JP2005162949A - Grouting material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grouting material coping with the practice and schedule of construction work, exhibiting a stable slurry state resistant to the change of fluidity even by leaving in a kneaded state before mixing a slurry containing a quick hardening agent with a cement suspension, free from abrupt change of the gelling time from a preset time in the case of mixing a kneaded slurry in use and having good strength developing property. <P>SOLUTION: The grouting material is produced by mixing a slurry A containing a gypsum mixture composed of gypsum anhydride and gypsum dihydrate at an (anhydride/dihydrate) weight ratio of 50/50 to 85/15 with a slurry B containing cement. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a cement-based injection material used when soft ground or the like is improved to a strong ground.

  As a measure to more firmly improve soft ground and unstable rock, an injection method is widely used in which cement-based slurry-like injection material is pumped into a soil particle gap or rock crack in soft ground. The slurry-like injection material used here generally has a large water / cement ratio, tends to cause material separation, and slows the setting / curing time (gelation time), causing the injection material to run away and exhibiting sufficient strength. There is a problem that cannot be obtained. As a method for solving these problems, an injection material that mixes a slurry containing a calcium aluminate-based rapid-hardening cement and a setting retarder with a slurry of a cement main material and adjusts the gelation time from 1 minute to several tens of minutes ( Patent Document 1), an injection material (Patent Document 2) containing calcium aluminate, inorganic sulfate, lithium compound, etc. and adjusting the particle size to improve the initial strength after gelation is known. Yes.

On the other hand, recently, in order to reduce the construction cost, it is desired to reduce the number of slurry injection pipes at the time of construction, and to obtain an injection consolidated body having a large diameter (improved diameter) of the injection consolidated body. There is also a demand for an injection material of about 1 to 3 hours. When the gelation time is about 1 minute to several tens of minutes, there is a problem that a wide range of improved diameters cannot be obtained, and the injection pressure suddenly rises during construction and the injection pipe and hose are blocked. In order to lengthen the gelation time, the amount of the setting retarder may be increased, but the curability may be significantly reduced. In addition, there are various actual construction conditions and environments, and there may be a situation in which, after the rapid hardening component-containing slurry and the cement-containing slurry are produced, both cannot be immediately mixed and injected due to some trouble. In that case, the slurry containing a rapid hardening component hardens | cures in a mixer, or the gelation time initially set after both slurry mixing shortens rapidly, and the problem that predetermined | prescribed property cannot be obtained generate | occur | produces.
Thus, the injection material corresponding to the actual work conditions and work convenience at the time of construction, i.e., a certain time before mixing the rapid hardening component-containing slurry and the cement-containing slurry exists in a stable slurry in which the flow properties and the like do not change, There is a demand for the development of an injecting material having a good strength development property, with the gelation time after mixing at the time of construction not changing more rapidly than the set time.
Japanese Patent Publication No.57-10058 JP 2000-281410 A

  The object of the present invention is to maintain the stability of the slurry without changing the fluidity of the slurry even if kneaded prior to mixing the slurry containing the rapid hardening component and the cement slurry. Thus, the gelation time after mixing at the time of construction is to provide an injection material that does not change more rapidly than the initial setting time and has good strength development.

  As a result of intensive studies to solve the above problems, the present inventors have found that a gypsum mixture containing anhydrous gypsum and dihydrate gypsum in a specific ratio and a slurry containing a rapid hardening component, and a slurry containing cement Can be used to adjust the gelation time up to about 3 hours without affecting the desired pot life even when kneaded. The present invention was completed by finding that the strength could be rapidly obtained after gelation without time change.

  That is, the present invention relates to a cement containing a slurry A containing a gypsum mixture having a mixing weight ratio of anhydrous gypsum to dihydrate gypsum (anhydrous gypsum / dihydrate gypsum) of 50/50 to 85/15 and a rapid hardening component, and cement. The injection material formed by mixing the contained slurry B is provided.

  The injection material of the present invention is a stable slurry that does not change its fluidity even if kneaded before mixing the rapid hardening component-containing slurry and the cement slurry, and is gelled when the kneaded slurry is mixed during construction. The time does not change abruptly from the initial setting time, and the strength development is good.

The injecting material of the present invention is obtained by mixing two types of slurry produced separately.
The first slurry is a slurry A containing a gypsum mixture having a mixing weight ratio of anhydrous gypsum to dihydrate gypsum (anhydrous gypsum / dihydrate gypsum) of 50/50 to 85/15 and a rapid hardening component.
Slurry A is a slurry which may contain a gypsum mixture of anhydrous gypsum and dihydrate gypsum, a rapid hardening component, water and, if necessary, optional components such as an alkali metal carbonate, a setting retarder, etc. Contains no other cement.

The rapid hardening component used in the slurry A is calcium aluminate, which is a general term for inorganic substances that mainly contain CaO and Al ₂ O ₃ and exhibit a hydration reaction. If necessary, other than CaO and Al ₂ O ₃ Other components such as SiO ₂ , CaF ₂ , Fe ₂ O _3, etc. may be compounds, composites, or solid solutions. The molar ratio of CaO / Al ₂ O ₃ of calcium aluminates is not particularly limited, but is preferably 1.0 to 1.5. In addition, commercially available calcium aluminates and commercially available calcium carbonate and aluminum oxide, which are raw materials for calcium aluminate, generally contain inevitable impurities such as SiO _2, but contain inevitable impurities in calcium aluminates. An amount of about 8% by weight or less is acceptable.

Calcium aluminates may be crystalline, amorphous, or a mixture of both, and need not be all amorphous, and those having a vitrification rate of about 25% by weight or more are preferable.
Also, the Blaine specific surface area in terms of exerting a setting accelerator operation and injection permeability 3000 cm ² / g or more, preferably 5000 cm ² / g or more it is desirable. If it is less than 3000 cm ² / g, sufficient strength development and injection permeability may not be obtained.

The gypsum used for the slurry A needs to be used in combination with anhydrous gypsum and dihydrate gypsum. By using anhydrous gypsum and dihydrate gypsum in a mixed weight ratio (anhydrous gypsum / dihydrate gypsum) 50/50 to 85/15, a desired gelation time can be secured even after slurry A is kneaded. It is possible to secure excellent strength. When the dihydrate gypsum is less than 15 parts by weight in 100 parts by weight of the gypsum mixture, it is difficult to ensure the gelation time when mixed with the slurry B after kneading, and when it exceeds 50 parts by weight, strength development is reduced.
Blaine specific surface area of the two kinds of gypsum to be used is not particularly limited, 4000 cm ² / g or more, preferably more 5000 cm ² / g or more.

  In order to further promote the hydration reaction, the slurry A may contain an alkali metal carbonate such as lithium carbonate, sodium carbonate, or potassium carbonate. As the alkali carbonate metal salt, it is preferable to use sodium carbonate and lithium carbonate in combination, since high strength can be imparted after gelation.

  Slurry A may contain a setting retarder to control the hydration reaction of calcium aluminates and adjust the gelation time. The setting retarder is not particularly limited as long as it is generally used in mortar or concrete. For example, oxycarboxylic acids such as citric acid, tartaric acid and gluconic acid, aminocarboxylic acid, phosphoric acid, boric acid, or theirs Salts, and citric acid, tartaric acid, and gluconic acid are particularly preferable.

  In addition to these components, as optional components that may be contained in the slurry A, for example, AE agent, water reducing agent, high performance water reducing agent, AE water reducing agent, high performance AE water reducing agent, foaming agent, antifoaming agent, thickening agent Admixtures such as agents and separation reducing agents; pozzolanic substances such as fly ash and silica fume; latent hydraulic substances such as various slag powders; filler materials such as limestone fine powders.

The blending ratio of each component in the slurry A is not particularly limited, but when it contains a gypsum mixture, a rapid hardening component, and an alkali metal carbonate, it is added (hereinafter this mixture is referred to as a rapid hardening material). The calcium aluminate is preferably 20 to 70 parts by weight, more preferably 30 to 60 parts by weight in 100 parts by weight of the total amount. If the amount is less than 20 parts by weight, sufficient rapid hardening may not be obtained. If the amount exceeds 70 parts by weight, the slurry A itself may condense, and sufficient pot life may not be obtained when kneaded.
The gypsum mixture is preferably 20 to 70 parts by weight, more preferably 30 to 60 parts by weight, per 100 parts by weight of the hardened material. When the amount is less than 20 parts by weight, the initial strength development may be reduced. When the amount exceeds 70 parts by weight, workability is reduced due to an increase in viscosity at the initial stage of mixing of slurry A and slurry B, and sufficient rapid hardening cannot be obtained. There is.
In the case of containing an alkali metal carbonate, 1 to 10 parts by weight is preferable, and 3 to 8 parts by weight is more preferable in 100 parts by weight of the rapid hardening material. If it is less than 1 part by weight, sufficient rapid hardening may not be obtained, and if it exceeds 10 parts by weight, long-term strength development may not be obtained. The sodium carbonate in the alkali metal carbonate is preferably 0.5 to 9.5 parts by weight, and the lithium carbonate is preferably 0.5 to 3.0 parts by weight. If the lithium carbonate is less than 0.5 parts by weight, the initial strength development is reduced, which is not preferable. If the lithium carbonate is more than 3.0 parts by weight, the curability may be reduced, and the cost increases.
When it contains a setting retarder, 0.1-5.0 weight part is preferable with respect to 100 weight part of rapid-hardening materials, and 0.5-3.0 weight part is more preferable. If the amount is less than 0.1 parts by weight, it is not preferable because sufficient pot life cannot be obtained. If the amount exceeds 5.0 parts by weight, it is not preferable because the setting delay effect is rapidly increased and a curing failure may occur. .

The particle size of the rapid hardwood slurry A is Blaine specific surface area in terms of exerting a setting accelerator operation and injection permeability 3000 cm ² / g or more, preferably desirable ones 5000~8000cm ² / g. If it is less than 3000 cm ² / g, sufficient strength development may not be obtained, and injection permeability cannot be expected. Further, if it exceeds 8000 cm ² / g, sufficient kneading time may not be ensured.

  The water of the slurry A is preferably 200 to 1000 parts by weight with respect to 100 parts by weight of the hardened material. If the amount is less than 200 parts by weight, the viscosity of the slurry A increases, and it may be difficult to increase the load during kneading or to perform kneading for a long time. On the other hand, if it exceeds 1000 parts by weight, curing failure may occur, which is not preferable.

  The second slurry is a cement suspension (slurry B) containing a cement other than the quick-hardening cement and water (slurry B), and does not contain any component that imparts quick setting, quick hardening, and quick hardening. Optional ingredients may be included. Here, as an arbitrary component permitted to contain, for example, AE agent, water reducing agent, high performance water reducing agent, AE water reducing agent, high performance AE water reducing agent, foaming agent, antifoaming agent, thickener, separation Admixtures such as reducing agents can be mentioned.

  The cement used for the slurry B is not particularly limited as long as it is a cement other than the quick-hardening cement. For example, Portland cement such as ordinary cement, early-strength cement, ultra-early-strength cement, moderately hot cement, low-heat cement, sulfate-resistant cement, and the like. , Blast furnace cement, fly ash cement, mixed cement such as silica cement, eco cement (ordinary type), fine particle cement, ultra fine particle cement, and the like can be used.

  The water of slurry B is preferably 80 to 200 parts by weight with respect to 100 parts by weight of cement. If the amount is less than 80 parts by weight, the viscosity of the slurry B increases, which causes an increase in load during mixing and a decrease in pumpability, which is not preferable. On the other hand, if it exceeds 200 parts by weight, material separation is likely to occur, and strength development after gelation is lowered, which is not preferable.

  The mixing ratio of the slurry A and the slurry B of the injection material of the present invention is not particularly limited, but the rapid hardening material in the slurry A is 10 to 50 parts by weight with respect to 100 parts by weight of the cement in the slurry B. Furthermore, it is preferable that it is 15-30 weight part. If it is less than 10 parts by weight, sufficient strength development may not be obtained, and if it exceeds 50 parts by weight, long-term strength development may be reduced.

  In the injection material of the present invention thus produced, even if the slurry A is kneaded, the viscosity and the like hardly change for about 2 hours immediately after kneading at room temperature. Can handle work abnormalities. Moreover, even if the slurry A and the slurry B are mixed after kneading, the predetermined gelation time hardly changes.

  The injection material construction method of the present invention may be performed by mixing, for example, equal amounts of slurry A and slurry B separately produced in advance at the construction site and injecting them into the ground to be injected. In this case, injection may be performed using a multiple tube, a Y-shaped tube, or the like while the slurry is being pumped or mixed at the injection port. The kneading mixer does not need to be a special mixer, and any general-purpose mixer can be used without any problem.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

Examples 1-12
The injection material described in Table 1 was manufactured, and the gelation time and compressive strength were measured.
The raw materials used for the production of the injection material were as follows.
(1) Calcium aluminates: Calcium carbonate and aluminum oxide, which are commercially available reagents, are set to have a predetermined CaO / Al ₂ O ₃ molar ratio, cooled to a vitrification ratio of 85% by weight, and then pulverized. The powder having a specific surface area of 5300 cm ² / g of Blaine was used. Table 1 shows the physical properties of the calcium aluminate produced.
(2) Anhydrous gypsum: Central Glass Co., Ltd. (3) Dihydrate gypsum: Noritake Company Limited (4) Sodium carbonate: Kanto Chemical Co., Inc., purity> 99.5%
(5) Lithium carbonate: manufactured by Kanto Chemical Co., Inc., purity> 99.5%
(6) Setting retarder: citric acid; manufactured by Kanto Chemical Co., Inc., purity> 99.5%
(7) Ordinary Portland cement: Taiheiyo Cement Co., Ltd.

Production of slurry A:
A predetermined setting retarder (citric acid) is added to the amount of water described in Table 1 in advance to prepare a kneaded water, and the materials (1) to (5) are blended as shown in Table 1. Then, the mixture was put into a grout mixer and kneaded at 20 ° C. for about 2 minutes to produce slurry A.

Production of cement suspension (slurry B):
175 kg of ordinary Portland cement and 144.4 kg of water were put into a grout mixer and kneaded at 20 ° C. for about 2 minutes to produce slurry B.

Evaluation of injection properties:
200 mL of slurry A and slurry B were alternately transferred at 20 ° C. for 1 minute by the cup inversion method, and then allowed to stand, and then the fluid was lost about 5 times at intervals of 5 minutes. Measured as the conversion time. In addition, an injection material obtained by mixing equal amounts of slurry A and slurry B into a cylindrical mold having a diameter of 50 mm and a height of 100 mm is filled immediately before gelation to prepare a specimen, and conforms to JIS A1216. The uniaxial compressive strength was measured at 1 day, 7 days and 28 days.
Table 2 shows the evaluation test results of the injection material.

The injecting material of the present invention had almost no change in gelation time even after kneading, and was excellent in compressive strength.

Claims (6)

  Mixing the gypsum mixture having a mixing weight ratio of anhydrous gypsum to dihydrate gypsum (anhydrogypsum / dihydrate gypsum) of 50/50 to 85/15 and slurry A containing the quick-hardening component and slurry B containing cement An injection material. Sudden hard component, CaO / Al ₂ O ₃ injection material according to claim 1, wherein (molar ratio) is calcium aluminates of 1.0 to 1.5.   The injection material according to claim 2, wherein the vitrification rate of the calcium aluminates is 25% by weight or more.   The injection material according to any one of claims 1 to 3, wherein the slurry A further contains an alkali metal carbonate.   The injection material according to claim 4, wherein the alkali metal carbonate is a mixture of lithium carbonate and sodium carbonate. Furthermore, the injection material of any one of Claims 1-5 in which the slurry A contains a setting retarder.