JPH025698B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] This invention relates to a method for producing lightweight cellular concrete using a new and useful foaming agent. [Prior art and its problems] There are two main methods for producing lightweight cellular concrete: the so-called post-form method, in which all the raw materials are mixed and then foamed in a mold, and the method in which foaming agent is foamed in advance. There is a so-called pre-form method in which foam is mixed with cement paste or cement mortar, and a so-called mix-form method in which foam is formed by stirring in a cement paste containing a foaming agent. Among these manufacturing methods, those using a foaming agent are the preform method and the mix foam method. The manufacturing method of lightweight cellular concrete using a foaming agent must satisfy the following requirements. (a) Specific gravity control: After foaming, defoaming and defoaming hardly occur, the amount of air is stabilized in cement slurry or mortar, and the strength and properties of concrete are not adversely affected. (b) Coarse foam: It is possible to suppress the generation of coarse foam during concrete production and pouring, and the produced lightweight cellular concrete can be used directly as a finishing base as a building material. (c) Water absorption/permeability: The bubbles formed in concrete are closed cells, and as a result, water absorption/permeability is low. (d) Strength: It does not adversely affect the physical properties of the cured product, especially the compressive strength. (e) Odor: There is no odor when used as a building material. (F) Chloride: It does not promote corrosion of metal fittings that come into contact with lightweight cellular concrete. (G) Fluidity: Fluidity (flow value) during pouring can be adjusted. Conventionally, foaming agents used in the manufacturing method of lightweight cellular concrete have mainly included protein decomposition products, and some surfactants have also been used. The protein degradation products used as foaming agents generally have good properties, however,
Among the above-mentioned requirements, the method for producing concrete using protein decomposition products does not fully satisfy the above-mentioned requirements regarding odor, since it emits a foul odor during the production of concrete and when used as a building material. In addition, attempts have been made to manufacture concrete using imidazoline-based and betaine-based amphoteric surfactants as foaming agents, but these contain chloride ions, which may be mixed into the concrete and corrode the reinforcing metal fittings. . This invention was made in view of the above-mentioned circumstances, and its purpose is to provide a manufacturing method that satisfies the requirements for the above-mentioned lightweight cellular concrete manufacturing method. [Means for Solving the Problems] The inventor has conducted various experiments and research in order to develop a manufacturing method that satisfies the requirements for a manufacturing method for lightweight cellular concrete using a foaming agent, and as a result, certain results have been discovered. It has been found that the use of surfactants as foaming agents is effective in achieving this objective. The method for producing lightweight aerated concrete of this invention is as follows:
When preparing a cellular concrete slurry from concrete raw materials, water, and a foaming agent, pouring the slurry into a formwork, and removing the mold after solidification and hardening to produce lightweight cellular concrete, the following general formula () is used. [Wherein R ¹ is a saturated or unsaturated aliphatic hydrocarbon group having 3 to 21 carbon atoms, R ² and R ³ are hydrogen or a hydroxyalkyl group having 1 to 4 carbon atoms], the following: General formula () [In the formula, R ¹ and R ² have the same meanings as above]
It is characterized by using a foaming agent containing at least one amide amino acid compound selected from the group consisting of the compound represented by: and salts thereof. Therefore, the foaming agent used in this invention is a compound of the general formula (), a compound of the general formula ()
or a salt thereof, or a mixture thereof. In the general formulas () and () of the amide amino acid compound, R ¹ is an odd number of saturated or unsaturated aliphatic carbon atoms having 3 to 21 carbon atoms, preferably 7 to 21 carbon atoms, and preferably 7 to 21 carbon atoms. It is a hydrogen group, and R ²
and R ³ are the same or different, and are hydrogen or a hydroxyalkyl group having 1 to 4 carbon atoms (preferably 2 to 3 carbon atoms). The salts include alkali metal salts, alkaline earth metal salts, and ammonium salts. In addition to using the foaming active ingredient alone, various stabilizers, adjuvants, accelerators, etc. can be added to the foaming agent in this invention. Next, the foaming agent of the present invention will be explained in relation to lightweight cellular concrete production methods, ie, the above-mentioned preform method and mix form method. When producing lightweight cellular concrete by the preform method, first, a foam made by foaming a mixture of cement paste or cement mortar and a foaming agent or a water-soluble thickener is prepared separately. In the method of this invention, the cement foaming agent is
At least per 100 parts by weight of cementitious material
0.01 parts by weight can be used, preferably 0.1 to 5 parts by weight. This is because if it exceeds the preferred range, foam stability will be lacking during cement slurry preparation, making it impossible to obtain the desired specific gravity. Cementitious materials used here include portland cement, mixed cement, alumina cement,
There are hydraulic lime and other hydraulic inorganic materials, and there are also those to which aggregates and fillers such as silica sand and perlite are added as necessary. In addition, water-soluble natural polymers and synthetic polymers that are used together with foaming agents as necessary in the production of this lightweight cellular concrete include methylcellulose (MC), ethylcellulose, methylethylcellulose, hydroxyethylcellulose, hydroxyethylmethylcellulose, There are synthetic polymers such as water-soluble cellulose derivatives such as hydroxypropyl methylcellulose and carboxymethylcellulose, polyvinyl alcohol, polyethylene oxide, and polyvinyl butyral. Preparation of cement paste or cement mortar can be carried out conventionally in the method of the present invention without any special method. For example, it is prepared by mixing a hydraulic inorganic material and aggregate with water in a ratio of 90/10 to 20/80. Foam is prepared by mixing water and a foaming agent with a thickener, an auxiliary agent, a stabilizer, etc., if necessary, and foaming the mixture by stirring or the like. Usually, the foam density is adjusted to 0.03 to 0.15 g/cm ³ and the foam viscosity is adjusted to 3000 cps or more. The foam prepared as described above is mixed with cement paste or mortar, and a lightweight cellular concrete product of a certain shape is obtained from the resulting cellular concrete slurry by a conventional method. That is, a cellular concrete slurry is poured into a formwork, and after it sets and hardens, it is removed from the mold to produce a lightweight cellular concrete product. Note that the obtained product can be further cured in an autoclave to strengthen its mechanical properties. The production of lightweight cellular concrete by the mix-form method is similar to the pre-form method described above, except that it is stirred and foamed in a cement paste containing a foaming agent. [Example] The present invention will be explained in detail using the following example. Example 1 Methyl coconut oil fatty acid (RCOOH) and N-(2-
Hydroxyethyl) ethylenediamine (NH ₂ CH ₂ CH ₂ NHCH ₂ CH ₂ OH) was subjected to a dehydration reaction at 200°C for 5 hours under a reduced pressure of 50 mmHg, and then recrystallized with petroleum ether to form an imidazoline compound.

Obtain [formula]. Add ethyl acrylate, water and a small amount of sodium hydroxide to the imidazoline compound, and
After reacting for a period of time, the mixture is saponified to obtain a 40% aqueous solution of a mixture of amide amino acid compounds represented by the following general formula. In the formula, R represents a coconut oil fatty acid residue ( _C7 to _C17 ). Example 2 Using the 40% aqueous solution obtained in Example 1 as a foaming agent,
Lightweight cellular concrete was manufactured by the preform method. Foam specific gravity prepared by a conventional method using a foaming agent of 2% by weight based on the solid content of the cement paste in a cement paste having the composition shown in Table 1 below.
Mixed with 0.1 foam. Table 1 Composition of cement paste (parts by weight) Ordinary Portland cement 48 Silica powder 50 Gypsum (2 water) 2 Water 50 The amount of bubbles added to the cement paste is the theoretical amount of bubbles that makes the specific gravity of the cellular cement paste 0.720. It was hot. The obtained cellular cement paste was poured into a formwork. After the cement has set and hardened, it is removed from the mold and
Concrete with a specific gravity of 0.72 was obtained. 180℃, 10atm,
It was cured in an autoclave for 6 hours. Cement paste with a specific gravity of 0.72 became 0.50 in an absolutely dry state after autoclave curing. After curing, it was left to air dry at a temperature of 20°C and a humidity of 60% to obtain lightweight aerated concrete. Specific gravity control, which is a requirement for foaming agents for this concrete,
Rough foam, water absorption/permeability, strength, odor, chloride, and fluidity were tested. The results are shown in Table 2. The test method for water absorption and water permeability is as follows. The water absorption rate is 10φ×4cm from the 10φ×10cm sample.
Cut out, wash the cut surface with water, and then dry at 70°C for 24 hours to use as a sample. Let the weight at this time be W ₀ . Immerse the sample 3 cm below the water surface and
Drain the water until there are no drips and measure the weight, making it W ₄₈ . Calculate the water absorption rate at the following times. Water absorption rate = W ₄₈ - W ₀ / W ₀ Prepare the same sample as the water absorption rate measurement sample, cut a 50cm plastic measuring cylinder (inner diameter approximately 29mm) and glue it with silicone caulking material. At the same time, seal the sides of the sample with caulking material. Leave this for 24 hours to harden. Pour water into the graduated cylinder to a height of 250mm,
The drop in water level after 5, 10, 30 minutes, 1, 2, 3, and 24 hours is measured in mm and used as the water permeability value. Example 3 Same as Example 2 except that 0.001 weight of methylcellulose was added to the foaming agent. The results are shown in Table 2. Examples 4 to 9 The same procedure as Example 2 was carried out except that the foaming agent shown in Table 2 was used. The results are shown in Table 2.

【table】

〔Effect of the invention〕

By the method of this invention, the following effects can be obtained. (a) After foaming, there is almost no defoaming or defoaming, the amount of air is stable in the cement slurry or mortar, and the specific gravity can be easily controlled. (b) The generation of coarse foam on the surface of the aerated concrete slurry can be suppressed. (c) Changing the air bubbles in concrete from open cells to closed cells to improve water absorption. (d) It does not adversely affect the compressive strength of lightweight aerated concrete products. (e) This method does not generate bad odors, which is a drawback of production methods using protein-based foaming agents. (F) Since it does not contain chlorides, it does not accelerate the corrosion of metals that come into contact with lightweight cellular concrete. (g) The fluidity of the aerated concrete slurry during pouring can be easily adjusted.

Claims (1)

[Claims] 1. Preparing a cellular concrete slurry from concrete raw materials, water, and a foaming agent, pouring the slurry into a formwork, and removing the mold after solidification and hardening to produce lightweight cellular concrete. , the following general formula () [Wherein R ¹ is a saturated or unsaturated aliphatic hydrocarbon group having 3 to 21 carbon atoms, R ² and R ³ are hydrogen or a hydroxyalkyl group having 1 to 4 carbon atoms], the following: General formula () [In the formula, R1 and R2 have the same meanings as above]
1. A method for producing lightweight cellular concrete, comprising using a foaming agent containing at least one amide amino acid compound selected from the group consisting of the compound represented by: and salts thereof.