Foaming agent for aerated concrete and method for producing aerated concrete

Abstract

To provide a foaming agent for foamed concrete, capable of preparing a foamed concrete slurry having excellent flowability at a low temperature.SOLUTION: A foaming agent for foamed concrete comprises: a compound (A) represented by R1O(AO)mSO3-M+ [R1 is a C8-20 aliphatic hydrocarbon group; AO is a C2-3 oxyalkylene group; m represents the average repetition number of AO and is a number from 0 to 10; M+ represents a counter cation and is an alkali metal ion, ammonium, protonated amine, or protonated alkanolamine]; one or more (B) selected from an amphoteric surfactant and an amine oxide surfactant; an alcohol (C) having a C8-20 aliphatic hydrocarbon group; and a compound (D) represented by R2O(CH2CH2O)pH [R2 is a C1-8 hydrocarbon group; and p is the repeat number of an oxyethylene group and is an integer from 1-3], wherein a mass ratio of A / B is 1 to 6.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a foaming agent for aerated concrete and a method for producing aerated concrete. [Background technology]

[0002] Aerated concrete is a lightweight civil engineering and construction material obtained by hardening an aerated concrete slurry made by mixing air bubbles with a hydraulic slurry such as cement milk or mortar, and is widely used for embankments and backfill materials. One of the properties required for aerated concrete slurry is high fluidity, and methods have been proposed to improve fluidity by devising the composition of the foaming agent (for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 58-11382 [Patent Document 2] Japanese Patent Application Publication No. 2018-177618 Summary of the Invention [Problem to be solved by the invention]

[0004] The fluidity of cellular concrete slurry tends to decrease at low temperatures, such as when the water temperature used in preparing the slurry is low, which can result in poor handling and workability. Conventional foaming agents are unable to adequately prevent the decrease in fluidity at low temperatures, and improvements are needed. An object of the present invention is to provide a foaming agent for aerated concrete that can prepare aerated concrete slurry that has excellent fluidity at low temperatures. [Means for solving the problem]

[0005] The present invention has the following aspects. [1] Component (A): a compound represented by the following general formula (I), (B) component: one or more selected from amphoteric surfactants and amine oxide surfactants; (C) component: an alcohol having an aliphatic hydrocarbon group having 8 to 20 carbon atoms; (D) component: a compound represented by the following general formula (II), A foaming agent for cellular concrete, wherein A / B, which represents the mass ratio of the content of the component (A) to the content of the component (B), is 1-6. R 1 O(AO) m SO3 - M + (I) [In the formula, R 1 is an aliphatic hydrocarbon group having 8 to 20 carbon atoms, AO is an oxyalkylene group having 2 to 3 carbon atoms, m represents the average number of repetitions of AO and is a number from 0 to 10, and M + represents a counter cation, which is an alkali metal ion, ammonium, a protonated amine, or a protonated alkanolamine. R 2 O(CH2CH2O) p H (II) [In the formula, R 2 is a hydrocarbon group having 1 to 8 carbon atoms, and p is the number of repetitions of the oxyethylene group and represents an integer of 1 to 3.]

[0006] [2] A method for producing aerated concrete, comprising foaming a foaming liquid containing the foaming agent for aerated concrete described in [1] to obtain a group of bubbles, mixing the group of bubbles with a hydraulic slurry to obtain aerated concrete slurry, and hardening the aerated concrete slurry to obtain aerated concrete. [Effects of the Invention]

[0007] According to the foaming agent for cellular concrete of the present invention, it is possible to prepare a cellular concrete slurry that has excellent fluidity at low temperatures. DETAILED DESCRIPTION OF THE INVENTION

[0008] <Foaming agent for aerated concrete> The foaming agent for cellular concrete of this embodiment (hereinafter sometimes simply referred to as foaming agent) is a liquid composition containing components (A) to (D). In this specification, a numerical range expressed by "to" means a numerical range in which the numbers before and after "to" are the lower and upper limits.

[0009] <Component (A)> Component (A) is a compound represented by the following general formula (I) and is an anionic surfactant. Component (A) contributes to the generation of bubbles. The interaction between component (A) and component (B) improves foaming ability and bubble fineness, and improves the fluidity of the aerated concrete slurry at low temperatures. R 1 O(AO) m SO3 - M + (I) In formula (I), R 1 is an aliphatic hydrocarbon group having 8 to 20 carbon atoms (a hydrocarbon group having no aromaticity), AO is an oxyalkylene group having 2 to 3 carbon atoms, m is a number from 0 to 10 representing the average number of repetitions of AO, and M + represents a counter cation, which is an alkali metal ion, ammonium, a protonated amine, or a protonated alkanolamine. The component (A) may be used alone or in combination of two or more.

[0010] R 1 The aliphatic hydrocarbon group as may be a chain hydrocarbon group or a cyclic hydrocarbon group, with a chain hydrocarbon group being preferred. R 1 The aliphatic hydrocarbon group as may be saturated or unsaturated, with saturated hydrocarbon groups being preferred. R is superior in terms of the strength of the bubbles it forms. 1 is preferably a straight-chain or branched-chain alkyl group. R 1 has 8 to 20 carbon atoms, preferably 9 to 16 carbon atoms, and more preferably 10 to 14 carbon atoms.

[0011] AO may be an oxyethylene group (hereinafter also referred to as "EO") or an oxypropylene group (hereinafter also referred to as "PO"), and (AO) m may have both EO and PO. When it has both, (AO) m The bond chain of EO and PO constituting the above may be in a block form or in a random form. When one type of component (A) is used, the value of m is 0 to 10, preferably 0 to 5, and more preferably 0 to 3. When two or more types of components (A) are used in combination, the average value of m across all components (A) is 0 to 10, preferably 0 to 8, and more preferably 0.2 to 4.

[0012] M + is R 1 O(AO) m SO3 - is the counter cation that forms a salt with The alkali metal counter cation is preferably sodium. Examples of the amine that can serve as the counter cation include primary to tertiary amines. Examples of the alkanolamine that can serve as the counter cation include monoethanolamine, diethanolamine, and triethanolamine. M has excellent low-temperature stability of foaming agent. + is preferably an alkali metal ion or a protonated alkanolamine.

[0013] As the component (A), one or more types of (A1) components in which m is zero and one or more types of (A2) components in which m is 1 or more may be used in combination. Component (A1) is an alkyl sulfate, preferably lauryl sulfate or tetradecyl sulfate, and the salt of component (A1) is preferably a sodium salt, an ammonium salt, or an alkanolamine salt. Component (A2) is an alkyl ether sulfate, and polyoxyethylene lauryl sulfate and polyoxyethylene tetradecyl sulfate are preferred. The average number of repeating EOs in component (A2) is preferably 1 to 8, more preferably 2 to 4. As the salt of component (A2), sodium salt, ammonium salt, and alkanolamine salt are preferred. When the (A1) component and the (A2) component are used in combination, the proportion of the (A1) component relative to the total of the (A1) component and the (A2) component is preferably 50 to 80 mass %, more preferably 70 to 77 mass %. When the balance between the (A1) component and the (A2) component is within the above range, fine bubbles can be obtained.

[0014] <(B) component> Component (B) is at least one selected from amphoteric surfactants and amine oxide surfactants. Component (B) interacts with component (A) to improve foaming properties and bubble fineness, and also to improve the fluidity of the aerated concrete slurry at low temperatures.

[0015] An amphoteric surfactant is a surfactant that has both an anionic group and a cationic group in the hydrophilic group of the molecule. Examples of amphoteric surfactants include betaine type, imidazoline type, alkylaminosulfone type, alkylaminocarboxylic acid type, alkylamidocarboxylic acid type, amide amino acid type, and phosphoric acid type. In terms of fineness of bubbles, betaine type surfactants are preferred, and carboxybetaine type amphoteric surfactants having a carboxylate type anion moiety are more preferred.

[0016] Examples of the carboxybetaine type amphoteric surfactant include alkylamide betaine type, alkyl betaine type, and imidazoline type. The alkylamidobetaine type has an amide group derived from a fatty acid amidoamine obtained by reacting a fatty acid with a diamine compound. The number of carbon atoms in the fatty acid is preferably 10 to 18, more preferably 12 to 16. Specific examples include coconut oil fatty acid amidopropyl betaine, lauric acid amidopropyl dimethylaminoacetic acid betaine, coconut alkylamidopropyl dimethylaminoacetic acid betaine, coconut oil fatty acid amidopropyl dimethylaminoacetic acid betaine (cocamidopropyl betaine), etc. The alkyl betaine type has a quaternary ammonium structure as the cationic moiety and a carboxylic acid structure as the anionic moiety. The number of carbon atoms in the fatty acid is preferably 10 to 18, more preferably 12 to 16. Specific examples include lauryl dimethyl amino acetic acid betaine and coconut alkyl dimethyl amino acetic acid betaine. The imidazoline type includes secondary amide type compounds in which the imidazoline ring is cleaved, and tertiary amide type compounds, such as 2-alkyl-N-carboxymethyl-N-hydroxyethyl imidazolinium betaine. Of these, alkylamidobetaine-type carboxybetaine amphoteric surfactants are more preferred.

[0017] Examples of the amine oxide surfactant include dodecyl dimethyl amine oxide, coconut alkyl dimethyl amine oxide, decyl dimethyl amine oxide, and tetradecyl dimethyl amine oxide.

[0018] As the component (B), one or more amphoteric surfactants may be used alone, one or more amine oxide surfactants may be used alone, or both may be used in combination. It is preferable that the component (B) contains at least one or more surfactants selected from the group consisting of betaine-type amphoteric surfactants and amine oxide-type surfactants.

[0019] <(C) component> The component (C) is an alcohol (aliphatic alcohol) having an aliphatic hydrocarbon group (a hydrocarbon group that is not aromatic) having 8 to 20 carbon atoms. Component (C) interacts with components (A) and (B) to densely arrange the molecules of components (A) and (B) at the bubble interface, improving the bubble viscosity and contributing to the formation of strong bubbles that are difficult to defoam. The component (C) may be used alone or in combination of two or more.

[0020] The aliphatic hydrocarbon group of component (C) may be a chain hydrocarbon group or a cyclic hydrocarbon group. The chain hydrocarbon may be linear or branched. A linear hydrocarbon group is preferred because it forms cells with excellent strength. The aliphatic hydrocarbon group of component (C) may be saturated or unsaturated. Component (C) is preferably a monohydric alcohol. Component (C) is preferably a primary alcohol or a secondary alcohol, more preferably a primary alcohol. The aliphatic hydrocarbon group of component (C) preferably has 8 to 16 carbon atoms, and more preferably 10 to 14 carbon atoms.

[0021] Examples of component (C) include chain saturated monohydric alcohols having 8 to 20 carbon atoms, chain unsaturated monohydric alcohols having 8 to 20 carbon atoms, and cyclic saturated monohydric alcohols having 8 to 20 carbon atoms. The primary chain saturated monohydric alcohol is octyl alcohol (CH 18 O), nonyl alcohol (CH 20 O), decyl alcohol (C 10 H 22 O), undecyl alcohol (C 11 H 24 O), lauryl alcohol (C 12 H 26 O), tridecyl alcohol (C 13 H 28 O), myristyl alcohol (C 14 H 30 O), pentadecyl alcohol (C 15 H 32 O), cetyl alcohol (C 16 H 34 O), stearyl alcohol (C 18 H 38O), nonadecyl alcohol (C 19 H 40 O) and others. The primary chain unsaturated monohydric alcohol is octenyl alcohol (CH 16 O), decenyl alcohol (C 10 H 20 O), dodecenyl alcohol (C 12 H 24 O), tridecenyl alcohol (C 13 H 26 O), pentadecenyl alcohol (C 15 H 30 O), oleyl alcohol (C 18 H 36 O), gadoleyl alcohol (C 20 H 40 O), linoleyl alcohol (C 18 H 34 O) and others. Examples of primary cyclic saturated monohydric alcohols include ethylcyclohexyl alcohol, propylcyclohexyl alcohol, octylcyclohexyl alcohol, and nonylcyclohexyl alcohol.

[0022] <(D) component> Component (D) is a compound represented by the following general formula (II): Component (D) is a glycol ether solvent. Component (D) contributes to the liquid stability of the foaming agent itself, preventing gel-like aggregation, cloudiness, sedimentation, etc., even at low temperatures. R 2 O(CH2CH2O) p H (II) In formula (II), R 2 is a hydrocarbon group having 1 to 8 carbon atoms, and p is the number of repetitions of the oxyethylene group and represents an integer of 1 to 3. The component (D) may be used alone or in combination of two or more.

[0023] R 2 The hydrocarbon group as may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group. R 2The aliphatic hydrocarbon group may be a chain hydrocarbon group or a cyclic hydrocarbon group. The chain hydrocarbon may be linear or branched. R 2 The aliphatic hydrocarbon group may be saturated or unsaturated. R 2 As the alkyl group, a linear or branched alkyl group having 1 to 8 carbon atoms or a phenyl group is preferred.

[0024] Examples of component (D) include cellosolves where p is 1, carbitols where p is 2, and triglycols where p is 3. For example, if p is 1 and R 2 is an alkyl group, p is 2, and R 2 is an alkyl group, p is 3, and R 2 is an alkyl group, p is 1, and R 2 is a phenyl group, p is 2, and R 2 is a phenyl group, p is 3, and R 2 is a phenyl group, triethylene glycol monophenyl ether is preferred. In terms of excellent liquid stability of the foaming agent, p is 1, 2 or 3, and R 2 More preferred are compounds in which is an alkyl group. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a t-butyl group, an n-hexyl group, and a 2-ethylhexyl group. In terms of excellent liquid stability at low temperatures, an n-butyl group or an i-butyl group is preferred.

[0025] <Water> The foaming agent preferably contains water. If the content of water relative to the total mass of the foaming agent is too high, it is impractical from a cost perspective, and if it is too low, the liquid stability is impaired. Therefore, it is preferable to set the content of water within a range that does not cause these inconveniences. For example, about 30 to 70 mass % is preferable, and about 40 to 50 mass % is more preferable.

[0026] <Other optional ingredients> The foaming agent may contain any other optional components in addition to the components (A) to (D) and water. The other optional components are preferably those that do not inhibit foaming properties and are soluble in water, such as polyethylene glycol, which is added to improve foam stability.

[0027] <Content> In the foaming agent, A / B, which represents the mass ratio of the content of component (A) to the content of component (B), is 1 to 6, preferably 2 to 5, and more preferably 3 to 4. When A / B is within the above range, the density of the bubbles is excellent, and it is easy to obtain sufficient fluidity of the cellular concrete slurry at low temperatures.

[0028] The total content of components (A) and (B) relative to the total of components (A) to (D) is preferably 40 to 70 mass%, more preferably 45 to 65 mass%, and even more preferably 50 to 60 mass%. When the content is equal to or greater than the lower limit of the above range, the effect of improving the fluidity of the cellular concrete slurry at low temperatures is excellent. When the content is equal to or less than the upper limit, the liquid stability of the foaming agent is excellent. The content of component (C) relative to the total of components (A) to (D) is preferably 2 to 15 mass%, more preferably 2 to 10 mass%, and even more preferably 4 to 8 mass%. When the content is equal to or greater than the lower limit of the above range, the effect of adding component (C) is likely to be sufficient. When the content is equal to or less than the upper limit, the liquid stability of the foaming agent is excellent. The content of component (D) relative to the total of components (A) to (D) is preferably 30 to 55 mass%, more preferably 30 to 50 mass%, and even more preferably 35 to 45 mass%. When the content is at least the lower limit of the above range, the effect of adding component (D) is easily achieved. When the content is at most the upper limit, excellent bubble strength is achieved. The total content of other optional components is preferably 0 to 10 mass %, more preferably 0 to 5 mass %, based on the total of components (A) to (D).

[0029] The foaming agent of the present embodiment can be obtained by uniformly mixing the components (A) to (D), water, and other optional components as required. The foaming agent of this embodiment is used to produce cellular concrete. The foaming agent of this embodiment is preferably diluted with water as needed. The amount of water used for dilution (dilution water) is preferably 1 to 200 times, and more preferably 50 to 100 times, the total mass of components (A) to (D).

[0030] <Method of manufacturing aerated concrete> The method for manufacturing aerated concrete of this embodiment involves foaming a foaming liquid containing the foaming agent of this embodiment to obtain a group of bubbles (foaming process), mixing the obtained group of bubbles with a hydraulic slurry to obtain aerated concrete slurry (mixing process), and hardening the obtained aerated concrete slurry to obtain aerated concrete (hardening process).

[0031] [Foaming process] First, the foaming agent of this embodiment is diluted with water (dilution water) to prepare a foaming liquid. The total content of components (A) to (D) relative to the total mass of the foamable liquid is preferably 0.6 to 2.7 mass%, more preferably 0.8 to 2.0 mass%, and even more preferably 0.9 to 1.5 mass%. When the content is at least the lower limit of the above range, excellent bubble strength is achieved, and when the content is at most the upper limit, excellent cost performance is achieved. The temperature of the dilution water is preferably 0 to 30° C. A temperature of 0 to 20° C. is more preferable in view of the greater effect of using the foaming agent of this embodiment. The foaming agent and dilution water can be mixed using, for example, a diaphragm pump.

[0032] Next, the foamable liquid is foamed to incorporate air and form bubbles. The bubbles are formed by a two-fluid mixing method of the foamable liquid and air. The two-fluid mixing can be performed, for example, by combining compressed air generated by a compressor and foamable liquid pumped by a diaphragm pump in a cylindrical manufacturing apparatus. The temperature of the foaming liquid used for foaming is preferably 0 to 30° C. A temperature of 0 to 20° C. is more preferable since the foaming agent of this embodiment has a significant effect. The temperature of the air used for foaming is preferably 0 to 30° C. A temperature of 0 to 20° C. is more preferable since the foaming agent of the present embodiment has a large effect.

[0033] The resulting bubbles consist of the foamable liquid and air. The foaming ratio when foaming the foamable liquid is preferably 5 to 50 times, more preferably 10 to 30 times. Here, the expansion ratio is a value obtained by the following method. The foaming ratio is the volume of the bubbles divided by the volume of the foamable liquid required to obtain those bubbles. For example, if the volume of the foamable liquid before foaming is V1 and the volume of the resulting bubbles (foamable liquid and air) is V2, then the foaming ratio (unit: times) = V2 / V1. The density of the resulting bubble group is 0.02 to 0.20 g / cm 3 is preferable, and 0.03 to 0.10 g / cm 3 is more preferred.

[0034] [Mixing process] Next, the resulting bubbles are mixed with a hydraulic slurry prepared in advance to obtain an aerated concrete slurry. Examples of hydraulic slurries include cement milk, which is a mixture of cement and water (mixing water), and mortar, which is a mixture of cement, water, and aggregate. Examples of cement include ordinary portland cement, belite cement, moderate heat cement, high early strength cement, ultra high early strength cement, and sulfate resistant cement. The hydraulic slurry may further contain known additives such as admixtures such as blast furnace slag, fly ash, silica fume, stone powder (calcium carbonate powder), and water-reducing agents such as air-entraining water-reducing agents, high-performance water-reducing agents, and high-performance air-entraining water-reducing agents.

[0035] The hydraulic slurry and the bubbles can be kneaded using, for example, a line mixer. The mixing ratio of the hydraulic slurry and the air bubbles can be designed according to the specific gravity of the hydraulic slurry and the specific gravity (air content) of the air bubbles so that the specific gravity (air content) of the aerated concrete slurry becomes a predetermined design value. The amount of air relative to the total volume of the aerated concrete slurry is preferably 40 to 80% by volume, more preferably 50 to 70% by volume. The specific gravity (air content) of the aerated concrete slurry can be set according to the specific gravity of the hardened product (aerated concrete) to be obtained.

[0036] [Curing process] The aerated concrete slurry can be hardened by any known method. For example, after the aerated concrete slurry is poured into a predetermined formwork or filled into a predetermined space, it can be cured by curing using methods such as air-dry curing, moist air curing, underwater curing, and heat-accelerated curing (steam curing, autoclave curing). In this way, a porous hardened product (cellular concrete) is obtained in which closed pores resulting from groups of air bubbles exist in the hardened product of the hydraulic slurry. [Example]

[0037] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following description.

[0038] <Raw materials used> [Component (A)] (A1-1) Sodium lauryl sulfate (BASF Japan Ltd. product name "Texapon OC-P"; in formula (I), R 1 is a linear alkyl group with 12 carbon atoms, m is zero, M +is a sodium ion). (A1-2) Triethanolamine lauryl sulfate (product name: Taipol NLT-42, Taiko Yushi Kagaku Kogyo Co., Ltd.; in formula (I), R 1 is a linear alkyl group with 12 carbon atoms, m is zero, M + is protonated triethanolamine). (A2-1) Sodium polyoxyethylene lauryl sulfate (product name "Shinoline SPE-1250" by New Japan Chemical Co., Ltd., in formula (I), R 1 is a linear alkyl group having 12 carbon atoms, AO is EO, m is 2, M + is a sodium ion). (A2-2) Sodium polyoxyethylene lauryl sulfate (product name "Shinoline SPE-1350" by New Japan Chemical Co., Ltd., in formula (I), R 1 is a linear alkyl group having 12 carbon atoms, AO is EO, m is 3, M + is a sodium ion).

[0039] [(B) Component] (B-1) Lauryl amidopropyl dimethylaminoacetic acid betaine (Lion Specialty Chemicals Co., Ltd. product name "Energycol L-30B"). (B-2) Coconut oil fatty acid amidopropyl dimethylaminoacetic acid betaine (Lion Specialty Chemicals Co., Ltd. product name "Energycol C-30B"). (B-3) Coco-alkyl dimethylamine oxide (Lion Specialty Chemicals Co., Ltd. product name "Cadenax DMC-W").

[0040] [(C) component] (C-1) Palm alcohol (product name "Conol 1275" by New Japan Chemical Co., Ltd., a mixture containing lauryl alcohol and myristyl alcohol). (C-2) Lauryl alcohol (product name "Conol 20P" by New Japan Chemical Co., Ltd.). (C-3) Decyl alcohol (product name "Conol 1098" by New Japan Chemical Co., Ltd.). (C-4) Octyl alcohol (product name: "Conol 10WS" by New Japan Chemical Co., Ltd.).

[0041] [(D) component] (D-1) Isobutyl glycol (manufactured by Nippon Nyukazai Co., Ltd., in which p is 1 in formula (II) and R 2 is an i-butyl group). (D-2) Butyl glycol (manufactured by Nippon Nyukazai Co., Ltd., in which p is 1 in formula (II) and R 2 is an n-butyl group). (D-3) Butyl diglycol (manufactured by Nippon Nyukazai Co., Ltd., in which p is 2 in formula (II) and R 2 is an n-butyl group).

[0042] <Examples 1 to 8 and Comparative Examples 1 to 4> According to the formulation shown in Table 1, components (A) to (D) and water were mixed to prepare a foaming agent for cellular concrete. The amounts in the table are pure equivalents. Ingredients without a listed amount in the table are not included. Using the foaming agents obtained in each example, the fluidity and bleeding rate of cellular concrete slurries at low temperatures were evaluated by the following methods. The results are shown in the table below. Bleeding is a phenomenon in which water seeps out of the concrete slurry after it has been poured. It is preferable to have as little bleeding water as possible.

[0043] In the table, (A+B) / (A-D) is the total content of components (A) and (B) relative to the total of components (A)-(D). C / (A-D) is the total content of component (C) relative to the total of components (A)-(D). D / (A-D) is the total content of component (D) relative to the total of components (A)-(D).

[0044] [Method for evaluating fluidity at low temperatures] (Sample preparation) The foaming agent was diluted 60 times using tap water (diluted water) adjusted to 10°C to obtain a foam liquid. The resulting foam liquid (10°C) was mixed with air (20°C) to foam the foam liquid, producing bubbles with a foaming ratio of 20 times. Separately, 1150 g of tap water (mixing water) adjusted to a temperature of 10°C and 1350 g of cement (blast furnace cement type B) were mixed to prepare cement milk (10°C). 175 g of the air bubbles obtained above was added to 2500 g of the obtained cement milk, and the mixture was kneaded for 1 minute to obtain an air-filled concrete slurry.

[0045] (fluidity test) The aerated concrete slurry obtained above was filled into a 500 mL cup (within 1 second, the inner diameter of the opening was 80 mm) and the cup was immediately rotated 180° so that the opening was facing downward. The aerated concrete slurry in the cup was visually observed to fall downward, and the fluidity was evaluated according to the following criteria. (Evaluation criteria) ○ (Good fluidity): The aerated concrete slurry flowed down continuously. × (poor fluidity): The aerated concrete slurry fell intermittently.

[0046] [Method for evaluating bleeding rate at low temperatures] (Sample preparation) Aerated concrete slurry was obtained in the same manner as in (Sample preparation) of the above [Method for evaluating fluidity at low temperatures].

[0047] (Bleeding rate measurement) The aerated concrete slurry obtained above was filled into a polyethylene bag 550 mm long, 50 mm in inner diameter, and 0.05 mm thick, to a height of 200 mm. The bag was then sealed, hung, and left to stand at room temperature. After 24 hours, the amount of drainage collected at the bottom of the bag (drainage volume after 24 hours) was measured. The bleeding rate (unit: volume %) was calculated by dividing the drainage volume after 24 hours by the volume of the aerated concrete slurry after 24 hours, as shown in the following formula. Bleeding rate = drainage volume after 24 hours / volume of aerated concrete slurry after 24 hours x 100 (Evaluation criteria) Good: Bleeding rate is less than 2%. △: Bleeding rate is 2% or more but less than 5%. ×: Bleeding rate is 5% or more.

[0048] [Table 1]

[0049] As shown in the results in Table 1, the cellular concrete slurries using the foaming agents of Examples 1 to 8 had excellent fluidity at low temperatures. On the other hand, Comparative Examples 1 and 2, in which the foaming agent did not contain component (B), and Comparative Examples 3 and 4, in which the A / B value was outside the range of the present invention, had poor fluidity at low temperatures.

Claims

1. Component (A): a compound represented by the following general formula (I), Component (B): one or more surfactants selected from the group consisting of carboxybetaine-type amphoteric surfactants and amine oxide-type surfactants; Component (C): an alcohol having an aliphatic hydrocarbon group having 8 to 20 carbon atoms; (D) component: a compound represented by the following general formula (II), A foaming agent for cellular concrete, wherein A / B, which represents the mass ratio of the content of the (A) component to the content of the (B) component, is 1 to 6. R １ O(AO) ｍ OO ３ － M ＋ ・・・(I) [In the formula, R １ is an aliphatic hydrocarbon group having 8 to 20 carbon atoms, AO is an oxyalkylene group having 2 to 3 carbon atoms, m represents the average number of repetitions of AO and is a number from 0 to 10, and M ＋ represents a counter cation, which is an alkali metal ion, ammonium, a protonated amine, or a protonated alkanolamine. R ２ O(CH ２ CH ２ O) ｐ H ・・・(II) [In the formula, R ２ is a hydrocarbon group having 1 to 8 carbon atoms, and p is the number of repetitions of the oxyethylene group and represents an integer of 1 to 3.

2. A method for producing aerated concrete, comprising foaming a foaming liquid containing the foaming agent for aerated concrete according to claim 1 to obtain a group of bubbles, mixing the group of bubbles with a hydraulic slurry to obtain aerated concrete slurry, and hardening the aerated concrete slurry to obtain aerated concrete.

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