JP2696752B2 - Ready-mixed concrete production equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ready-mixed concrete manufacturing apparatus, and more particularly to a ready-mixed concrete manufacturing apparatus suitable for use in mass concrete members and the like. 2. Description of the Related Art When constructing so-called mass concrete members used for dams, bridge piers, nuclear reactor facilities, etc., cracks occur in the mass concrete members due to temperature stress caused by heat of hydration of cement. Because it is easy
Preventing this is an important issue in quality control of concrete. As a method of preventing the cracking of the mass concrete member, a pre-cooling method is used in which the temperature at which the concrete is kneaded is lowered to suppress the amount of change in the concrete temperature and the temperature difference in the member caused by the heat of hydration of the cement. A construction method called a construction method is known. [0003] The pre-cooling method uses cold water, cold air,
Alternatively, the respective constituent materials of the concrete such as aggregates are cooled in advance using ice or the like before mixing, and the cooled materials are mixed to lower the temperature at which the concrete is kneaded, and the concrete thus obtained is pressed. This is a construction method that reduces cracks due to thermal stress. As an example of a means for realizing this pre-cooling method, a pipe is inserted into an aggregate bottle for temporarily storing aggregate, and a liquefied gas such as liquefied nitrogen or cold air is injected from the pipe toward the aggregate. Means such as cooling the aggregates, or the aggregate bottle is made to have a closed structure, the surface water of the aggregates is evaporated by reducing the pressure in the aggregate bottles, and the aggregates are cooled by the latent heat. Means have been proposed. [0004] However, the means for realizing the above-mentioned conventional pre-cooling method has the following problems. (1) In a means for cooling the aggregate by inserting a pipe into the aggregate bottle and injecting a liquefied gas or cold air from the pipe toward the aggregate, the liquefied gas or the cool air is cooled by the aggregate. It is difficult to spray and diffuse to every corner of the bottle. Therefore, since this liquefied gas or cold air is difficult to uniformly diffuse into the gaps between the aggregates, the cooling efficiency of the aggregates is poor, and a large amount of liquefied gas or cold air is required to cool down to a predetermined low temperature, Since the time required for cooling becomes longer, the cost increases. (2) When the aggregate is cooled to zero or less, the surface water of the aggregate is frozen and an ice layer is formed on the surface of the aggregate. When cooled in a state of being stored in a bottle, the ice layers on the surface of the aggregate fuse with each other, whereby the aggregates are fixed as if they were frozen soil. Therefore, if the aggregates stick together to form a lump, the lump is caught and cannot be taken out of the aggregate bottle, and even if it can be taken out, the lump gets in the way and cannot be put into the hopper opening. There was a problem. Also, when kneading aggregate mass and other materials such as cement, the aggregate mass may be kneaded without being sufficiently separated. In such a case, a homogeneous and high-quality raw material may be obtained. There was a problem that concrete could not be manufactured. [0005] The present invention has been made in view of the above problems, and has as its object to provide a ready-mixed concrete production apparatus for producing a high-productivity, homogeneous and high-quality ready-mixed concrete. SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides an aggregate mixer for stirring aggregates, and an aggregate provided in the aggregate mixer. A cooling device that cools the aggregate by spraying a low-temperature liquid or gas on the aggregate, a concrete mixer that kneads the cooled aggregate and other concrete constituent materials, and a gas or cold air that evaporates from inside the aggregate mixer. And an exhaust duct for blowing to a sand / gravel stocker or a concrete mixer, and inside the aggregate mixer and inside the pile of aggregate, a spray nozzle for liquid or gas sent from a cooling device is provided. It is characterized by being provided. In the present invention, by employing the above configuration, the aggregate is cooled while being stirred, so that the aggregate can be kept separated. Therefore, the aggregate can be easily taken out from the aggregate mixer, and after it is taken out, the lump smoothly falls into the mixer without being caught by the hopper opening, which causes trouble in the operation of the concrete plant during the production of ready-mixed concrete. It is less likely to occur, which leads to better work efficiency and consequently higher productivity. Further, since the cooled aggregates dropped into the mixer are separated, the aggregates are uniformly distributed at the time of kneading with the cement or the like, so that a homogeneous and high-quality ready-mixed concrete can be manufactured. Further, since the refrigerant is directly blown into the aggregate layer of the aggregate, the cooling efficiency is excellent. Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a diagram showing a ready-mixed concrete production device. In FIG. 2, reference numeral 1 denotes a sand stocker in which sand (fine aggregate) 3 is stored, and reference numeral 2 denotes a gravel stocker in which gravel (coarse aggregate) 4 is stored. Reference numeral 5 denotes a sand meter for measuring the sand 3 supplied from the sand stocker 1, and reference numeral 6 denotes a gravel meter for measuring the gravel 4 supplied from the gravel stocker 2. An aggregate hopper 7 for temporarily storing the measured sand 3 and gravel 4 is provided below the sand weighing device 5 and the gravel weighing device 6.
A cooling aggregate manufacturing device 8 is interposed between the sand meter 5 and the aggregate hopper 7. In addition, this aggregate hopper 7
For example, it is desirable that the heat insulating effect is improved by installing a heat insulating material on the wall surface or the like.
If it is not necessary to temporarily store the aggregate hopper 7, the aggregate hopper 7 is omitted. On the other hand, reference numeral 9 denotes a cement stocker for temporarily storing cement, and a cement meter 10 is connected below the cement stocker. A concrete mixer 11 for kneading concrete constituent materials such as cement and aggregate is provided below the supply port of the cement meter 10 and the aggregate supply port of the aggregate hopper 7. In addition, this concrete mixer 11
Also, similarly to the aggregate hopper 7, it is desirable that the heat insulating effect is improved by, for example, applying a heat insulating material to the wall surface. In the figure, concrete mixer 1
The device for supplying the mixing water to 1 is omitted for simplification of the description. Next, the cooling aggregate manufacturing apparatus 8 will be described. The cooling aggregate manufacturing apparatus 8 is provided with an aggregate mixer 12 for stirring the sand 3 and an aggregate mixer 12 attached to the aggregate mixer 12. The cooling device 13 cools the sand 3 by blowing a liquefied gas or cold air onto the sand 3. The aggregate mixer 12 includes a trough-shaped drum 14, a substantially disk-shaped lid 15 having a closed upper end opening of the drum 14, and a support leg 1 provided at the bottom of the drum 14.
6 form the outer shell. In the lid 15,
An aggregate inlet (not shown) for introducing aggregate into the drum 14 is provided, and an aggregate outlet (not shown) from the drum 14 is provided at the bottom of the drum 14. A column 17 is projected from the center of the drum 14 and is fixed thereto.
7 supported rotatably in the horizontal direction with respect to 7
Is attached. A plurality of arms 19, 19,... Extending radially from the rotor 18 are provided on the outer periphery of the rotor 18, and these arms 19, 19,.
At the tip end, scrapers 20, 20,... For stirring the sand 3 and the like stored in the drum 14 are provided to extend substantially downward. At the bottom of the drum 14, the rotor 1
A pulley 21 whose rotation shaft is connected to 8 is supported rotatably in the horizontal direction. Reference numeral 22 denotes the rotor 18
The driving shaft of the motor 22 is connected to a pulley 23 provided at the lower end of the motor 22. A V-belt 24 is provided between the pulleys 21 and 23.
Is wound, the rotational driving force of the motor 22 is transmitted to the rotor 18. In addition, similarly to the concrete mixer 11, it is desirable that the heat insulating effect of the aggregate mixer 12 is improved by, for example, applying a heat insulating material to a wall surface thereof. On the other hand, the cooling device 13 is provided with a liquefied gas or cold air storage tank 24 installed adjacent to the aggregate mixer 12 or at another location.
Control device 25 for controlling the supply amount of liquefied gas and the like supplied from the liquefied gas, supply pipe 26 for supplying liquefied gas and the like from control device 25 to aggregate mixer 12, and supply pipe 26
A plurality of spray nozzles 27, 27, which are provided at the leading end and are provided at the lower end and the bottom plate on the drum 14 side of the aggregate mixer 12 to blow out liquefied gas and the like toward the inside of the bottom of the drum 14.
…. That is, the spray nozzle 27,
The liquefied gas and the like supplied from 27,.
2 is directly sprayed toward the aggregate (sand 3) stored at the bottom of the second. Reference numeral 28 is provided on the lid 15 of the aggregate mixer 12, and after the liquefied gas supplied to the aggregate mixer 12 is vaporized, the vaporized gas is supplied to the aggregate mixer 12 or supplied. An exhaust duct 29 for discharging the cold air to the outside of the system is a sieve for adjusting the particle size of the sand discharged from the aggregate discharge port (not shown). The low-temperature gas discharged from the exhaust duct 28 is supplied to the sand, the gravel stockers 1 and 2 or the concrete mixer 11 as needed, and is used for pre-cooling the sand 3 and the gravel 4 or for cooling at the time of concrete kneading. Next, a method of cooling the aggregate using the cooling aggregate manufacturing apparatus 8 having the above-described configuration will be described. First, sand 3 is fed by a conveyor or the like (not shown).
Is transported and put into the sand stocker 1 in advance. next,
At the time of concrete production, the sand 3 is supplied from the sand stocker 1 to the sand meter 5 as appropriate, and the sand 3 is weighed in accordance with a prescribed concrete composition. The weighed sand 3 is put into the drum 14 of the aggregate mixer 12. After the sand 3 is charged into the drum 14, the motor 22 is driven to drive the scraper 20,
Are moved in a circular motion in the mixer 12, whereby the sand 3 is stirred in the drum 14. Then, while the sand 3 is being stirred, the controller 25 controls the supply pipe 2 from the tank 24.
The liquefied gas or the like is sprayed through the nozzles 27, 27,.
Liquefied gas and the like to these spray nozzles 2
, 27,... Are blown into the bottom of the drum 14 to directly blow liquefied gas or the like onto the sand 3 at the bottom. Therefore, the surface water on the surface of the sand 3 is frozen by instantly cooling the sand 3 to zero or less, and a water layer is formed on the surface of the sand 3. When the sand 3 is cooled to -5 ° C to -10 ° C or less, the ice layers on the surface of the sand 3 repel each other, and the sand 3 particles fuse with each other to form a lump of frozen sand. Less. Here, the sand 3 usually used for the production of concrete has a surface water of 5 to 10%, but if the amount of the surface water is considered to be insufficient, the sand 3 is used in advance. It is preferable to adjust the amount of surface water by spraying water. The discharge amount of the liquefied gas or the like from the spray nozzles 27 is arbitrary, but the discharge amount, the rotation amount of the scrapers 20, 20,... Of the aggregate mixer 12, and the residence time in the mixer 12 By appropriately adjusting and selecting the above, it is possible to correspond to a desired cooling temperature in accordance with the type of the material to be cooled. When the surface water amount and cooling conditions of the sand 3 are appropriately changed in this way, the surface water of the sand 3 forms an ice layer on the surface of the particles of the sand 3 or a part of the ice layer is separated from the particles of the sand 3. And become fine ice grains and sand 3
It may be mixed between particles. Thereafter, while continuing to stir the sand 3 by the scrapers 20, 20,..., The sand 3 is discharged from the aggregate discharge port (not shown) and passed through the sieve 29 to obtain the particle size. Is adjusted and then put into the aggregate hopper 7. As a result, the sand 3 having an ice layer formed on the surface in advance
Can be manufactured. The aggregate mixer 12
When the sand 3 is not cooled in the spray nozzle 2
By appropriately blowing out gaseous nitrogen, air, or the like from 7, 27,..., It is possible to prevent the nozzles 27, 27,. Then, the gravel stocker 2 and the gravel 4
Is supplied to the aggregate hopper 7 after being measured by the gravel measuring device 6. And the low-temperature sand 3,
And gravel 4, cement, water or ice granules,
Further, if necessary, various admixtures are mixed to produce ready-mixed concrete. The method of mixing the constituent materials of the ready-mixed concrete is arbitrary, but as an example, first, low-temperature sand 3 and gravel 4 are charged into the concrete mixer 11 from the aggregate hopper 7, and then fine cement, water or ice is added. It is preferable that raw concrete is manufactured by putting the granules in the concrete mixer 11 in the order of granules and kneading them. Of course, these may be put into the concrete mixer 11 at once. Therefore, the cooling aggregate manufacturing apparatus 8 described above is used.
According to the above, by cooling the sand 3 to -5 ° C or less, the sand 3
Surface water can be frozen, so that an ice layer can be formed in advance on the surface of the sand 3 before mixing each concrete constituent material such as cement and aggregate. In addition, since the sand 3 is cooled by spraying a liquefied gas or the like on the sand 3 while stirring the sand 3 by the aggregate mixer 12, the liquefied gas or the like is uniformly diffused into the gaps between the sands 3. Is done. Therefore,
Since the cooling efficiency of the sand 3 by the liquefied gas or the like is remarkably improved as compared with the conventional one, the cost required for cooling the sand 3 can be reduced. At the same time, the sand 3 is agitated, so that the particles of the sand 3 are hardly fused to each other after the ice layer is formed, thereby suppressing the solidification of the sand 3 after cooling. It becomes possible. Then, the cooling aggregate manufacturing apparatus 8 described above
Accordingly, if the ready-mixed concrete is manufactured using the sand 3 having an ice layer formed on the surface, effects such as a reduction in the temperature at which the concrete is kneaded and an increase in the concrete strength can be obtained in the same step. That is, due to the presence of the ice layer on the surface of the sand 3, when mixing concrete constituent materials such as cement, the cement particles 51, 51,. Adheres evenly to Therefore, the kneading temperature of the concrete is lowered by the latent heat of the ice and the cold heat of the sand 3, and the cement particles 51 are uniformly dispersed, so that the unit water volume can be reduced, and the concrete obtained by this can be reduced. Can be increased in strength. Furthermore, since a dense cement paste is formed on the surface of the sand 3 during kneading, the bonding strength between the sand 3 or between the sand 3 and the gravel (coarse aggregate) 4 is increased, and the strength of the concrete is also increased from this surface. Can be increased. Therefore, if concrete is manufactured using the sand 3 having an ice layer formed on the surface, a decrease in the temperature at which the concrete is kneaded and an increase in the concrete strength can be realized at the same time. Can be reduced. Particularly, in this embodiment, since ultra-low temperature liquid called liquefied gas is used for cooling the sand 3, the surface water of the sand 3 can be instantaneously frozen and efficiently, and the temperature of the sand 3 itself can be reduced. Can easily be reduced to several tens of degrees below zero, so that the above-described concrete kneading temperature lowering efficiency is further improved. Next, FIG. 3 is a view showing another cooling aggregate producing apparatus 8. As shown in FIG. The cooling aggregate manufacturing device 8 includes an aggregate mixer 12 for stirring the aggregate and a cooling device 13 attached to the aggregate mixer 12, similarly to the cooling aggregate manufacturing device 8 of the above-described embodiment. It is schematically configured. The aggregate mixer 12 has a substantially cylindrical outer shape 2.
A layered housing 30 is provided, and the housing 30 is provided with an aggregate inlet 31 and an aggregate outlet 32 on the upper and lower surfaces of one end (the left end in the figure), respectively. In the chambers 34, 34 of the housing 30,
Screw conveyors 35, 35 are provided. The rotating shafts 36, 36 of the screw conveyors 35, 35 extend in the longitudinal direction of the chambers 34, 34,
Both ends are supported by the housings 30, 30, whereby the screw conveyor 35 is rotatably supported with respect to the housing 30. The other ends (right ends in the figure) of the housings 30 of the rotating shafts 36, 36 protrude outward from the housing 30, and
Gears 37, 37 are coaxially mounted on the projecting portions 6, 6, respectively. The gears 37 and 37 are attached to each other by meshing with each other, and the lower gear 37 has a gear 3 connected to a drive shaft of a motor 38.
9 are fitted and attached. That is, the rotational driving force of the motor 38 is transmitted to the screw conveyors 35, 35 via the gears 37, 39, respectively, and the screw conveyors 35, 35 rotate in directions opposite to each other. Note that, similarly to the above-described embodiment, it is desirable that the heat-insulating effect of the aggregate mixer 12 in this embodiment is improved by, for example, applying a heat-insulating material to the wall surface. On the other hand, like the cooling device 13 in the above embodiment, the cooling device 13 includes a liquefied gas or cold air storage tank, and a control device (a liquefied gas or the like) supplied from the tank. A supply pipe 40 for supplying liquefied gas or the like from the control device to the aggregate mixer 12, and a supply pipe 40 provided at the tip of the supply pipe 40.
The spray nozzle 41 is disposed at the bottom of the chamber 34 of the aggregate mixer 12 and blows liquefied gas or the like inward from the bottom of the chamber 34. It is to be noted that, similarly to the above embodiment, reference numeral 4
Reference numeral 2 denotes an exhaust duct provided in communication with the lower chamber 34 in the housing 30, and reference numeral 43 denotes a sieve. The method of manufacturing the sand 3 having the ice layer formed on the surface thereof using the cooling aggregate manufacturing apparatus 8 having the above-described configuration is substantially the same as the above-described cooling aggregate manufacturing method. That is, the sand 3 is appropriately supplied from the sand stocker 1 to the cooling aggregate manufacturing apparatus 8, and the cooling aggregate manufacturing apparatus 8
By cooling the sand 3, the ice layer is formed on the surface. Specifically, the housing 3 is connected via the aggregate input port 31.
After the sand 3 is charged into the housing 0, the screw conveyors 35 and 35 in the housing 30 are rotated by driving the motor 38, thereby transporting the sand 3 from the aggregate input port 31 to the aggregate supply port 32. Then, the sand 3 is stirred by the screw conveyors 35 and 35. Then, while the sand 3 is being stirred, the control device controls the supply pipe 40 from the tank.
Liquefied nitrogen is blown in from the bottom of the chamber 34 through the spray nozzle 41 by supplying liquefied gas or the like to the spray nozzle 41 through
Spray directly on the bottom of the. Therefore, the surface water on the surface of the sand 3 is frozen by instantly cooling the sand 3 to zero or less, and an ice layer is formed on the surface of the sand 3. Next, an experimental example of a method for manufacturing a cooled aggregate using the above-described apparatus for manufacturing a cooled aggregate will be described. Fifth
The figure shows the relationship between the amount of liquid nitrogen used (vertical axis) and the temperature drop ΔT of the cooling aggregate (cooling sand 100 kg) when the water content γm of the sand is changed (horizontal axis). . It can be understood that the aggregate (sand) can be efficiently cooled even when a relatively small amount of liquid nitrogen is used. Also, from the results of this experiment, assuming that the gravel temperature Tg = 3 ° C., the water temperature Tw = 20 ° C., and the cement temperature Tc = 60 ° C., the use of about 10 liters of liquefied nitrogen would increase the concrete lifting temperature. It was confirmed that the temperature could be reduced by about 1 ° C. The ready-mixed concrete production apparatus of the present invention is not limited to the above-described embodiment, and various modifications are possible. As an example, it is needless to say that the aggregate having an ice layer formed on the surface thereof is not limited to the sand 3 but can be similarly applied to coarse aggregate such as the gravel 4. An aggregate mixer 12 for stirring the sand 3
However, the type and the shape are not limited to the mixer as in the above-described embodiment, and it goes without saying that a well-known stirrer capable of uniformly stirring sand may be used. As described above in detail, according to the present invention, an aggregate mixer for stirring the aggregate, a cooling device for cooling the aggregate, the cooled aggregate and other concrete A concrete mixer for kneading the constituent materials, and an exhaust duct for blowing gas or cold air from inside the aggregate mixer, which are sent out of the cooling device inside the aggregate mixer and inside the pile of aggregate. Since the liquid or gas spray nozzle is provided, troubles in operation of the concrete plant during production of ready-mixed concrete are less likely to occur, and therefore, work efficiency is excellent, and as a result, productivity is increased. In addition, since the cooled aggregates dropped into the mixer are separated, when kneading with cement, etc., the aggregates are uniformly distributed and the heat exchange efficiency is good, so homogenous and high quality ready-mixed concrete can be obtained by kneading for a short time. Can be manufactured. Further, since the refrigerant is directly blown into the aggregated layer of the aggregate, the cooling efficiency is excellent.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing a ready-mixed concrete manufacturing apparatus. FIG. 2 is a sectional view of a cooling aggregate manufacturing apparatus. FIG. 3 is a schematic view showing another embodiment of a cooling aggregate manufacturing apparatus. FIG. 4 is a cross-sectional view showing a state of sand at a time when the sand is put into a concrete mixer. FIG. 5 is a diagram showing the relationship between the water content of sand and the amount of liquid nitrogen used. [Description of Signs] 3 Sand (aggregate) 8 Cooling aggregate manufacturing apparatus 11 Concrete mixer 12 Aggregate mixer 13 Cooling apparatus 27 Spray nozzle 28 Exhaust duct 50 Ice layer

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Sadao Goto               Tokyo Gas Minato-ku 1-5-20 Tokyo Gas Co., Ltd.               In the formula company (72) Inventor Koji Minegishi               Tokyo Gas Minato-ku 1-5-20 Tokyo Gas Co., Ltd.               In the formula company (72) Inventor Kenichi Ohshita               Tokyo Gas, 8-11-37 Akasaka, Minato-ku, Tokyo               Chemical Co., Ltd. (72) Inventor Daisuke Ishikura               Tokyo Gas, 8-11-37 Akasaka, Minato-ku, Tokyo               Chemical Co., Ltd. (72) Inventor Yoshiaki Negami               Shimizu, 2-6-1 Kyobashi, Chuo-ku, Tokyo               Construction Co., Ltd. (72) Inventor Sada Ono               Shimizu, 2-6-1 Kyobashi, Chuo-ku, Tokyo               Construction Co., Ltd. (72) Inventor Kazuya Kamezaki               Shimizu, 2-6-1 Kyobashi, Chuo-ku, Tokyo               Construction Co., Ltd. (72) Inventor Katsuhiko Kimura               Shimizu, 2-6-1 Kyobashi, Chuo-ku, Tokyo               Construction Co., Ltd. (72) Inventor Takashi Kuwahara               Shimizu, 2-6-1 Kyobashi, Chuo-ku, Tokyo               Construction Co., Ltd. (72) Inventor Yasuo Kajioka               Shimizu, 2-6-1 Kyobashi, Chuo-ku, Tokyo               Construction Co., Ltd.

Claims (1)

(57) [Claims] An aggregate mixer for stirring the aggregate, a cooling device provided in the aggregate mixer, and cooling the aggregate by spraying a low-temperature liquid or gas on the aggregate in the aggregate mixer; and a cooled aggregate. A concrete mixer for kneading other concrete constituent materials, and an exhaust duct for discharging vaporized gas or cold wind from the inside of the aggregate mixer to the outside and sending it to a sand / gravel stocker or a concrete mixer; And a spray nozzle for a liquid or a gas discharged from a cooling device is provided inside the aggregate and inside the sedimentary layer of the aggregate.