JP2009114024A - Foam mortar kneaded product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a foam mortar suitable as a filling material for a charging process for a gas pipe which has a low specific gravity, a low strength, a high gas permeability and a low heat-generation, and a flowability in pressure feeding and a bleeding resistance as well. <P>SOLUTION: The foam mortar kneaded product is prepared by mixing cement C, a finely powdered aggregate P (e.g. limestone fine powder), mixing water W<SB>1</SB>and (A) a foaming agent mixed with one or both of an amine oxide type surfactant and a fluorine-based surfactant or (B) an anionic or a nonionic foaming agent to have a mixing composition satisfying (1) an air quantity; 63-75 vol.%, (2) a water powder ratio W<SB>1</SB>/(C+P); 0.35-0.70, (3) a cement powder ratio C/(C+P); ≥0.35, and a compressive strength at the age of 28 days of 0.1-0.7 N/mm<SP>2</SP>. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a foamed mortar kneaded material that has air permeability after curing and exhibits low strength that can be excavated manually, and is particularly suitable for a filler used in a gas pipe filling method.

  Conventionally, “foam mortar” is used for backfilling underground structures, lightweight embankment, backfilling tunnels and shields, and so on. . In recent years, the foam mortar is expected to be applied in various applications as a material that can make use of properties such as lightness, heat insulation and shock absorption in addition to low strength. One such application is a filler used in a gas pipe filling method. The gas pipe filling method is a method in which a filler is filled between the buried gas pipe and the outer pipe covering it, but in the unlikely event that gas leaks from the gas pipe, the gas buried in the filler The filler is required to have high air permeability so that the gas can reach the position of the leak sensor.

  Conventional foaming agents for foam mortar are mainly made of anionic surfactant as the main component, but in this kind of foam mortar, the anionic surfactant is calcium hydroxide generated by hydration of cement. Reacts with to produce a hydrophobic calcium salt, and the cured foam mortar becomes impermeable (impermeable). For this reason, it is difficult to apply to the filler use of the gas pipe filling method. Therefore, a foaming agent having an amine oxide type nonionic surfactant as a main component has been developed. Patent Document 1 uses this foaming agent to provide good permeability without imparting hydrophobic properties to the cell mortar. A technique for imparting temper is disclosed.

  In addition, in the foamed cement milk that does not use aggregates, if the amount of cement is reduced to suppress the strength, the water cement ratio (W / C) increases and bleeding tends to occur. Conversely, when the amount of cement is increased, excessive strength, temperature rise due to hydration reaction, fluidity / long-distance pumpability due to increased viscosity, etc. are likely to occur. As a technique for solving such a problem, Patent Document 3 describes a technique using ferronickel slag having a large specific gravity with a maximum particle size of 0.02 mm or less as an aggregate.

  On the other hand, as a technique for obtaining foam cement milk and foam mortar that do not cause volume reduction after curing, use of a foaming agent containing a fluorosurfactant (hereinafter referred to as a "foaming agent containing a fluorosurfactant") Is known to be effective (Patent Document 2). In addition, it is known that adding fine calcium carbonate powder is effective in suppressing the strength of the bubble mortar (Patent Document 4).

Japanese Patent Laid-Open No. 2005-60188 JP-A-11-1000028 JP-A-9-249441 Japanese Patent Laid-Open No. 3-115146

The following properties are desired for the filling material of the gas pipe filling method.
(I) Low specific gravity (density). In order to stably prevent the gas pipe from floating in the filler, for example, the specific gravity (density) is preferably about 0.50 to 0.65 g / cm ³ or less.
(Ii) Low strength. Low strength is required to enable excavation of the filler by manpower in an emergency.
(Iii) Excellent air permeability. An air permeability coefficient of 1 × 10 ⁻¹ cm / sec or more is required in order to enable gas detection with a gas leak sensor embedded in the filler when a gas leak occurs.
(Iv) Low exothermic property. If the amount of heat generated during curing is large, the surface protective film of the gas pipe (iron pipe) may be deteriorated and rust may be generated. In addition, the elongation due to thermal expansion of the gas pipe is unfavorable. Low exothermicity is desired such that the gas pipe temperature is, for example, 60 ° C. or lower.
(V) In addition, fluidity is good in pumping during filling, and material separation (bleeding) does not occur.

  However, it is very difficult to satisfy all of these in cementitious materials. For example, when the amount of air (bubble amount) is increased in order to ensure low specific gravity and air permeability, the bubble stability is lowered, and the bubbles disappear or the fluidity is lowered by pressure feeding. When the bubbles disappear, air permeability can no longer be secured. Conversely, reducing the amount of air is a disadvantageous factor for low specific gravity, low strength, and high air permeability, and it is difficult to satisfy predetermined characteristics. Further, reducing the cement is effective in reducing the strength and suppressing the amount of heat generation, but on the other hand, it causes bleeding and material separation due to a decrease in viscosity.

  According to the technique using the amine oxide type nonionic surfactant of Patent Document 1, it is possible to obtain a bubble mortar having a bubble amount of 70% or more. However, there is no known mortar having a composition that satisfies the above required properties (i) to (v). Simply applying a foaming agent containing this type of surfactant as the component described above requires the above requirements. Characteristics cannot be cleared.

  Although the technology of Patent Document 2 uses a foaming agent containing a fluorosurfactant that is excellent in bubble stability, it is a bubble mortar suitable for a filling material in a gas pipe filling method that simultaneously satisfies the above characteristics. There is no teaching on the formulation of

  The technique of Patent Document 3 uses ferronickel slag having a large specific gravity (density), so that it is easy to adjust the strength of the bubble mortar, but sufficient gas permeability can be obtained as a filling material for the gas pipe filling method. When trying to secure the amount of bubbles, material separation tends to occur. In fact, the amount of air in the bubble mortar disclosed in this document is at most about 45%.

  In the technique of Patent Document 4, a fine powder of calcium carbonate is used for the aggregate, but the air amount is still limited to a maximum of 45% by volume. In this case, the air permeability as a filler for the gas pipe filling method is insufficient. This document also teaches nothing about a method for obtaining a bubble mortar that satisfies the above-mentioned characteristics at the same time.

  Thus, the filler suitable for the filling method in a gas pipe which satisfy | fills each characteristic of said (i)-(v) has not yet appeared. In view of the present situation, the present invention is intended to provide a bubble mortar that satisfies the above requirements.

The above-mentioned purpose is to satisfy the following (1) to (3) by mixing cement C, fine powder aggregate P, kneaded water W ₁ and bubbles foamed using the foaming agent shown in (A) below. This is achieved by a foam mortar kneaded product having a blended composition.
(A) Foaming agent containing one or both of amine oxide type surfactant and fluorosurfactant (1) Air content; 63 to 75% by volume
(2) Water powder ratio W _{1 / (} C + P); 0.35 to 0.70
(3) Cement powder ratio C / (C + P); range in which the compressive strength is 0.35 or more and the compressive strength at 28 days of age is 0.1 to 0.7 N / mm ²

Or the thing of the following (B) can be prescribed | regulated as a foaming agent. That is, in the present invention, the cement C, fine powder aggregate P, by mixing bubbles by foaming with a foaming agent shown in Mixing water W ₁ and below (B), wherein the (1) to (3) A foamed mortar kneaded material having a composition to satisfy is provided.
(B) Anionic or nonionic foaming agent

  Examples of the foaming agent include those containing an amine oxide type nonionic surfactant as a component. Limestone fine powder is suitable as the fine powder aggregate P. In particular, it is preferable to use a fine limestone powder having a Blaine specific surface area of 0.5 to 2.5 times that of cement C. The kneaded material may contain an admixture or an admixture that can be added to a general cell mortar as long as the effects of the present invention are not impaired.

  According to the present invention, a foam mortar having both “low specific gravity”, “low strength”, “high air permeability”, and “low heat generation” and also having “flowability” and “bleeding resistance” is realized. It became possible. Although this foam mortar can be applied to various uses, it is particularly suitable for a filler used in a gas pipe filling method. Moreover, since the base mortar for making this mortar kneaded material can be made into a composition excellent in long-distance pumpability, after the base mortar is pumped to the vicinity of the setting site, the bubbles are mixed and cast. Easy to apply to construction methods. Therefore, the present invention contributes particularly to the spread of the gas pipe filling method.

  In order to improve the air permeability in the foam mortar, it is necessary to increase the amount of air in the mortar kneaded material, but that alone is not sufficient. In the mortar hardened body after the foamed mortar kneaded product has been placed, voids (open cells) serving as gas passages must be formed. As a result of detailed studies by the inventors, it is difficult to obtain a hardened mortar cured product with a general anionic or cationic foaming agent, which is not suitable for the present invention. This is presumed that the hydrophobic calcium salt film remaining on the inner surface of the foam after curing protects the matrix and makes it difficult to form open cells.

  On the other hand, in the case of an anionic or nonionic foaming agent, highly stable bubbles can be formed by devising a surfactant component. In addition, it was confirmed that bubbles foamed using an amine oxide type surfactant or a foaming agent containing a fluorine-based surfactant have extremely good stability in a mortar kneaded product. That is, the bubbles are hard to break through the processes of kneading, pumping, and placing, and remain in a highly uniform distribution state while maintaining a healthy void shape in the mortar after placement. Even if it is a foaming agent mainly composed of an anionic surfactant, the adverse effect on the air permeability caused by the reaction between the anion and calcium hydroxide can be reduced by adding an amine oxide type surfactant or a fluorochemical surfactant. Almost no problem. This is because the stability of the bubbles in the mortar kneaded material is high, and even when a hydrophobic reaction product is generated due to the formation of a nearly spherical space reflecting the shape of the original bubbles, it is derived from the bubbles. It is assumed that there is sufficient space in the gap to allow gas to pass. In particular, a nonionic or amphoteric surfactant as a main component makes it difficult to form a hydrophobic calcium salt, and a further improvement in air permeability can be expected.

  Also, it is thought that a cement paste skeleton mixed with fine powder is formed between the voids derived from the bubbles in the hardened mortar, but the fine powder weakens the matrix surrounding the bubbles (cement). It is presumed to have an action of forming a weak part of the film. In this case, the matrix is easily broken by an external force such as volume expansion or drying shrinkage during heat generation during curing, which is advantageous for the formation of open cells. In fact, according to the present invention, good air permeability can be obtained. Therefore, the skeleton is mixed with fine powder aggregate particles having a particle size relatively close to that of cement particles. It is inferred that it has a “skeletal structure”. In any case, in the foam mortar in which the mortar kneaded product of the present invention is cured, by matching the voids derived from healthy bubbles using the above-mentioned type of foaming agent and the skeletal structure mixed with fine powder aggregate It is considered that high air permeability can be obtained.

Hereinafter, matters for specifying the present invention will be described.
[Cement C]
Normal Portland cement can be used. For example, ordinary Portland cement, moderately hot Portland cement, low heat Portland cement, and the like can be mentioned.

[Fine powder aggregate P]
As the fine powder aggregate P, a natural mineral-derived inorganic powder having a specific gravity (density) as small as cement C or less and a brane specific surface area of 0.5 to 2.5 times that of cement C is suitable. When the specific gravity (density) is higher than that of cement, it is not only disadvantageous for lowering the specific gravity of the foamed mortar after hardening, but also material separation tends to occur, making it difficult to apply to a construction method in which the base mortar is pumped over a long distance. The specific surface area of the brane is a factor that greatly depends on the particle diameter, but in the case of fine powder obtained by pulverizing natural minerals, if the specific surface area of the brane is 0.5 to 2.5 times that of the cement C, it is close to the cement particle. Since it has a particle size, resistance to material separation is increased.

  Fly ash-based fine powder (eg blast furnace slag) may contain components that cause problems in gas detection, and there are also those that tend to hinder bubble stability (eg fly ash). Inorganic powder should be used.

Among them, limestone fine powder (tankal) obtained by crushing and classifying limestone is preferable, and those having a Blaine specific surface area of 0.5 to 2.5 times that of cement C are particularly preferable. An average particle size of about 3 to 20 μm is a suitable target. In addition to the main component CaCO ₃ , the limestone fine powder is usually Mg of 5 mass% or less in terms of MgO, Fe is 1 mass% or less in terms of Fe ₂ O ₃ , and Al is 5 mass% or less in terms of Al ₂ O ₃ , Si is contained in a range of 5% by mass or less in terms of SiO ₂ .

[Mixing water W _1]
General mortar and concrete that can be used for underground water, tap water or the like can be used for Mixing water W _1.

(Foaming agent)
As the foaming agent applied in the present invention, an anionic or nonionic one can be adopted. In particular, an amine oxide type surfactant or a foaming agent containing a fluorosurfactant is a suitable target. This type of foaming agent exhibits excellent bubble stability as described above. What is necessary is just to employ | adopt the type which mix | blends any one surfactant among an amine oxide type surfactant and a fluorine-type surfactant, However, You may employ | adopt the type which mix | blends these both. In addition, it is thought that in the case of blending a fluorosurfactant, it is possible to improve the bubble stability even if it is cationic.

  In particular, foaming agents composed of amine oxide type nonionic surfactants are different from foaming agents composed of conventional anionic surfactants in that they have hydrophobic properties in cellular mortar and concrete. Combined with limestone fine powder (cell stability that maintains sound bubbles until the hardening stage and ability to form open cells by synergistic weakening of the matrix surrounding the bubbles). . Examples of the foaming agent containing an amine oxide type nonionic surfactant as a component include “Air Ball S” manufactured by Daiichi Kasei Sangyo. This type of foaming agent, like other general foaming agents, may be used after being diluted with water, for example, about 10 to 30 times. A known method can be applied as the foaming method. It is desirable to foam so that the volume after foaming is 20 to 30 times the amount of the diluted foaming agent.

[Air volume]
If the amount of air in the kneaded material supplied by the bubbles is too small, it is impossible to achieve a low specific gravity and high air permeability of the foamed mortar cured body. As a result of various studies, in the case where the fine powder aggregate P is blended and the bubbles foamed using the type of foaming agent described above are mixed, if the amount of air falls below 63% by volume, Even if the body ratio W ₁ / (C + P) and the cement powder ratio C / (C + P) are changed, the air permeability coefficient of 1 × 10 ^-1 cm / sec or more, which is desired for the filling material in the gas pipe filling method, is realized. May not find a solution to do this. On the other hand, if the amount of air exceeds 75% by volume, the foam stability may be insufficient even when an appropriate foaming agent is used. In this case, the fluidity (flow) of the foam mortar is lowered particularly after pumping. There is a concern to do. Therefore, the amount of air in the mortar kneaded material is adjusted in the range of 63 to 75% by volume.

[Water powder ratio W ₁ / (C + P)]
If the water-powder ratio W ₁ / (C + P) is too small, the amount of powder is relatively large, and in the base mortar before mixing with bubbles, the pumpability decreases due to increased viscosity. There is also a concern that the kneaded product may interfere with the pumpability at the time of placing. As a result of various studies, the water powder ratio W ₁ / (C + P) is preferably 0.35 or more. On the other hand, when the water powder ratio W ₁ / (C + P) becomes too large, the viscosity is lowered, and the base mortar and the foamed mortar kneaded material are liable to cause material separation. Further, it was found that when the water powder ratio W ₁ / (C + P) is increased, the degree of freedom of blending for realizing the air permeability coefficient of 1 × 10 ⁻¹ cm / sec or more becomes narrower. For these reasons, the upper limit of the water powder ratio W ₁ / (C + P) is defined as 0.70.

[Cement powder ratio C / (C + P)]
As described above, the filling material of the gas pipe filling method is required to have low strength that can be excavated by human power. According to the inventors' investigation, this type of foamed mortar hardened body has a compressive strength of 28 days of age. Is 0.7 N / mm ² or less, it can be applied to a filling material for a gas pipe filling method. More preferably, it is 0.6 N / mm ² or less. However, it is necessary to apply a certain restraining force between the gas pipe and the outer pipe. As a result of the investigation, the strength of the foamed mortar hardened body is 0.1 N / mm ² or more as the compressive strength at the age of 28 days. It is desirable that

The cement powder ratio C / (C + P) is a factor that greatly affects the strength of the foamed mortar hardened body, and generally the strength level of the mortar hardened body increases as the cement powder ratio C / (C + P) increases. Tend to. However, even if only this cement powder ratio C / (C + P) is set alone, the strength level of the cured foam mortar cannot be controlled to a desired value. This is because the strength level varies depending on the amount of air and the water powder ratio W ₁ / (C + P). Therefore, in the present invention, the air amount and the water powder ratio W ₁ / (C + P) are set to the above-mentioned appropriate ranges, respectively, and the compressive strength at the age of 28 days of the cement powder ratio C / (C + P) is 0.00. 1 to 0.7 N / mm ^2, preferably in the range of 0.1 to 0.6 N / mm ² .

The inventors have conducted numerous bubble mortar blending experiments to determine the “air permeability coefficient” of the cured product by “air amount”, “water powder ratio W ₁ / (C + P)” and “cement powder ratio C / (C + P)”. "," Strength "and" specific gravity (density) "were found to be controllable over a fairly wide range. That is, when “air quantity”, “water powder ratio W ₁ / (C + P)”, and “cement powder ratio C / (C + P)” are taken as variables, “air permeability coefficient”, “strength” and It was found that “specific gravity (density)” can be regarded as a function using the above variables. A regression equation that accurately represents the functional relationship can be set based on many blending experiment results. According to this, the cement powder ratio C / (C + P) is set in the range where the compressive strength at the age of 28 days is 0.1 to 0.7 N / mm ^2, preferably 0.1 to 0.6 N / mm ^2. Can be easily implemented.

However, if the cement powder ratio C / (C + P) is too small, the amount of fine powder aggregate P is relatively increased, and both the base mortar and the foam mortar kneaded material have material separation (sedimentation) and free water due to viscosity reduction. There is concern about bleeding due to inability to restrain. According to a detailed examination, it was found that the cement powder ratio C / (C + P) is desirably adjusted within a range of 0.35 or more. Accordingly, the cement powder ratio C / (C + P) is 0.35 or more and the compressive strength at 28 days of age is 0.1 to 0.7 N / mm ^2, preferably 0.1 to 0.6 N / mm ^2. Specified in range.

[Production of foam mortar kneaded product]
The foamed mortar kneaded product of the present invention can be produced by the same method as in the case of conventional general foamed mortar. For example, diluting water W ₂ and foaming agent F of the type described above are put into a mixer to make foam, and then mixing water W ₁ , fine powder aggregate P and cement C are put into the mixer. Then, a kneading method (mixing method) can be employed. In addition, a base mortar is prepared by kneading premixed water W ₁ , fine powder aggregate P, and cement C, and bubbles are generated separately from foaming agent F diluted with water W ₂ using a foaming device. A method (preform method) of mixing the above with the base mortar can be employed. According to the blend of the foam mortar kneaded material of the present invention, a base mortar having excellent long-distance pumpability and material separation resistance (cement C, fine powder aggregate P, mixed water W ₁ before mixing the bubbles). For example, a production method in which the base mortar is transferred to the placement site by long-distance pumping of, for example, about 6000 m and mixed with bubbles by the preform method immediately before the placement can be suitably employed. Of course, since it has excellent bubble stability, the bubble mortar produced by the mixing method and the preform method can be pumped by about 500 m.

The following materials were prepared.
Cement C: ordinary Portland cement, specific gravity (density) 3.15 g / cm ³ , Blaine specific surface area 3300 cm ² / g
Fine powder aggregate P; fine limestone powder, specific gravity (density) 2.70 g / cm ³ , Blaine specific surface area 5000 cm ² / g
・ Mixed water W ₁ ： Tap water ・ Foaming agent F; Foaming agent “Airball S” series with amine oxide type nonionic surfactants manufactured by Daiichi Kasei Sangyo ・ Diluted water W ₂ ; Tap water

Using these materials, a foam mortar kneaded product of each formulation shown in Table 1 was produced by a preform method. Specifically, made based mortar cement C, fine powder aggregate P, and Mixing water W ₁ was kneaded in a mixer. Separately, foaming agent F was diluted with dilution water W ₂ and foamed with a foaming apparatus to form bubbles (cream-like). The base mortar was put into a container containing bubbles and kneaded to obtain a foam mortar kneaded material as a test material. The amount of air was determined according to Japan Highway Public Corporation JHS A313 “Testing method for air mortar and air milk”.

  The sample collected from the base mortar is subjected to the P funnel flow-down test (method in accordance with JHSA 313 “Testing method for air mortar and air milk”), and the length of the base mortar when assuming a gas pipe filling method Distance pumpability was evaluated. That is, when the P funnel flow test value is 9.5 sec or less, it is evaluated as ◯ (long-distance pumping property: good), and when it exceeds 9.5 sec and 12 sec or less, △ evaluation (long-distance pumping property; slightly good), exceeds 12 sec Was indicated as x evaluation (long-distance pumpability; poor).

About the foam mortar kneaded material, the flow value and specific gravity (density) were measured. These were performed by the method based on Japan Highway Public Corporation JHS A313 "Testing method of air mortar and air milk". Assuming placement in the gas pipe filling method, a flow value of 200 mm or more is evaluated as ◯ (fluidity: good), and a value of 170 mm or more but less than 200 mm is evaluated as △ (fluidity; slightly good), less than 170 mm Was evaluated as x evaluation (fluidity; poor). As for the specific gravity, assuming a filler in the gas pipe filling method, those having a specific gravity (density) of 0.63 g / cm ³ or less are evaluated as ○ (passed), and those exceeding it are evaluated as × (failed). ).

A cured product of the foam mortar kneaded product was prepared, and the compressive strength and air permeability coefficient at the age of 28 days were measured. The compressive strength was determined by a method based on JIS R5201 “Physical testing method for cement”. The air permeability coefficient is a formula for calculating the air permeability coefficient based on the commonly used formula for calculating the air permeability. Obtained by applying to. Assuming a filler in the gas pipe filling method, those with a compressive strength in the range of 0.1 to 0.7 N / mm ² are evaluated as ○ (passed), and those that deviate from it are evaluated as × (failed). The air permeability coefficient of 1 × 10 ⁻¹ cm / sec or more was evaluated as ○ evaluation (pass), and the air permeability coefficient was evaluated as × evaluation (fail).
These results are shown in Table 1. In the table, a hyphen (“−”) is an item not measured. In addition, about the thing of this invention example, although the gas pipe surface temperature at the time of hardening was measured using the thermocouple, all did not exceed 60 degreeC.

  As can be seen from Table 1, the examples of the present invention had a composition satisfying the conditions (1) to (3), and a cell mortar exhibiting high air permeability, low strength, and low specific gravity could be realized. In addition, it is possible to adopt a blend that has these characteristics and has good long-distance pumpability as a base mortar and fluidity as a bubble mortar, and is suitable for use as a filler in a gas pipe filling method. Can be provided.

On the other hand, Comparative Example No. 2 was inferior in specific gravity and air permeability coefficient because the amount of air was too small. Nos. 4, 6, and 7 are those that did not adopt a blend that can realize low strength. These satisfy the low strength by changing the blending composition in the direction of increasing the water powder ratio W ₁ / (C + P) of (2) or the direction of decreasing the cement powder ratio C / (C + P) of (3). It becomes possible. If the regression equation is obtained as described above, such a failure in blending design can be effectively prevented.

  All the foam mortar kneaded materials having the composition of the present invention examples shown in Table 1 were subjected to a bleeding test in which the kneaded material immediately after kneading was placed in a 500 mL (milliliter) graduated cylinder to a scale height of 500 mL and left for 120 minutes. .

  As a result, no water was observed at the bottom of the graduated cylinder, and no bleeding was observed. From this, it can be seen that the bubbles foamed by the amine oxide type nonionic surfactant are extremely stable even if they are contained in an air amount as high as 70%.

Claims (5)

Cement C, fine powder aggregate P, mixing water W ₁ and bubbles foamed using the foaming agent shown in (A) below were mixed to obtain a composition satisfying the following (1) to (3). Bubble mortar kneaded product.
(A) Foaming agent containing one or both of amine oxide type surfactant and fluorosurfactant (1) Air content; 63 to 75% by volume
(2) Water powder ratio W _{1 / (} C + P); 0.35 to 0.70
(3) Cement powder ratio C / (C + P); range in which the compressive strength is 0.35 or more and the compressive strength at 28 days of age is 0.1 to 0.7 N / mm ² Cement C, fine powder aggregate P, by mixing bubbles by foaming with a foaming agent shown in Mixing water and W ₁ and below (B), and a blend composition satisfying the following (1) to (3) Bubble mortar kneaded product.
(B) Anionic or nonionic foaming agent (1) Air content: 63 to 75 vol%
(2) Water powder ratio W _{1 / (} C + P); 0.35 to 0.70
(3) Cement powder ratio C / (C + P); range in which the compressive strength is 0.35 or more and the compressive strength at 28 days of age is 0.1 to 0.7 N / mm ²   The foam mortar kneaded product according to claim 1, wherein the foaming agent contains an amine oxide type nonionic surfactant as a component.   The foam mortar kneaded product according to any one of claims 1 to 3, wherein the fine powder aggregate P is limestone fine powder.   The foam mortar kneaded product according to any one of claims 1 to 3, wherein the fine powder aggregate P is a fine limestone powder having a Blaine specific surface area of 0.5 to 2.5 times that of the cement C.