JPH08218634A - Method of placing concrete - Google Patents

Abstract

PURPOSE: To provide a concrete structure with which a work for placing concrete can be made convenient in a reduced burden, which can reduce a construction cost, and which does not crack after curing and has a strength with less unevenness. CONSTITUTION: Rich-mix concrete 1 ready-mixed is fed under a pressure by a concrete pump, and is placed in a form, and a vibration cylinder 2 is inserted in the concrete ready-mixed before the concrete is cured, so that the concrete is vibrated to cause mortar slurry 3 to ooze out through holes for extraction. The mortar slurry 3 pooled in the cylinder 2 is fed by a feed pump 6, and is then mixed in a lean-mix concrete ready-mixed and successively fed before the slurry 3 is cured, so that the concrete is turned into rich-mix concrete, that is, the slurry 3 is used as a fluidizing agent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a concrete pouring method, and more particularly to a concrete pouring method in which mortar slurry is used as a fluidizing agent when fresh concrete is pumped by a concrete pump and driven into a mold.

[0002]

2. Description of the Related Art Conventionally, when placing concrete,
Concrete pouring by so-called pumping method, in which ready-mixed concrete is pumped by a concrete pump and driven into a form, is widely used in various structures and in sites with bad topographical conditions. In this type of pumping method, in order to improve the pumpability and the familiarity of the form, the ready-mixed concrete to be pumped is a mixture of sand, cement and water more than necessary, that is, a rich mixture.

[0003]

However, in the casting using the conventional pumping method, as described above, the ready-mixed concrete is kneaded with more sand, cement or water to form a rich mixture, resulting in a hydration reaction. Because of the breathing that occurs before the start of aging and the water film that forms on the bottom surface of the aggregate, it is easy for cracks to form in the concrete after hardening. In addition, there is a problem that the strength of the upper part and the lower part of the aggregate tend to vary during the consolidation and settlement of the aggregate.

Conventionally, in order to avoid such a problem, the height of a single driving operation is kept low, and a hand waiting time is provided to slow down the work progress. In addition, a hard-mixed ready-mixed concrete with a low water content is sufficient in terms of strength after curing, but a fluidizer is used in order to avoid the difficulty of pumping and improve the workability of placing. Is also increasing. However, there is a problem that any of these measures will increase the construction cost.

Incidentally, the applicant has already proposed a concrete placing technique in Japanese Patent Publication No. 6-43753 in order to solve the above problems. With this technology, the mortar slurry that has exuded into the cylinder is sucked out by a vacuum device,
By mixing the mortar slurry that has been sucked out and collected into a poorly mixed ready-mixed concrete on the inlet side of a concrete pump by a pump, it becomes possible to drive a poorly-mixed ready-mixed concrete by a construction method using a concrete pump.

However, when the above-mentioned mortar slurry is sucked out by a vacuum device, if the height difference between the vacuum device and the suction port is large, the suction head becomes small because the specific gravity of the mortar slurry is large. Therefore, in the case of a deep mold, it is necessary to lower the entire vacuum device to reduce the height difference. However, up and down movement of the heavy vacuum device in a narrow mold requires a large number of manpower and causes a large work load. There is also a demand for simplifying the configuration of the device to be used, reducing the device cost and the amount of power used, and lowering the construction cost.

The present invention has been made to solve the above-mentioned conventional problems, and makes it possible to simplify the work of placing concrete, reduce the work load, and reduce the construction cost and the construction cost. It is an object of the present invention to provide a concrete pouring method that can obtain concrete that does not crack after hardening and has little variation in strength.

[0008]

In order to achieve the above-mentioned object, the present invention has the following constitution. That is, the invention of claim 1 is, in the concrete pouring method, a step of pumping the ready-mixed concrete with a rich mixture by a concrete pump to drive it into the form, and the injected ready-mixed concrete is not yet solidified in the form. Sometimes, insert a tubular material with a hole through which only mortar slurry can pass into the ready-mixed concrete, and
A step of oscillating to allow only the mortar slurry in the ready-mixed concrete to exude from the hole and withdraw; a step of sending the withdrawn mortar slurry collected in the tube material by a feed pump provided in the tube material; The process of mixing the mortar slurry into the subsequent poor mix of raw mix on the entrance side before it is solidified to make the ready mix rich, and pumping the rich mix of the subsequent ready mix with the concrete pump. And a step of driving the mortar slurry into the formwork as a fluidizing agent.

[0009]

The well-known matters concerning general properties of concrete which are deeply related to the present invention will be listed. (i) The strength of concrete is comparable to that of water-cement (concrete practice: Yoshii Shoten, published in 1986). (ii) If the amount of water is constant, the higher the amount of cement, the higher the strength. (iii) The softness of ready-mixed concrete changes depending on the amount of water mixed. (iv) If the slump is too large, the raw concrete is not preferable, because the material separation is likely to occur, the unit water content is large and the adhesion cracks are likely to occur, the strength variation is large, and the unit cement content is large, which is uneconomical. The points increase. (v) In the pump construction method, if the ready-mixed concrete is a small kneading mixture of slump, the pumping efficiency is significantly reduced and the risk of blockage is increased.
It is often pumped by m (concrete practice). (vi) Fresh concrete is in a resting period of hydration reaction during transportation, and concrete strength does not decrease until transportation time is about 2 hours (concrete practice mentioned above). Also, cement is generally added with gypsum to slow the rate of hydration and does not set immediately. In addition, it is known in the field of chemistry that, among the particles of cement, particles that are completely absorbed in hydration are probably 20 to 30% of the total (concrete thing: Bunichi General Publishing, published in 1986). .

From the above items (i) to (vi), in the case of the ready-mixed concrete placed by the pump construction method, in order to eliminate cracks and variations in the strength of the concrete after hardening while maintaining the strength of the concrete, a large slump is required. The mortar slurry should be drained from the ready-mixed concrete and made into a small slump-hard paste. In addition, if the extracted mortar slurry is mixed with the ready-mixed concrete before being pumped by a pump, a large slump with a rich mixture, that is, a high-flowable ready-mixed concrete is obtained, so that the ready-mixed concrete transported by a mixer truck or the like is slumped. Even small things can be pumped with a concrete pump. Furthermore, before the hardening of the mortar slurry extracted from the ready-mixed concrete after casting, as in the above, it is mixed with the slump's small hard-mixed ready-mixed concrete to make the ready-mixed mixture rich and flow You can improve your sex.

The present invention has been made based on the above. At the same time, the inventor, when repeatedly using the mortar slurry in the mold as a fluidizing agent when pouring ready-mixed concrete, the mortar slurry exuded and extracted into the vibrating tubular material is taken into the concrete pump inlet side. Paying attention to the point that it is necessary to send the mortar slurry to the cylindrical material without using a vacuum device, and by providing a small feed pump (for example, vertical pump) to the tubular material. , Simplify the device configuration and work.

That is, in the present invention, first, fresh concrete containing a rich mixture is pressure-fed by a concrete pump to be driven into a mold to perform the present casting. In this case, the ready-mixed rich mixture has high fluidity and does not hinder the pumping by the concrete pump. In addition, the ready-mixed concrete may be rich-mixed ready-mixed one or a poorly-mixed ready-mixed concrete which is added with sand, cement, water or mortar slurry before pumping to make the rich-blended combination. When the ready-mixed concrete that has been driven in is in a state where it does not harden yet in the formwork, sand, a tube material having a hole through which only a mortar slurry that is a mixture of cement and water can be inserted into the ready-mixed concrete, And vibrate it,
The mortar slurry having high fluidity in the ready-mixed concrete is exuded and extracted from the holes. As a result, the ready-mixed mortar from which the mortar slurry has been extracted becomes a poorly-mixed and hard-mixed product having a low water content, so that high strength and a fine finish can be obtained after curing.

Then, the mortar slurry that has been extracted and accumulated in the tubular material is sent by a feed pump provided in the tubular material. The sent mortar slurry is mixed into the subsequent poorly mixed ready mixed concrete on the side where the concrete pump enters before it is hardened to make the ready mixed rich mixture. Then, the succeeding ready-mixed concrete mixed with the rich mixture is pressure-fed by a concrete pump and driven into the form.

The sucked-out mortar slurry can be mixed with fresh mixed concrete in the concrete pump receiving hopper or the concrete mixer. By repeating the above-described steps, it becomes possible to easily place a poorly mixed and hard-mixed ready-mixed concrete which has been conventionally impossible to be pumped, and the mold fits well. In other words, by using the mortar slurry as a fluidizing agent (by repeatedly using it if continuously mixed in the subsequent ready-mixed concrete), high strength can be obtained with poorly-mixed inexpensive ready-mixed concrete.

In general, a commercially available vacuum device requires an electric power of 1050 w and a lift of 2.7 m when sucking water, and the main body of the machine is bulky. Since the mortar slurry is a fluid having a specific gravity of 2.1 for sucking from the top of the mold, only about half the lift of water can be expected. Although it is effective for molds with no depth such as slabs and floor slabs, a separate device is required to remove from molds with large depth such as pillars and abutments.

A pump is provided in the vibrating cylinder to satisfy the above-mentioned requirements. Since the suction port is opened to the bottom of the cylinder, the suction lift is almost zero. A small pump is sufficient because the discharge head has little energy loss. The small discharge amount can be covered by increasing the number of units used. Since the device is small and the manufacturing cost is low, the feed capacity is higher than that of the vacuum device. Also, because the device configuration is small, the mortar slurry is extracted to every corner of the mold,
It can be vigorously compacted. Further, since the vibrating device and the feed pump are integrally provided on the cylindrical member, they can be moved collectively when the mortar slurry is taken out from the mold, so that the handling is simple.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a configuration explanatory view of a mortar slurry extracting section according to a concrete pouring method of the present invention,
FIG. 2 is an explanatory view of a placing method using the mortar slurry extracting portion. In the embodiment, as shown in FIG. 2, when the fresh mixed concrete 1 is pumped by the concrete pump car 10 and driven into the mold 11, the mortar slurry 3 in the fresh mixed concrete 1 which is cast using the mortar slurry extracting section is used. The collected mortar slurry 3 is mixed into the subsequent raw concrete before being collected and pumped by the concrete pump car 10.

The mortar slurry extracting portion shown in FIG. 1 mainly has a vibrating cylinder 2, a vibrating device 4, and a feed pump 6. The vibrating cylinder 2 is inserted from above into the ready-mixed concrete 1 cast in the mold 11, and has a hole 5 through which only the mortar slurry 3 in the ready-mixed concrete 1 can pass.

The vibrating cylinder 2 is used by being inserted into the ready-mixed concrete 1 from above, and as shown in FIG. 1, has a substantially elliptic cylindrical shape with a lower end 2b closed, and its surface. A large number of holes 5 communicating from the surface to the inside are formed. Further, since the lower end portion 2b of the vibrating cylinder 2 is closed, the vibrating cylinder 2 has a container shape and the mortar slurry 3 exuding through the hole 5 is temporarily stored (accumulated) in the space above the lower end portion 2b. It is like this. For this lower end portion 2b, a shape such as a hemispherical shape or a tapered shape that can be easily inserted into the ready-mixed concrete 1 can be selected. Further, the hole 5 of the vibrating cylinder 2 is
The mortar slurry 3 can be passed through and the aggregate 7 can be blocked. The size of the hole 5 is, for example, as shown in FIG.
As shown in FIG. 2, the aggregate 7 can be formed to have a size substantially corresponding to the diameter of the aggregate 7. For example, inner diameter 3.5m
It can be m.

The vibrating device 4 is a vibrating body composed of a bar-shaped vibrator, and is fixed to the inner wall 2a of the vibrating cylinder 2 by fastening it with bolts or the like to vibrate the vibrating cylinder 2 to vibrate the raw concrete 1 Only the mortar slurry 3 is exuded from the inside through the hole 5 (shown by a solid arrow c in FIG. 1) and extracted.

The feed pump 6 is provided in the vibrating cylinder 2, sends out the mortar slurry 3 that is extracted and accumulated in the vibrating cylinder 2, and receives the hopper of the concrete pump car 10 through the flexible pipe 8. 1
It leads to the 0a side and the concrete mixer truck 12. In addition, in the embodiment, the feed pump 6 has pump blades (for example, a spiral shape) 6d inside the cylindrical body 6c, the lower end portion 6a is an inlet of the mortar slurry, and the lower end portion 6a vibrates. It is positioned so as to be immersed in the mortar slurry accumulated in the cylinder 2, and is fixed in the vibration cylinder 2 together with the vibration device 4. Also,
The feed pump 6 is driven by the motor 9 of the drive source of the vibrating device 4 from the respective upper end portions 6b and 4a, so that the structure is downsized. The feed pump 6 may be a vertical pump, a mohno pump, a sand pump, or a vortex. Further, when a plurality of the vibrating cylinders 2 and the feed pumps 6 are used, the mortar slurry is sent from the feed pump 6 as it is, but in addition, a pump portion (reference numeral 16) for sending the mortar slurry 3 to the receiving hopper 10a side at a time. ) Is provided in the middle of the feeding route of the mortar slurry 3. Further, the drive motor of the feed pump 6 may be placed separately from the pump 6, and the feed pump 6 may be driven by a universal joint. Thereby, even if the vibration device 4 is driven, the vibrating cylinder 2 can be easily handled even if the drive motor is increased in size. In FIG. 2, reference numeral 13 is a vibration device 4 and a pump 6.
It is a generator that generates power to be supplied to.

Next, an example in which the concrete pouring method of the present invention is carried out by using the mortar slurry sampling portion will be described. First, the ready-mixed concrete 1 that has been richly mixed in advance is pressure-fed by a concrete pump (concrete pump car 10) and driven into the mold 11. Next, when the driven raw concrete 1 is not yet solidified in the mold 11, the mortar slurry extraction part is vertically inserted into the raw concrete 1 and inserted. At the same time, the vibrating device 2 is vibrated by the vibrating device 4.
Is vibrated, and only the mortar slurry 3 in the ready-mixed concrete is exuded from the hole 5 and extracted. At this time, as shown in FIG. 1, the mortar slurry 3 drops on the lower end portion 2b in the vibrating cylinder 2 as shown by reference numeral c and accumulates as shown by reference numeral 3a. Before the collected mortar slurry is solidified, it is fed into the mixer 12a of the mixer truck 12 or the receiving hopper 10a of the concrete pump by the feed pump 6 provided in the vibrating cylinder 2, and the mixer 12a.
It mixes into the subsequent raw mix of poor composition inside or in the receiving hopper 10a, and changes the raw mix 1 into a ready mixed mix of high fluidity and easy to cast.

The subsequent ready-mixed concrete mixed with the rich mixture is pressure-fed by a concrete pump (concrete pump car 10) and driven into the mold 11. Therefore, the ready-mixed concrete 1 can be easily sent by the concrete pump and can be placed in the mold 11. Further, the extracted mortar slurry 3 may be put into the mixer 12a of the mixer truck 12 as described above and mixed into the subsequent ready-mixed concrete 1 in the mixer 12a. Further, the mortar slurry 3 may be received in the pump truck 10 receiving hopper. It may be put in 10a and mixed in the subsequent raw concrete 1 sent from the mixer truck 12 in this hopper. In any case, the mortar slurry 3 is used as a fluidizing agent by being mixed with the subsequent ready-mixed concrete 1.

When the mortar slurry 3 in the ready-mixed concrete 1 that has been once cast is mixed in the subsequent fresh mix 1, when the mixed mortar slurry 3 is extracted again after the mixed fresh concrete 1 has been cast, the mortar slurry 3 previously mixed in is mixed. Then, the mortar slurry 3 in the subsequent ready-mixed concrete 1 is extracted, and the mortar slurry as the fluidizing agent is gradually replaced. Therefore, the mortar slurry 3 is repeatedly used part by part.

Further, in the above case, when the vibrating cylinder 2b is inserted into the ready-mixed concrete 1 placed evenly, 3 minutes of the mortar slurry is extracted, so that breathing water, aggregates 7 and water film on the lower surface of the reinforcing bar are formed. It also disappears and removes air bubbles that stick to the formwork and remain. Further, the slump of the ready-mixed concrete 1 after the casting is rapidly lowered, and the earth pressure on the form becomes close to zero. At this time, if the tool is used for tucking up and it is compacted with a foot, there is no sinking action of the aggregate, and the variation in the finished strength is almost eliminated. It has also been confirmed by experiments that no material separation occurs.

[0026]

As described above, according to the present invention,
With the feed pump, the mortar slurry can be sufficiently extracted from the deep formwork, and the energy (electric power) required for the work can be drastically reduced, so the power usage cost of the equipment can be reduced and the construction cost can be reduced. it can. Also,
Since the device configuration is small, the device cost is reduced. further,
The feed pump is provided in the tubular material, and although the discharge amount and the lifting height are inferior, the feed capacity is not insufficient, and the work can be reduced because the size is reduced and the work load can be reduced.

Further, since the feed pump provided in the tubular member is a small-sized device, the mortar slurry feeding capacity higher than that of the vacuum device can be obtained by increasing the required number. Since the device configuration does not increase in size, the mortar slurry can be extracted to every corner of the ready-mixed concrete in the mold to carefully perform vibration compaction. Therefore, concrete that does not crack, has no air bubbles, and has little variation in strength can be obtained in the entire form. In addition, since the floating water, sand, and cement components are removed, there will be no leavetance on the surface of the concrete after hardening. Also, if the step of mixing the absorbed mortar slurry into the subsequent ready-mixed concrete and further extracting the mortar slurry after placing the ready-mixed concrete is repeated, the absorbed mortar slurry will be replaced one after another, so it will be effective as a fluidizing agent. It lasts until the end. Also, when the mortar slurry is extracted, the fluidity of the ready-mixed concrete is lost, the bearing capacity is increased, and the earth pressure applied to the formwork is extremely reduced, so continuous splicing can be performed and a large amount of castings such as retaining walls can be placed at once. Therefore, the construction cost can be significantly reduced. In addition, ready-mixed concrete with extremely low water content is suitable for placing in cold regions. Also, for the same reason, it becomes possible to pump the mass concrete for dams and levees, which was considered impossible in the past.

[Brief description of drawings]

FIG. 1 is an explanatory view of a mortarial slurry extracting section for concrete provided in a concrete placing apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory view of a usage state of the concrete placing device according to the embodiment.

[Explanation of symbols]

 1 Ready-mixed concrete placed in the mold 2 Vibration cylinder 3 Mortar slurry 4 Vibration device 5 Hole 6 Feed pump 7 Aggregate 10 Pump car 10a Receiving hopper 11 Form frame 12 Mixer car 12a Mixer 13 Generator

Claims (1)

[Claims] 1. A method for placing concrete in which mortar is used when the ready-mixed concrete with a rich mixture is pumped by a concrete pump to drive it into the form, and when the injected ready-mixed concrete is not yet solidified in the form. Inserting a tubular material having a hole through which only slurry can be passed into the ready-mixed concrete, and vibrating it so that only the mortar slurry in the ready-mixed concrete is exuded and extracted from the hole; The step of sending the mortar slurry accumulated in the material by the feed pump provided in the tubular material, and mixing the mortar slurry sent into the raw material of the poor mixture of the subsequent poor mixture on the inlet side before it is solidified yet Of the mortar slurry including the step of making the rich mixture of A method of placing concrete, characterized in that it is used as a fluidizing agent.