JPH0629422B2 - Material for consolidation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a consolidating material containing water glass and lime, which is mainly used as a ground injection chemical, and has a high strength even at a long gelation time. And a solidifying material excellent in long-term solidifying strength.

[Conventional technology]

Conventionally, as a ground injection drug, water glass grout (suspension type grout), which is a mixture of water glass and a suspending reaction agent such as cement, or water glass, such as an organic reaction agent or an inorganic salt, is used. A water glass grout to which a solution-type reactive agent is added is known.

Among them, water-glass grout using a solution-type reactive agent has an advantage that it has better permeability than that using a suspension-type reactive agent, but has low strength, especially when adjusting the gelation time for a long time. In this case, the amount of the reaction agent is reduced, so that a large amount of unreacted SiO ₂ remains in the water glass,
For this reason, there is a problem that the strength is further lowered and the long-term consolidation strength cannot be obtained.

Further, the suspension type grout using cement also has the same problem as described above when the gelation time is adjusted to be long.

Therefore, a cement water glass grout using water glass with a low molar ratio has been proposed as a water glass grout for adjusting the gelation time to be long. (Japanese Patent Publication No. 51-8486). However, even in this case, the gelation time is increased from a few minutes to about 10 minutes at most, which makes it impossible to stir and mix the water glass and the reactant in the mixer, and then to pour both. I had no choice but to take the means of joining them with a tube and injecting them as they were. Therefore,
In such a combined injection, not only the infiltration effect is not sufficiently obtained, but also the mixing of the injection material is insufficient and the reaction becomes incomplete, so that the solidified matter in the ground is stable for a long period of time. It didn't happen.

A method has also been proposed in which the reactant is injected into the ground in advance, and then water glass with a low molar ratio is injected into this injection point.However, in this method, both liquids are reacted at a constant ratio in the ground. It is practically impossible to do so, and thus it is difficult to expect a sufficient consolidation effect or a long-term consolidation effect.

In addition, in order to set a long gelling time, first mix water glass and a small amount of cement, and then pour the above-prepared liquid into the ground, or mix the calcium compound with water and let it stand still. A method is known in which the slurries are mixed with water glass having a low molar ratio and water glass grout containing an extremely small amount of a water-soluble calcium compound is injected into the ground.

However, although the grouts used in these construction methods contain fine particles of calcium compounds of about 10 microns, they are substantially the same as solution-type water glass grouts, and the calcium content relative to the SiO ₂ content in the water glass is extremely high. Therefore, a large amount of unreacted SiO ₂ remains, resulting in low consolidation strength and poor durability.

[Problems to be solved by the invention]

The water glass grout in the above-mentioned conventional method reduces the amount of the reaction agent with respect to SiO ₂ in the water glass and prolongs the gelation time. Therefore, the consolidation strength is reduced and the durability is also deteriorated. Therefore, if the amount of the reactant is increased, the gelation time will be shortened, and it will not be possible to perform sufficient mixing in the mixer. Therefore, the injection pipe rod may be used to join the water glass or the reactant in advance in the ground. After injecting into the soil, the other was injected later to react in the ground, and the reaction was insufficient, and the consolidation strength or durability could not be obtained.

Therefore, although the object of the present invention is to use a sufficient amount of the reactant for reacting the SiO ₂ content in the water glass,
A long gelling time, which is long enough to mix water glass and a reactant in a mixer and slowly inject it into the ground, is obtained, that is, high gelling strength is obtained with a long gelling time, and permeability and long It is an object of the present invention to provide a consolidation material which retains durability for a certain period of time and has improved the above-mentioned drawbacks existing in the known art.

[Means for solving problems]

In order to achieve the above-mentioned object, the present invention is characterized by containing water glass and lime, and satisfying the following requirements.

(1) SiO ₂ / Na ₂ O is in a molar ratio range of 1.5 to 2.2.

(2) The CaO / SiO ₂ molar ratio is within the range of 0.2 to 2.0.

(3) The content of SiO ₂ is 0.07 mol or more per 100 cc of the material.

(4) The content of lime must be 1 g or more per 100 cc of the material.

In the present invention described above, the water glass is a liquid or powdery water glass having a molar ratio of 1.5 to 2.2, or a water glass adjusted to the above molar ratio by adding an alkali such as caustic soda or sodium carbonate to the liquid water glass. is there. As the molar ratio becomes lower than 1.5, the silica content of water glass tends to be precipitated without reacting with the reaction agent, not only it becomes difficult to obtain stable grout, but also the strength is lowered and even if the calcium content is increased, it becomes solid. It becomes hard to tie. Also, as the molar ratio becomes higher than 2.2, long-term consolidation strength decreases, durability becomes difficult to obtain, and the presence of a small amount of calcium content accelerates gelation and is sufficient for reaction with SiO ₂ content. It becomes impossible to mix in a large amount of calcium.

Further, the lime is basic calcium carbonate (CaCO ₃ .Ca (O) such as quick lime, slaked lime or dolomite.
It is derived from H) ₂ ) or limestone and has Ca (OH) ₂ as an active ingredient.

Hereinafter, the present invention will be described in detail by the following experimental examples.

Experiment -1] 3 water glass (molar ratio _{2.94, SiO 2: 28.29%,} Na
₂ O: 9.94%, specific gravity 1.4) and slaked lime gelation time were measured, and the results are shown in Table 1.

From Table-1, it can be seen that in No. 3 water glass, the gelation time is short with any amount of Ca (OH) ₂ . Further, the strength is also small, for example, in the case of Sample No. 3, the consolidated standard sand is about 1.5 kg / cm ² after 30 days and about 0.8 kg / cm ² after 1 month of underwater curing.

[Experiment-2] Table-2 shows the experimental results of the water glass aqueous solution-cement system.

The water glass aqueous solution was prepared by adding caustic soda to the water glass of Experiment-1 to adjust the molar ratio. The SiO ₂ content was 0.165 mol per 100 cc of the mixed liquid (liquid A and liquid B).

From Table 2, it can be seen that when the molar ratio is low, the gelation time of the water glass-cement system is long, but the consolidation property is extremely poor and the gelation becomes unstable.

[Experiment-3] Table 3 shows the experimental results of the water-glass aqueous solution-cement or slaked lime supernatant liquid system having a molar ratio of 2.0 or 1.0.

In addition, the water glass aqueous solution is the water glass of Experiment-1
25 cc was used per unit, and caustic soda was added to adjust the molar ratio.
In addition, mix the cement or slaked lime supernatant with 100 cc of water and mix 20 g each of the cement or slaked lime.
After standing still for 50 hours, 50 cc of the above-prepared liquid was taken as the liquid B.

Uniaxial compressive strength (kg / cm ² ) of consolidated standard sand in Table 3
3 days later, in the order of sample No. 0.8, 0.7,-,
After 0.5 and 1 month, it showed 0.5, 0.4,-, and 0.3, which was found to be too weak for the purpose of injection.

[Experiment-4] No. 3 water glass of Experiment-1 was added to 25cc (0.165
Mol), and caustic soda was added thereto to adjust the molar ratio. Also, the amount of slaked lime added is 0.5 g per 100 cc of the mixed solution.
(0.007 mol) to 25 g (0.338 mol) in the range,
The gelation time was measured for each of these and the results are shown in Table 4.

From Table-4, Ca (OH) ₂ is 1g per 100cc of the mixed solution.
Or more, and _SiO 2 / _Na 2 O (mole ratio) 2.2 to 1.
5. When CaO / SiO ₂ (molar ratio) is 0.2 to 2.0, it can be seen that there is a gelation time of 10 seconds to several minutes and a long gelation region of several tens of minutes to several hundred minutes.

It should be noted that even if the SiO ₂ / Na ₂ O (molar ratio) is 1.5 or less, there is a long gelation region, but it is preferable to set the molar ratio too low for both economical reasons and the reason for alkalizing groundwater. In addition, the caking property is also reduced.

Experiment -5] SiO ₂ / _{Na 2} O (mole ratio) is 2.0, CaO / SiO
₂ (molar ratio) of 1.0, Si per 100 cc of liquid mixture
The gelation experiment was conducted by changing the content of O ₂ . Also,
Set to SiO ₂ / Na ₂ O (molar ratio) 1.5, CaO / S
Gelation experiments were conducted by changing the contents of SiO ₂ (molar ratio) and SiO ₂ per 100 cc of the mixed solution. The results are shown in Table-5, Table-6 and Table-7. In addition, SiO ₂ / N
A long-term strength test was conducted by changing a ₂ O and CaO / SiO ₂ , and the measurement results are shown in Table-8.

From the above measurement results, it can be seen that the gelation time is shorter as the content of SiO ₂ is larger and the CaO / SiO ₂ (molar ratio) is larger. In particular, it can be seen that when the SiO ₂ / Na ₂ O (molar ratio) is 2.0 to 1.5, there is a region of sufficiently long gelation time despite the CaO / SiO ₂ ratio being a sufficiently large value of around 1. That is, a sufficiently long gelling time can be obtained by using Ca (OH) ₂ in an amount sufficient to react with SiO _{2 in} water glass, so that a large consolidation strength is obtained and a long-term solidification excellent in durability is obtained. The binding strength can be obtained.

Further, from Table-5, Table-7 and Table-8, it can be seen that the lower the water glass molar ratio, the higher the long-term strength.
Furthermore, comparing No. 3 water glass (molar ratio 2.94) with water glass with a molar ratio of 2.0, long-term strength decreases with No. 3 water glass, whereas long-term strength increases with water ratio of 2.0. I understand that Furthermore, it can be seen that the long-term strength is highest at a molar ratio of 1.5 to 2.2.

It should be noted that the present invention obtains a greater strength as compared with the one using the slaked lime precipitating liquid in Experiment-2, but this depends on the use of slaked lime. For example,
Slaked lime is a powder having a specific surface area of about 10,000 cm ² / g, and when this is suspended in a sufficient amount in the water glass, SiO ₂ is adsorbed and reacted around the powdery calcium compound to form a gel. Fill the space between soil particles while forming a strong structure inside. Further, since slaked lime continues to form calcium silicate by supplying Ca ions to SiO ₂ in water glass for a long period of time, the slaked lime is stronger than the case of the above-prepared liquid and exhibits an excellent long-term strength effect. .

Regarding the molar ratio of water glass, when the molar ratio becomes 2.2, the long-term strength becomes superior as compared with the case above this, and when the molar ratio becomes 2.0 or less, even if slaked lime is added near the equivalent, A unique region appears that gives an extremely long gelation time of ten to several hours.

[Experiment-6] The gelation time was measured for a mixed system of water glass, slaked lime, and another reactant, and the results are shown in Table-9. Table-
9, the SiO ₂ content per 100 cc of the mixed solution was 0.198
It is a mole.

From Table-9, a water-soluble calcium compound such as CaCl ₂ is instantly set, the gelation time cannot be lengthened regardless of the molar ratio of water glass, and CaCO
₃ cannot react with water glass unless the water glass has a high alkali ratio of about 1, whereas slaked lime is 1.5 to 2.2.
It can also react with water glass with a molar ratio of, to obtain the gelling time most suitable for injection, and by using it in combination with other calcium compounds of slaked lime, the molar ratio is 1.5 to
It can be seen that a grout having a sufficiently long gelation time is obtained in a wide range of water glass of 2.2.

This is probably because slaked lime is not only sparingly soluble but also has an optimum solubility. That is, the solubility of Ca (OH) ₂ is 0.117 g / 100 g, and C
aCO ₃ (solubility 0.0065 g / 100 g) and calcium silicate are relatively large, and thus, even if the solubility is too low, the reactivity becomes low, which is not preferable as the calcium compound of the present invention. Seem.

Therefore, slaked lime can obtain a gelling time suitable for injection with an alkali amount of water glass smaller than CaCO _3, and is extremely excellent from the economical point of view and also from the point of not increasing the alkalinity in the ground. Can be said.

In the present invention, lime may be used in combination with other water-soluble reaction agents.

Further, the present invention is obtained by mixing in a mixer at the time of construction, but if necessary, prepare water glass as solution A and a lime compound solution as solution B, and join these solutions A and B into the ground. Alternatively, a mixed solution of water glass and lime may be prepared as solution A, and while feeding this solution, another reactant or water glass having an arbitrary molar ratio (more than the water glass used in the present invention, The gelation time can be shortened by adding water glass with a high ratio), and the resulting mixture can be injected into the ground.

[Action]

In the present invention, lime is allowed to exist in water glass in a suspended state to prevent the reaction from proceeding at a time, and the SiO in the mixed solution is prevented.
₂ amount, lime amount, molar ratio of SiO ₂ and Na ₂ O, SiO ₂
By setting the molar ratio of CaO to CaO within the above-mentioned specific range, a long gelling time, high consolidation strength and long-term durability which cannot be considered in the conventional low molar ratio water glass-cement grout can be obtained.

〔The invention's effect〕

As described above, the caking material according to the present invention is a caking material most suitable as an injectable liquid for ground caking, as it obtains caking strength even if the gelation time is lengthened and has excellent long-term durability. .

Claims (2)

[Claims] 1. The following requirements including water glass and lime:
A consolidating material comprising (1) to (4). (1) SiO ₂ / Na ₂ O is in a molar ratio range of 1.5 to 2.2. (2) The CaO / SiO ₂ molar ratio is within the range of 0.2 to 2.0. (3) The content of SiO ₂ is 0.07 mol or more per 100 cc of the material. (4) The content of lime must be 1 g or more per 100 cc of the material. 2. The caking material according to claim 1, wherein the lime is quicklime or slaked lime.