JPH08239255A - Bleeding reducer for cement-based grouting material - Google Patents

Abstract

PURPOSE: To obtain an agent intended to suppress the bleeding and secure the fluidity of a mixture of soil and a curing agent, by blending water-glass with a water reducing agent for cement. CONSTITUTION: This bleeding reducer for cement-based grouting materials is obtained by blending 100 pts.wt. of water-glass with 1-20 pts.wt. of an active ingredient, i.e., a water reducing agent for cement. An aqueous solution containing 0.2-10 pts.wt. of this bleeding reducer is added to 100 pts.wt. of cement followed by addition of sand and clay, and the resultant mixture is kneaded under agitation in a mixer to prepare a blend slurry, which is, in turn, injected into the ground by high-pressure injection method to stabilize the ground.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a breathing reducing agent for cement-based grout materials. More specifically, the present invention relates to a breathing reducing agent for cement-based grout materials, which comprises water glass and a water reducing agent for cement.

[0002]

2. Description of the Related Art Conventionally, a cement slurry containing cement and water is injected as a hardening agent into the ground by a high-pressure injection method, and the mixture is stirred and mixed with soil to be hardened to stabilize the ground. A method is known in which a water reducing agent for cement such as a polyalkylaryl sulfonate condensate or a polycarboxylic acid salt is added to secure the fluidity of a mixture of a hardener and soil. However, in this method, in the case of sand ground, the mixture of the hardening material and soil causes a breathing phenomenon, which causes a problem that the improved ground sinks.

As a method for ensuring fluidity, a method is known in which a clay mineral such as bentonite is blended and a water reducing agent for cement is added (Japanese Patent Laid-Open No. 61-268).
812, JP-A-6-256056, etc.). However, bentonite is difficult to dissolve in water. Therefore, it is necessary to install a dissolving tank for bentonite separately from the water reducing agent for cement when preparing the cement slurry, which is complicated in terms of equipment or operation.

Further, a method is known in which water glass is added to a fly ash type grout material to suppress the breathing phenomenon (JP-A-1-234492). But,
Although the fluidity is maintained for a long time due to the looseness of fly ash, the fluidity is lost in a short time even if it is added to the grout material containing only cement.

[0005]

DISCLOSURE OF THE INVENTION An object of the present invention is to suppress the bleeding phenomenon of a mixture of hardener and soil in a method of injecting cement-based grout material into the ground by a high pressure injection method in order to stabilize the ground. And to provide a uniform admixture that ensures the fluidity of the mixture of hardener and soil. Therefore, the present inventor, as a result of diligent research, found that by adding a mixture of water glass and a water reducing agent for cement, it is possible to suppress the breathing phenomenon and secure fluidity, and based on this finding, the present invention The invention was completed.

[0006]

According to the present invention, the following (1) and (2) are provided. (1) A breathing reducing agent for cement-based grout materials, which comprises water glass and a water reducing agent for cement. (2) A bleeding reducing method for a cement-based grout material, comprising adding 0.2 to 10 parts by weight of a bleeding-reducing agent for a cement-based grout material to 100 parts by weight of cement.

The water glass used in the present invention is another name for sodium silicate and is represented by the chemical formula of Na ₂ O.nSiO ₂ .mH ₂ O. JIS K 1408 has Na ₂ O and S
No. 1, No. 2, and No. 3 are standardized according to the content of iO ₂ , and it is needless to say that these can be used, but water glass having any other Na ₂ O / SiO ₂ molar ratio is used. can do.

The water reducing agent for cement used in the present invention is
Conventionally, it is known as a water reducing agent for cement compounds, and is one selected from polycarboxylic acid salts, condensates of aromatic sulfonates, lignin sulfonates, and condensates of melamine sulfonates. Alternatively, it is a mixture of two or more kinds.

As the polycarboxylic acid salt, an alkali metal salt of a homopolymer of an α, β-unsaturated carboxylic acid or a copolymer of an α, β-unsaturated carboxylic acid and an ethylenically unsaturated compound copolymerizable with the α, β-unsaturated carboxylic acid. , Water-soluble salts such as alkaline earth metal salts and lower amine salts. The α, β-unsaturated carboxylic acid is an unsaturated carboxylic acid having a carboxyl group or an acid anhydride group or an acid anhydride thereof, and specific examples include acrylic acid, methacrylic acid, maleic acid, fumaric acid, Examples thereof include itaconic acid, maleic anhydride and itaconic anhydride.

Any copolymerizable ethylenically unsaturated compound may be used as long as it can be radically copolymerized with α, β-unsaturated carboxylic acid, and specific examples thereof include ethylene, propylene, butene, Isobutene, 2-
Olefin-based monomers such as methyl-butene-1,2-methyl-butene-2, hexene, octene, diisobutylene, cyclopentene, cyclohexene; styrene, vinyltoluene, α-methyl-styrene, coumarone, intene, methyl-vinyl-ether. , Ethyl acrylate, butyl acrylate, methyl methacrylate, vinyl acetate,
Examples thereof include polar or non-polar vinyl monomers such as vinylpyrrolidone.

Among them, a water-soluble sodium salt of a copolymer of maleic anhydride and an olefinic monomer having 4 to 8 carbon atoms is used because of its compatibility with water glass and the fluidity of a mixture of a hardening material and soil. preferable.

The condensate of an aromatic sulfonate is a sulfonated product of a monocyclic or polycyclic aromatic hydrocarbon compound such as benzene, naphthalene, anthracene, etc. NH _2, -OH, -
1 to 1 substituents such as COOH and an alkyl group having 1 to 2 carbon atoms
Examples thereof include water-soluble salts such as alkali metal salts, alkaline earth metal salts and lower amine salts obtained by condensing a sulfonated product of two compounds with an aliphatic aldehyde such as formaldehyde.

As the lignin sulfonate, an alkali metal salt, an alkaline earth metal salt or a lower amine obtained by reducing the saccharide content by a known method using the sulfurous acid valve drainage as a raw material or by subjecting it to an ultrafiltration treatment. Water-soluble salts such as salts are mentioned.

As the condensate of melamine sulfonate,
Alkali metal salts or alkaline earth metal salts of melamine sulfonic acid condensed with an aliphatic aldehyde such as formaldehyde, or a mixture of melamine sulfonic acid and urea, phenol, phenol sulfonic acid mixed with an aliphatic aldehyde such as formaldehyde. And water-soluble salts such as lower amine salts.

The breathing reducing agent for cement-based grout materials of the present invention is a mixture of water glass and a water reducing agent for cement. The amount of water glass or cement water reducing agent used is
Usually, it is 1 to 20 parts by weight, preferably 2 to 10 parts by weight of the active ingredient of the water reducing agent for cement with respect to 100 parts by weight of water glass.

In this case, if the amount of the water-reducing agent for cement is too small, the fluidity of the cement-based grout and the mixture of the hardening material and the soil will be deteriorated, which is not preferable. Further, if the water-reducing agent for cement is excessively large, the effect of reducing breathing is reduced and the compatibility between the water glass and the water-reducing agent for cement is deteriorated, and precipitation or two-phase separation occurs, which is not preferable.

By adding the cement-based grout breathing reducing agent of the present invention to the cement slurry,
It is possible to reduce the bleeding of the cement-based grout material. The amount used is usually 0.2 to 10 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of cement. The effect of the amount used is not necessarily uniform depending on the ratio of water glass and water reducing agent used for cement, but in general, if the amount used is too small, the breathing reduction effect will be small and the cement grout and hardening material and soil will be less effective. It is not preferable because the fluidity of the mixture also decreases. Further, an excessively large amount is not economically preferable. In addition, compounding agents such as a dispersant, an air speeding agent, an antifoaming agent, a cement setting accelerator, and a cement setting retarder can be used in combination as long as the effects of the present invention are not substantially impaired.

The cement-based grout material which can use the breathing reducing agent for cement-based grout of the present invention is a highly fluid cement composed of cement and water, which is suitable for injection into the ground by a high pressure injection method. It is a slurry. The type of cement that can be used is not particularly limited, and specific examples thereof include ordinary Portland cement, early strength Portland cement, intermediate heat Portland cement, alumina cement, fly ash cement,
Examples thereof include blast furnace cement, silica cement, slag cement, and various mixed cements.

[0019]

EXAMPLES The present invention will be described in more detail with reference to the following examples. The parts and% in the examples, comparative examples and reference examples are based on weight unless otherwise specified. (Test method) (1) Compatibility of water glass and water reducing agent for cement Water glass and water reducing agent for cement are mixed at various mixing ratios,
The mixture was allowed to stand and the presence or absence of precipitation and two-phase separation was observed. (2) Preparation of a mixture of cement-based grout material and soil Cement-based grout material for jet grout (cement =
760 kg / m ³ , aqueous solution of admixture = 760 kg /
m ² ) and soil were mixed to prepare two types of formulations shown in Table 1, assuming sand ground and cohesive ground.

[0020]

[Table 1]

Note 1): Ordinary boltland cement Note 2): Tap water (including admixture to cement = 1.58%) Note 3): Toyoura standard sand (water content = 10%) Note 4): Kaolin ( (SAM clay, water content = 80%)

Next, cement is added to an aqueous solution of a mixture of water glass and a water-reducing agent for cement, and then sand and clay are added, followed by stirring and mixing for 1 minute with a mixer (TK homomixer manufactured by Tokushu Kiki Kogyo). Then, a blended slurry was prepared. (3) P funnel flow-down time (fluidity test) Immediately after preparation, the mixture slurry prepared in (2) was prepared according to "Japanese Society of Civil Engineers Standards, Fluidity Test Method for Injection Mortar of Prepacked Concrete (JSCE-1986)".
The flow-down time by the P funnel was measured after 1 hour, 2 hours and 3 hours (unit: second). The shorter the flowing time is, the better the fluidity is, and if it exceeds 15 seconds, the construction will be hindered. (4) Breathing rate test The mixture slurry prepared in (2) was used in accordance with "Japan Society of Civil Engineers Standard: Breathing rate test method for injected mortar of prepacked concrete (JSCE-1986)" according to 3
Measure the amount of breathing water after 20 hours and 20 hours,
It was expressed as a ratio to the blended amount (unit:%). The smaller the value, the better the breathing property. (5) Compressive strength From the compound slurry prepared in (2), "Method of creating a specimen without compaction of stabilized soil by" Society for Geotechnical Engineering "(J
SF T-821) ", diameter 5 cm, length 10 cm
A cylindrical specimen of was prepared, cured in water, and the compressive strength after 7 days was measured (unit: kg / cm ³ ).

(Reference Example 1) Preparation of sodium salt of C5 olefin-maleic anhydride copolymer 98 parts of maleic anhydride in an autoclave, C5 olefin fraction obtained by extractive distillation from C5 fraction obtained by purification of naphtha (Pentene-1 = 5.3%, Penten-2
= 5.3%, 2-methyl-butene-1 = 7.9%, 2-
Methyl-butene-2 = 3.7%, n-pentane = 43.
6%, 1-pentane = 28.8% and the like) 380 parts (including 87 parts of C5 olefin) and 4 parts of benzoyl peroxide were charged and reacted at 70 to 75 ° C. for 3 hours with stirring. After the completion of the polymerization reaction, 280 parts of a 25% NaOH aqueous solution was added, neutralization reaction was carried out at 70 ° C., unreacted C5 olefin and C5 paraffin were distilled off, and a sodium salt of C5 olefin-maleic anhydride copolymer with PH = 10. An aqueous solution (active ingredient concentration = 40%) was obtained (cement water reducing agent A).

Reference Example 2 Preparation of Sodium Salt of Formalin Condensate of Naphthalene-Sulfonic Acid 100 parts of β-naphthalene-sulfonic acid and 20 parts of water were added to 8 parts.
While maintaining the temperature at 5 ° C, 42 parts of 37% formalin was added dropwise over 3 hours. After the addition of formalin, the mixture was further stirred at 100 ° C. for 7 hours for reaction. During this period, 45 parts of water was dropped. After the condensation reaction product was rimmed, it was further subjected to sodation to obtain an aqueous sodium salt solution of the formalin condensate of naphthalene-sulfonic acid containing 85% mononuclear body (concentration of active ingredient = 40%) (cement water reducing agent B). . .

Reference Example 3 Preparation of Sodium Salt of Lignin Sulfonic Acid The sulfite pulp effluent was subjected to ultrafiltration using a cellulose membrane having a separation limit molecular weight of 6000, and sugar content (pentose conversion) = 1.5%, Those having a molecular weight of 2000 or less = 20
%, 10,000 or more molecular weight = 42% sodium ligninsulfonate aqueous solution (active ingredient concentration = 40
%) (Cement water reducing agent C).

Reference Example 4 Preparation of Sodium Salt of Condensate of Melamine Sulfonate While keeping 126 parts of melamine and 41 parts of phenol at 80 ° C., 400 parts of 37% formalin was added dropwise over 5 hours. After the reaction solution became transparent, 90 parts of sodium sulfite, 74 parts of sodium hydrogen sulfite and 2 parts of water were added at 60 ° C.
00 parts was added, the mixture was heated again to 80 ° C., and stirred for 2 hours to react. After cooling to 50 ° C. and adding sulfuric acid to adjust the pH to 4.5, the mixture was reacted at 50 ° C. for 5 hours. PH by adding NaOH
= 10 to obtain an aqueous sodium salt solution (concentration of active ingredient = 40%) of the desired condensate of melamine sulfonate (cement water reducing agent D).

(Example 1) Compatibility of water glass No. 3 and water-reducing agent for cement 100 parts of water glass No. 3 was mixed with an aqueous solution of water-reducing agent for cement (variable amount) shown in Table 2, and the resulting mixture was mixed. The condition was observed. Table 2 shows the results.

[0028]

[Table 2]

(Example 2) Compatibility of water glass No. 4 and water reducing agent for cement 100 parts of water glass No. 4 was mixed with an aqueous solution of water reducing agent for cement (variable amount) shown in Table 3, and the resulting mixture was mixed. The condition was observed. The results are shown in Table 3.

[0030]

[Table 3]

(Examples 3 to 11, Comparative Examples 1 to 5) The breathing reducing agent, which is a mixture of water glass No. 3 and the aqueous solution of the water reducing agent for cement prepared in Reference Example, was mixed with Compounds A and B.
The fluidity, breathing rate, and compressive strength of each of the formulations were measured when they were added. The results are shown in Table 4. The amount of the breathing reducing agent used is parts by weight based on 100 parts by weight of cement.

[0032]

[Table 4]

From Table 4, when the water-reducing agent for cement alone is used, the breathing reduction in Formulation A (for sand ground) is remarkable. Further, when water glass is used alone, although the effect of improving breathing is slightly seen in the blend A, the fluidity of the blend B (corresponding to the viscous landbed) is remarkably lowered. On the other hand, when the breathing reducing agent of the present invention is used, it can be seen that the improvement of the breathing in the formulation A and the securing of the fluidity of the formulation B can both be achieved.

(Examples 12 to 15) The fluidity of each compound when a mixture of water glass No. 4 and an aqueous solution of a water reducing agent for cement prepared in Reference Example was added to compounds A and B, respectively. It was measured. The results are shown in Table 5. The amount of the breathing reducing agent used is parts by weight based on 100 parts by weight of cement.

[0035]

[Table 5]

It can be seen from Table 5 that even when water glass No. 4 is used, the breathing reducing agent of the present invention can achieve both improvement of breathing in formulation A and securing of fluidity of formulation B.

[0037]

As described above, according to the present invention, a uniform mixture of water glass and a water reducing agent for cement is injected into the ground by the high pressure injection method to suppress the bleeding phenomenon of the mixture of the hardening material and the soil. In addition, liquidity can be secured.

The embodiment of the present invention is as follows. (1) A breathing reducing agent for cement-based grout materials, which comprises water glass and a water reducing agent for cement. (2) A breathing reducing agent for a cement-based grout material, which comprises 1 to 20 parts by weight of the active ingredient of a water reducing agent for cement mixed with 100 parts by weight of water glass. (3) The water reducing agent for cement is one or a mixture of two or more selected from polycarboxylic acid salts, condensates of aromatic sulfonates, lignososulfonates and condensates of melamine sulfonates. ) Or (2) a breathing reducing agent for cement-based grout materials. (4) The polycarboxylic acid salt is maleic anhydride and has 4 carbon atoms.
The breathing reducing agent for cement-based grout material according to the above (3), which is a water-soluble salt of a copolymer with an olefin having 1 to 8. (5) Reducing the bleeding of the cement-based grout material, characterized in that 0.2 to 10 parts by weight of the bleeding-reducing agent for the cement-based grout material of (1) to (4) is added to 100 parts by weight of the cement. Method.

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Claims (2)

[Claims] 1. A breathing reducing agent for cement-based grout materials, which comprises water glass and a water reducing agent for cement. 2. The bleeding reducing agent for cement-based grout material according to claim 1 is added to 100 parts by weight of cement.
A method for reducing breathing of a cement-based grout material, which comprises adding 2 to 10 parts by weight.