammonia, which consists in applying to concrete structures that emit ammonia, an oxidizing solution using a foam roller or other means of applying liquid materials in order to impregnate concrete with a solution. The oxidizing agent solution is a sodium hypochlorite solution with the addition of fulleroid type carbon clusters (fullerenes). Fullerenes are a solution modifier, because facilitate penetration deep into concrete, i.e. enhance the penetration properties of the solution (see RF patent No. 2496751 according to class IPC C04B 41/72, 2013).

The disadvantage of this method is the incomplete removal of ammonia from concrete structures, because The chemical decomposition of salts continues.

The closest in technical essence is the method of using a heat gun, in which they affect the hydration process in concrete by heating it. Concrete is dried, which leads to inhibition of the hydration process and, as a result, to a decrease in the release of ammonia.

The disadvantage of this method is that the drying process occurs only on the surface of the walls and the problem of drying the entire concrete layer is not solved, and therefore, the hydration process inside the concrete layer is not completely excluded, and, as a result, ammonia is not excluded later. In addition, the salts inside the concrete have been preserved, and upon repeated wetting, the emission process will resume.

The objective of the present invention was to develop a method for processing concrete structures, providing a slowdown and complete exclusion of these harmful reactions.

This problem is solved by the fact that a method for processing concrete structures from ammonia is proposed, which consists in influencing the hydration process in concrete structures by heating it, and the hydration process is affected by microwave radiation. Pre-determined in concrete structures: the percentage of salts, humidity outside, humidity inside, humidity and air temperature, the thickness of the concrete structure, then the appropriate strength and duration of the microwave radiation is sent to the concrete structure being processed, the process is controlled by a control unit consisting of gas analyzers and pyrometers.

And microwave radiation is affected by a device consisting of a power supply unit, a voltage stabilization and control unit, a magnetron and a waveguide, and a cooling unit.

In addition, the presence of finishes, the presence of other materials outside and inside the concrete, the nature of the premises bordering the machined surfaces are additionally determined.

The technical result of the invention is that in a solid alkaline medium there is a slow hydrolysis of urea salts and, therefore, their slow decomposition into NH ₃ and other simplest components (CO, CO ₂ , NO, etc.). Microwave radiation heats the polar molecules, and above all water, while it evaporates and, as a result, the hydrolysis process stops completely. Then the temperature rises to 130-150 ° C and the decomposition of the remaining urea salts under the influence of temperature into ammonia and biuret begins: NH ₂ CONH ₂ → NH ₂ -CO-NH-CO-NH ₂ + NH ₃ . Biuret subsequently decomposes into its simplest components. Since the temperature is higher than 130 ° C, the medium is solid, alkaline and there is no hydrolysis, further reactions with the formation of ammonia do not occur. As a result, the complete elimination of the cause of the smell of ammonia. In addition to stopping the hydration process, there is also a melting of ammonium salts and their complete decomposition in a dry environment.

An example of the method of processing concrete structures

To implement this method, a device is used consisting of a power supply unit, a voltage stabilization and control unit, a magnetron and a waveguide. Also, a separate unit is a cooling system in two versions: air or water, depending on operating conditions and component equipment. In addition, there is a separate environmental control unit, consisting of gas analyzers and pyrometers that collect information about ongoing processes. When processing concrete structures, the following factors are taken into account: the percentage of salts in the concrete, the humidity of the concrete outside, the humidity of the concrete inside, the humidity and air temperature, the thickness of the concrete, the presence of finishes, the presence of other materials outside and inside the concrete, the nature of the rooms bordering the surfaces to be treated. Depending on these factors, a certain number of corresponding blocks are used. For example, when processing a concrete wall with an area of 10 m ² , the processing time may be 30 minutes, and at the maximum concentration of salts in concrete, the processing time for the same area is 5-6 hours.

Example

One block of average power of 1 kW of output energy allows processing a concrete structure of 30 × 30 cm in size, 20 cm in depth, with a urea salt content of at least 10% of the mass of concrete in 12 hours.

The method has been tested and successfully carried out since 2012 in the city of Cherepovets, Vologda region. The results of studies by specialized organizations show, in particular, a decrease in the concentration of ammonia by tens and hundreds of times, to acceptable standards.

Using the proposed method for processing concrete structures eliminates the formation of ammonia in the room after processing through the use of microwave radiation. Microwave radiation acts immediately on the entire thickness of concrete, and not just on its surface, and allows for complete dehydration of the material. Microwave radiation also allows you to keep the required temperature at which there is no harm to materials: no damage to the material being drained, wiring, plastic elements, etc.

Claims (3)

1. The method of processing concrete structures from ammonia, namely, that they influence the hydration process in concrete structures by heating it, moreover, the hydration process is affected by microwave radiation, characterized in that it is previously determined in concrete structures: percentage of salts, humidity outside, humidity inside, humidity and air temperature, the thickness of the concrete structure, then the appropriate strength and duration of the microwave radiation is sent to the processed concrete structure, control the ongoing process with a control unit consisting of gas analyzers and pyrometers. 2. The method of processing concrete structures from ammonia according to claim 1, characterized in that they are affected by a microwave radiation device consisting of a power supply unit, a voltage and control stabilization unit, a magnetron and a waveguide, and a cooling unit. 3. The method of processing concrete structures from ammonia under item 1, characterized in that it further determines the presence of finishes, the presence of other materials outside and inside the concrete, the nature of the premises bordering the machined surfaces.