JP2001158676A - Solidified substance of water-retaining concrete and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solidified substance of a concrete, suitable for the use as a paving material of an urban area, and a water-retaining structural material, and further to provide a method for producing the solidified substance. SOLUTION: This solidified substance of a water-retaining concrete, having fine open cells communicating with the surface part of the solidified substance of the concrete is obtained by immersing a lightweight aggregate having fine open cells in an aqueous solution containing a plenty of carbon dioxide gas, taking out the aggregate from the aqueous solution, kneading the resultant aggregate with a cement and water, and solidifying the kneaded product.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solidified concrete having water retention and a method for producing the same.

[0002]

2. Description of the Related Art Various types of concrete solidified bodies are known, and among them, those having added value by imparting water retention, water permeability and the like have been developed. For example, Japanese Patent Application Laid-Open No. Hei 3-217509 discloses a technique for reducing the amount of water and forming a large number of voids between aggregates when kneading the aggregates with cement, water, or the like. ing.

[0003] The water-permeable concrete solidified body manufactured by the technique of forming a large number of voids between the aggregates described above, when water is poured onto the upper surface, the water flows down through the voids and flows down. Leaked from If this solidified body is placed on a soil with low water permeability, etc., water can be temporarily held in the voids, but in this case, the water gradually flows out after a certain period of time. Therefore, it is impossible to keep water for a long time. In particular, when sand or the like having good water permeability is used as a foundation for the concrete solidified body, water in the void is immediately discharged, and even a small amount of water remaining on the surface of the void is lost in a short time by drying.

[0004] On the other hand, various types of aggregates for solidified concrete have been put into practical use, among which are porous lightweight aggregates. This lightweight aggregate is manufactured by, for example, finely pulverizing granulated slag, mixing a foaming agent, and firing at a high temperature, and has many fine continuous voids inside the aggregate itself. Because of its light weight, it is often used to produce lightweight concrete solids.

[0005] This kind of lightweight aggregate has a problem that it is difficult to determine a water-cement ratio at the time of kneading because a large amount of water can be held in the fine continuous voids. This is because if the lightweight aggregate is dry, a large amount of water added at the time of kneading is absorbed by the fine continuous voids, and if it is sufficiently wet, water is hardly absorbed. Therefore, in actual use, in order to prevent the effect of the dry state on the water cement ratio, this lightweight aggregate is often immersed in water before use.

[0006] As described above, the fine continuous voids of the lightweight aggregate can absorb and hold a large amount of water, and since the voids are fine, there is a property that the capillary action works and the retained water is not easily discharged. . In addition, since the loss of water due to drying also occurs from the surface of the lightweight aggregate, it takes a considerably long time until all the water inside disappears. For this reason, it is considered that when a lightweight aggregate is used for all or a part of the aggregate when manufacturing the concrete solid, a concrete solid having excellent water retentivity capable of retaining water for a long time can be obtained.

[0007]

However, if the lightweight aggregate having fine continuous voids is kneaded together with cement and water, the cement paste covers the surface of the lightweight aggregate, and the kneaded material is solidified to concrete. Even if the solidified body is manufactured, only the solidified body in which the surface of the lightweight aggregate is covered can be obtained. Since the solidified body is in a state where the entrance of the fine continuous void is covered, even if water is poured from above, water cannot enter the inside of the fine continuous void and water retention cannot be obtained.

[0008] Recently, a rise in the temperature of an urban area in summer due to the heat island effect has become a problem. In order to suppress this phenomenon, attempts have been made to increase the water retention of streets and the like. No solidified concrete having excellent water retentivity was obtained. Therefore, the present invention provides a concrete solidified body which can be used as a building or a pavement material in an urban area or the like and has a moderate strength and excellent water retention by effectively utilizing the lightweight aggregate, and a method for producing the same. The challenge is to do.

[0009]

In order to solve the above problems, the present invention employs the following configuration. That is, the solidified water-retaining concrete according to the present invention includes a lightweight aggregate having fine continuous voids, and the fine continuous voids of the lightweight aggregate communicate with the surface of the solidified concrete. .

[0010] The method for producing a concrete solidified body according to the present invention comprises a step of immersing a lightweight aggregate having fine continuous voids in an aqueous solution rich in carbon dioxide gas, and a step of cementing the lightweight aggregate immersed in the aqueous solution. And a step of kneading together with water and solidifying the obtained kneaded material.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with specific examples. First, the aggregate used in the present invention is an aggregate having fine continuous voids therein. For example, a known granulated slag can be suitably used as the aggregate. Further, as the cement, various conventionally known cements such as blast furnace cement, Portland cement, special cement and the like can be used.

In producing the solidified concrete body of the present invention, first, an aggregate having fine continuous voids is pre-treated.
This pretreatment is a step of immersing the aggregate in an aqueous solution containing a large amount of carbon dioxide. Examples of the aqueous solution containing a large amount of carbon dioxide include, for example, a solution in which carbon dioxide is pressurized and dissolved in water, and a solution in which carbonate such as sodium bicarbonate is dissolved in water (in order to generate carbon dioxide, an acid is used. Need to be added or heated) can be used. The aggregate is immersed in an aqueous solution containing a large amount of carbon dioxide, so that the inside of the fine continuous voids is filled with the aqueous solution containing carbon dioxide, and then the aggregate is removed from the aqueous solution.

Next, the aggregate filled with the aqueous solution containing carbon dioxide in the fine continuous voids is kneaded with cement, water and other additives (hardening accelerator, expanding agent, pigment, etc.) added as required. Manufacture concrete kneaded material. The desired concrete solidified body is obtained by filling and kneading the kneaded material in a predetermined mold.

Although the cement paste covers the surface of the aggregate by the above-mentioned kneading, an aqueous solution containing a large amount of carbon dioxide is contained in the fine continuous voids, and the carbon dioxide is gradually released. This gas opens a hole in the cement paste, and the fine continuous voids of the aggregate communicate with the outside. In addition, even if the through holes are closed again by filling the kneaded material into the mold, it takes time for the cement paste to harden, and the continuous continuous carbon dioxide gas connects the fine continuous voids to the outside of the solidified body. A through hole is formed, and the fine continuous void communicates with the outside again.

The solidified concrete obtained may or may not have a gap between the aggregates. If there is no gap between the aggregates, the water poured from above the solidified concrete hardly reaches the aggregate inside, but the fine continuous voids of the aggregate near the surface are caused by the released carbon dioxide gas. It penetrates through the opened through-hole and is retained in the gap.

On the other hand, if there is a gap between the aggregates, water is also retained in the gap between the aggregates, so that not only the water retention of the solidified concrete body is further improved but also the water permeability can be obtained. .

The solidified concrete obtained as described above has fine continuous voids inside the aggregate, and the fine continuous voids communicate with the outer surface through the through-holes. It penetrates through the through holes into the fine internal voids and is retained therein. This water evaporates slowly over time, taking away the surrounding heat. For this reason, if it is used as a pavement or a structural material for an urban area, it is expected to prevent a remarkable temperature rise in summer.

[0018]

As is apparent from the above description, according to the present invention, a concrete solidified body having excellent water retention having fine continuous voids communicating with the outer surface of the concrete solidified body inside the aggregate can be relatively easily prepared. Can be obtained.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C04B 111: 40 C04B 111: 40

Claims (2)

[Claims] Claims 1. A lightweight aggregate having fine continuous voids,
Further, the solidified water-retentive concrete is characterized in that the fine continuous voids of the lightweight aggregate communicate with the surface of the solidified concrete. 2. A method in which a lightweight aggregate having fine continuous voids is immersed in an aqueous solution rich in carbon dioxide gas, and then the lightweight aggregate removed from the aqueous solution is kneaded with cement and water to be solidified. A method for producing a solidified water-retaining concrete.