JPS6311558A - Manufacture of concrete - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) This invention relates to a manufacturing method for Funk'J-), and in particular to a method for manufacturing Funk'J-), which has high strength and durability.
This relates to a method for producing snoring.

(Prior Art) It is known that by adding as little water as possible to cement and kneading it, a strong concrete can be obtained when the mixture is hardened. However, in actual operation, the concrete is mixed by adding more water than is required to harden the cement, and then allowed to harden. The reason for this is that unless such a large amount of water is added, concrete cannot be easily mixed, transported, placed, and compacted.

Thus, because a large amount of water had to be added, conventional concrete had the disadvantage of low strength. The reason why the strength decreases is that when concrete is mixed with a large amount of water, no matter how tightly it is compacted, the excess water remains as voids, which causes stress to concentrate in the concrete. It is explained that this is because it is easier to do.

When voids exist in concrete, not only does the strength of the concrete become weaker, but water also enters the voids and deteriorates the concrete, reducing the durability of the concrete.Furthermore, the reinforcing steel that coexists there is also susceptible to corrosion. This further reduces the durability of the concrete. Therefore, adding Taisha water brought about a fatal drawback to concrete.

Therefore, attempts were made to reduce the amount of water used.

When making concrete, the amount of water added to cement is called the water-cement ratio, and a proposal has been made to reduce the water-cement ratio as much as possible. One of the proposals is to add a water reducer into the cement slurry. In this method, by adding a water-reducing agent, the water-reducing agent is adsorbed to the cement particles, forming a diffused electric double layer, and achieving the effect of dispersing the cement particles, thus increasing the workability of the cement slurry with a small amount of water. This is the entire principle.

(Problems to be Solved by the Invention) Using a water reducing agent can certainly reduce the water-cement ratio. As a result, the strength of concrete could be improved. 1. If a water reducer is used, there are disadvantages such as retardation of setting and hardening and little effect in reducing breathing.

Therefore, rather than reducing the water-cement ratio, an attempt was made to capture excess water in the final stage of kneading to improve strength and reduce breathing without reducing workability. This invention was made with this purpose in mind.

(Means for Solving the Problem) The inventor came up with the idea of using a highly water-absorbing polymer instead of a water reducing agent. A highly water-absorbent polymeric substance is a polymeric substance that absorbs a large amount of water and swells. More specifically, a highly water-absorbing polymeric material is a polymeric material that has the ability to absorb 400 times its weight or more of water when immersed in water at room temperature. It has been found that concrete with high strength can be obtained by mixing such polymeric substances in the form of fine particles of 50 microns or less with cement slurry in an appropriate ratio and curing the mixture. This invention was made based on such knowledge.

In this invention, water-insoluble polymeric substances, which have the ability to absorb 400 times more water by weight when immersed in water at room temperature, are made into fine particles of 50 microns or less and added to cement slurry mixed with water. It relates to a method for producing concrete, characterized in that the particles described above are mixed in a proportion of 0.5-5% by weight, and the mixture is subsequently hardened.

As mentioned above, when immersed in water at room temperature,
A water-insoluble polymer substance (hereinafter referred to as a water-absorbing material) is used, which has the ability to absorb 400 times or more of water by weight. Water-absorbing materials differ from conventionally used water-reducing agents in that they are insoluble in water. That is, all conventional water reducing agents are soluble in water and have been added to cement slurry as an aqueous solution. However,
The water-absorbing material used in this invention differs from conventional water-reducing agents in that it absorbs water and swells, but does not dissolve in water and therefore cannot form a solution.

The water absorption rate of the water-absorbing material is determined appropriately depending on the time from when the water-absorbing material is added to the cement slurry to the end of compaction. For example, if a long time of 1 hour is required from addition to compaction, use a water-absorbing material that has a slow water absorption rate if possible. On the other hand, if the process from addition to compaction is completed in a short time, use a water-absorbing substance that absorbs water as quickly as possible.

The water-absorbing material is composed of an ionic network made of a polymer electrolyte, mobile ions made of its counter ions, and water. Such water-absorbing materials are already known as superabsorbent resins.

As the water-absorbing material, a copolymer of acrylate is particularly suitable. For example, it is a water-absorbing resin sold by Seitetsu Kagaku Kogyo Co., Ltd. under the name Aqua Keep, or a water-absorbing resin sold by Sumitomo Chemical Co., Ltd. under the name Sumikagel or Igetagel.

The water absorbent is used in advance as fine particles of 50 microns or less. That is, when water-absorbing material is used as large particles,
This is because large cavities will be created in the concrete, which will actually weaken the concrete, but if these particles are made into fine particles of 50 microns or less, large cavities will not be created and the strength will be improved.

Water absorbents are added after water and aggregate are mixed with cement. That is, cement is mixed with gravel, sand, etc., water is added to this to form a cement slurry, and then a water absorbent is added. This is until the point of pouring and compaction.
This is to prevent the water absorbent from absorbing too much water in the slurry.

The water absorbent is added at a rate of 0.5-5% by weight of the cement overlay. Water absorption is added to the cement slurry, but the addition ratio is 0 based on the cement weight in the slurry.
．． It should be within the range of 5-5 fold ffi%.

This is because the effect is not sufficient when the amount of water absorption is less than 0.5% by weight; on the contrary, the amount of water absorption increases,
This is because if the content exceeds 5% by weight, the viscosity of the slurry increases and workability decreases.

(Function) Immediately after adding the water absorbent, cement slurry with water absorbent added exhibits the same fluidity as ordinary cement slurry to which no water absorbent has been added. can be processed in the same way.

Therefore, there is almost no change during compaction. However, since the water absorbent then absorbs excess water in the cement slurry, the cement slurry hardens with less water, thus providing concrete with greater strength.

(Effect of the invention) According to Kono Invention 2, the water absorbent is made into fine particles of 50 microns or less, and these particles are blended into the cement slurry mixed with water at a small proportion of 0.5-5 flk% of the cement weight. It is easy to mix and can be poured immediately after mixing, so it can be handled in the same way as conventional cement slurry. In this way, after pouring and compacting the slurry containing the water-absorbing material, the water-absorbing material absorbs excess water in the slurry, and moreover, when the water-absorbing material is immersed in water at room temperature, its weight increases by more than 400 times. Since it has the ability to absorb water, the slurry will harden with less water, thus producing concrete with greater strength.In addition, the water absorbed material is dispersed in fine particles of 50 microns or less. Since it is easy to use, it occupies a small volume in the concrete and is dispersed, so it does not create large cavities. Therefore, the obtained concrete becomes dense and has high strength. This invention brings such excellent effects.

(Example) Examples will be described below to clarify the excellent effects of the method of this invention.

Example In this example, a pulverized super absorbent resin (trade name: Aqua Keep, manufactured by Steel Chemical Co., Ltd.) containing an acrylate copolymer as a main component was used as the water absorbent.

The pulverized particles used were particles of 100 microns or less that had passed through a 200 mesh sieve.

First, 1040 y of standard sand was added to 520 y of early strength cement and mixed, and 888 y of water was added and mixed to make a cement slurry with a water-cement ratio of 65%. Add 8y of the above water absorbent (L5 weight ffi% to cement), mix well, and immediately mix this mixture into 4X4X16
It was poured into the w formwork. No pleasing (water seepage) was observed after pouring. After curing this at room temperature for two weeks, its compressive strength and bending strength were measured. The results were as shown in Table 1 below.

Comparative Example In the above example, the water absorbent was not used, but the process was carried out in exactly the same manner as in the example above. Pleasing was observed after pouring. The compressive strength and bending strength were as shown in Table 2 below.

Table 2 Comparison of the above Examples and Comparative Examples reveals that both the compressive strength and the bending strength are considerably improved according to the present invention.

Claims (1)

[Claims] When immersed in water at room temperature, a water-insoluble polymer substance that has the ability to absorb more than 400 times its weight in water is made into fine particles of 50 microns or less, and 0.5 of the weight of cement is added to a cement slurry mixed with water. - A method for producing concrete, characterized in that the above particles are mixed in a proportion of 5% by weight, and then the mixed slurry is hardened.