JPH1067546A - Cement grout modifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a modifier of cement grout capable of preventing bleeding and also generating of hardened contraction crack by adding a small amount thereof to usual grout material. SOLUTION: This cement grout modifier contains SiO2 , Al2 O3 and a minute amount of Fe2 O3 , and is composed of an inert fine hollow spherical light weight aggregate having a dry true specific gravity within a range of 0.7-0.9 and 0.05-5 pts.wt. of a powder wet dispersant based on 100 pts.wt. of the fine hollow spherical light weight aggregate, 0.5-10 pts.wt. of a powder viscosity conditioner, as necessary, and further 10-250 pts.wt. of emulsion-formable resin powder, as necessary. A grout hardened material formed from a grout solution mixed with the modifier does not generate bleeding nor crack and further has an excellent compression strength.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement grout modifier for preventing corrosion of a PC steel wire used in a sheath having a PC structure and capable of preventing the breathing and cracking of cement grout.

[0002]

2. Description of the Related Art Portland cement, a water reducing agent, water and aluminum powder are conventionally contained as grout materials for forming a PC structure, and the water / cement ratio is 40.
Cement milk in the range of .about.45% and having a specific gravity of about 2 has been used.

[0003] The problem with this cement milk is the occurrence of hardening shrinkage cracks due to bleeding due to the sedimentation of the cement and hydration of the cement. As a method for preventing such breathing, a method for preventing breathing using a thickener or a rheology modifier and an improved method derived from this method are employed. Also, as a method of preventing hardening shrinkage cracks, aluminum powder is mixed into cement milk, the aluminum powder is reacted with the cement milk component to generate hydrogen gas, and the grout agent is foamed and expanded by the hydrogen gas. A method of preventing the occurrence of cracks by employing a method of hardening while curing or a method of using an aggregate to alleviate hardening shrinkage has been studied.

[0004]

However, the above-mentioned lively and improved techniques do not completely eliminate the occurrence of the above-mentioned breathing or hardening shrinkage cracks. New problems have also arisen.

For example, in order to prevent breathing,
There is a method of blending a grout solution with a thickening agent to make the grout solution a non-Nutrian solution and preventing bleeding.However, if the thickening agent is blended enough to prevent bleeding, the viscosity of the grout solution itself increases, resulting in grouting. The fluidity of the liquid is significantly reduced. For this reason, the workability is remarkably reduced due to a decrease in the fluidity of the high-viscosity grout liquid using the thickener. Therefore, it is virtually impossible to completely prevent breathing using a thickener. Further, the method using a rheology modifier does not provide a sufficient anti-breathing effect.

As a method for preventing the shrinkage due to hardening, a method has been adopted in which the aluminum powder is used to react with an alkali component in the cement to expand and expand using hydrogen gas, thereby preventing the cracks. It is said that the hydrogen gas thus generated causes hydrogen embrittlement cracking of high-strength steel such as PC steel wire and causes delayed fracture. It has also been studied to prevent the occurrence of hardening shrinkage cracks by using aggregates such as silica sand.However, such aggregates such as silica sand have a high sedimentation property in cement milk, so that uniform grout can be formed. difficult.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a cement grout modifier which can prevent bleeding by adding a small amount to a conventional grout material and also prevent hardening shrinkage cracks. I have.
Further, the present invention provides a cement grout modifier capable of retaining a fluidity required as a grout material by adding a small amount to the grout material and preventing the occurrence of cracks without foaming and expansion. The purpose is.

[0008]

The first cement grout modifier of the present invention comprises SiO ₂ , Al ₂ O ₃ and a trace amount of Fe ₂ O.
₃ and an inert fine hollow sphere lightweight aggregate having a dry true specific gravity in the range of 0.7 to 0.9, and 0.05 to 500 parts by weight of the fine hollow lightweight aggregate. 5 parts by weight of a powder wetting and dispersing agent.

The second cement grout modifier of the present invention contains SiO ₂ , Al ₂ O ₃ and a trace amount of Fe ₂ O _3, and has a dry true specific gravity of 0.7 to 0.9. Inactive micro hollow sphere lightweight aggregate inside the micro hollow lightweight aggregate 1
It is characterized by comprising from 0.5 to 5 parts by weight of a powder wetting and dispersing agent and from 0.5 to 10 parts by weight of a powder viscosity modifier with respect to 00 parts by weight.

Further, the third cement grout modifier of the present invention contains SiO ₂ , Al ₂ O ₃ and a small amount of Fe ₂ O _3, and has a dry true specific gravity of 0.7 to 0.9. Inactive micro hollow sphere lightweight aggregate in there, 0.05 to 5 parts by weight of powder wetting and dispersing agent, and 0.5 to 10 parts by weight of powder with respect to 100 parts by weight of the micro hollow lightweight aggregate A viscosity modifier and 1
0 to 250 parts by weight of a resin powder capable of forming an emulsion.

The resin powder capable of forming an emulsion used in the present invention is preferably a vinyl acetate copolymer powder and / or an acrylic copolymer powder. -Based copolymer powder is ethylene-vinyl acetate copolymer and / or vinyl acetate
Particularly preferred is a vinyl versatate copolymer.

The cement grout modifier of the present invention, as a lightweight aggregate, has a dry true specific gravity in the range of 0.7 to 0.9 and a particle size usually in the range of 60 to 200 μm,
A small amount of Fe ₂ O containing SiO ₂ and Al ₂ O ₃ as main components
A micro hollow spherical lightweight aggregate containing ₃ is contained.
This fine hollow spherical lightweight aggregate is inert and does not react with alkali aggregate. Since this fine hollow spherical lightweight aggregate usually shows a water absorption of about 16%, when it is mixed with a grout liquid and contains water, its apparent specific gravity becomes 0.8 to 1.0, and Disperse evenly. This state can be considered as a state where a colloid of giant particles is generated, and the action of the powder wetting and dispersing agent and / or the powder viscosity modifier and the resin powder capable of forming an emulsion cause the cement component slurried to float. It cannot be settled because it is disturbed by the lightweight aggregate. The cement component dispersed uniformly without settling does not separate from water when it hardens, so that the use of the grout liquid of the present invention does not cause water bleeding, and therefore the upper part of the hardened concrete (grout liquid) (In the vicinity of the upper end of the injection part). Furthermore, the above-mentioned action exerted by the lightweight aggregate as described above is similar to the case where a fiber derivative such as carboxymethylcellulose, a paste-like substance such as polyvinyl alcohol or sodium polyacrylate, which has been conventionally performed, is used. Since it is different from the anti-settling action of the grout component due to the increase in viscosity of
Even if the cement grout modifier of the present invention is used, the viscosity of the grout liquid does not become abnormally high, and therefore, the grouting liquid injection workability is remarkably improved.

Further, the minute hollow lightweight aggregate used in the present invention is a minute hollow sphere, and since the aggregate has a small particle diameter and a spherical shape, it is extremely difficult to mix with a slurry. Disperse stably.

[0014]

DETAILED DESCRIPTION OF THE INVENTION Next, the cement grout modifier of the present invention will be specifically described. First, the first cement grout modifier of the present invention will be specifically described.

The fine hollow sphere lightweight aggregate used in the present invention contains SiO ₂ and Al ₂ O ₃ as main components and further contains a trace amount of Fe ₂ O ₃ . The content of SiO _{2 in} the fine hollow sphere lightweight aggregate is usually 55 to 55.
67% by weight, and the content of Al ₂ O ₃ is usually from 26 to
35% by weight, and the content of Fe ₂ O ₃ is usually 0.5.
-4% by weight, and Na ₂
O, K ₂ O, etc. may be contained. The dry true specific gravity of this micro hollow sphere lightweight aggregate is in the range of 0.7 to 0.9, preferably in the range of 0.78 to 0.87. The fine hollow sphere lightweight aggregate having such a dry true specific gravity, when containing water, usually has a specific gravity of about 0.8 to 1.0, preferably about 0.8.
When the water-containing micro hollow spherical lightweight aggregate is mixed with the grout liquid, it becomes a state of being stably suspended in the slurry, thereby preventing sedimentation of Portland cement over time. it can. In addition, the average particle size of the fine hollow sphere lightweight aggregate is usually 45 to 300 μm,
Preferably it is in the range of 60 to 200 μm. further,
The water absorption of the outer shell of this micro hollow sphere lightweight aggregate is usually 1
It is in the range of 1-21%, preferably 14-18%. The cement grout modifier of the present invention containing the fine hollow sphere lightweight aggregate having such a water absorption rate, the water or the like infiltrates into the outer shell in the slurry, and the apparent specific gravity of the fine hollow spherical lightweight aggregate is reduced. Usually, it is about 0.8 to 1.0, and this fine hollow sphere lightweight aggregate floats well in the grout liquid to prevent sedimentation of other components.

Further, as described above, the form of the minute hollow sphere lightweight aggregate is a sphere, and by making it spherical, the floating stability of the minute hollow sphere lightweight aggregate in the grout liquid is improved. .

Conventionally, mica, mudstone-based vermiculite, obsidian, perlite-based pearlite, alumina balloons, shirasu balloons, and the like have been used to reduce the weight of mortar. On the other hand, it is so low that the above-mentioned operation cannot be achieved.

The powder wetting and dispersing agent to be added to the first cement grout modifier of the present invention is a water reducing agent for assisting the dispersion of cement. Use a powdered water reducing agent. As a powder wetting and dispersing agent which is such a powdery water reducing agent, lignin sulfonic acid type water reducing agent, naphthalene sulfonic acid type water reducing agent, condensed triazine type water reducing agent, polycarboxylic acid ether type water reducing agent, polyoxyethylene alkyl ether A water reducing agent, a polyalkylsulfonic acid-based water reducing agent, a phosphate ester-based water reducing agent, and the like are known. In the present invention, a naphthalene sulfonic acid-based water reducing agent which can be pre-packed and is in powder form among these water reducing agents It is preferred to use

In the cement grout modifier of the present invention, the powder wetting and dispersing agent is a fine hollow spherical lightweight aggregate 10
It is necessary to use it in an amount within the range of 0.05 to 5 parts by weight with respect to 0 parts by weight, and it is more preferable to use it in an amount of 0.2 to 0.4 parts by weight. If the amount of the powder wetting and dispersing agent is less than 0.05% by weight, the desired dispersibility cannot be obtained, and even if the amount exceeds 5 parts by weight, the dispersing property is increased. Does not improve.

The second cement grout modifier of the present invention comprises the above-mentioned fine hollow spherical lightweight aggregate, a powder wetting and dispersing agent, and a powder viscosity modifier. Here, the types and amounts of the fine hollow spherical lightweight aggregate and the powder wetting and dispersing agent are the same as those of the first cement grout modifier.

Examples of the powder viscosity modifier to be added to the second cement grout modifier of the present invention include fiber derivative polymer compounds such as hydroxyethylcellulose, hydroxypropylcellulose, carboxymethylcellulose and methylcellulose, and poly (meth) acrylic. Polyacrylic acid-based polymer compounds such as alkali metal salts of acids and ammonium salts of poly (meth) acrylic acid; vinyl acetate-based polymer compounds such as polyvinyl alcohol; organic polymer compounds such as polyethylene glycol; Mineral compounds can be mentioned. Among them, fiber derivative-based polymer compounds, particularly hydroxymethylcellulose and polyethylene glycol, are particularly preferable in the present invention because they are easily dissolved in room-temperature water and have a large thickening effect even in a small amount. These viscosity modifiers are powders and can be prepacked with the micro-hollow spherical lightweight aggregate and the powder wetting and dispersing agent.

In the second cement grout modifier of the present invention, the amount of the powder viscosity modifier is in the range of 0.5 to 10 parts by weight, preferably 100 parts by weight of the fine hollow spherical lightweight aggregate. Is used in amounts ranging from 2 to 8 parts by weight. By using the powder viscosity modifier in an amount within this range, breathing can be efficiently prevented, and the compressive strength of the cured product of the grout liquid to which the second cement grout modifier of the present invention is added is reduced. It does not drop.

The third cement grout modifier of the present invention contains a resin powder capable of forming an emulsion, in addition to the fine hollow spherical lightweight aggregate, powder wetting and dispersing agent, and powder viscosity modifier.

In the third cement grout modifier of the present invention, the types and the amounts of the fine hollow spherical lightweight aggregate, the powder wetting and dispersing agent and the powder viscosity modifier are the same as described above. The resin powder capable of forming an emulsion constituting the third cement grout modifier of the present invention has a property of forming an emulsion and dispersing by mixing with water.

For example, such a resin powder is prepared by first polymerizing a raw material monomer in a state of being dispersed in an aqueous medium using a dispersant or an emulsifier, thereby producing an emulsion in which the resin powder is dispersed in the aqueous medium. And then separating the resin powder dispersed in the emulsion from the aqueous medium. This resin powder
For example, it can be prepared by separating from the aqueous medium from the emulsion by a method of removing the aqueous medium using a spray drier or the like. When the resin powder thus obtained is injected and stirred, it is dispersed again in water to form an emulsion. The resin powder capable of forming this emulsion may contain a small amount of an inorganic fine powder such as amorphous silica in order to prevent secondary aggregation during storage.

In the present invention, as a resin powder capable of forming an emulsion, it is preferable to use a vinyl acetate copolymer powder and an acrylic copolymer powder. As the vinyl acetate copolymer powder, vinyl acetate and a monomer copolymerizable with the vinyl acetate (eg, ethylene, vinyl versatate, vinyl chloride, (meth) acrylic acid or (meth) acrylate) And the like. Examples of such vinyl acetate-based copolymer powders include ethylene-vinyl acetate copolymer powder, vinyl acetate-vinyl versatate copolymer powder, vinyl acetate-vinyl chloride copolymer powder, vinyl acetate Examples thereof include (meth) acrylic acid copolymer powder and vinyl acetate / (meth) acrylate copolymer powder. When the vinyl acetate copolymer powder is an ethylene / vinyl acetate copolymer, the vinyl acetate content in the ethylene / vinyl acetate copolymer is preferably 75% or less. The copolymer powder having such a vinyl acetate content shows good alkali resistance. In the case of a vinyl acetate / vinyl versatate copolymer, the vinyl versatate content in the vinyl acetate / vinyl versatate copolymer is preferably 35% or more.

Examples of the acrylic copolymer powder used as a resin powder capable of forming an emulsion in the present invention include (meth) acrylic ester copolymer powder, (meth) acrylic acid / (meth) acrylic acid. Acrylic ester copolymer powder, styrene / (meth) acrylic ester copolymer powder, and vinyl acetate / (meth) acrylic ester copolymer powder can be mentioned.

Examples of the dispersant or emulsifier used for producing such resin particles include a hydrophilic polymer such as polyvinyl alcohol, a nonionic emulsifier, and an anionic emulsifier. For example, by using the above polyvinyl alcohol, a protective colloid is formed, polymerization can be performed stably, and when water is poured into the resin powder separated from the emulsion, the resin powder is re-dispersed well in water. Is done.

The average particle size of the resin powder capable of forming such an emulsion is usually in the range of 30 to 90 μm, preferably 40 to 70 μm. When the reaction is carried out in an aqueous medium as described above, the above-mentioned monomers bond more randomly to form a copolymer as compared with resin particles formed by, for example, a solution polymerization method.

By using a resin powder capable of forming an emulsion as described above, the cement grout modifier of the present invention can be stably stored for a long period of time. In addition, by using a resin powder capable of forming this emulsion, it is possible to prevent a decrease in the compressive strength of the cured grout due to a decrease in the content of the cement component in the cement grout due to the incorporation of the minute hollow spherical lightweight aggregate. be able to.
For example, when the third cement grout modifier of the present invention is added so that the amount of the resin powder is in the range of 5 to 15% by weight with respect to Portland cement, the compressive strength of the cured grout is not compounded. Usually more than 10-50%
Get higher.

In the third cement grout modifier of the present invention, the resin powder capable of forming the emulsion is 10 to 250 parts by weight per 100 parts by weight of the fine hollow spherical lightweight aggregate.
It is used in an amount in the range of 30 parts by weight, preferably 30 to 200 parts by weight, more preferably 100 to 200 parts by weight.
By using a resin powder capable of forming an emulsion within the above range, a cured grout having high compressive strength can be obtained. The amount of the resin powder can be used beyond the upper limit of the range specified in the present invention. However, the improvement of the effect by using such a large amount of the resin powder is very small. This leads to higher body costs.

The first to third cement grout modifiers of the present invention can be produced by weighing and mixing each powdery component. The first to third cement grout modifiers of the present invention are added when mixing water with a cement component such as Portland cement and kneading. A typical example of a cement component to which the cement grout modifier of the present invention is added is portland cement, which is made of tricalcium silicate (C ₃ S).
And dicalcium silicate (C ₂ S) as a main component. This Portland cement includes
There are ordinary Portland cement, early-strength Portland cement, ultra-high-strength Portland cement, moderate Portland cement, white Portland cement, and the like. In the present invention, any of these portland cements can be used.

When the cement component such as Portland cement is kneaded, the amount of water is usually from 0.33 to 2.33, preferably 0, expressed as a water / cement ratio (W / C). It is in the range of .57 to 1.17.

The first and second cement grout modifiers of the present invention are used in an amount of usually 0.5 to 10% by weight, preferably 3 to 6% by weight based on the weight of cement used. And the third cement grout modifier of the present invention is usually 1 to 25, based on the weight of cement used.
%, Preferably in the range of 5 to 15% by weight. By adding and kneading the cement grout modifier of the present invention in such an amount, a grout liquid with less breathing can be prepared, and the compressive strength of the cured grout does not decrease. Further, by adding the cement grout modifier of the present invention, cracks do not occur in the cured grout.

In preparing the grout liquid by adding the cement grout modifier of the present invention, other components can be blended in addition to the cement, water and the cement grout modifier of the present invention. .

For example, when the third cement grout modifier of the present invention is added, a polyisocyanate compound or the like can be used in combination. When using such a polyisocyanate compound, it is preferable that the resin particles capable of forming an emulsion have a polar group to which the polyisocyanate compound can be bonded, and in this case, the acid value is 3 to 10 mgKOH / g. A copolymer within the range, or
Copolymers having a hydroxyl value in the range of 1 to 10 mgKOH / g can be used.

Further, the grout liquid to which the first to third cement grout modifiers of the present invention are added may contain a fiber reinforcing agent such as alkali-resistant glass fiber.

[0038]

The cement grout modifier, which improves the breathability by using a thickener conventionally used, cannot completely prevent the breathing with the thickener alone because the specific gravity of the cement is large. That, if a thickener is added to such an extent that bleeding can be prevented, the viscosity of the cement grout solution becomes too high and the fluidity of the cement grout solution decreases, resulting in reduced workability. However, there is a problem that it is not possible to reduce the shrinkage of the cured grout when it is cured, so that it is not possible to prevent the occurrence of cracks in the cured grout.

The cement grout modifier of the present invention utilizes the excellent properties of a specific fine hollow sphere lightweight aggregate to add a powder wetting and dispersing agent, a powder viscosity modifier, and a resin capable of forming an emulsion. Since the powder is blended, these components interact with each other to almost completely prevent bleeding of the hardened cement grout containing the cement grout modifier, and cracks are generated in the hardened cement grout. Never do.

Further, the cured product of the cement grout liquid containing the cement grout modifier of the present invention has a compressive strength equal to or higher than that of the conventional non-breathing type cement grout liquid.

The component forming the cement grout modifier of the present invention is stable to alkali and does not react with an alkali component to generate hydrogen gas like aluminum powder. The steel wire does not undergo hydrogen embrittlement.

[0042]

EXAMPLES Next, the grout liquid of the present invention will be described with reference to examples, but the present invention is not limited to these examples.

[0043]

EXAMPLE 1 A dry true specific gravity of 0.8, containing about 65% by weight of SiO ₂ , about 33% by weight of Al ₂ O ₃ and about ₂ % by weight of Fe ₂ O ₃ and a trace amount of alkali metal 100 parts by weight of a fine hollow sphere lightweight aggregate having an average particle diameter of 120 μm, and a naphthalenesulfonic acid-based wetting and dispersing agent (compound name of main component:
0.3 parts by weight of condensed sodium naphthalenesulfonate (hereinafter the same) were mixed in advance with a V-type mixer to produce a grout modifier.

This grout modifier was added to a cement grout having a W / C of 0.42, comprising Portland cement, a water reducing agent and water, in an amount of 5 parts by weight based on the weight of Portland cement.
The resulting mixture was kneaded and kneaded to obtain a grout liquid so as to obtain a weight%.

With respect to the obtained grout liquid, the viscosity of the grout liquid, breathing after curing, generation of cracks after curing, and compressive strength were measured as follows. Viscosity of grout liquid : The outflow time was measured using a PC grout flow cone (J10 funnel) having a 640 cc container and an outlet of 10 mmφ specified by the Japan Society of Civil Engineers.

Breathing amount : The breathing amount was measured according to JISS-A-1123 "Breathing test method for concrete". Compression strength index: JIS-R-5201 by 'physical testing method of cement "was measured compressive strength of the cement grout hardened body.

The results are shown in Table 1.

[0048]

Comparative Example 1 W / 100 parts by weight of Portland cement and 0.2 parts by weight of a naphthalenesulfonic acid-based water reducing agent (main compound name: condensed sodium naphthalenesulfonic acid)
A cement grout having a C of 0.42 was prepared, and the viscosity of the grout liquid, breathing after curing, generation of cracks, and compressive strength were measured in the same manner as in Example 1.

Table 1 shows the results.

[0050]

Comparative Example 2 100 parts by weight of poly and land cement, 0.2 part by weight of a naphthalenesulfonic acid-based water reducing agent (compound name of main component: condensed sodium naphthalenesulfonate) and 8 parts by weight of polyethylene glycol (weight average molecular weight: 6000) An anti-breathing cement grout having a W / C of 0.42 was prepared.

For the anti-breathing type cement grout (non-breathing cement grout), the viscosity of the grout liquid, breathing after curing, crack generation after curing, and compressive strength were measured in the same manner as in Example 1.

Table 1 shows the results.

[0053]

[Table 1]

[0054]

Examples 2-1 to 2-4 A dry true specific gravity of 0.8, SiO ₂
About 65% by weight, about 33% by weight of Al ₂ O ₃ and Fe ₂
Containing about 2% by weight of O ₃ and a trace amount of alkali metal;
40 parts by weight of a fine hollow sphere lightweight aggregate having an average particle diameter of 120 μm, and the naphthalenesulfonic acid-based wetting and dispersing agent 0.3.
Parts by weight and a hydroxyethylcellulose-based viscosity modifier 5
Parts by weight were mixed in advance with a V-type mixer to produce a grout modifier.

This grout modifier was added to a cement grout having a W / C of 0.42, comprising Portland cement, a water reducing agent and water, in an amount of 1% based on the weight of Portland cement.
% By weight (Example 2-1), 3% by weight (Example 2-2), 5% by weight (Example 2-3) and 7% by weight (Example 2-4). A grout solution was obtained.

With respect to the obtained grout liquid, the viscosity of the grout liquid, breathing after curing, generation of cracks after curing, and compressive strength were measured by the methods shown in Example 1. Table 2 shows the results. Table 2 also shows the results of Comparative Example 2 described above.

[0057]

[Table 2]

[0058]

Examples 3-1 and 3-2 The dry true specific gravity was 0.8
A fine hollow sphere lightweight aggregate containing about 65% by weight of iO ₂ , about 33% by weight of Al ₂ O ₃ , about ₂ % by weight of Fe ₂ O ₃ , and a trace amount of alkali metal, and having an average particle diameter of 120 μm. 1
00 parts by weight, 0.3 parts by weight of the naphthalenesulfonic acid-based wetting and dispersing agent, 5 parts by weight of a hydroxyethyl cellulose-based viscosity modifier, and an ethylene-vinyl acetate copolymer powder having a vinyl acetate content of 75% (average particle diameter : 65 μm) 60
Parts by weight were mixed in advance with a V-type mixer to produce a grout modifier.

This grout modifier was added to a cement grout having a W / C of 0.42, comprising Portland cement, a water reducing agent and water, in an amount of 6% based on the weight of Portland cement.
A grout liquid was obtained by compounding and kneading so as to be 1 wt% (Example 3-1) and 12.5 wt% (Example 3-2).

With respect to the obtained grout liquid, the viscosity of the grout liquid, breathing after curing, generation of cracks after curing, and compressive strength were measured by the methods shown in Example 1. Table 3 shows the results. Table 3 also shows the results of Comparative Example 2 described above.

[0061]

EXAMPLE 4 The dry true specific gravity is 0.8, containing about 65% by weight of SiO ₂ , about 33% by weight of Al ₂ O ₃ and about ₂ % by weight of Fe ₂ O ₃ and a trace amount of alkali metal. 40 parts by weight of a fine hollow sphere lightweight aggregate having an average particle size of 120 μm, 0.3 parts by weight of the naphthalenesulfonic acid-based wetting and dispersing agent, 1 part by weight of a hydroxyethylcellulose-based viscosity modifier, and vinyl versatate content 35% vinyl acetate versatate copolymer (average particle size: 60 μm) 60
Parts by weight were mixed in advance with a V-type mixer to produce a grout modifier.

This grout modifier was added to a cement grout having a W / C of 0.42, comprising portland cement, a water reducing agent, and water, based on the weight of Portland cement.
A grout solution was obtained by mixing and kneading so as to have a concentration of 12.5% by weight.

With respect to the obtained grout liquid, the viscosity of the grout liquid, breathing after curing, generation of cracks after curing, and compressive strength were measured by the methods shown in Example 1. Table 3 shows the results.

[0064]

Example 5 The dry true specific gravity is 0.8, containing about 65% by weight of SiO ₂ , about 33% by weight of Al ₂ O ₃ and about ₂ % by weight of Fe ₂ O ₃ and a trace amount of alkali metal. 40 parts by weight of a fine hollow sphere lightweight aggregate having an average particle diameter of 120 μm, 0.3 parts by weight of the naphthalenesulfonic acid-based wet dispersant, 1 part by weight of a hydroxyethylcellulose-based viscosity modifier, and a methacrylate polymer 60 parts by weight of a powder (a homopolymer of methyl methacrylate, average particle size: 60 μm) was previously mixed with a V-type mixer to produce a grout modifier.

This grout modifier was added to a cement grout having a W / C of 0.42, comprising portland cement, a water reducing agent, and water, based on the weight of Portland cement.
A grout solution was obtained by mixing and kneading so as to have a concentration of 12.5% by weight.

With respect to the obtained grout liquid, the viscosity of the grout liquid, breathing after curing, generation of cracks after curing, and compressive strength were measured by the methods shown in Example 1. Table 3 shows the results.

[0067]

[Table 3]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical indication // C04B 111: 70

Claims (5)

[Claims] An inert fine hollow sphere lightweight aggregate containing SiO ₂ , Al ₂ O ₃ and a trace amount of Fe ₂ O ₃ and having a dry true specific gravity in the range of 0.7 to 0.9. A cement grout modifier comprising 0.05 to 5 parts by weight of a powder wetting and dispersing agent with respect to 100 parts by weight of the minute hollow lightweight aggregate. 2. An inert fine hollow sphere lightweight aggregate containing SiO ₂ , Al ₂ O ₃ and a trace amount of Fe ₂ O ₃ and having a dry true specific gravity in the range of 0.7 to 0.9. A cement grout comprising: 0.05 to 5 parts by weight of a powder wetting and dispersing agent; and 0.5 to 10 parts by weight of a powder viscosity modifier based on 100 parts by weight of the micro hollow lightweight aggregate. Modifier. 3. An inert fine hollow sphere lightweight aggregate containing SiO ₂ , Al ₂ O ₃ and a trace amount of Fe ₂ O ₃ and having a dry true specific gravity in the range of 0.7 to 0.9. With respect to 100 parts by weight of the fine hollow lightweight aggregate, 0.05 to 5 parts by weight of a powder wetting and dispersing agent, 0.5 to 10 parts by weight of a powder viscosity modifier, and 10 to 250 parts by weight of an emulsion are mixed. A cement grout modifier comprising a resin powder that can be formed. 4. A resin powder capable of forming an emulsion,
4. The cement grout modifier according to claim 3, wherein the cement grout modifier is a vinyl acetate copolymer powder and / or an acrylic copolymer powder. 5. The cement grout according to claim 4, wherein the vinyl acetate copolymer powder is an ethylene / vinyl acetate copolymer and / or a vinyl acetate / vinyl versatate copolymer. Modifier.