JPS5818340B2 - Manufacturing method of cement concrete porous body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a porous cement concrete body, particularly a porous cement concrete body having a bulk specific gravity of 0.5 or less and containing interconnected air cells.

In general, porous bodies are known to have various functions such as filtration, air permeability, shock absorption, capillary action, high specific surface area, and flow control.

And recently. New application fields for porous materials that combine these functions are attracting attention.

Most of the bubbles in this type of porous material are not closed cells;
A plurality of cells are connected to each other in a continuous state.

In addition, various metals, plastics, glasses, etc. have been used as the material for this type of porous material in the past, and the combination of the unique properties of each material and the general properties of the porous material is difficult to achieve. It is being

On the other hand, cement is an inexpensive and easily available industrial material, and has the characteristics of being excellent in strength, durability, and fire resistance.

What is particularly interesting is that the hydrate structure in the hardened cement has a layered structure and its specific surface area is extremely large.

For example, tobermorite gel has a specific surface area of several 100 m/g.

The present inventors focused on the above-mentioned properties of cement, and by producing a concrete porous body using cement having such properties, they obtained an industrial material that has both the properties of cement and the general functions of a porous body. I am planning to
As a result of extensive research, the present invention has been completed.

The method for producing a cement concrete porous body containing mutually continuous cells according to the present invention comprises a rapid setting cement or a binder containing the rapid setting cement, an aggregate, and a sulfonate type anionic surfactant or ) A method for producing a cement concrete porous body having a bulk specific gravity of 0.5 or less by molding and curing a foamed concrete slurry containing a sulfate ester salt type anionic surfactant, which comprises a rapid-setting cement or a rapid-setting As the cement-containing binder, a material that completes the setting reaction of the above-mentioned foamed concrete slurry within 15 minutes at a temperature of 40°C or lower is selected, and the above-mentioned surfactant is selected based on the weight of solids in the foamed concrete slurry. It is characterized by using 0.2 to 3 ratios.

Cement concrete is a composite consisting of aggregate and various cement water minerals, and its properties are difficult to explain unequivocally, but under normal conditions, after mixing concrete,
It starts setting and hardening in about an hour, and the bulk specific gravity after hardening is 1.8 to 2.4 in a dry state.

Therefore, in order to produce a cement concrete porous body having a bulk specific gravity of 0.5 or less, it is necessary to introduce at least four times the volume of air bubbles into the concrete slurry.

However, it is technically extremely difficult to introduce such a large amount of air bubbles into concrete slurry and to keep the air bubbles stably and homogeneously dispersed until the above-mentioned time when cement concrete starts setting and hardening.G).

Normally, the cellular phase and the solid phase (concrete material) are separated due to the significant difference in specific gravity between the concrete material particles and the air bubbles, while the air bubbles coalesce to form large voids in the hardened concrete.

These problems can be improved to some extent by using a foam stabilizer in combination to reinforce the strength of the foam film.

However, most of the cells in the cement concrete porous body obtained in this manner are closed cells, and are not open cells as contemplated by the present invention.

In addition, the introduction of such a large amount of bubbles is problematic from another technical standpoint.

That is, the stable introduction of such a large amount of bubbles usually
It reduces the fluidity of concrete slurry and makes casting work extremely difficult.

The present inventors solved the above problem by using sulfonate type anionic surfactants and sulfate ester salt type anionic surfactants alone or in combination as foaming agents, and using cement or cement-containing binders in foamed concrete. It has been found that a solution may be achieved by using a fast-setting cement or cement-containing binder such that the setting reaction of the slurry is completed within 15 minutes at a temperature below 40°C.

It has also been found that in order to form open cells in a concrete hardened body, the specific gravity of the hardened concrete must be 0.5 or less in a dry state.

Furthermore, by incorporating a setting retarder into the foamed concrete slurry, a concrete porous body containing a large amount of open cells can be obtained by making the hardening time of the slurry coincide with the time when the cells burst and become open. found.

As the sulfonate type anionic surfactant and the sulfate ester salt type anionic surfactant used in the present invention, those conventionally used in the field of cement concrete can be applied as they are.

That is, specific examples of the former include alkylarylsulfonic acids (for example, alkylphenylsulfonic acids of CI2 to C18), alkylsulfonic acids (for example, alkylsulfonic acids of Eva CI2 to C18), or α-sulfonated fatty acids (for example, alkylsulfonic acids of CI2 to C18). C18 α-sulfonated fatty acids), etc.
There are surfactants comprising Jium salts or α-sulfonated fatty acid esters (for example, CI2 to C18 α-sulfonated fatty acid esters).

Specific examples of the latter include sulfate ester salts of higher alkyl or higher alkylaryl polyethylene glycol ethers (for example, nonylphenyl tetraethylene oxide ether sulfate ester soda) or sulfate ester salts of higher alcohols.

Various substances have been known as foaming agents for cement concrete, such as glue, albumin, casein, glucozide, cabonine-containing substances, natural or synthetic resins, cellulose derivatives, chrycerol, and phenols. The addition of will reduce the fluidity of the cement-concrete slurry, making casting work extremely difficult.

In addition, when these foaming agents are used, concrete material particles such as cement are not uniformly dispersed on the foam film, but aggregate and unevenly distributed in the foam space, so when the foam film disappears, the hardened concrete becomes extremely brittle. It becomes an organization and even collapses.

On the other hand, the foaming agent used in the present invention described above has a small cohesive force between foams, improves the fluidity of the slurry,
Furthermore, it has excellent dispersibility for particles of concrete materials such as cement, and has the effect of coating material particles such as cement with a uniform thickness on the foam membrane.

In the method of the present invention, the amount of the sulfonate salt type anionic surfactant and the sulfate salt type anionic surfactant is as follows:
Amount of water in concrete slurry, type of concrete,
Although it varies depending on the type of surfactant used, foaming method, etc., it is usually in the range of 0.2% to 3%, preferably 0.2% to 1%, based on the solid weight of the foamed concrete slurry. It is within.

Even if the amount used exceeds 3 parts, the foaming power is not improved at all, but rather has a negative effect on the strength.

Moreover, if the amount used is less than 0.2%, sufficient foaming power cannot be obtained to obtain a porous body having a specific gravity of 0.5 or less, which is the object of the present invention.

The air bubbles in the concrete slurry foamed using the above-mentioned surfactant become active within 15 minutes after the slurry is prepared.

Therefore, the cement used in the present invention must be a fast-setting cement that completes setting when the air bubbles in the slurry become active.

Cement setting can also be promoted by increasing the temperature of the slurry, but the higher the temperature, the more unstable the bubbles become and the easier they become to disappear, so it is necessary to avoid raising the temperature to over 40℃. No.

Cement 1~, which completes the setting of the slurry within 15 minutes at a temperature below 40°C, can be prepared by mixing ordinary Portland cement with alumina cement in a predetermined ratio, or by mixing 11CaO, 7A1203, CaF2 or 12CaO.
- It can be prepared by mixing 7A1203 and Ceracola (a commercially available product is, for example, "Jet Cement" (trade name) manufactured by Onoda Cement Co., Ltd.).

Furthermore, the cement disclosed in Japanese Patent Application Laid-open No. 49-52216 can also be used.

In particular, this cement has high early strength, the hardening speed can be easily controlled by using a setting retarder, and it also promotes the partial destruction and continuity of air bubbles caused by rapid changes in the atmosphere due to high water usage reaction heat, melt deposition, transition, etc. It has the characteristic that it can be done.

Note that the above cement does not necessarily need to be used alone, and lime powder may be mixed as necessary.

By the method described above, it is also possible to produce a novel lightweight concrete porous body having a specific gravity of approximately 0.2 (dry state) after hardening.

However, if the porous body is required to have strength and durability, it is advantageous for the product to have a higher specific gravity.

However, a porous material having a specific gravity higher than 05 increases the thickness of the matrix and prevents the formation of continuous pores, making it impossible to obtain a product with good functionality as a porous material.

In the method of the present invention, a cement retarder can be included in the concrete slurry.

The time at which the setting of the above-mentioned rapid hardening cement is completed tends to be somewhat earlier than the time at which the bubbles are partially ruptured and become continuous.

Therefore, by including a cement retardant in the concrete slurry, the setting time can be delayed to coincide with the time of partial bursting and continuousization of the bubbles.

Therefore, by using a setting retarder in combination, it is possible to further increase the proportion of open cells in the total number of cells in the hardened concrete.

Since the surfactant used in the method of the present invention also has a setting retarding effect on cement, a relatively small amount of the above-mentioned setting retarder is sufficient.

The specific amount added varies depending on the nature of the cement used (the degree of rapid hardening), the amount of surfactant used, etc.
Usually, it is in the range of 0.02% to 0.5% of the solid content weight in the foamed concrete slurry.

The curing reaction of the foamed concrete slurry molded body may be carried out by natural curing, steam curing, or autoclave curing, but autoclave curing is recommended in order to increase the strength of the product in a short period of time. desirable.

Next, examples of the present invention will be described.

Example 1 (1) Binding material Ordinary Portland cement I-9.6 kg Alumina cement 2.4 kg Calcium hydroxide 0.48 kg (2) Bone
Crushed silica sand (powderness 3600Cnt/g) 5.0k
g (3) Foaming agent Sodium dodecylbenzenesulfonate 50.9 (4) Set retarder Sodium citrate 5.0 g In a tank equipped with a foaming stirrer, water 9.51 (water temperature 30°C) and a foaming agent and a setting retarder were added and stirred to form fine bubbles.

Next, a mixture of binder and aggregate was added thereto and stirred and kneaded for 2 minutes to prepare foamed concrete slurry.

Immediately, the foamed slurry was poured into a predetermined mold, molded, and left in a humid atmosphere (30° C., 100% relative humidity).

The foamed concrete slurry began to set and harden approximately 8 minutes after mixing.

After 3 hours, the mold was removed and autoclaved at 182° C. and 10 atm for 8 hours.

The obtained concrete porous body has a bulk specific gravity of 0.38, a compressive strength of 26.2 kg/crd, and a bending strength of 8.5 ky/crd.
It was ffl.

In addition, the obtained concrete porous body was 30×30×10
Cut into pieces with an inner diameter of 4-. Fix a 9cIrL glass tube with oil clay and stand it upright, then fill the glass tube with water (
The water column height (20 crfL) and water permeation rate were measured.

As a result, the water in the glass tube penetrated in a short period of 9 minutes.

This means that the cells in the porous material are open cells.

Additionally, for reference, the fractured surface of this porous body was observed using a scanning electron microscope.

Figures 1 and 2 are photographs showing the results.

As shown in Figure 1, the matrix portion of the porous material is extremely thin compared to ordinary cellular concrete, and the foam membranes are in contact with each other, and concrete material particles such as cement are often It can be seen that the cells were uniformly dispersed and most of the cells were open cells.

FIG. 2 shows the results of observing the structure of the cured product at higher magnification, and clearly shows that the specific surface area is extremely high.

Example 2 (1) Binder jet cement 12 kg (manufactured by Onoda Cement Co., Ltd.) (2) Aggregate crushed silica sand (powderity 36007/, ?) 5 kg (
3) Foaming agent nonylphenyl tetraethylene oxide ether sulfate ester soda 80g (4) A concrete porous body was prepared in exactly the same manner as in Example 1 without using a setting retarder.

In this case, the foamed concrete slurry began to harden in about 13 minutes.

The obtained porous body has a bulk specific gravity of 0.45, a compressive strength of 15.8/ffl, and a bending strength of 3.7 kg/crt! Met.

Furthermore, as a result of measuring the water permeation rate using the same method as in Example 1, water penetrated in about 17 minutes.

Comparative Example 1 Example 1 except that the amount of foaming agent used was 20.9
A concrete porous body was prepared by the same method.

The obtained porous body has a bulk specific gravity o of 53 and a compressive strength of 48.3
kg/cr/l, bending strength 14.6 kg/cyt!
Met.

Further, the water permeability of this porous body was tested by the same method as in Example 1, and as a result, it took about 3 hours and 20 minutes for the water in the glass tube to penetrate.

This is a significantly longer time than the porous material of Example 1,
This is thought to be due to the fact that most of the bubbles are closed cells.

Comparative example 2 (1) Binding material ordinary Portland cement 12 kg (2) Bone
Crushed silica sand (powderness 3600CIIt/, 9)
5 kg (3) Foaming agent protein solution (solid content: 20 parts) 350 ml (4) Bubble stabilizer methyl cellulose 12 g A concrete porous body was prepared by the same procedure as in Example 1, except that the bubble stabilizer was used. .

Note that this foamed concrete slurry was observed to be hardened to the touch only after one day and night had passed after kneading.

Further, autoclave curing was performed at 182° C. and 10 atm for 8 hours.

The specific gravity of this porous body is 0.42, and the compressive strength is 2.5.9
/at/l and was extremely fragile.

As described above, according to the present invention, a porous cement concrete body having a small specific gravity and open cells can be manufactured.

Moreover, due to the rapid hardening of cement, sedimentation and separation of concrete material particles does not occur and a homogeneous porous body can be obtained.

Therefore, it is easy to manufacture large-sized porous bodies.

According to the method of the present invention, a unique inorganic material that has both the microscopic aspects of a cement hydrate structure and the macroscopic aspects of a porous body can be produced, and can be used in a variety of applications such as adsorbents, sound absorbing materials, catalyst supports, etc. Be expected.

In addition, as a modification of the present invention, various reinforcing materials and fillers such as sand, fly ash, and slag may be added to the foamed slurry in order to further increase the mechanical strength of the cement concrete porous body or to increase its volume. , red mud, perlite, shirasu balloons, mineral fibers, and organic fibers can be added.

[Brief explanation of drawings]

FIGS. 1 and 2 are scanning electron micrographs of a fractured surface of a cement concrete porous material produced by the method of the present invention.

Claims (1)

[Scope of Claims] 1 Rapid-setting cement or a binder containing rapid-setting cement;
Porous cement concrete with a bulk specific gravity of 0.5 or less is formed by molding and curing a foamed concrete slurry containing aggregate and a sulfonate type anionic surfactant or (and) a sulfate salt type anionic surfactant. In the method for manufacturing a concrete body, a quick-setting cement or a binder containing a quick-setting cement is selected that allows the setting reaction of the foamed concrete slurry to be completed within 15 minutes at a temperature of 40° C. or lower, and the above-mentioned interface is selected. A method for producing a porous cement concrete body containing interconnected air cells, characterized in that an activator is used in an amount of 0.2 to 3 times the weight of solids in a foamed concrete slurry. 2 Rapid-setting cement or binding material containing rapid-setting cement,
Porous cement concrete with a bulk specific gravity of 0.5 or less is formed by molding and curing a foamed concrete slurry containing aggregate and a sulfonate type anionic surfactant or (and) a sulfate salt type anionic surfactant. In the method for manufacturing a concrete body, a quick-setting cement or a binder containing a quick-setting cement is selected that allows the setting reaction of the foamed concrete slurry to be completed within 15 minutes at a temperature of 40° C. or lower, and the above-mentioned interface is selected. An activator is used in an amount of 0.2 to 3% based on the solid weight in the foamed concrete slurry, and a setting retarder is added in an amount of 0.02 to 0.5% based on the solid weight in the foamed concrete slurry. 1. A method for producing a cement concrete porous body containing mutually continuous cells, characterized in that the hardening time of the slurry is made to match the time when the cells in the slurry become open.