JPH1135361A - Production of cement-air milk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce the cement-air milk having excellent filling properties by mixing cement with at least one inorganic additive selected from bentonite, metakaolin and calcium silicate hydrate, each in a dry state, then adding water to the resulting mixture to form cement milk and thereafter subjecting the cement milk to foaming treatment. SOLUTION: This production comprises: mixing cement with an at least one inorganic additive selected from bentonite having particle size capable of passing through a 200 mesh sieve, metakaolin having an Si/Al atomic ratio of 1.1 to 1.3 and calcium silicate hydrate having a Ca/Si atomic ratio of 1.0 to 4.0 and a 5 to 35% ignition loss, in an additive/cement weight ratio of 7/93 to 40/60 to prepare a cement mixture; then, mixing the prepared cement mixture with water in a water/(cement mixture) weight ratio of 100/100 to 250/100 to form cement milk; blowing a protein-based foaming agent, etc., together with compressed air, into a foaming equipment contg. the cement milk to foam the cement milk and to produce the objective cement-air milk that contains 5 to 70 vol.% of air bubbles having 10 to 1,000 μm bubble size. The cement-air milk has a 160 to 500 mm flow value and a 0.5 to 1.5 g/cm<3> unit weight.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing cement air milk. More specifically, the present invention relates to a method for easily and efficiently producing cement air milk useful for backfilling civil engineering structures, filling voids, embedding lightweight materials, and landfilling.

[0002]

2. Description of the Related Art Conventionally, cement air milk is used for cement,
Water was added, and this cement milk was subjected to a foaming treatment to produce it. In order to avoid the occurrence of material / water separation during the construction, cement air milk manufactured by such a conventional method uses a cylinder (inner diameter 8 cm × height 8 cm) method (Nippon Road) in order to avoid the occurrence of material / water separation. Public Corporation Standards, "Test Methods for Air Mortar and Air Milk" J
HSA 313-1992, consistency test method, cylinder method). This reduces the flow value to about 200mm
To be higher it is necessary to have a higher content of water in the cement air milk, and in this way,
The resulting cement air milk material / water separation or material /
This is because bubble separation becomes excessive and desired molding and hardening become difficult, and the strength distribution of the obtained cement air milk cured product becomes extremely uneven.

[0003] On the other hand, if the flow value of the cement air milk is too small, for example, if it is 160 mm or less, there are inconveniences such as difficulty in pumping the cement air milk by pumping. For this reason, it was necessary to control the flow value of the conventional cement air milk within a relatively narrow range of 160 to 200 mm. However, 160-200
In cement air milk controlled to a flow value of mm, if the strength value required for the cured product obtained therefrom is set, there will also be restrictions on the water / cement compounding ratio and bubble content, and the unit cement amount and unit The amount of water is determined. For this reason, the unit volume weight of the cement air milk obtained by such a conventional method is approximately 0.5 to 0.5.
It is restricted to 7 g / cm ³ .

Further, since the pumpability of cement air milk is better as the flow value is larger, the practical upper limit value of the present cement air milk flow value is 200 mm.
Can be increased to, for example, about 500 mm, and therefore, has practically excellent pumping performance, does not cause material / water separation or material / bubble separation, and has sufficient strength for practical use; There has been a strong demand for a method for producing cement air milk capable of producing a cured product having a uniform strength distribution.

Further, when conventional cement air milk is used, the upper limit of the unit volume weight is about 0.7 g / cm ^3.
If this is to be increased to more than 0.7 g / cm ^3, it is necessary to increase the cement content. However, when the content of cement is increased, the viscosity of the obtained cement air milk increases, the workability decreases,
In addition, the obtained cement hardened body has an unnecessarily high strength, resulting in an economic disadvantage that the cost is increased. Further, when it is expected that re-digging is performed on the cement air milk hardened body, the high strength of the hardened body makes re-digging difficult. Further, an increase in the amount of unit cement in the cement air milk causes an increase in the calorific value of hydration, so that there is also a problem that bubbles are destroyed and the bubble content is reduced.

In order to cope with the above-mentioned problems, in order to increase the unit volume weight of cement air milk to more than 0.7 t / m ² , sand is added to cement air milk.
Air mortar has been made. However, in order to use air mortar, it is necessary to solve various problems such as securing sand stock space, quality control of sand (moisture preparation (management), etc.), difficulty in obtaining high quality products, and enlargement of kneading equipment. In addition, there is a disadvantage that the workability of the sand-mixed air mortar is significantly poorer than that of the conventional cement air milk. Especially when construction is performed in mountainous areas or places such as steep slopes of road slopes, the use of conventional air mortar is inappropriate, and the use of cement air milk with good workability is not recommended. Is desired.

[0007]

DISCLOSURE OF THE INVENTION The present invention has a high fluidity,
Provided is a method for producing cement air milk, which has a preventive property against material / water separation or material / bubble separation, is excellent in fillability and workability, and can obtain a cured product having desired unit volume weight and strength. Things.

[0008]

SUMMARY OF THE INVENTION The present invention provides a cement air-mix.
Luk is manufactured using cement, bentonite,
Olin, and having a Ca / Si atomic ratio of 1.0 to 4.0
Calcium silicate which exhibits a loss on ignition of 5-35%
Hydrate (hereinafter referred to as special admixture A)
Inorganic additives, including at least one, are mixed in a dry state in advance.
Water is added to the cementitious mixture and
It is characterized in that a foaming treatment is applied to the cement milk. Ki
As a foam treatment method, use a foaming agent etc.
Method of mixing and foaming, producing bubbles in advance, cement
Either of the methods of mixing into milk can be used. Of the present invention
In the preparation of the cementitious mixture of the
The weight ratio of the mechanical additive to the cement is 7: 93-
Preferably, the ratio is 40:60. Of the production method of the present invention
In preparing the aqueous mixture, water and the cement-based mixture are used.
The weight ratio with the compound is 100: 100 to 250: 10
It is preferably 0. In the production method of the present invention,
The cement air milk has a flow of 160 to 500 mm.
Value and 0.5-1.5 g / cm^ThreeWith a unit volume weight of
Is preferred. In the production method of the present invention,
0.5 to 30 kg / cm ^TwoUniaxial compression strength
It is preferable to form a cured product having a degree.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the method for producing cement air milk according to the present invention, cement and an inorganic additive are mixed in advance to prepare a cement mixture. The inorganic additive is an inorganic additive containing at least one selected from bentonite, metakaolin, and special admixture A, and the special admixture A has a Ca / Si atomic ratio of 1.0 to 1.0.
4.0 and the loss on ignition is 5-35%
It is. Ignition loss means that a test sample is treated at 950 ° C for 6 hours.
It is the ratio (percent) of the weight loss (weight) value to the original weight value when ignited for 0 minutes.

[0010] The cement used in the present invention includes ordinary cement, early-strength cement, ultra-high-strength cement, white cement,
And various portlide cements such as sulfate-resistant cement, and at least one of these, blast furnace slag,
And / or a mixed cement consisting of a mixture with fly ash and the like.

There is no particular limitation on the grade of bentonite used in the present invention.
It preferably has a particle size of 0 mesh pass or less,
It preferably has a particle size of 50 to 300 mesh passes. As the metakaolin used in the present invention, for example, those disclosed in Japanese Patent Publication No. 7-33271 can be used. Such metakaolin is produced by calcining at least one selected from natural kaolin, halloysite, and synthetic kaolin at a temperature of 630 to 870 ° C. The metakaolin is a particle mainly composed of an amorphous portion having a Si / Al composition ratio of 1.1 to 1.3. The metakaolin particles have a particle diameter of 8 μm or less, and the average particle diameter is , 0.5 to 2.0 μm and a specific gravity of 2.45 to 2.55.

In the method of the present invention, the special admixture A used as an inorganic additive is described in, for example, JP-A-9-48.
No. 650 can be used, and its particle size is preferably 20 μm or less.

In the preparation of the dry mixture of the present invention, the weight ratio of the inorganic additive to the cement is 7:
93:40:60, preferably 15:85
More preferably, the ratio is 40:60. If the weight ratio is less than 7:93, there may be a disadvantage that the cement and the inorganic additive are difficult to be uniformly dispersed,
If it exceeds 40:60, the desired strength may not be obtained. Mixing of the cement and the inorganic additive can be performed using a usual dry mixer, for example, a V-type mixer.

In the method of the present invention, water is added to the cementitious mixture to prepare a cement milk, which is subjected to a foaming treatment. The preparation of the cement milk and the foaming treatment may be performed sequentially or simultaneously. In this cement milk, the weight ratio of water to the cementitious mixture is from 100: 100 to 250: 10.
0, preferably 100: 100 to 200: 1
More preferably, it is 00. When this compounding ratio is 10
If the ratio is less than 0: 100, there may be a disadvantage that a predetermined flow value cannot be obtained.
If the ratio is larger than 50: 100, there may be a disadvantage that a predetermined strength can not be obtained.

As the foaming agent used in the method of the present invention, conventionally known foaming agents, for example, a protein foaming agent and a surfactant foaming agent can be used. These are preferably mixed by a preform method (prefoaming method).

In the foaming treatment in the method of the present invention, the foaming operation is performed on the cement milk by a conventionally known foaming operation (for example, a foaming agent is forcibly blown into a foaming device simultaneously with compressed air to generate bubbles. Is mixed with cement milk). By this foaming treatment, fine bubbles are introduced into the cement milk. At this time, the obtained cement air milk preferably contains 5 to 70% by volume of air bubbles, and preferably 10 to 65% by volume. preferable. The air bubbles preferably have a particle diameter of 10 to 1000 μm. If the bubble content is less than 5% by volume, there may be a disadvantage that a predetermined unit weight cannot be obtained,
If it becomes higher, there may be a disadvantage that a predetermined strength expression cannot be obtained. Further, when the particle diameter of the bubbles is larger than 1000 μm, the bubbles may be easily defoamed, and the bubbles may not be dispersed, resulting in a disadvantage that the material becomes a non-uniform material. May be very difficult. Generally, the addition foaming operation can be performed within a range of 0 to 60 ° C, but is preferably performed at normal temperature (5 ° C to 35 ° C).

The cement air milk produced by the method of the present invention may contain, if necessary, one or more additives selected from a water reducing agent, a retarder, a quick-setting agent and the like. Is preferably about 5% by weight or less based on the weight of cement.

The cement air milk produced by the method of the present invention preferably has a flow value of 160 to 500 mm, and more preferably has a flow value of 200 to 500 mm. Also, unit weight of the cement air milk is preferably 0.5 to 1.5 g / cm ^2, more preferably 0.5 to 1.2 g / cm ^2. When the flow value of the cement air milk is less than 160 mm, the fluidity is practically insufficient and the pumpability is insufficient. When the flow value is more than 500 mm, the material is easily separated. May occur. Also, the unit volume weight of cement air milk is
If the amount is less than 0.5 g / cm ² , a disadvantage that desired strength is not exhibited may occur.
When it is larger than g / cm ² , the weight becomes equal to that of the ordinary ground, and there may be a disadvantage that the light weight effect is lost.

The cement air milk produced by the method of the present invention is used for required applications, for example, backfilling, filling of voids, lightweight embankment, landfill, and the like, and is hardened. The unconfined compressive strength of the cured product of this cement air milk is 0.5 to 30 kg / cm.
² , more preferably 1 to ²⁰ kg / cm ² . Uniaxial compressive strength of cured product is 0.5kg / cm
^If it is less than ² , the mechanical strength of the cured body may be insufficient for practical use, and if it is higher than 30 kg / cm ² , it may cause inconvenience that re-digging becomes difficult. .

The method of the present invention is further described by the following examples. (A) However, the materials used in the following Examples and Comparative Examples were as follows. (1) Cement: Blast furnace B-type cement manufactured by Sumitomo Osaka Cement Co., Ltd. (2) Dry additive: (A) Bentonite, manufactured by Toyonjun Yoko Co., Ltd. Particle size 300 mesh, trademark: "Asama" Particle size 200 mesh, trademark: " Haruna ”(b) Metakaolin, manufactured by Hayashi Kasei Co., Ltd. Trademark:“ Metamax EF ”Particle size: 0.5-2.0μ (c) Special admixture A, Ca / Si manufactured by Sumitomo Osaka Cement Co., Ltd. Atomic ratio: 3.0 Ignition loss: 15% Particle size: 20 μm or less (d) Clay fine powder (comparative example), Sumitomo Osaka Cement Co., Ltd.
Trade mark: “Sumicre” Specific surface area: 5500 cm ² / g or more (e) Limestone powder (comparative example), manufactured by Calceed Co., Ltd. Trade mark: “CALTAC” Specific surface area: 5000 cm ² / g

(B) The test method was as follows. (1) Flow value Conforms to the cylinder method of the consistency test method of the Japan Highway Public Corporation Standards “Test methods for air mortar and air milk” (JHS A 313-1992). (2) Bleeding rate and material separation conditions For bleeding rate and expansion rate of mortar infused concrete (JSCE-
1986) ”, and the bleeding rate was measured 24 hours later, or the material separation was visually observed. The Japan Society of Civil Engineers Concrete Specifications execution stipulates that the bleeding rate after 3 hours is 3% or less. (No test on material separation of air milk and air mortar) (3) Strength Geotechnical Society standard “Uniaxial compression test (JIS A121)
6) Specimen size φ5 × 10 cm Further, the performance of the test cement air milk was determined according to the following criteria. (Generally, in cement air milk, when solid matter / water separation occurs, bleeding water may not be generated in the upper part, and solid matter (containing air bubbles) may be separated in the upper part, and bleeding water may be separated in the lower part.
In addition, a bubble layer is formed in an upper part, a water layer is formed in a central part, and a solid material layer is formed in a lower part.

Judgment symbol content ○ Material / water separation and bleeding are not recognized, the flow value is 160 mm or more, and the strength of the cured product is 0.5 kgf / cm ² or more. Δ: Bleeding of water and defoaming of bubbles are 0 to 3%, the flow value is 160 mm or more, and the strength of the cured product is 0.5 kgf / cm ² or more. C: Water bleeding and bubble defoaming exceeding 3%, and material separation observed. Those having a flow value of less than 160 mm, or those having a cured body strength of less than 0.5 kgf / cm ² . ◎ Among those marked with ○, those with a flow value of 200 mm or more and high fluidity. ◇ Out of の も の, the cured product has a strength of 1 to 20 kgf / cm ² . [Note] The items marked with ◎ and △ above were not obtained with conventional cement air milk.

Comparative Examples 1 and 2 In Comparative Example 1, air milk was prepared according to the formulation shown in Table 1. In Comparative Example 1, sand was added, and an air mortar was prepared according to the formulation shown in Table 1. Comparative Example 1,
And 2, Sumishield A (S-
1) is used at an addition amount of 1/600 of the amount of air, and the ratio of solid materials (cement (C) and sand (S)) to water (W), W / C or W / (C + S) is 100 % And the amount of air introduced into each air milk or air mortar was changed in 5 steps to prepare an air milk or air mortar having a unit volume weight as shown in Table 1. Table 1 shows the test results.

[0024]

[Table 1] From the results of Comparative Example 1, when no inorganic additive was added,
In air milk with W / C = 100%, separation occurred at all set unit weights of 0.6 to 1.5. Therefore, when the W / C is higher than 100% (the amount of water is large), the air milk is more easily separated. Also, from the results of Comparative Example 2, it was confirmed that when the flow value of the air mortar exceeded 200 mm, the air mortar was remarkably easily separated.

[0025] In the same manner as in Example 1 Comparative Example 1 was prepared Eamiruku and tested.
However, the special admixture A was added to the blast furnace type B cement in the amount shown in Table 2, water and a foaming agent were added to the cementitious mixture, and foaming treatment was performed. Table 2 shows the test results.

[0026]

[Table 2]

Example 2 An air milk was prepared and tested in the same manner as in Example 1.
However, as an inorganic additive, instead of the special admixture A,
Bentonite 300 mesh was used. Table 3 shows the test results.

[0028]

[Table 3]

Example 3 An air milk was prepared in the same manner as in Example 1 and subjected to a test. However, bentonite 200 mesh was used instead of the special admixture A as an inorganic additive. Table 4 shows the test results.

[0030]

[Table 4]

Example 4 An air milk was prepared in the same manner as in Example 1 and subjected to a test. However, metakaolin was used in place of the special admixture A as an inorganic additive. Table 5 shows the test results.

[0032]

[Table 5]

Comparative Example 3 An air milk was prepared in the same manner as in Example 1 and subjected to a test. However, limestone powder was used instead of the special admixture A as an inorganic additive. Table 6 shows the test results.

[0034]

[Table 6]

Comparative Example 4 An air milk was prepared in the same manner as in Example 1 and subjected to a test. However, clay fine powder was used instead of the special admixture A as an inorganic additive. Table 7 shows the test results.

[0036]

[Table 7]

In the first embodiment, W / (C + A) = 1
00%, when the amount of the special admixture A added is 15%, in the range of 0.8 to 1.6 g / cm ^{3 in} unit volume weight, there is no separation of air milk, high fluidity is exhibited, and good cured body strength is obtained Was done. In Example 2, W / (C + A) = 100%
In the case of using bentonite (300 mesh), good results were obtained in the range of a unit volume weight of 0.8 to 1.0 g / cm ³ , and in Example 3, bentonite (20 mesh) was used.
0 mesh), good results were obtained within the range of a unit volume weight of 0.6 to 1.0. Further, in Example 4, when W / (C + A) = 100%, when metakaolin was used, good results were obtained within a unit volume weight of 0.6 to 1.2 g / cm ³ . However, in Comparative Examples 3 and 4, when W / (C + A) = 100%, if limestone powder or clay fine powder was used, the obtained air milk was remarkably easily separated and was not practical.

Example 5 An air milk was prepared in the same manner as in Example 1 and subjected to a test. However, a special admixture A, bentonite (300 mesh), or metakaolin was used as an inorganic additive, and the respective addition rates were set to two levels of 15% and 30%, and W (C + A) was set to 150%. Table 8 shows the compounding ratio.

[0039]

[Table 8]

Table 9 shows the test results of each air milk.

[0041]

[Table 9]

Example 6 An air milk was prepared in the same manner as in Example 1 and subjected to a test. However, a special admixture A, bentonite (300 mesh), or metakaolin was used as an inorganic additive, and the respective addition rates were set to two levels of 30% and 45%, and W (C + A) was set to 200%. Table 10 shows the component mixing ratios.

[0043]

[Table 10]

Table 11 shows the test results of the above air milks.

[0045]

[Table 11]

Example 7 An air milk was prepared in the same manner as in Example 1 and subjected to a test. However, a special admixture A, bentonite (300 mesh), or metakaolin was used as an inorganic additive, and the respective addition rates were set to two levels of 45% and 60%, and W (C + A) was set to 250%. The composition ratios of the components are shown in Table 12.

[0047]

[Table 12]

Table 13 shows the test results of each air milk.

[0049]

[Table 13]

Comparative Example 5 In the same manner as in Example 2, an air milk was prepared and subjected to a test. However, the bentonite (200 mesh) was mixed with water without dry mixing with the blast furnace cement, allowed to swell at room temperature for 24 hours, and mixed with cement, water and a foaming agent. The addition rate of the swollen bentonite was 15%, and the set unit volume weight was 1.506. The flow value of the obtained air milk was 157 mm, and the flowability was poor.

[0051]

According to the method of the present invention, by mixing a specific inorganic additive into the cement, the cement air milk obtained therefrom exhibits excellent fluidity and anti-separation properties and has appropriate mechanical strength. A porous cured body can be formed.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C04B 14:10 14:04) 103: 48 111: 40 C09K 103: 00

Claims (5)

[Claims] 1. The cement is selected from bentonite, metakaolin and calcium silicate hydrate having a Ca / Si atomic ratio of 1.0 to 4.0 and exhibiting a loss on ignition of 5 to 35%. In addition, an inorganic additive containing at least one kind,
A method for producing cement air milk, which comprises mixing in advance to form a cementitious mixture, then adding water to form cement milk, and subjecting the cement milk to foaming treatment. 2. In the preparation of the cementitious mixture,
The weight ratio of the inorganic additive to the cement is 7:
The production method according to claim 1, wherein the ratio is 93 to 40:60. 3. In the preparation of the cement milk, the weight ratio of water to the cementitious mixture is 100: 10.
The production method according to claim 1, wherein the ratio is 0 to 250: 100. 4. The cement air milk according to claim 1, wherein
Having a unit weight of flow value and 0.5 to 1.5 g / cm ³ of 300 mm, the manufacturing method according to claim 1. 5. The method according to claim 1, wherein said cement air milk is 0.5 to 3 times.
Forming a cured product having a uniaxial compressive strength of 0 kg / cm ² ,
The method according to claim 1.