JP2592495B2 - Admixture for concrete - Google Patents

Description

The present invention relates to an admixture for cement, mortar, and concrete, and more particularly to an air entraining agent (hereinafter referred to as an AE agent). The present invention relates to an AE agent capable of preventing the amount of air in cement, mortar and concrete from decreasing with time.

[Prior art] By using an AE agent that gives air entrainment to cement slurry, mortar and concrete, (1) improvement in freeze-thaw resistance, (2) improvement in workability, and (3) improvement in pumpability (4) There are effects such as a decrease in breathing due to an increase in the water retention capacity of air bubbles, and (5) a decrease in unit water volume. Commonly used AE agents include anionic surfactants such as resin acid Na salt, alkylbenzene sulfonate, triethanolamine salt of alkyl sulfonic acid, polyoxyethylene alkyl sulfate, and polyoxyethylene alkyl phenol. Nonionic activators and the like. In addition, examples of the air entraining type water reducing agent include lignin sulfonic acid salt and alkyl naphthalene sulfonic acid formalin condensate. On the other hand, examples of the low-foaming water reducing agent, that is, a water reducing agent in which the amount of air in concrete is 3% or less in a normal amount, include β-naphthalenesulfonic acid formalin polycondensate, melamine formalin condensing agent sulfonate, and the like. . Normally, the amount of air entrained in concrete by the combination of AE agent and water reducing agent is constant (4
± 1%), and preferably does not decrease with time.

[Problems to be solved by the invention]

However, the amount of air entrained by the conventional AE agent will decrease drastically over time due to factors such as the water-cement ratio of the concrete, the mix of the concrete, the softness of the concrete, and the fly ash substitution rate of the cement. There was a disadvantage.

[Means for solving the problem]

The present invention has been made to improve the above-mentioned disadvantages of the conventional AE agent. Normally, concrete contains air bubbles of 1 to 2% without using an AE agent, but air bubbles are actively entrained by using an AE agent. When an anionic surfactant is used as the AE agent, since the surface tension of the water in the concrete is lowered, bubbles are easily introduced by a little stirring as compared with water containing no surfactant. In the surrounding water, the lipophilic group of the anionic surfactant is oriented toward the gas side, and the hydrophilic group is oriented toward the water side. As the addition amount of the activator increases, the distance between the molecules becomes closer, the intermolecular attraction increases, and the bubbles are stabilized. However,
It is said that when a low-foaming water reducing agent is added to the active agent, the active agent enters between the molecules of the active agent, weakens the intermolecular attractive force, and easily breaks bubbles. Of course, defoaming may be performed by cement, aggregate, or blades of a mixer. Also, the diameter of the entrained bubble is
When the thickness is 20 μm or less, the internal pressure of the bubbles rapidly increases, and the bubbles dissolve in water and disappear.

The present inventors have conducted intensive studies on a method capable of entraining air bubbles from one to the next even if air bubbles in the concrete entrained by the activator are defoamed, and the average particle diameter is 0.05 to 100 μm.
It has been found that when a resin acid or a metal complex of a resin acid insoluble or water-insoluble in water of m is added to concrete, the target air volume can be maintained for a long time, and the present invention has been completed. That is, fine particles of a resin complex or a divalent or higher metal complex of a resin acid are water-insoluble or hardly soluble in ordinary water, but when added to concrete, react with alkali ions eluted from the concrete, become soluble, and gradually become soluble. It elutes, lowers the surface tension of the concrete, embraces the air by the stirring force of the concrete mixer to form bubbles, and compensates for the amount of bubbles that have been defoamed for the reasons described above, thereby stabilizing the amount of air with time.

In the present invention, a metal complex refers to a complex in which a carboxyl group and a polyvalent metal in a resin acid are bonded intramolecularly or intermolecularly to form a hardly water-soluble or insoluble compound.
Further, in the present invention, the resin acid is a general term for organic acids that are present in free or as an ester in a natural resin, and the particle size of the resin acid or metal complex fine particles thereof is formed so as not to adversely affect the physical properties of concrete. The smaller is preferable. However, if it is too small, the surface area of the fine particles increases, almost dissolves during the concrete kneading, and the temporal stability of the air amount deteriorates. On the other hand, if the particle size is too large, the surface area of the fine particles will be small, the amount of addition to obtain the target air amount will be large, and the entire amount will not be dissolved at the time of placing the concrete, undissolved particles will remain, reducing the strength of the concrete. Wake up is not preferred. From these, the average particle size is 0.
It is necessary that the thickness is from 0.05 to 100 μm, preferably 0.05
5050 μm.

As the resin acid used in the present invention, a commercially available resin acid can be used as long as it has a desired average particle size. If the particle size is too large, it is used after crushing.

The polyvalent metal used in the production of the polyvalent metal complex of the resin acid is a divalent or higher valent metal, and forms a compound showing water-insolubility or poorly water-soluble by bonding intramolecularly or intermolecularly to the carboxy group of the resin acid. Anything can be used. The amount added to the resin acid is 50-50 of the neutralization equivalent of the resin acid.
0% is desirable. Practical compounds include Ca, Mg, Ba, Z
Hydroxides of n, Fe and Al are generally used, but they may be used in the form of salts such as carbonic acid, sulfuric acid and nitric acid, or oxidized forms. The polyvalent metal complex of the resin acid can be easily formed by mixing the above-mentioned polyvalent metal compound with a water suspension of the resin acid or an aqueous solution of an alkali metal salt of the resin acid. At this time, heat treatment is a preferable method from the viewpoint of accelerating the reaction. Due to the reaction between the resin acid and the polyvalent metal compound, all may be in the form of a polyvalent metal complex, or the complex may be partially complex and the remainder may be in the form of a mixture with a free resin acid, in any case. There is no significant difference in effect. Fine particles of resin acid are fine when stored as fine powder, but when stored in a water suspension, they gradually dissolve, and the long-term retention of air when used as an AE agent is inferior to that of a polyvalent metal complex Therefore, in the present invention, a method of forming a polyvalent metal complex is preferable.

The admixture for concrete of the present invention can be used in combination with other admixtures such as a commercially available water reducing agent, slump loss inhibitor, fast-strength agent, foaming agent, defoaming agent and the like. As the form of the admixture of the present invention, there are a powder and a granule, a water suspension, and it is also possible to mix the admixture with cement in advance. As for the time of addition to the concrete, it can be added at any time up to the time of placing the concrete, and the effect is sufficiently exhibited. When transporting concrete with a ready-mixed concrete mixer truck, it is desirable to provide appropriate stirring. Also, in the case of mixed concrete, remixing is necessary.

The amount added to the cement varies depending on the composition of the concrete, the softness, and the type of the combined admixture, but is usually 0.001 to 0.1% with respect to the cement.

〔Example〕

 Hereinafter, the effects of the present invention will be described with reference to examples.

Example 1 Hydrocarbon compound 14.6%, rosin derivative compound 27.3
%, 50 g of a resin acid composed of 58.1% of a phenolic compound (manufactured by Hercules, USA; VIN SOL resin) as shown in Table 1
A trivalent or trivalent metal compound was added, and 900 g of water was added thereto, followed by stirring with a juice mixer for 30 seconds. 200g of this suspension together with 500g of glass beads (0.5mm in diameter) and a sand glider (Igarashi Machine Manufacturing Co., Ltd .; No.TSG-6H)
, Pulverized at 1500 rpm while cooling, and after the pulverization, remove the glass beads with a filter and measure the particle size (manufactured by Shimadzu Corporation; sedimentation type particle size distribution analyzer / SA-CP3)
Shape). The obtained suspension was added to concrete, and the time-dependent change in the amount of air, slump, and compressive strength were measured. The water reducing agent used in combination was a highly condensed β-naphthalenesulfonic acid formalin high-condensate Ca salt, a finely divided product of lower olefin (carbon number 4) and maleic anhydride copolymer (average particle size 0.10 μm) in a solid content ratio of 95: 5. It was blended, and 0.5% of cement was added in terms of solid content. The mixer used was a tilting cylinder type, which was stirred for up to 60 minutes by rotating 4 times per minute after concrete kneading.

Vinsol (a product sold by Yamamune Chemical Co., Ltd.), which is a Na salt of resin acid, was used as a comparative AE agent.

Table 1 shows the <Blending of concrete> W / C = 55.5% S / A = 50.0% C = 320kg / m 3 ( central Portland cement) fine aggregate = Kinokawa production assembly aggregate = Takarazuka production crushed stone Results As is clear from Table 1, the product of the present invention, which is obtained by mixing a resin acid and a polyvalent metal compound and finely pulverizing, does not decrease the compressive strength of the concrete, and the target concrete air volume (4 ±
1%) for a long time. In contrast, monovalent metal salts (Na
Vinsol, which is an aqueous solution of salt, cannot maintain the target amount of air for a long time, and it can be said that the product of the present invention is an excellent AE agent.

Example 2 A mixture of various resin acids and a polyvalent metal compound obtained in Example 1 was heated at 90 ° C. for 5 hours. About this one,
The time change of the air amount was measured by a concrete test.
Concrete was mixed and tested in the same manner as in Example 1. Table 2 shows the results.

The fine particles of the present invention, which are obtained by blending a resin acid and a polymetal compound, finely pulverizing, and further heat-treating, can reduce the concrete compressive strength without reducing the target concrete air volume (4 ± 1%). It is understood that this is an excellent AE agent that holds for a long time.

Example 3 A predetermined amount of a divalent or trivalent metal compound shown in Table 3 (1.2 times the neutralization equivalent of the carboxyl group of the resin acid) was added to 50 g of the same resin acid as in Example 1, and the mixture was heated at 85 ° C. for 10 hours. After stirring and cooling, it was confirmed by infrared absorption spectrum that it had become a metal salt. About this thing, the time-dependent change of the air amount was measured by the concrete test. Concrete was mixed and tested in the same manner as in Example 1. Table 3 shows the results.

It can be seen that the finely divided resin acid polyvalent metal complex obtained by the heat treatment according to the present invention has the effect of maintaining the target air amount for a long time without lowering the compressive strength of concrete.

Example 4 Hydrocarbon compound 14.8%, rosin derivative compound 27.4
%, A resin acid composed of 58.0% of a phenolic compound (manufactured by Hercules, USA; VIN SOL resin), and 900 g of water were added thereto, followed by stirring with a shoe mixer for 30 seconds. 200g of this suspension together with 500g of glass beads (0.5mm in diameter) and a sand glider (Igarashi Machine Manufacturing Co., Ltd .; No.TSG-6H)
And then pulverize at 1500 rpm while cooling, remove the glass beads with a filter after pulverization, and measure the particle size (Shimadzu Corporation; sedimentation type particle size distribution analyzer / SA-CP3 type)
did. The obtained suspension was added to concrete, and the amount of air was changed with time, slump, and compressive strength were measured. The water reducing agent used is a calcium salt of β-naphthalenesulfonic acid formalin highly condensed product, fine particles of lower olefin (carbon number 4) and maleic anhydride copolymer (average particle size 0.10 μm) blended at a solid content ratio of 95: 5. 0.5% of cement was added in terms of solid content. In addition, the mixer used was tilted and rotated four times a minute after concrete kneading, and stirred for 60 minutes.

Vinsol (a product sold by Yamamune Chemical Co., Ltd.), which is a Na salt of resin acid, was used as a comparative AE agent.

<Concrete composition> W / C = 55.7% S / A = 50.0% C = 320 kg / m ³ (Central Portland cement) Fine aggregate = Kinokawa coarse aggregate = Takarazuka crushed stone The results are shown in Table 4. As shown in Table 4, the commercially available AE agent Vinsol has a drastic decrease in the amount of air with time immediately after kneading. On the other hand, the product of the present invention has high stability over time and is found to be an excellent AE agent ensuring 4 ± 1%. It can be seen that the initial amount of air in the resin acid fine particles increases, but the stability with time of the bubbles can be further improved by adding a small amount of an antifoaming agent thereto (Experiment Nos. 2 and 3). When the particle size increases (Experiment No. 6), the amount of air decreases slightly with time. In this case, the air amount is further stabilized by adding a small amount of a commercially available AE agent (Experiment No. 7). It can be seen that it can be converted to.

Claims (2)

(57) [Claims] An average particle size of from 0.05 to 0.05 which is insoluble or poorly soluble in water.
A concrete admixture containing 100 μm fine particle resin acid or a divalent or higher metal complex of resin acid. 2. The concrete admixture according to claim 1, further comprising a water reducing agent.