JPH0737021B2 - Concrete production method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a concrete production method for producing a concrete having a low kneading temperature by producing a slurry (an aqueous solution containing a cement component) under cooling. is there.

[Conventional technology]

For example, in dam concrete, in order to suppress the internal temperature after placing concrete and prevent cracking,
It is necessary to set the concrete driving temperature to 25 ° C or lower.
Therefore, conventionally, there has been provided a technique for suppressing the temperature at the concrete production stage to a low level by using a low temperature liquefied gas such as liquefied nitrogen.

As such a technique, (a) a method of injecting a low-temperature liquefied gas into concrete being mixed with a mixer or a truck mixer, (b) a low-temperature liquefied gas is injected into an aggregate stored in an aggregate bottle, and the aggregate is cooled. What to put in the mixer,
(C) While agitating sand, a low-temperature liquefied gas is sprayed onto the sand, and the cooled sand is added to a mixer. (D)
It has been proposed to inject low-temperature liquefied gas into kneading water and add the cooled kneading water to a mixer.

However, in such conventional concrete cooling technology, in the cooling of the concrete of the above (a), the contact surface of the low-temperature liquefied gas injection surface and the concrete is limited,
Most of it is released as an unused gas, the heat transfer efficiency is extremely poor, and as a result only 40 to 50% of the utilization efficiency is obtained, which is uneconomical, and in the above (b) cooling of the aggregate,
Since the water in the tank and the water on the surface of the aggregate condense, the aggregates are bound together in the tank, making it difficult to pull out from the gate. In addition, in the stirring and cooling of the sand in (c) above, it is necessary to modify the equipment because it must be installed in the batcher plant for stirring and cooling the sand in the stirring tank. Cooling is not sufficient to obtain the required cooling calories in the case of concrete that uses only a small amount of mixing water, such as RCD concrete, and requires auxiliary cooling in combination with cooling of other admixtures. There was a problem to do. Further, there is also a method of producing ice and producing cooled kneading water and using this, but there is a problem that a separate means for storing and transporting the ice is required, and the equipment must be modified.

On the other hand, in contrast to the above-mentioned method, the present applicant previously applied for a technique of making a mixture of water and ice by blowing low-temperature liquefied gas into water in a water tank and using this for cooling concrete (actual application (No. 1-129039), it has become possible to solve the above problems. This method has the advantage that the usage efficiency can be increased to 90% or more from the temperature of the low-temperature liquefied gas and the amount of ice produced. Further, such an ice-water mixture is a sherbet-like substance having high fluidity even at 0 ° C., and has an advantage that it can be easily transported by a pipe by a pump or the like.

[Problems to be Solved by the Invention]

However, in the case of using such an ice-water mixture, if these are left to stand in the tank for a certain time, the ice rises and concentrates in the upper layer, and there is a tendency to condense here, and in addition to the above low-temperature liquefied gas water. During the blowing of ice, convection becomes stagnant as the amount of ice generated increases, and a passage of the low temperature liquefied gas is created in the ice water mixture, and the low temperature liquefied gas that has been blown directly blows out (tunnel phenomenon). However, there is a problem that the use efficiency of the low temperature liquefied gas is significantly deteriorated.

The present invention has been made by paying attention to the above-mentioned conventional problems, mixing water consisting of a mixture of water or ice with an admixture, cement, or a mixture of cement and an admixture, stirring, circulation. To produce a low temperature slurry by efficiently contacting with a low temperature liquefied gas, mixing the low temperature slurry with other concrete materials in a mixer, a concrete manufacturing method capable of producing a concrete with a low kneading temperature, The purpose is to provide.

[Means for Solving the Problems]

The concrete producing method according to the present invention is made in view of the above-mentioned object, and the gist thereof is to measure the amount of kneading water made of water or a mixture of water and an admixture in a water measuring tank, and to measure a cement measuring tank. In, weigh the amount of cement or the mixture of cement and admixture, and stir the weighing objects weighed in each of the above-mentioned weighing tanks in the stirring tank to form a slurry-like stirring material, and from the low-temperature gas supply section, a low-temperature liquefied gas Is injected into the agitated material of the agitation tank, and the low temperature agitated material produced in the agitation tank is supplied to the mixer to produce a concrete. At the same time as injecting upward from above, the upper and lower parts of the stirring tank are connected by pipes, and the agitated material in the stirring tank is pumped in the direction opposite to the injection direction of the low temperature liquefied gas In concrete production method is characterized in that so as to circulate.

Here, an admixture is a cement added as a component of concrete for the purpose of improving the properties of concrete.
Materials other than water and aggregate that are used in small amounts and are used chemically, and include AE agents, water reducing agents, quick-setting agents, coloring agents, etc.

In addition, the admixture is one of the materials other than the above cement, water, and aggregate, which has a large amount of use and whose volume is related to the calculation of the mix of concrete, such as fly ash, blast furnace slag, and stone powder. Some include.

[Action]

In the present invention, the low temperature liquefied gas is injected into the produced slurry-like agitated product in the agitation tank to produce ice crystals. Since the cement or cement and the admixture contained in the agitated product has a smaller specific heat than water, cooling by the low-temperature liquefied gas will be faster than that of water, and therefore ice will be generated on the surface of the cement particles or the admixture particles. It's easy to do. Also, since cement or cement and admixture has a larger specific gravity than water,
The ice crystals containing the cement particles and the admixture particles have a specific gravity larger than that of ice crystals alone. Therefore, ice crystals do not rise easily due to buoyancy, so they have good dispersibility.
A low-fluid slurry-like agitated substance having a high fluidity is produced. The generated low-temperature agitated product is easily conveyed to a mixer using a pump or the like, and is kneaded with other concrete materials to produce concrete having a low kneading temperature.

Further, the low temperature liquefied gas is injected upward from the lower part of the stirring tank, and at the same time, a tunnel phenomenon as a passage of the low temperature liquefied gas is generated by continuing the injection, thereby hindering the diffusion of the refrigerant into the tank. For this purpose, the upper and lower parts of the stirring tank are connected by a pipe, and the agitated material is drawn from the bottom of the stirring tank by a pump and sent to the upper part of the stirring tank, so that stirring is performed in the direction opposite to the injection direction of the low temperature liquefied gas. A flow of material occurs which causes heat transfer of the cold gas within the vessel.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block connection diagram showing a schematic configuration of the present invention, in which 1 is a water measuring tank, into which an admixture 2 and water 3 are added from the outside, and a mixing water 4 having a preset measured value is mixed. Can be discharged. 5 is a cement measuring tank,
The cement 6 or the admixture 7 is input from the outside, and either the cement, the admixture or a mixture thereof having a set measurement value can be discharged. 8 is a stirring tank,
Mixing water measured in each of the above measuring tanks, and either cement or a mixture of cement and an admixture,
Stir to produce a slurry-like agitator. A low-temperature gas supply unit 9 for injecting a low-temperature liquefied gas into an agitated product is connected to the stirring tank 8 via a gas supply pipe 16. Reference numeral 10 is a mixer for kneading the low-temperature agitated substance generated in the agitation tank 8 and sent through the pipe 15 and the separately charged aggregate.

FIG. 2 is a configuration diagram showing a slurry circulation system in the stirring tank 8 shown in FIG. A circulation pipe 12 communicates with the upper and lower portions of the stirring tank 8, and a motor pump 13 and a three-way valve 14 are connected in the middle of the circulation pipe 12 as shown in the drawing. One output end of the three-way valve 14 is a pipe 15 having one end opened to the mixer 10 for concrete mixing.
It is connected to the. Reference numeral 16 denotes a gas supply pipe whose one end is connected to the lower portion of the stirring tank 8, and the low temperature liquefied gas is supplied from the low temperature gas supply unit 9 into the stirring tank 8 through the gas supply pipe 16. Further, 17 is a gas supply valve.

Next, the operation will be described. As shown in FIG. 1, water 3
The admixture 2 and the admixture 2 are supplied into the water measuring tank 1 at a predetermined ratio to generate the kneading water 4. On the other hand, a certain proportion of cement 6
Alternatively, a mixture of the cement 6 and the admixture 7 is supplied into the cement measuring tank 5. Next, a precalculated amount of the kneading water 4 and the cement 6 or any of the above mixtures is weighed and put into the stirring tank 8. In this stirring tank 8,
By the forced circulation by the motor pump 13 and the circulation pipe 12 shown in FIG. 2, the mixture is agitated and kneaded to produce a slurry-like agitated product. Further, the low-temperature liquefied gas is injected into the agitated material during the agitation through the gas supply pipe 16. The cold liquefied gas contacts the agitator and produces a cold slurry, for example by heat transfer from -196 ° C to the equilibrium temperature. According to experiments, the heat transfer efficiency at this time is 90% or more. If the three-way valve 14 is switched so that the motor pump 13 is driven and the circulation pipe 12 is in communication while stirring the agitated material, the agitated material drawn from the bottom of the agitation tank 8 by the operation of the motor pump 13 The agitated material is sent to the upper part of the agitation tank 8 and is forcibly circulated. Further, since the low temperature liquefied gas is injected upward so as to resist this flow, heat transfer is sufficiently performed. Since the amounts of the kneading water 4, the cement 6 or the cement 6 and the admixture 7 are measured in advance, the amount of low temperature liquefied gas for cooling the slurry to a predetermined temperature can be easily calculated. Further, the water mixed in the slurry in the stirring tank 8 is cooled by the low temperature liquefied gas to be crystallized into ice crystals, and the slurry as a whole contains no ice crystals.
It becomes a liquid substance at ℃. The specific heat of cement and admixture is lower than that of water, about 0.25. Therefore, cooling by the low-temperature liquefied gas proceeds faster than water, so that water is likely to be condensed on the surface of the cement particles or the admixture particles.

Further, since the specific gravity of cement and the admixture (about 3.1) is larger than that of water, the ice crystals encapsulating the cement particles or the admixture particles have a larger specific gravity than the ice crystals of only ice. Therefore, there is little tendency to rise due to buoyancy and to agglomerate in the upper layer portion, and since the dispersibility is good, the passage of low temperature liquefied gas does not occur and heat transfer is not biased to some ice crystals. Furthermore, while the entire slurry is forcedly circulated by the pump 13,
Since the ice crystals are crushed by the blades in the pump 13, a sherbet-like slurry having high fluidity can be obtained by using the low temperature liquefied gas with good efficiency. Such a sherbet slurry can be pumped by switching the three-way valve 14.
Thus, it is easily conveyed to the mixer 10 through the pipe 15.
If the sherbet-like slurry conveyed by the mixer 10 is kneaded with the aggregate and optionally other concrete material,
A concrete with low kneading temperature and fluidity can be obtained. Further, when the admixture is mixed, the fluidity of the concrete is further increased by the action of the admixture.

Unlike the batch processing method shown in FIG. 2, FIG. 3 shows a continuous processing method in which two sets of stirring tank 8, circulation pipe 12 and motor pump 13 are installed side by side. According to this, while stirring and cooling the slurry in one stirring tank 8, the low temperature slurry generated from the other stirring tank 8 by switching the three-way valve 14 is transferred to the mixer 10 via the transfer pipe 15. Can be transported. Therefore, the low temperature slurry can be continuously or intermittently supplied from the two stirring tanks 8 to the mixer 10.

Further, the concrete manufacturing method of the present invention cools not only water but also cement and admixture, so that sufficient cooling calories can be given even in RCD concrete, and fresh cement after manufacturing can reach 60 ° C. Therefore, it is also effective as a cement cooling method.

〔The invention's effect〕

According to the concrete production method of the present invention, not only the flow work such as simply injecting the low-temperature liquefied gas into the stirring tank and introducing the mixture of the agitated materials into the mixer, but also the low-temperature liquefied gas from the lower part of the stirring tank upwards. At the same time as it was injected toward, the upper and lower parts of the stirring tank were connected by pipes, and the agitated material in the stirring tank was circulated in the opposite direction to the low temperature liquefied gas by a pump so that these could be contacted efficiently. Therefore, a certain passage is generated in the agitated material in the agitation tank by the low temperature liquefied gas, so-called tunnel phenomenon is prevented, sufficient stirring and mixing is ensured, and the use efficiency of the low temperature liquefied gas is improved.

Further, in the present invention, the low temperature liquefied gas is injected from the lower portion of the stirring tank, the upper and lower portions of the stirring tank are connected by a pipe, and the agitated material is circulated in the direction opposite to the above gas, thereby simplifying the equipment itself. be able to.

[Brief description of drawings]

FIG. 1 is a block connection diagram showing a schematic configuration of a concrete producing method according to the present invention, FIG. 2 is a configuration diagram showing a circulation system of a stirred product centering on a stirring tank, and FIG. 3 is a circulation system of a stirred product. It is a block diagram which shows another Example. 1 ... water measuring tank, 5 ... cement measuring tank, 8 ... stirring tank, 9 ... low temperature gas supply section, 10 ... mixer, 12 ... circulation pipe, 13 ... motor pump.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kimihiro Aso 2-5-8 Kita-Aoyama, Minato-ku, Tokyo Intra-company group (72) Inventor Nobuo Ishiguro 1-1-9 Shinonome, Koto-ku, Tokyo Taisan (72) Inventor Akira Haga 1-9-1, Shinonome, Koto-ku, Tokyo Taisan Co., Ltd. (72) Akira Takagi 2-234 Koyasu-dori, Kanagawa-ku, Yokohama, Kanagawa Prefecture 56) References Japanese Unexamined Patent Publication No. 63-39303 (JP, A) Fukukaihei 3-68409 (JP, U)

Claims (1)

[Claims] 1. An amount of kneading water made of water or a mixture of water and an admixture is measured in a water measuring tank, and the amount of cement or a mixture of cement and an admixture added is measured in a cement measuring tank. Weigh and stir the objects weighed in each of the above-mentioned weighing tanks to form a slurry-like agitated product, and inject the low-temperature liquefied gas from the low-temperature gas supply unit into the agitated product of the agitating tank, and in the agitating tank, In the method for producing concrete, which is produced by supplying the produced low-temperature agitated material to a mixer, injecting the low-temperature liquefied gas from the lower part of the agitating tank to the upper side, and simultaneously injecting the same at the upper and lower sides of the agitating tank. A method for producing concrete, characterized in that the parts are connected by a pipe, and the agitated material in the agitation tank is circulated in a direction opposite to the injection direction of the low temperature liquefied gas by a pump.