JPH08120926A - Method for placing concrete in cold time - Google Patents

Abstract

PURPOSE: To evenly heat the concrete to the appropriate temperature in a short time at a concrete placing field in cold time. CONSTITUTION: The concrete C at a low temperature, which flows inside of a concrete pipeline 5, is led into a heating tube 6 by the drive of a pump 2b, and this concrete C is irradiated with the microwave through a waveguide 7 connected to the heating tube 6. The microwave passes through the concrete C, and simultaneously, the microwave performs dielectric heating with the dielectric loss of the moisture included in the concrete C, and the concrete C is evenly heated in a short time, and discharged to the placing position A in this heating condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for constructing concrete in cold weather, which is used for placing concrete while heating it.

[0002]

2. Description of the Related Art It is necessary to secure the mixing temperature of concrete at 5 ° C. or higher as one of the measures for preventing the development of initial strength and the occurrence of initial frost damage during construction of cold concrete. Is said to be.

For this reason, conventionally, for example, the mixing material is heated in a concrete manufacturing plant, the mixing temperature of the concrete is set to about 20 ° C., and the concrete at this temperature is transferred to a mixer car (agitator truck) and mixed and mixed while being mixed. It is transported to the construction site.

[0004]

However, even in such a case, the outside air temperature may be extremely low, and if it takes a long time to transfer to the site, the temperature may drop below 5 ° C. It was difficult to control, and once the temperature became 5 ° C. or less, it was difficult to reheat because it was a material having a large heat capacity.

Therefore, the present invention is to solve the above problems, and to provide a method for constructing cold-concrete in a cold-concrete pouring site so that the concrete can be heated to an appropriate temperature in a short time. To aim.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, and it is desirable to irradiate a concrete at low temperature with microwaves at the place of placing the concrete in the cold to obtain the desired concrete. The construction method of the cold concrete is characterized in that the material is heated to the temperature of 1) and then placed at the placing position.

Further, according to the present invention, a waveguide is connected to the concrete transportation pipe according to the concrete pouring method or the transportation method, and the microwave is irradiated into the concrete through the waveguide (claim 2). It is also possible to connect a waveguide to the bucket portion of the concrete pump and irradiate microwave into the concrete through the waveguide (Claim 3), or connect the waveguide to the concrete hopper. However, it is also possible to irradiate microwave into the concrete through the waveguide (claim 3).

[0008]

In this construction method, when the concrete is irradiated with microwaves, the microwaves cause the water contained in the concrete to generate heat due to dielectric loss, and raise the temperature of the concrete in a short time.

According to the second aspect of the present invention, it is suitable for continuously pouring concrete using a concrete transport pipe, and the concrete is continuously heated when passing through the microwave irradiation site.

In the third aspect of the present invention, the heating is performed immediately before being transported by the concrete pump.

In the case of claim 4, the present invention is applied in the case of placing concrete directly from the hopper, and a predetermined amount of concrete is simultaneously heated.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is an explanatory view showing a first embodiment in which the method for constructing cold-concrete concrete according to the present invention is applied to a method for continuously placing concrete through concrete piping. Is a concrete mixer truck 1, a pump truck 2, and a heating truck 4 equipped with a microwave generator 3, and the concrete C delivered from the mixer truck 1 to a concrete bucket 2a mounted on the pump truck 2 is a concrete pump 2b. Is continuously transported through the concrete pipe 5 connected thereto and is placed at the placing position A.

Although the microwave generator 3 is not shown,
A microwave source such as a magnetron and a control unit for the microwave source are built-in. As shown in an enlarged view of a part of the drawing, a heating pipe 6 flanged in the middle of the concrete pipe 5
To the waveguide via the waveguide 7. The end of the waveguide 7 on the outlet side is closed by a lid 8 made of a microwave transmitting material such as ceramics to prevent the concrete C from flowing into the waveguide 7. The control unit of the microwave generator 3 inputs signals from an inlet temperature detection unit and an outlet temperature detection unit (not shown) provided in the heating pipe 6,
The drive control is performed to adjust the microwave intensity of the microwave source so that the outlet temperature is always at least 5 ° C. or higher in accordance with the heat drop regardless of the variation of the inlet temperature.

In the above structure, the low temperature concrete C flowing in the concrete pipe 5 by the drive of the pump 2b is introduced into the heating pipe 6, and the microwave is radiated through the waveguide 7. The microwave transmits the concrete C, and at the same time, the moisture contained in the concrete C is dielectrically heated by the dielectric loss, so that the concrete C is uniformly heated in a short time, whereby the outlet side temperature is at least 5 ° C.
The temperature is raised as described above, and the material is discharged to the pouring position A in this heated state.

Since the heating pipe 6 and the concrete pipe 5 are made of an electromagnetic shielding material such as a steel pipe, problems such as microwave leakage can be avoided.

FIG. 2 shows a second embodiment of the construction method according to the present invention. The same parts as those in the first embodiment will be designated by the same reference numerals, and different parts will be described by using different reference numerals.

In the figure, the pump car 2 receives the concrete C discharged from the discharge chute 1a of the mixer car 1 as described above, and temporarily stores the concrete C therein.
In this embodiment, the upper portion of the bucket 2a is closed by the steel lid 11, and the waveguide 7 is connected to the top of the center of the lid 11 so that the microwave radiating portion is directed downward. It has a structure. Also, the discharge chute 1a
At the protruding end of the bucket 2a of the
2 are arranged.

Therefore, by irradiating the inside of the bucket 2a with the microwave generated by the microwave generator (not shown) through the waveguide 7, the concrete C stored inside is heated.

When it is detected that the temperature has risen to a desired temperature through a temperature detector (not shown), microwave irradiation is stopped, and at this point the pump is driven to transport the heated concrete C to the pouring site. Then, the work of supplying new concrete C through the discharge chute 1a is repeated.

Therefore, according to this embodiment, batch processing can be performed by heating the temporarily stored concrete C, and the temperature control becomes easier. Since this method can also carry out continuous transportation and heating, it can be controlled to obtain the best placing temperature according to the ambient temperature and the like.

In this method also, the bucket unit 10
Since the inside is closed by the lid 11 and electromagnetically shielded, microwave leakage can be easily avoided.

FIG. 3 is an explanatory view showing a third embodiment when the method of the present invention is applied to a hopper for pouring concrete.

The upper opening of the concrete hopper 20 in the figure is openably and closably closed by a steel lid 21 via a hinge or the like, and concrete stored inside through a waveguide 7 connected to the top of the lid 21. C is irradiated with microwaves to heat it.

Batch processing is also possible in this embodiment,
The heat treatment can be easily performed in a large amount at one time.
Also, in this embodiment, microwave leakage can be easily avoided.

[0026]

INDUSTRIAL APPLICABILITY As described in detail in the above examples, in the method for constructing cold concrete according to the present invention, the concrete is heated to a desired temperature by irradiating it with microwaves. Since it is to be placed at the pouring site, the concrete supplied to the pouring site can be heated to a desired temperature uniformly and in a short time.
It is suitable for preventing initial frost damage.

In the method according to the second aspect, the concrete transported by the transport pipe is continuously heated when passing through the microwave irradiation location, which is suitable for continuous pouring.

In the method of claim 3, the concrete is heated immediately before being transported by a concrete pump, and in the method of claim 4, the method is applied when the concrete is directly poured from the hopper, and a predetermined amount of concrete is applied. Since they are heated at the same time, they are suitable for the case where the heat treatment is performed in a batch system and then the casting is performed.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a first embodiment in which the method of the present invention is applied to a continuous pouring method using a concrete transport pipe.

FIG. 2 is an explanatory view showing a second embodiment of the method of the present invention.

FIG. 3 is an explanatory view showing a third embodiment when the method of the present invention is applied to a hopper for pouring concrete.

[Explanation of symbols]

 2 Pump car 3 Microwave generator 5 Concrete transport pipe 6 Heating pipe 7 Waveguide 10 Bucket part 20 Hopper C Concrete A Placement position

Claims (4)

[Claims] 1. At a pouring site of concrete in the cold,
A method for constructing cold-weather concrete, which comprises irradiating low-temperature concrete with microwaves to heat the concrete to a desired temperature and then placing it at a placing position. 2. The method for constructing cold concrete according to claim 1, wherein a waveguide is connected to the concrete transportation pipe, and microwaves are applied to the concrete through the waveguide. 3. The method for constructing cold concrete according to claim 1, wherein a waveguide is connected to a bucket portion of the concrete pump, and microwaves are radiated into the concrete through the waveguide. 4. The method for constructing cold concrete according to claim 1, wherein a waveguide is connected to the concrete hopper, and microwaves are radiated into the concrete through the waveguide.