JPH04298598A - Grout - Google Patents

Abstract

PURPOSE:To obtain a grout which requires a long time for gelling and is excellent in permeability as well as solidifying strength and durability. CONSTITUTION:A grout mainly comprising minute particles of silica (colloidal silica) obtained by bringing water glass into contact with an ion-exchanging resin to remove Na ions of the water glass and calcium carbonate, and mixed therewith an inorganic compound or water glass.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a ground injection material mainly composed of ultrafine silica (hereinafter referred to as "colloidal silica") obtained by removing Na ions from water glass and calcium carbonate. The present invention relates to ground injection materials that require a long gelation time and have excellent permeability, consolidation strength and durability.

0002

BACKGROUND OF THE INVENTION As a grout using water glass, grout made of water glass and an acidic reactant is conventionally known. This grout solidifies in the strongly alkaline region and cannot be gelled for a long time, resulting in poor permeability and failure to obtain high strength.

[0003] As a method to improve this, an acidic silica sol obtained by mixing water glass and an excess of an acidic reactant,
A method using a basic reactant is known. but,
In this method, if the water glass concentration is increased to obtain high strength, it becomes difficult to maintain a long gelation time.
Furthermore, due to gel shrinkage phenomenon, when injected into coarse soil layers, water permeability decreases in the long term, making it unsatisfactory as a permanent grout.

[0004]Recently, limes (especially calcium carbonate) or limes and pozzolans have been used together with water glass with a low molar ratio, which results in less shrinkage of the volume of the solids and the formation of fine particles. Grouts with relatively excellent permeability are being developed by using lime and pozzolan. However, the drawback of this grout is that it is strongly alkaline because it is mainly composed of water glass with a low molar ratio, and the injection liquid itself exhibits a severe thixotropic phenomenon, which poses problems in its handling, injection operation, etc.

[0005] Also known is a grout whose main material is neutral silica with a high molar ratio (SiO2/Na2O molar ratio>50) and which uses an inorganic salt of a polyvalent metal as a hardening agent. Although this can improve strength without causing pollution, further improvement in strength, permeability, and permanence are desired.

[0006]

[Problems to be Solved by the Invention] The present inventor has conducted extensive research in order to solve the above-mentioned problems and develop a ground injection material that has greater strength and permeability, and is highly durable. We have developed a ground injection material using ultrafine silica (colloidal silica) obtained by bringing water glass into contact with an ion exchange resin to remove alkali in the water glass, and have completed the present invention.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a ground injection material that requires a long gelation time, has excellent permeability, and also has excellent consolidation strength and durability.

[0008]

[Means for Solving the Problems] In order to achieve the above-mentioned object, according to the present invention, ultrafine silica particles (colloidal The main materials are silica) and calcium carbonate, which are mixed with an inorganic compound or water glass.

Colloidal silica has an average particle size of 10 to 2
A translucent aqueous dispersion of ultrafine silica particles with a diameter of 0 mμ and invisible to the naked eye, which forms strong bridges between particles over a short period of time (several seconds) to a long period of time (several 100 minutes) by interacting with a wide range of inorganic compounds. It becomes a cured product with a structure. This cured product does not exhibit strong alkalinity like ordinary water glass grout, the gelation time can be easily adjusted, no gel shrinkage is observed, and it exhibits low viscosity and excellent permeability.

However, it has been found that among these various inorganic compounds, calcium carbonate alone does not react with colloidal silica, and colloidal silica does not gel. By adding and mixing other inorganic compounds other than calcium carbonate (including the homologous magnesium carbonate) or water glass to this unreacted mixed system of colloidal silica and calcium carbonate, the advantages of calcium carbonate can be enhanced. We have successfully developed a grout that combines the advantages of colloidal silica, leading to the present invention.

That is, the present invention can obtain a synergistic effect from both the ease of controlling gelation over a long period of time of the system consisting of colloidal silica and an inorganic compound, and the high strength of calcium carbonate. did it.

[0012] Calcium carbonate and colloidal silica do not directly react to form a gel, but colloidal silica reacts with other inorganic compounds to form a strong bridge structure between particles. Calcium carbonate has almost no effect on the reaction rate of this reaction, and it is thought that it gradually penetrates into this cross-linked structure and bonds firmly, forming a denser structure in the entire gel. .

[0013]

[Examples] The present invention will be specifically explained below with reference to Examples.

1. Materials used (1) Water glass specific gravity: 1.40 (15℃), SiO2: 28
．． 9%, Na2O: 9.5%, viscosity: 140c
p (20°C) JIS No. 3 water glass was used. (2) Colloidal Silica Colloidal silica having the physical properties shown in Table 1 below, which was obtained by treating the above JIS No. 3 water glass with a hydrogen type cation exchange resin, was used.

[Table 1] (3) Inorganic compounds Single or multiple inorganic compounds that can adjust the pH of colloidal silica from weakly acidic to weakly alkaline can be used in a wide range of ways, with the exception of calcium carbonate (including the homologous magnesium carbonate). Examples of the invention include first grade reagents of potassium chloride and sodium hydrogen sulfate (KCl, NaHSO4
・H2O) was used. (4) Calcium Carbonate Industrial heavy calcium carbonate was used. (Similar results are obtained using the same family of magnesium carbonate.)

0
015]2. A system consisting of colloidal silica, calcium carbonate, and an inorganic compound or water glass Regarding the system of various combinations consisting of colloidal silica, calcium carbonate, an inorganic compound, or water glass according to the present invention shown in Table 2, the SiO2 amount, pH, gel at that time The curing time was measured and the results are shown in Table 2. Furthermore, Table 3 shows the results showing the unconfined compressive strength of these homogels and sand gels when cured in water. As a control, a system with the same formulation without the addition of calcium carbonate was also compared. Implementation temperature is 20±2℃
Let's do it.

[0016]

[Table 2]

[0017]

[Table 3]

3. Discussion of implementation results From Tables 2 and 3, as well as observations made during the implementation, the following phenomenon could be clearly seen.

(1) Colloidal silica/inorganic compound/
The system according to the invention consisting of calcium carbonate (sample no. 2)
, 3, 4, 6, 7, 8, 14, 15, 16, 18, 19
, 20), the pH increases slightly compared to the control system lacking calcium carbonate (sample numbers 1, 5, 13, and 17), but there is no significant difference, and the pH remains almost weakly alkaline to weakly acidic, and the gelation time is several seconds. Easy adjustment in 10 minutes. The system according to the present invention consisting of colloidal silica, water glass, and calcium carbonate (sample numbers 10, 11, 12, 22, 23, 24) is different from the control system lacking calcium carbonate (sample numbers 9, 21).
), the pH is lower and the strong alkali is weakened, and the gelation time is slightly faster, making it easier to adjust over a long period of time.

(2) The strength of the solidified body when cured in water is significantly strengthened in the system according to the present invention in which calcium carbonate is added to both the homogel and the sand gel, and the strength increases markedly with the passage of curing days.

(3) The viscosity of the blended liquid (AB combined liquid in Table 2) is extremely low because the viscosity of the colloidal silica used is 14 cps, which is extremely low compared to the 140 cps of No. 3 water glass used. In addition, there is almost no syneresis water in the homogel, and there is almost no contraction of the solids.
Combined with the long gelation time compared to conventional water glass grout, it can be expected to have extremely excellent permeability and permanence.

[0022]

[Effects of the Invention] As described above, it is recognized that the ground consolidation material according to the present invention can produce the following effects by synergistically utilizing the respective advantages of colloidal silica and calcium carbonate. (1) It is easy to adjust the gelation time over a long period of time. (2) Gel has little shrinkage. (3) It has lower viscosity than conventional water glass grout. (4) It has high strength and becomes stronger as time passes. (5) From the above, we can fully expect a grout with extremely excellent permeability and permanence. (6) The solidified material is almost neutral or has a softened strong alkali of water glass, which is excellent from an environmental conservation perspective.

Claims (4)

[Claims] Claim 1: The main ingredients are ultrafine silica obtained by contacting water glass with an ion exchange resin to remove Na ions from the water glass, and calcium carbonate, and an inorganic compound or water glass is mixed therein. Ground injection material. [Claim 2] The ultrafine silica particles have an average particle diameter of 10 to 2.
The ground injection material according to claim 1, which is a translucent water dispersion with a diameter of 0 mμ. 3. The ground injection material according to claim 1, wherein the inorganic compound is an inorganic compound other than calcium carbonate. 4. The ground injection material according to claim 3, wherein the inorganic compound is potassium chloride or sodium hydrogen sulfate.