JP2000034461A - Aid for start of pressurized feed for concrete feed pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a smooth start of the pressurized feed of concrete with the use of a small amt. of an aid for the start by employing a water-absorbent resin. SOLUTION: The use of a water-soluble resin, in addition to a water- absorbent resin, is pref.; usually, it is pref. that the proportion of a water-soluble resin is lower than 80 wt.% based on the sum of the water-absorbent and water- soluble resins. Examples of the water-absorbent resin are a crosslinked polyacrylic acid, a crosslinked polyacrylate, a crosslinked polyethylene oxide, a crosslinked ethylene oxide-propylene oxide copolymer, and a water-absorbent polyurethane. Examples of the water-soluble resin are guar gum, methylcellulose, hydroxyethylcellulose, and polyvinyl alcohol. The inititor is usually dispersed in water just before its use, and the resultant dispersion is charged into the hopper of a concrete pump. Pref., the concn. of the initiator in the dispersion is 0.01-5 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a pumping initiator, and more particularly to a pumping initiator for a concrete pump.

[0002]

2. Description of the Related Art In a foundation work for a building or a construction work for a concrete building, an operation of driving concrete into a predetermined place is performed. Conventionally, in such concrete driving work, concrete transported from a ready-mixed concrete plant by a concrete mixer truck is transported to a predetermined driving place using a bucket, a cart, a belt conveyor, a chute, or the like. However, such a concrete transporting operation has problems that it is necessary to rely on human power and that the driving position cannot be easily changed.

For this reason, recently, a method of using a concrete pump and a transport pipe to transport concrete supplied to a hopper to a predetermined driving work place has been widely adopted. In this method, concrete in a hopper is pumped into a transport pipe using a concrete pump, and the concrete is transported to a target driving place through the transport pipe. Incidentally, the types of concrete pumps used in this method include a piston type, a squeeze type, and a diaphragm type. Recently, the use of the piston type and the squeeze type is increasing. In addition, concrete pumps are classified into stationary, trailer and on-vehicle types depending on the type of movement. Here, the onboard concrete pump is
It is generally called a pump car, and among them, the one equipped with a long transport pipe is called a boom type.

[0004] When concrete is pumped using a concrete pump and a transport pipe, a hopper is previously filled with a cement paste or mortar as a pumping initiator, and this pumping initiator is first fed into the transport pipe. Subsequently, while the ready-mixed concrete is poured into the hopper, the ready-mixed concrete is continuously fed into the transport pipe and pressure-fed. Here, the pumping agent is sent first because the concrete pump often does not operate smoothly when the ready-mixed concrete is poured directly into the transport pipe, and the transport pipe is blocked, making it impossible to pump the ready-mixed concrete. This is because it may be.

However, in the above-mentioned method using cement paste or mortar as a pressure-feeding initiator, a hardening reaction proceeds during transportation or while the concrete is being driven at the place where the concrete is to be poured. There is a need. In addition, this method requires a large amount of cement paste or mortar, which is a pumping initiator, to be used in order to obtain a desired effect. Likely to adversely affect the quality of the product.

An object of the present invention is to provide a pumping initiator for a concrete pump that can start pumping concrete smoothly with a small amount of use.

[0007]

The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have started pumping for a concrete pump containing a water-absorbent resin or a mixture of a water-absorbent resin and a water-soluble resin. The present inventors have found that when the agent dispersed in water is fed into a transport pipe, and then concrete is fed into the transport pipe, the concrete pump operates smoothly and the transport pipe is hardly clogged, thus completing the present invention.

That is, the pumping initiator for a concrete pump of the present invention contains a water-absorbing resin. The pumping initiator preferably further contains a water-soluble resin. In this case, the content of the water-soluble resin is usually less than 80% by weight of the total amount with the water-absorbing resin.

The water-absorbing resin used in such a concrete pump pressure-initiating initiator includes, for example, a crosslinked product of polyacrylic acid, a crosslinked product of polyacrylate, a crosslinked product of polyethylene oxide, and a copolymer of ethylene oxide and propylene oxide. It is at least one selected from the group consisting of a crosslinked product of a coalesced product and water-absorbing urethane. The water-soluble resin contained together with the water-absorbent resin is, for example, at least one selected from the group consisting of guar gum, methyl cellulose, hydroxyethyl cellulose, and polyvinyl alcohol.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The pumping initiator for concrete pumps of the present invention is usually in the form of powder and may be composed of only a water-absorbing resin, or may contain other components in addition to the water-absorbing resin. May be. The water absorbent resin used in the present invention is
There is no particular limitation, and various known (preferably powdery) materials which are insoluble in water and which can preferably form spherical particles upon absorption of water.

Specific examples of the above-mentioned water-absorbing resin include a crosslinked product of polyacrylic acid, a crosslinked product of polyacrylate, a crosslinked product of acrylic acid-vinyl alcohol copolymer, and an acrylate-vinyl alcohol copolymer. Crosslinked product of starch-
Crosslinked product of acrylic acid graft copolymer, crosslinked product of starch-acrylate graft copolymer, crosslinked product of isobutylene-maleic acid copolymer, crosslinked product of isobutylene-maleic acid copolymer, styrene-maleic anhydride Crosslinked product of acid copolymer or salt thereof, crosslinked product of saponified vinyl ester-ethylenically unsaturated carboxylic acid copolymer, crosslinked product of saponified vinyl ester-ethylenically unsaturated carboxylic acid derivative copolymer, polyethylene oxide , An ethylene oxide-propylene oxide copolymer cross-linked product, and water-absorbing urethane.

Incidentally, the acrylate and maleate constituting the water-absorbing resin mentioned in this example include:
Monovalent alkali metal salts such as sodium salts and potassium salts are preferably used. Further, the above-mentioned water-absorbing resins may be used alone or in combination of two or more. In addition, as the water-absorbing resin, a crosslinked product of polyacrylic acid, a crosslinked product of polyacrylate, a crosslinked product of polyethylene oxide, a crosslinked product of polyethylene oxide, in that industrial production is easy and easily available and handling is easy. −
It is preferable to use a crosslinked product of a propylene oxide copolymer and water-absorbing urethane.

[0013] The pumping initiator for a concrete pump of the present invention may contain a water-soluble resin in addition to the water-absorbing resin described above. In this case, the pumping initiator of the present invention can start pumping concrete more smoothly than in the case where the above-described water-absorbing resin is used alone.

The water-soluble resin that can be used in the present invention is not particularly limited, and is preferably a known various powdery resin. Examples thereof include guar gum, locust bingham, quinceed gum, gum arabic, and the like. Natural water-soluble resins such as sodium alginate, starch, gelatin and chitosan, carboxymethylcellulose, carboxymethylcellulose salts, hydroxyethylcellulose,
Semi-synthetic water-soluble resins such as hydroxypropylcellulose, methylcellulose, hydroxyethylmethylcellulose, hydroxypropylmethylcellulose and hydroxyethylethylcellulose, and synthetic water-soluble resins such as polyacrylamide, polyethylene oxide, polyvinyl alcohol, sodium polyacrylate and polyvinylpyrrolidone. Can be.

Of these, guar gum, methylcellulose, hydroxyethylcellulose, and polyvinyl alcohol are preferably used because they are easily available and have little effect on concrete. In addition, each of the above-mentioned various water-soluble resins may be used alone, or two or more of them may be used in combination.

When the pumping initiator for a concrete pump of the present invention contains the above-mentioned water-soluble resin, the mixing ratio of the above-mentioned water-absorbent resin and the water-soluble resin is usually the sum of the water-absorbent resin and the water-soluble resin. The ratio of the water-soluble resin to the amount is preferably set to be less than 80% by weight, and more preferably set to be less than 60% by weight. When the mixing ratio of the water-soluble resin is 80% by weight or more, it is difficult for the water-absorbing resin to exert the bearing effect described later, and smooth pumping of concrete in the transport pipe may be spoiled.

Next, a method of using the pumping initiator for a concrete pump of the present invention will be described. The pumping initiator for a concrete pump of the present invention is usually dispersed in water immediately before use, and is poured into a hopper of a concrete pump as a dispersion obtained thereby. When preparing the dispersion, the concentration of the pumping initiator for the concrete pump is usually
It is preferably set to 0.01 to 5% by weight, and 0.1 to 5% by weight.
More preferably, it is set to 2% by weight. This concentration is 0.
When the amount is less than 01% by weight, the viscosity of the dispersion is insufficient, and the pressure-feeding initiator may not be able to exert the required effect. vice versa,
If the content exceeds 5% by weight, the fluidity of the dispersion liquid may decrease, and it may be difficult to handle the dispersion liquid.

When the above-mentioned dispersion liquid is prepared, the pumping initiator of the present invention is prepared in the form of a paste or a solution using a surfactant soluble in water or a solvent such as glycerin or polyethylene glycol in advance. After that, they may be dispersed in water. Further, in order to enhance the dispersibility of the pumping initiator of the present invention in the dispersion, various dispersants, for example, inorganic powders such as silica sand, fume silica, fly ash and shirasu balloon, walnut shell, etc. at the time of preparing the dispersion. Organic powders such as powder, rice husk powder, wood powder and coconut husk powder can be appropriately added to water. In addition, such a dispersant may be previously added to the pumping initiator of the present invention.

The above-mentioned dispersion liquid put into the hopper is
It is pumped into the transport pipe by a concrete pump. Subsequently, when the concrete is put into the hopper and the pumping by the concrete pump is started, the concrete flows smoothly in the transport pipe due to the pumping initiator of the present invention contained in the above-mentioned dispersion liquid pumped earlier. . This is because the water-absorbent resin constituting the pumping initiator of the present invention in the dispersion liquid absorbs and swells to form spherical particles, and the particles adhere to the inner wall of the transport pipe and exhibit an effect like a bearing,
It is considered that the friction between the inner wall of the transport pipe and the concrete being pumped is reduced (this is referred to as a “bearing effect” in this specification).

In the case where the pressure-feeding initiator of the present invention further contains the above-mentioned water-soluble resin, the above-mentioned dispersion is given an appropriate viscosity, thereby preventing the air from leaking into the working part of the concrete pump. In addition, since lubricity can be imparted to the inner wall of the transport pipe and the surface of the water-absorbed and swollen water-absorbent resin particles, the concrete can be more smoothly pumped in the transport pipe.

Incidentally, the amount of the above-mentioned dispersion prepared using the pumping initiator of the present invention can be appropriately set according to the capacity of the concrete pump to be used, the inner diameter and the length of the transport pipe, and the like. However, it is usually about 10 to 25 liters. Therefore, in view of the above-described concentration of the pumping initiator of the present invention contained in the dispersion, the amount of the pumping initiator of the present invention required to prepare the required amount of the dispersion is usually several hundred grams, Specifically, it is about 1 to 1,250 g, which is extremely small compared to the required amount of a conventional pumping initiator, that is, cement paste or mortar (usually 500 to 1,500 kg). For this reason, the pumping initiator of the present invention is easy to carry and can easily prepare a dispersion anytime and anywhere as long as a required amount of water is provided, and the pumping of concrete by a concrete pump is economical and economical. You can easily get started.

Moreover, since the required amount of the pumping initiator of the present invention is extremely small as compared with the conventional one, as described above, the proportion of the total amount of the concrete to be pumped is very small. Even hard to damage the quality of concrete.

[0023]

Example 1 80 g of a crosslinked product of sodium polyacrylate as a water-absorbing resin (trade name "Aqua Keep" of Sumitomo Seika Co., Ltd.)
And a commercially available guar gum made of Pakistan which is a water-soluble resin 2
0 g was mixed with a mixer to prepare 100 g of a pumping initiator.

Next, 15 liters of water was stored in a hopper of a concrete pump truck with a boom, and the entire amount of the above-described pressure-feeding initiator was charged into the water to prepare a dispersion. And
After the concrete pump is started and the dispersion liquid is fed into the transport pipe, then concrete is put into the hopper from the concrete mixer truck, and the concrete (total amount = 4.5 m ³ ) is continuously pumped into the transport pipe. did. At this time, the transport pipe was not blocked, and the concrete pump continued to operate continuously and smoothly, so that the concrete could be pumped smoothly.

Example 2 Crosslinked product of sodium polyacrylate as a water-absorbing resin (trade name “Aquakeep” of Sumitomo Seika Co., Ltd.) 80
g, 20 g of methylcellulose as a water-soluble resin (trade name of "Metroise" of Shin-Etsu Chemical Co., Ltd.) and 2 g of hydrophilic fumed silica as a dispersant were mixed using a mixer to prepare 102 g of a pressure-feeding initiator. When the obtained pumping initiator was used in the same manner as in Example 1,
The same results as in Example 1 were obtained.

Example 3 Crosslinked product of sodium polyacrylate as a water-absorbing resin (trade name "Aquakeep" of Sumitomo Seika Co., Ltd.) 50
g, water-soluble resin hydroxyethyl cellulose powder (trade name “Fujichem HEC” of Sumitomo Seika Co., Ltd.) 50
g and 20 g of polyethylene glycol as a solvent were mixed to prepare 120 g of a paste-like pressure-feeding initiator. When the obtained pressure-feeding initiator was used in the same manner as in Example 1, the same results as in Example 1 were obtained.

Example 4 180 g of a crosslinked product of polyethylene oxide as a water-absorbing resin (trade name "Aqua Coke" of Sumitomo Seika Co., Ltd.)
And 20 g of polyvinyl alcohol powder as a water-soluble resin
Was mixed using a mixer to prepare 200 g of a pumping initiator. The obtained pumping initiator was used in the same manner as in Example 1 except that the amount of water stored in the hopper was changed to 20 liters, and the same results as in Example 1 were obtained. .

Example 5 A crosslinked product of sodium polyacrylate as a water-absorbent resin (trade name "Aqua Keep" of Sumitomo Seika Co., Ltd.) 100
A pumping initiator consisting only of g was prepared. When the obtained pressure-feeding initiator was used in the same manner as in Example 1, the same results as in Example 1 were obtained.

[0029]

The pumping initiator for a concrete pump of the present invention contains a water-absorbing resin as described above, so that the pumping of concrete through a transport pipe can be started smoothly with a small amount of use. In particular, when the pumping initiator further contains a water-soluble resin, the pumping of concrete can be started more smoothly.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yuji Shinkai 1st Irifune-cho, Himeji-shi, Hyogo Sumitomo Seika Co., Ltd. (72) Inventor Kenji Wada 4-7 Kitahama, Chuo-ku, Osaka-shi, Osaka No. 28 Sumitomo Seika Co., Ltd. Osaka head office F-term (reference) 4G056 AA07 AA23 CE04 CE05

Claims (5)

[Claims] 1. A pumping initiator for a concrete pump containing a water-absorbing resin. 2. The pumping initiator for a concrete pump according to claim 1, further comprising a water-soluble resin. 3. The pumping initiator for a concrete pump according to claim 2, wherein the content of said water-soluble resin is less than 80% by weight of the total amount with said water-absorbing resin. 4. The water-absorbent resin is selected from the group consisting of a crosslinked product of polyacrylic acid, a crosslinked product of polyacrylate, a crosslinked product of polyethylene oxide, a crosslinked product of ethylene oxide-propylene oxide copolymer, and water-absorbing urethane. The pumping initiator for a concrete pump according to claim 1, 2 or 3, which is at least one selected from the group consisting of: 5. The pumping initiator for a concrete pump according to claim 2, wherein the water-soluble resin is at least one selected from the group consisting of guar gum, methylcellulose, hydroxyethylcellulose and polyvinyl alcohol.