KR101411260B1 - High-efficient and uniformly-heating system for precast concrete using microwave, and preparation method of precast concrete using the same - Google Patents

Abstract

The present invention relates to a high-efficiency uniformly-heating system for manufacturing precast concrete using microwaves and method for manufacturing precast concrete using the same. More particularly, the present invention provides a heating system for manufacturing precast concrete that can reduce the initial hydration time of concrete poured into a form and thus can reduce time for manufacturing precast concrete greatly by heating the form using the heating system using microwaves in manufacturing precast concrete products such as bridge deck panels, girders, boxes, beams, culverts, retaining walls, piles, track slabs and concrete sleepers; and a method for manufacturing precast concrete using the same. The heating system for precast concrete using microwaves according to the present invention heats uniformly and rapidly using microwaves, can reduce costs for manufacturing factory products or cast-in-place precast concrete greatly by heating a form using microwaves in manufacturing precast concrete products, and can solve the problems of high energy and high costs in a steam curing method by an oil or gas boiler.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-efficiency uniform heating system for manufacturing precast concrete using microwave and a method of manufacturing precast concrete using the same,

The present invention relates to a high-efficiency uniform heating system for manufacturing precast concrete using microwave and a method of manufacturing precast concrete using the same. More particularly, the present invention relates to a method for manufacturing precast concrete using microwave, The present invention relates to a precast concrete manufacturing technology capable of remarkably reducing manufacturing costs in the manufacture of factory products or on-site pre-cast concrete by heating a form using a microwave heating system in manufacturing precast concrete products such as automobiles, sleepers, and the like.

A form refers to a temporary structure used during the process of manufacturing a concrete structure until the concrete is cured. Since it is a temporary structure, it is common to separate and reuse concrete after curing of concrete is completed. Concrete structures can be mass-produced at the factory or at the construction site, depending on their type and needs. Whether the mass production of the concrete or the production of the site is necessary, the formwork is necessary to accurately determine the shape and dimensions of the concrete structure.

Generally, a method of manufacturing a precast concrete product using an existing form is as follows: a form is installed in the form of a concrete product to be manufactured, a reinforcing assembly is embedded in the form, and then a concrete is laid and cured. (Fig. 1)

The energy cost is the most important factor in the construction period of the precast concrete. In order to minimize the energy cost, conventionally, the steam curing method is used, and the fuel used in the steam generator is a city gas, LPG, light oil, kerosene, Bunker C oil, or the like. FIG. 1 is a view schematically showing a conventional process of manufacturing a bridge girder by a steam curing method, and FIGS. 2 (a) to 2 (d) are views showing a conventional steam curing method. As shown in FIG. 1 and FIG. 2A to FIG. 2D, conventionally, after the shape of a concrete structure is formed using a form 10 (reinforcing bars 11 are reinforced if necessary) A method was used in which the entire concrete structure was covered with the pouch 12 and the curing time of the concrete structure 14 was shortened by raising the temperature (for example, 65 ° C or less) by generating steam using a boiler. This steam curing method has the effect of reducing the total curing time, but since the boiler must be operated in order to generate the steam, the consumption of oil, electricity, and gas used in the boiler is very large, There was a problem that efficiency was very low due to a large amount of leaking. The steam curing method may be used indoors or outdoors, that is, in a construction site, but the loss is larger when used in a construction site.

For example, Korean Unexamined Patent Application Publication No. 2004-0094208 discloses a method of forming a movable mold and providing a vibrating device to itself to easily and quickly install and dismantle a mold, The present invention provides a formwork device for making precast concrete beams that can be easily constructed. A concrete casting apparatus for manufacturing a precast concrete beam includes a base for performing a role of a work platform, a pair of form members disposed in a state of being opposed to each other on the base and each of a single member, And a movable member that moves the form member integrally along the base when the form members are installed and dismounted. The present invention also provides a molding apparatus for precast concrete beam fabrication.

Korean Patent Laid-Open Publication No. 2001-0111787 discloses a precast concrete column connecting a lower precast concrete column and an upper precast concrete column by using a form such as a precast concrete form or an iron form form without using a separate mechanical device And a method of constructing a column using the same.

Korean Patent Laid-Open Publication No. 2009-0086825 discloses a heating system for concrete curing that can shorten the concrete curing time in winter by attaching a heating cable composed of a constant-temperature electric wire to an outer surface of a mold, .

Korean Patent Registration No. 10-0625782 discloses a method of constructing a reinforced concrete pier structure by using a precast concrete segment manufactured as a segment of a predetermined height as a formwork, and a pier structure thereof.

Korean Patent Publication No. 2011-0052994 discloses a highly durable precast permanent formwork using a steel fiber reinforced cement composite. The steel fiber reinforced cement composite is composed of cement, reactive powder, sand, filler, thickener, water reducing agent and steel fiber, In order to ensure the integrity with the concrete, the permanent mold having the surface composed of the projecting ribs and the coarse aggregate is subjected to wet curing for 1 to 3 days, and then is cured at a temperature of 60 to 110 DEG C for 2 to 4 days A method of manufacturing by pre-casting through the step of curing is proposed.

Korean Patent Registration No. 10-0971003 also discloses a method for constructing a cast casting pact and a prefabricated precast pier using the same.

However, the related arts cited above have some similarities in terms of the construction of the precast pier structure, but they are less relevant to the purpose of improving the workability even when the outdoor air temperature is low, such as during the winter season, by efficiently heating the precast concrete.

In order to solve the problems of the prior art, the applicant of the present invention has proposed a new method which can shorten the production period of precast concrete due to concrete curing by raising the temperature of the mold by microwave without using a huge amount of electricity, oil, Technology. (Korean Patent Application No.10-2011-0130015, Patent Registration No. 10-1272148) Using the above patented technology, the heat efficiency and the concrete promoting curing effect are excellent, so that it is free from the use of a large amount of fuel such as oil or gas It is possible to drastically shorten the production period of the cast concrete. However, since the heat transfer efficiency is somewhat insufficient, uniform heat generation can not be performed as a whole.

The present invention has been developed in order to solve the problems found in the existing technology proposed by the applicant as described above. The first problem to be solved by the present invention is to provide a method of manufacturing a precast concrete, The concrete is cured by promoting the curing of the concrete by applying the exothermic system to the precast concrete without using fuel such as oil or gas. The precast concrete is produced, and the heat generation efficiency and the heat transfer efficiency are excellent, And to provide a new environmentally friendly high efficiency heating system capable of improving the quality of materials such as the compressive strength of concrete.

A second object of the present invention is to provide a method of manufacturing precast concrete which can accelerate and cure high quality precast concrete using the new environmentally friendly high efficiency heating system according to the present invention.

In order to achieve the first object of the present invention,

A heating system which is attached to an outer panel of a partition provided in a precast concrete manufacturing mold and generates microwave by power supply,

A microwave generator for generating microwaves;

A waveguide connected at one end to the microwave generator and having a pipe shape for receiving a microwave generated from the microwave generator and transmitting the received microwave to the reflector;

A reflector having a sealed inner space for diffusing the microwave transmitted from the waveguide and sharing the inner space with the waveguide;

A distribution plate provided on the opposite side with respect to the waveguide and the sealed inner space and having a distribution hole for passing a microwave that is irregularly reflected by the reflection portion; A heating element which is provided on the opposite side of the reflection part and is in close contact with the distribution plate and absorbs microwaves passing through the distribution hole to generate heat;

And a cavity cover which is connected to the upper ends of the side plates and forms a closed reflective part together with the side plates, A cavity for transferring heat generated from the heating element to the outside; And

A temperature controller for controlling a heat generation temperature of the heating element;

And,

Wherein the heating element is a ceramic composition comprising a rapid cooling steel making slag having a particle size of 5.0 mm or less and a sphericity of 0.5 or more and silicon carbide particles having a particle size of 5.0 mm or less at a ratio of 100: 0.1 to 100 by weight. Provides a heating system.

In order to achieve the second object of the present invention,

(a) attaching a heating system for manufacturing precast concrete using a microwave according to the present invention to an outer panel of a partition of the installed mold after a reinforcing bar for precast concrete is installed and a mold is installed;

(b) casting concrete into the installed mold;

(c) supplying power to the heating system for manufacturing precast concrete using the microwave of (a) to generate heat; And

(d) curing the poured concrete

The present invention also provides a method of manufacturing precast concrete.

The advantages of the high efficiency uniform heating system for manufacturing precast concrete using microwave and the method of manufacturing precast concrete using the microwave according to the present invention will be described as follows.

1. It does not require complicated electrical wiring work such as a separate heating line work because it uses a module type or an integral type heating system which is generated by microwave, attached to a partition panel of a precast concrete manufacturing mold. In addition, after the precast concrete structure is manufactured, the separation operation is completed only by separating the heat generation system from the partition, so there is no difficulty in separating the system, so the operation is simplified and the workability is excellent.

2. In addition, the heating system for manufacturing precast concrete using the microwave used in the present invention reaches a desired temperature for a short time even if electricity is supplied for only a few minutes to several tens of minutes, and the temperature is not easily cooled after that, Energy efficiency can be improved by significantly reducing power consumption compared to the conventional heating system.

3. The heating system for manufacturing precast concrete using the microwave used in the present invention can be easily changed in design according to the partition form of the formwork, so that it can be used in any kind of precast concrete production environment where the conventional formwork work such as indoor or outdoor production It can be used freely.

4. The heating system for precast concrete production using the microwave used in the present invention can be applied regardless of the external temperature, and therefore, it has a great effect when the outside air temperature is low, such as in the winter season and the winter season where concrete curing time is long.

5. In addition, since the conventional steam curing method requires equipment such as a boiler, a curing agent, and oil, it is necessary to carry out a complicated and difficult preliminary work such as moving and installing them together in the field production. However, The preheating system for precast concrete manufacturing using microwaves does not require complicated work because it only needs to carry the manufactured module and attach it directly to the partition panel of the formwork. In addition, in the steam curing method, there is no need to use a large amount of fuel and electricity such as oil or gas used for generating steam, so that energy consumption can be remarkably lowered, and an environmental problem caused by toxic gas generated by burning fuel also occurs There is an advantage not to be.

6. In addition, a heating element that generates heat by microwaves is used in combination with materials having excellent heat generation efficiency, that is, energy efficiency, and materials having energy transfer efficiency, that is, excellent energy release rate, at an optimum ratio. The heat uniformity is remarkably improved as compared with the conventional materials.

7. Also, since the internal structure of the heating system is designed so that the microwave can be efficiently distributed as a whole in order to prevent the microwave from being irradiated only locally, the uniform heating effect can be further increased in addition to the material design.

8. Therefore, it is possible to manufacture precast concrete of high quality because it is possible to obtain homogeneous concrete properties by solving the problems of cracking due to the occurrence of local overheating and problems of unevenness of physical properties such as compressive strength.

1 is a view showing a process of a conventional steam curing method.
FIGS. 2A to 2D are diagrams sequentially showing conventional steam curing methods.
3 is a plan view showing an example of a heating system for manufacturing precast concrete using a microwave according to an embodiment of the present invention.
4 is a side sectional view showing an example of a heat generating system for manufacturing precast concrete using a microwave according to an embodiment of the present invention.
5A to 5D are plan views showing some examples of distribution plates applied to a heating system for manufacturing precast concrete using a microwave according to an embodiment of the present invention.
FIG. 6 shows an external shape of a heating element used in a heating system for manufacturing precast concrete using a microwave according to an embodiment of the present invention.
7 is a graph showing internal energy and emission energy evaluation results of rapid cooling steel slag, silicon carbide, and mixtures thereof according to an embodiment of the present invention.
8A and 8B are views illustrating a process of curing concrete using a heating system for manufacturing precast concrete using a microwave according to an embodiment of the present invention.
9 is a flowchart illustrating a method of manufacturing precast concrete using a heating system for manufacturing precast concrete using a microwave according to an embodiment of the present invention.

In the present invention, the meaning of " ideal " means that the value is not less than the corresponding value, and generally has an upper limit that is reasonably understandable in the field to which the present technology belongs. Means that the invention has a lower limit of common sense and reasonably understandable in the field to which the present invention belongs, it should be understood as an expression for expressing the invention in a simple and clear manner.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention.

FIGS. 1 and 2A to 2D are views showing a process of manufacturing a precast concrete by a conventional steam curing method. In the conventional steam curing method, concrete (13) is laid in the formwork after the form (10) is installed, and then the concrete structure is covered with the curing cloth (12). Then, the steam generated in the boil- To increase the temperature. In such a steam curing method, steam is generated using a boiler, so that a great amount of fuel and electricity such as oil and gas are used, and a considerable amount of generated steam leaks into gaps between the curing plugs, resulting in a problem of inefficiency.

FIG. 3 is a plan view showing an example of a heat generating system for manufacturing precast concrete using a microwave according to an embodiment of the present invention, and FIG. 4 is a side sectional view thereof.

3 and 4, a heating system 20 for manufacturing precast concrete using a microwave according to the present invention is attached to an outer panel of a partition provided in a precast concrete manufacturing mold, and a microwave is generated A heat generating system for generating heat,

A microwave generator 21 for generating a microwave;

A waveguide 22 connected at one end to the microwave generator 21 and having a pipe shape for receiving microwave generated from the microwave generator and transmitting the received microwave to the reflector;

A reflector 24 having a sealed inner space 23 for diffusing the microwave transmitted from the waveguide and sharing the inner space with the waveguide;

A distribution plate (25) provided on the opposite side of the waveguide and the sealed inner space and having a distribution hole (26) for passing a microwave that is irregularly reflected by the reflection portion;

A heating element (27) provided on the opposite side of the reflection part to closely contact the distribution plate and absorbing microwaves passing through the distribution hole to generate heat; And

A bottom plate (28-1) provided outside the heating element in close contact with a heating element, a side plate (28-2) connected to both side ends integrally with the bottom plate, and an upper A cavity 28 composed of a cavity cover 28-3 forming a closed reflective part 24 and transmitting heat generated from the heating element to the outside,

And,

The heating element is a ceramic composition comprising a rapid cooling steel making slag having a particle size of 5.0 mm or less, a sphericity of 0.5 or more, and silicon carbide particles having a particle size of 5.0 mm or less at a weight ratio of 100: 0.1 to 100.

In the present invention, the microwave generator or other magnetron is connected to a power source by a high voltage transformer 29, and an air cooling type cooling device (for example, a cooling fan 30) for cooling the heat generated in the microwave generator, It is preferable that an apparatus is provided.

In addition, it is preferable that a protective cover 31 for protecting the internal devices such as the microwave generator, the high voltage transformer, and the cooling device is fixed to the cavity cover 28-3.

The cavity 28 is provided with a temperature sensor 32 for detecting the temperature of the cavity. The temperature sensor is connected to the temperature controller 33 to control operation of the microwave generator and the cooling device according to the temperature of the cavity. .

In addition, it is preferable that a case 34 for protecting internal devices is provided outside the microwave generator, the waveguide, and the cavity. The case 34 may be made of a plastic material to reduce weight and may be manufactured by injection molding or extrusion molding.

Further, it is preferable that the heat insulating material 35 is attached to the cavity cover 28-3 in order to prevent the heat generated inside from being diverted to the opposite side of the heating object. Glass wool, gypsum, heat-resistant plastic, heat-resistant ceramic, heat-resistant paper or stone powder can be used as the material of the heat-insulating material.

Wherein the heating element comprises a metal oxide including an iron oxide compound and is heated by a microwave of 300 MHz to 300 GHz. Specifically, the heating element uses a heating element composition that generates heat by using the microwave described above. Specifically, the heating element has a quenching steel slag having a particle size of 5.0 mm or less, a sphericity of 0.5 or more, and silicon carbide particles having a particle size of 5.0 mm or less, Or a cured product obtained by mixing cement in a weight ratio of 0.1 to 50 to 100 parts by weight of the ceramic composition and curing the mixture by hydration with an appropriate amount of water is used. In this case, when the ceramic composition is used as it is, it is preferable to adhere to the bottom plate using a heat-resistant bond. For example, the ceramic composition may be mixed with the heat-resistant bond and attached to the bottom plate.

The heating system for manufacturing precast concrete using the microwave can quickly heat the surface of precast concrete to be heated through the heating element only by generating microwaves by applying power to the micro generator.

The microwave generator, the waveguide, and the heating element are preferably modularized in the form of being mounted inside the cavity and installed in the heating object, but the present invention is not limited thereto and various design modifications are possible.

In particular, it is preferable that the waveguide has a tubular shape in which one end thereof is directly connected to the microwave generator and the other end is connected to a reflector having a closed space therein.

The microwave generator (magnetron) is connected to the high voltage transformer and the high voltage transformer is connected to the external power source. The high voltage transformer transforms a commercial AC voltage input from the outside into a high voltage (for example, about 2 kilovolts [kV]) suitable for generating a high frequency and applies it to the magnetron. The magnetron generates high frequency oscillation by a high voltage applied from a high voltage transformer Thereby generating microwaves.

It is preferable to use the 2,450 MHz band in order to utilize the advantage of the microwave frequency, such as Industrial, Scientific and Medical (ISM) frequency. However, it is not limited to this, Microwave having a frequency in the range of 300 GHz can be used in various ways.

A cooling device (e.g., a cooling fan) is installed around the magnetron to cool the high temperature generated by the magnetron when the magnetron is driven. A cooling device is connected to the fan motor. A voltage (commercial AC voltage) When the motor is applied to the motor, the fan motor is operated, and the fan of the cooling device is driven by the fan motor to blow the external cool air to the magnetron, thereby cooling the high temperature generated in the magnetron.

The microwave generator is fixed to the side surface of one end of the waveguide by a fixing bracket and is connected to the side surface of one end of the waveguide by a coupling tube protruding from the back surface of the microwave generator, Can be delivered to the department.

These microwave generators are consumables and must be replaced when they reach their end of life. In the heating system for precast concrete production using microwave according to the present invention, the microwave generator can be easily replaced as if replacing a bulb. Therefore, the heating system for manufacturing precast concrete using the microwave according to the present invention can be used semi-permanently only when the microwave generator is replaced periodically or when a fault occurs.

In the present invention, the heating element has heat resistance and has a heat resistant plate structure having a long length and a ceramic material (see FIG. 6). When a microwave is irradiated on a ceramic material plate having a high dielectric loss factor, Heat is generated by dipole rotation.

Meanwhile, as described above, since the microwave generator is installed on the side surface of one end of the waveguide to supply microwaves, a portion directly connected to the waveguide in the reflection portion receives a lot of microwaves and receives less influence of microwaves. In order to smoothly diffuse the microwave, a distribution plate is disposed in the middle of the distribution plate so that the microwave is substantially reflected in the distribution plate, so that a certain degree of microwave can be absorbed .

Some forms of distribution plates with distribution holes in the present invention are as shown in Figs. 5A to 5D.

As shown in FIGS. 5A to 5D, it is preferable that the distribution plate is symmetrically formed around the waveguide without forming a distribution hole in a portion immediately before the waveguide. However, they are not necessarily provided symmetrically but may be provided asymmetrically. In this case, the shape of the dispensing hole may be variously designed such as a circle, an ellipse, and a square.

Further, since the density of the microwave is decreased as the distance from the waveguide decreases, it is preferable that the size of the distribution hole increases as the distance from the waveguide increases, so that the heat is further generated farther from the waveguide, Do.

Also, in the present invention, since the waveguide can be biased not only at the center of the distribution plate, but also at one point away from the waveguide, it is preferable that the distribution hole is optimally designed so that absorption of the microwave is smooth.

In the present invention, the material used as the distribution plate is preferably a material that reflects without absorbing microwaves, and examples thereof include steel, aluminum, or copper.

Further, in the present invention, it is preferable that the distribution plate has a smooth plate shape or a plate shape which is uneven on the surface.

Hereinafter, the heating element 27 used in the heating system for manufacturing precast concrete using the microwave used in the present invention will be described in detail.

The heating element according to the present invention is preferably a ceramic composition comprising a rapid cooling steel making slag having a particle size of 5.0 mm or less, a sphericity of 0.5 or more, and silicon carbide particles having a particle size of 5.0 mm or less at a weight ratio of 100: 0.1 to 100. In the present invention, the particle size of the rapid-cooling steelmaking slag is more preferably 3.0 mm or less, and still more preferably 1.0 mm or less. In addition, in the present invention, the silicon carbide particles preferably have a particle size of 3.0 mm or less, more preferably 1.0 mm or less. The mixing weight ratio of the rapid-cooling steelmaking slag to the silicon carbide particles is preferably 100: 0.1 to 50, more preferably 100: 0.5 to 20. The heating element may be used as the ceramic composition itself. However, when the cured body 19 obtained by mixing cement with 100 parts by weight of the ceramic composition at a weight ratio of 0.1 to 50, and adding an appropriate amount of water and kneading the mixture by hydration, Is more preferably used. In this case, since the content of the ceramic composition is high and a small amount of cement is contained, it shows a dark gray or light black color from the outside. Fig. 6 shows the outer shape of the cured body. Such a cured body may be used as it is in the shape of Fig. 6, or may be used in a state in which the surface is flat. When the ceramic composition is used as it is, it is preferable to adhere to the bottom plate using a heat-resistant bond.

Conventionally, the slag discharged from a steel mill is treated by discharging the slag into a slag pot disposed in a lower portion of a converter or an electric furnace and then discharging the slag to a treatment plant. In the conventional treatment method, a large amount of water is sprayed on the discharged slag to cool the slag The iron content in the slag after solidification and subsequent crushing process is selected through a magnetic separator to be used as a steel source, and the remaining slag is mostly used as an aggregate such as landfill or road pavement because it has no special purpose. However, when the waste slag is simply buried in the landfill, the cost of the landfill is inconvenient and the burden of the landfill is considerably burdensome if the amount of the landfill is large. Therefore, there is an environmental problem, .

The steel slag cooled by the cooling (slow cooling) is called a slow cooling steel slag and contains a large amount of free limite (free CaO) ₂ ). Since the calcium hydroxide formed is bulky and prone to be differentiated from free lime, when used as a roadbed material, there is a problem that the road is flooded and the differentiated calcium hydroxide causes pollution of air and water quality. In addition, because calcium hydroxide is alkaline, it causes soil contamination and its use as road pavement aggregate is also very limited.

Rapid cooling steel slag was introduced to solve the problem of the slow cooling steel slag. Rapid cooling steel slag can be produced by a method of dropping a hot molten slag and spraying a high speed air stream to shake a hot molten slag to rapidly cool it by a high speed air stream and to make it into a fine powder form. When this method is used, slag in the form of fine powder is produced instead of bulk slag, so there is no need of separate crushing process and the effect of reducing the amount of free limes. However, since conventional quench steelmaking slag has focused on reducing the amount of free limes and using it as a construction aggregate, the development of new capacity has been sluggish.

The present invention has developed a new application of such a rapid steelmaking slag, and the rapid cooling steel slag absorbs microwaves and finds a property of generating heat, and uses this as a heat generating material.

The rapid-cooling steelmaking slag used in the present invention is not produced by using conventional quenching steelmaking slag which is conventionally used but is manufactured in a refined form by using a special sorting and refining method.

Hereinafter, such a selection / purification method will be described in more detail.

First, an example of a method of manufacturing the rapid cooling steelmaking slag according to the present invention is as follows. That is, the rapid cooling steelmaking slag having a particle diameter of 5.0 mm or less is selected through a sieving process in a first step, and a magnetic separator having a magnetic force of 500 gauss or more, preferably 700 to 5,000 gauss is used as a second step Only the particles having the microwave absorption efficiency required in the present invention are selected, and only spherical particles having a spherical modulus of 0.5 or more are selected through a spherical separator. At this time, the above-described seeding process, spherical sorting process, and magnetic force selecting process may be performed in sequence or simultaneously, all of which are included in the scope of the present invention. In the present invention, the rapid-cooling steelmaking slag obtained through such a special sorting and refining operation is simply referred to as " MIP (Microwave-irradiated pyrogen) ".

In the present invention, the particle size of the quench-hardened steelmaking slag is preferably 5.0 mm or less and the spherical ratio is required to be 0.5 or more. If the particle size exceeds 5.0 mm, if the particle size is excessively large, the total cross-sectional area is not large, and heat efficiency and heat transfer efficiency are deteriorated. The sphericity ratio is, in other words, the shape factor, which means the ratio of the smallest diameter to the longest side diameter of the particles. If the sphericity of the rapid cooling steel slag having a sphericity ratio of less than 0.5 results in a distorted shape, In this case, the spark may occur. Since the energy is concentrated only at the pointed portion or the angled portion and energy loss occurs, the efficiency of heat generation in the whole particle is lowered. Therefore, the sphericity should be selected to be 0.5 or more do. This rapid steelmaking slag has the characteristics of a semi-insulator between the conductor and the non-conductor, so that absorption heating and induction heating are performed, and the internal microwave is transferred according to the charging state. That is, when the microwave is applied to the continuous spherical rapid cooling steel making slag, the microwave is transferred along the rapid cooling steel slag due to the surface effect, and absorption heating and induction heating are performed in the adjacent rapid cooling steel slag as before.

The present inventors have proposed a technique of utilizing a rapid-cooling steelmaking slag composition as a heating element to be generated by microwave through the above-mentioned patent (Korean Patent Application No. 10-2011-0032313).

However, the rapid-cooling steelmaking slag composition described in the above patent has a very high energy generated by the specific heat and the microwave, but it is not so fast in terms of the transfer speed for transferring it to the periphery, i.e., the energy release rate, And it is found that there is a problem that it takes a lot of time and the local fever progresses. As a result of repeated research efforts to overcome these problems, it has been found that a combination of quenching steel slag and silicon carbide (SiC) can be solved. That is, in the case of silicon carbide, which has been known as a material capable of being heated by microwaves, the energy generated by the specific heat and microwave is lower than that of the rapid-cooling steel slag as shown in Table 1 below, The rate of transfer is much higher than that of rapid cooling steelmaking slag. Accordingly, the present inventors have found that when mixed with silicon carbide having a high energy transfer rate, problems of low energy transfer and uneven heat generation, which were problems in using the conventional quenching steel slag alone, can be solved.

Rapid cooling steelmaking slag (MIP) Silicon carbide (SiC) specific heat 0.1807 Cal / g 占 폚 0.1624 Cal / g 占 폚 Energy release rate 0.343 W / m · K 170 W / m · K

Table 2 shows the results of measurement of heat efficiency by microwave using silicon carbide, MIP and water. Using Equation 1, the thermal energy used to raise the temperature is expressed as the used power, and the energy efficiency is calculated based on the ratio of the used power according to the input power using Equation 2.

unit sign Silicon carbide (SiC) MIP water Mass (g) M 200 200 200 Specific heat (Cal / g · ° C) Cp 0.1624 0.1807 One Temperature difference (℃) ΔT 79.1 152.8 22.5 Time (seconds) t 60 60 60 Power (W) P 179.8 386.5 315 Incoming power (W) Pin 700 700 700 Energy efficiency η 0.26 0.55 0.45

(수식1)

(수식2)

(Equation 1)

(Equation 2)

As shown in the above Table 2, it can be seen that the efficiency of heat generated by the microwave for the same input power is more than twice that of the hydrocarbon. 0

The results of internal energy and emission energy of MIP, silicon carbide, and mixtures thereof obtained through the above experiment are shown in FIG. As shown in FIG. 7, the MIP heating element has a high energy generation rate but a low transfer rate. Conversely, the SiC generates a relatively small amount of energy but has a high speed of transferring the energy. Both effects can be achieved. (This experiment was conducted by Korea Polymer Research Institute, Korea). Specific heat analysis was performed using Perkin-Elmer DSC 4000 by KS M 3049 method. Thermal conductivity was measured by Mathis TC -30. In the case of the mixture of the present invention, MIP: SiC was mixed in a weight ratio of 100: 0.5.

As can be seen from the experimental results shown in FIG. 7, in the case of MIP alone, the internal energy is raised by microwave irradiation, but the emission energy is low. In the case of silicon carbide alone, the internal energy raised by microwave irradiation is not limited to MIP, Is very high.

Therefore, when the MIP and silicon carbide are mixed with each other using such a characteristic, the internal energy is relatively high and the energy release property is maintained high. Thus, the problem of using the existing MIP alone can be solved.

In the present invention, such MIP, that is, a rapid cooling steel making slag having a particle size of 5.0 mm or less and a sphericity of 0.5 or more is mixed with silicon carbide particles having a particle size of 5.0 mm or less at an optimum ratio. Since silicon carbide is about 30 to 50 times higher in price than MIP in terms of unit cost, it is not economically advantageous to use a large amount of silicon carbide. Therefore, silicon carbide should be used in an optimum ratio. In the present invention, By weight, and more preferably 100: 0.1 to 50 parts by weight. If the silicon carbide is used in an amount of less than 0.1 part by weight based on 100 parts by weight of MIP, the energy transfer efficiency is lowered. Therefore, it is difficult to solve the problem when the conventional MIP is used alone. If the silicon carbide is used excessively in excess of 100 parts by weight, It is undesirable because the price may fall and the unit price may rise too much and the economic effect may decrease.

In the present invention, the ceramic composition containing the rapid-cooling steelmaking slag (MIP) having a particle size of 5.0 mm or less and a sphericity of 0.5 or more and silicon carbide (SiC) particles having a particle size of 5.0 mm or less in an optimum ratio may be used as it is, Is used as a cured form by mixing cement and water. The reason for using such a cured form is that when the uncured particle (particle) form is used, the handling property is not good and there is a fear that the cement is caught in one side. In the case of cured cement, the latent heat is retained for a long time This is because there is also an effect. In the present invention, the cement mixed with the ceramic composition, for example, Portland cement, is preferably mixed with 100 parts by weight of the ceramic composition in a weight ratio of 0.1 to 50, and the mixture is hydrated by adding an appropriate amount of water, Whereby a cured product is obtained. In this case, the thickness of the cured product may vary depending on the application, and it is preferably 1 to 100 mm for general use.

In the present invention, the ceramic composition may further include a metal oxide, which is conventionally known to absorb microwaves. The content of the metal oxide is preferably in the range of 0.1 to 100 parts by weight, more preferably 0.5 to 50 parts by weight to be. The size of the ceramic composition is preferably 5.0 mm or less, more preferably 3.0 mm or less, and still more preferably 1.0 mm or less. Examples of such metal oxides are iron oxides, and specific examples thereof include Fe ₂ O ₃ , Fe ₃ O ₄ and FeO. Examples of other metal oxides include Al ₂ O ₃ , CaO, SiO ₂ , TiO ₂ , MgO, and the like.

In the present invention, a heating system is manufactured using a heating element that generates heat by the microwave, and the structure of the heating system is as described above.

8A and 8B are views illustrating a process of curing concrete using a heating system for manufacturing precast concrete using a microwave according to an embodiment of the present invention.

8A and 8B, a heating system 20 for manufacturing precast concrete using a microwave according to the present invention is inserted into each partition 15 of a mold for precast concrete production and attached to the outer panel 16 So that the work is very easy and the hydration and curing of the concrete (13) are promoted by the heat generated in the heat generation system without supplying the curing pot or steam separately. In some cases, such as in an outdoor environment, the curing cloth may be supplementarily used to block direct contact with the outside air.

The heating system for manufacturing precast concrete using a microwave according to the present invention has an advantage that it does not need to consume power excessively in order to maintain the set temperature because the temperature rises rapidly due to the characteristics of the heating body material and the temperature rises gradually once . In addition, the quality of the cured concrete such as strength and durability can satisfy the required quality and above, and uniform quality can be ensured due to uniform heat generation.

In addition, after the precast concrete is manufactured, the heating system 20 needs to be separated from the partition 15 of the formwork, so that complicated work for disassembly and disassembly is not necessary, and the heat generation system can be easily reused.

9 is a flowchart illustrating a method of manufacturing precast concrete using a heating system for manufacturing precast concrete using a microwave according to an embodiment of the present invention.

As shown in FIG. 9, the precast concrete manufacturing method according to the present invention

(a) a step (S100) of attaching a heating system for manufacturing precast concrete using the microwave according to the present invention to an outer panel of a partition of the installed formwork after the reinforcement for precast concrete is installed and a form is installed;

(b) pouring concrete into the installed mold (S200);

(c) a step (S300) of supplying power to the heating system for manufacturing precast concrete using the microwave in step (a) to generate heat; And

(d) curing the poured concrete (S400)

And a control unit.

In general, in the case of a form, a partition is installed outside the form to prevent the form from being transformed or deformed. In the present invention, a device (system) capable of generating heat is installed in the partition to rapidly form the precast concrete Is a feature of the invention. In the conventional method of manufacturing precast concrete, a mold is manufactured and installed, concrete is poured into the concrete, curing is cured for accelerated curing, and steam is blown from the outside. In the case of the conventional method, the boiler must be used to supply the hot steam. Therefore, the fuel cost is high, and in particular, in the case of the on-site precast concrete, there is a problem that time and cost are required to transport and install the boiler.

The present invention has been developed to solve the problems of the prior art,

In the method of manufacturing precast concrete according to the present invention, first, reinforcement for precast concrete is installed and a formwork for supporting the precast concrete is installed. Next, a heating system using the microwave according to the present invention is attached to a panel of each partition of the installed mold.

In order to accelerate curing by attaching a heating system using a microwave according to an embodiment of the present invention to a partition of a precast concrete mold according to an embodiment of the present invention, a heating system using a microwave according to the present invention It is possible to proceed with the production of the precast concrete.

Then, concrete is poured into the mold. Next, power is supplied to a heating system using microwaves according to the present invention attached to the formwork partition to heat the surface of the mold to forcibly induce initial hydration of the poured concrete. Since the hydration of concrete is difficult to proceed when the temperature is low as in winter, if hydration of the concrete is induced by forced heating, natural hydration will be promoted after that, so that curing of the concrete can be promoted.

The high efficiency uniform heating system for manufacturing precast concrete using microwave according to the present invention and the method of manufacturing precast concrete using the same are described above. The high-efficiency uniform heating system for the precast concrete production using the microwave according to the present invention can be used for the precast concrete requiring early curing of the concrete, Making it possible to manufacture effectively. In particular, since the heating system for precast concrete using microwave according to the present invention cures concrete by using the high heat generated from the ceramic material by the irradiation of microwave, compared to the conventional steam precast concrete precast concrete manufacturing method, It is possible to remarkably reduce the cost of production of precast concrete, and it is possible to apply not only to the factory production but also to the field production, thereby remarkably reducing the construction cost. Furthermore, the possibility of uneven heating, which was a problem in the technique disclosed by the present inventors in the past, and the possibility of cracking due to the uneven heating can also be solved by the present technology.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, something to do.

10: Precast concrete formworks
11: Reinforcement 12: Curing foil
13: Concrete poured 14: Cured concrete
15: partition 16: outer panel
19: MIP hardened body 20: heating system
21: Microwave generator 22: Waveguide
23: inner space 24:
25: Distribution board 26: Distribution board
27: heating element 28: cavity
28-1: bottom plate 28-2: side plate
28-3: Cavity cover 29: High voltage transformer
30: cooling fan 31: protective cover
32: temperature sensor 33: temperature controller
34: Case 35: Insulation
36: Capacitor 37: Capacitor holder

Claims (16)

A heating system which is attached to an outer panel of a partition provided in a precast concrete manufacturing mold and generates microwave by power supply,
A microwave generator for generating microwaves;
A waveguide connected at one end to the microwave generator and having a pipe shape for receiving a microwave generated from the microwave generator and transmitting the received microwave to the reflector;
A reflector having a sealed inner space for diffusing the microwave transmitted from the waveguide and sharing the inner space with the waveguide;
A distribution plate provided on the opposite side with respect to the waveguide and the sealed inner space and having a distribution hole for passing a microwave that is irregularly reflected by the reflection portion; A heating element which is provided on the opposite side of the reflection part and is in close contact with the distribution plate and absorbs microwaves passing through the distribution hole to generate heat;
And a cavity cover which is connected to the upper ends of the side plates and forms a closed reflective part together with the side plates, A cavity for transferring heat generated from the heating element to the outside; And
A temperature controller for controlling a heat generation temperature of the heating element;
And,
Wherein the heating element is a ceramic composition comprising a rapid cooling steel making slag having a particle size of 5.0 mm or less and a sphericity of 0.5 or more and silicon carbide particles having a particle size of 5.0 mm or less at a ratio of 100: 0.1 to 100 by weight. Heating system.
[2] The heating system according to claim 1, wherein the heating element is a cured body obtained by mixing 100 parts by weight of the ceramic composition with 0.1 to 50 parts by weight of the cement, and curing the mixture by hydration with water.
The heating system according to claim 1, wherein the heating element is attached to the bottom plate using a heat-resistant bond.
The heating system of claim 1, wherein the microwave generator is connected to a power source by a high voltage transformer.
[6] The heating system for manufacturing precast concrete using microwave according to claim 4, wherein a cooling device for cooling the heat generated in the microwave generator is provided around the microwave generator.
The heating system for manufacturing precast concrete using microwave according to claim 5, wherein a protective cover for protecting the microwave generator, the high voltage transformer, and the cooling device is fixed to the cavity cover.
The microwave generator according to claim 1, wherein the cavity is provided with a temperature sensor for detecting the temperature of the cavity, and the temperature sensor is connected to a temperature controller to control the temperature of the microwave generator according to the temperature of the cavity. Heating system for cast concrete production.
The heating system for manufacturing precast concrete using microwave according to claim 1, wherein a case for protecting internal devices is provided outside the microwave generator, the waveguide, and the cavity.
The heating system for manufacturing precast concrete using microwave according to claim 1, wherein a heat insulating material is attached to the cavity cover to prevent heat generated inside the cavity cover from dissipating to the opposite side of the concrete to be heated.
[3] The heating system for manufacturing precast concrete using microwave according to claim 1, wherein the distribution hole is not formed in a front portion of the wave guide, but is symmetrically or asymmetrically formed around the wave guide.
[3] The heating system for manufacturing precast concrete using microwave according to claim 1, wherein the distribution holes are arranged to be larger in size away from the wave guide.
[3] The heating system for manufacturing precast concrete using microwave according to claim 1, wherein the distribution holes are formed in a circular, elliptical or rectangular shape.
The heating system according to claim 1, wherein the distribution plate is a steel material, an aluminum material, or a copper material.
The heating system for manufacturing precast concrete according to claim 1, wherein the distribution plate is a plate-like or uneven plate-like shape.
The heating system according to claim 1, wherein the ceramic composition further comprises 0.1 to 100 parts by weight of a metal oxide.
(a) installing reinforcing bars for precast concrete and installing molds, and attaching a heating system for manufacturing precast concrete using a microwave according to claim 1 to a partition outer panel of the installed molds;
(b) casting concrete into the installed mold;
(c) supplying power to the heating system for manufacturing precast concrete using the microwave of (a) to generate heat; And
(d) curing the poured concrete
Wherein the pre-cast concrete is produced by the method.

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