JPH01239043A - Material for consolidation - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to a consolidation material that contains pozzolan, which is amorphous fine particle silica, in addition to water glass as a silica component, and is mainly used as a ground injection material. In particular, it not only exhibits high consolidation strength, but also has high long-term consolidation strength, and furthermore, the gelation time can be easily adjusted, and in particular, high consolidation strength can be obtained by adjusting the gelation time to a long time. , and also relates to a consolidation material with excellent permeability.

[Conventional technology]

Traditionally, water glass grout (suspension type grout), which is made by adding a suspended reactant such as cement to water glass, or water glass with an organic reactant or an inorganic salt, has been used as straw material for ground injection. Water glass grout made by adding a solution-based reactant is known.

Among these, water glass grout using a solution-based reactant has the advantage of superior permeability than one using a suspension-based reactant, but its strength is low, especially when adjusting the gelation time to a long time. The amount of reactant used is small, so a large amount of unreacted Sin remains in the water glass.
For this reason, there was a problem in that the strength was further reduced and the strength for long-term consolidation could not be obtained.

Furthermore, suspension grout using cement also had the same problem as described above when the gelation time was adjusted to be long.

Therefore, a cement water glass grout using a low molar ratio of water glass has been proposed as a water glass grout with a long gelation time. (Special Publication No. 51-8486). However, even in this case, the gelation time is only a few minutes to IO minutes long at most, and it is not possible to mix the water glass and the reactant thoroughly in a mixer before injecting it, and it is not possible to inject both. I had no choice but to use a tube to join them and inject them directly. Therefore, with such joint injection, not only is it not possible to obtain a sufficient infiltration effect, but also the mixing of the injection agent is insufficient, resulting in an incomplete reaction, which makes it difficult for the solidified material in the ground to remain stable for a long period of time. It didn't become a thing.

In addition, in order to set a longer gelation time, there is a method of first mixing water glass with a small amount of cement and injecting this superfluous liquid into the ground, or a method of mixing a calcium compound with water and letting it stand, and then A method is known in which water glass grout containing a very small amount of water-soluble calcium compounds is injected into the ground by mixing a water glass solution with a low molar ratio of water glass.

However, although the grout used in these methods contains fine particles of calcium compounds of about 10 microns, it is essentially the same as solution-type water glass grout, and the calcium content is extremely low compared to the Sigh content contained in the water glass. Therefore, a large amount of unreacted SiO□ remains, resulting in low consolidation strength and poor durability.

Furthermore, an injection material containing an ultrafine silica solution obtained by removing alkali metals from water glass using an ion exchange resin and a salt has been proposed, but the ultrafine silica is mostly in the neutral range, It reacts instantaneously with compounds containing polyvalent metal ions such as lime, and a long gelation time cannot be obtained.

In addition, as a method of consolidating highly water-containing ground by utilizing the digestive action of quicklime, an injection material made by adding water glass to quicklime and water slag is known, but water slag mainly contains crystalline calcium silicate. As a component, the particle size is large and the reactivity is extremely low. Therefore, not only is the permeability poor, but it is also almost impossible to adjust the gelation time.

Furthermore, injection materials containing a caustic soda solution of non-colloidal silica and calcium salts as reactants are known, but this not only causes insufficient reaction of the material, but also has an uncertain gelation time. It is easy to escape and leak outside the injection target, and alkaline content is also likely to be eluted.

In addition, there is also known an injection material made by adding caustic soda to water glass to lower the molar ratio of water glass, and then adding and mixing sodium aluminate to this, but since sodium aluminate is easily soluble, However, the gelation time is short, and it is difficult to adjust the gelation time to 10 minutes or more in practice.

Additionally, a method has been proposed in which a reactant is injected into the ground in advance, and then water glass with a low molar ratio is injected into the injection location, but in this method, both liquids are mixed into the ground at a fixed ratio. It is virtually impossible to react,
For this reason, it is difficult to expect a sufficient solidification effect or long-term solidification effect.

[Problem that the invention seeks to solve]

In addition to the above-mentioned drawbacks, the various water glass grouts used in the conventional methods described above are all inferior in the durability of the consolidated product, that is, in the long-term consolidation strength.

The reason for this is that the main component of the solidified material is only silica derived from water glass, and since this water glass is almost a complete solution, the molecular weight of the silica contained in water glass is extremely small. This is because the resulting gel also contains a large amount of unstable silica, and as a result, the silica content is eluted from the solidified material over a long period of time, resulting in a decrease in long-term strength.

Therefore, the purpose of the present invention is to use pozzolan, which is fine particles of amorphous silica, in addition to water glass as the silica component, and to set the molar ratio of SiOx/Me2O in the mixed system to 2.5 or less, This not only stabilizes the silica content and exhibits high consolidation strength, but also increases long-term consolidation strength, improves permeability, and
It is an object of the present invention to provide a material for consolidation, in which the gelation time can be easily adjusted, and in particular, the gelation time can be adjusted to a long time to obtain high consolidation strength, and which improves the drawbacks of the above-mentioned known techniques.

[Means for solving problems]

In order to achieve the above object, the present invention contains water glass, pozzolan, and lime, and the S i L/Met O of the mixed system has a molar ratio of 2.5 or less. characterized by something. However, here, 5if2 is a silica component originating from water glass, Me and O are substances originating from water glass, and Me is an alkali metal.

Furthermore, the above-described present invention may further contain an alkaline agent such as caustic alkali in addition to the three-component system. In this case as well, the molar ratio of SiO□/M e tO in these mixed systems is 2.5 or less, SiO is the silica content caused by water glass, and MezO is the substance caused by water glass and the alkali agent. is the total amount of

The water glass used in the present invention is a liquid or powdered water glass such as sodium orthosilicate or sodium metasilicate, and in particular, one having a molar ratio (S i Ox / Mete) of 2.5 or less is used, but a mixture When the system contains an alkaline agent, the molar ratio of water glass is not limited to 2.5 or less. However, in this case, the amount of alkali agent used is determined by the molar ratio (SiQ z / M ez O) is 2.5 or less,
Preferably it is 2.5 to 0.5. As the alkaline agent used here, a caustic alkali such as caustic soda or a water-soluble alkaline agent such as an alkali metal salt of carbonic acid is suitable, but a caustic alkali is particularly suitable. This alkaline agent may be used by being mixed with water glass in advance, or may be used by being mixed with water glass at the site, or may be used by being mixed with pozzolan. In general, water glass aqueous solutions are usually produced by the melting method and the wet method.The former is produced by melting silicic acid and soda ash and dissolving the obtained soda silicate glass in water, and the latter is produced by dissolving in water liquid caustic soda and silicic acid as raw materials. It is manufactured by using powder and directly obtaining a sodium silicate solution without taking it out as sodium silicate glass.

Furthermore, the pozzolan used in the present invention is an amorphous 5 inch
It is a highly reactive fine powder with a large specific surface area, and contains SiO□, which is easily eluted with alkali. Although it does not completely dissolve at room temperature due to the action of alkali, the Si on the surface of the particle is It becomes easily reactive and reacts with lime to form insoluble silicates such as calcium silicate and become crystals. In other words, pozzolan itself does not react with water glass and solidify, but it gradually reacts with calcium hydroxide at room temperature to create an insoluble compound, which is a so-called pozzolan-reacting amorphous mineral fine powder. . Specifically, acid clay, diatomaceous earth, silica, volcanic ash, synthetic silica,
Examples include fly ash, burned powder of papermaking sludge, etc.

Furthermore, the lime used in the present invention is powder of natural calcium compounds such as quicklime, slaked lime, limestone, and dolomite, or powder of synthetic calcium compounds based on these substances, and among these, quicklime and slaked lime are particularly preferred. The amount used is such that the molar ratio is 0.2 or more with respect to the total amount of silica caused by water glass and pozzolan in the mixed system, that is, the amount such that the molar ratio of lime/Stow is 0.2 or more. preferable.

In addition to being poured into the ground, the above-mentioned consolidation material of the present invention can be mixed with soil, sand, etc., stirred, sprayed onto the soil, or replaced with soil to construct earth structures or the structures themselves. is also used. In particular, the present invention is extremely effective in improving soil, such as organic soil improvement, where conventional cement and lime cannot be used effectively.

[Effect]

Normally, when lime is added to water glass with a molar ratio of 2.5 or more, whether the water glass is made by the melting method or the wet method, lime similar to that used in modern times is added to the SiO□ of the water glass. And gelation occurs in a few seconds, and it takes several tens of minutes,
It is not possible to extend the gelation time beyond 60 minutes. The reason for this is that commercially available water glass manufactured by the melting method or wet method contains a large amount of colloidal silicic acid with a large molecular weight, so it easily gels. It turned into a gel,
The gelled material has weak bonds and low strength.

However, when the above-mentioned water glass having a molar ratio of 2.5 or less is used in combination with silica from pozzolan, the gelation time becomes longer and the gelled product becomes stronger even though the silica content is the same concentration. Furthermore, instead of the water glass with a low molar ratio mentioned above, by using an alkaline agent together with water glass of any molar ratio, the alkaline agent acts on the water glass and pozzolan. Even though the silica content/alkali caused by water glass + alkaline agent (molar ratio) is the same as that of the above-mentioned water glass, the gelation time is longer and the gelled product is also stronger.

In other words, when an alkaline agent is further added to a mixed system of water glass, pozzolan, and lime, the water glass and pozzolan will react with the silica content of several tens of minutes to several tens of minutes, even though lime is added to the mixture. It solidifies with an extremely long gelation time.

In general, when pozzolan is mixed with a low-alkali water glass aqueous solution with a molar ratio of 2.5 or less at room temperature, a portion of the pozzolan is dissolved by the alkali, and the dissolved silica and the silica in the water glass surround it. state, indicating a suspended state. This is presumed to be because pozzolan has a very large specific surface area, and the surface has excellent surface activity due to the action of alkali. Therefore, if lime is present here, the pozzolanization effect occurs in a short period of time compared to the normal pozzolanization effect (several months to several years) and under conditions of high moisture. (If only lime and pozzolan are brought into a high-moisture state, that is, in a solution state, they will precipitate, and the whole will hardly solidify or harden, or if it does, it will not proceed in a short period of time.) It is thought that it reacts with SiO□ originating from water glass in a highly alkaline environment and then reacts with the surface-activated pozzolan to form an inert and strong polyvalent metal silicate. Moreover, since lime is a poorly soluble powder, even if a sufficient amount is added, the gelation time is short (but it is not), and moreover, over a long period of time, Ca
” to develop long-term strength.

Furthermore, in the present invention, since the silica content is composed of water glass and pozzolan silica content, the silica content of pozzolan is added to the silica content of water glass, making the silica concentration higher than that of water glass alone, and the silica content of pozzolan is Because it is in a suspended state, it does not react immediately, so even if the concentration of the caking agent is increased, the gelation time will not be shortened compared to when water glass alone is used as the silica component, and the gelation time will be maintained for a long time. However, high strength and long-term consolidation strength can be obtained.

Moreover, as the alkali content of pozzolan increases, the surface reactivity is activated, and the molar ratio of the water glass aqueous solution is 5iO.
When the value of z/MezO is less than 2.5, or when an alkali is added to water glass to lower the molar ratio of SiO□/MezO, high strength can be obtained with a long gelation time, and Oral strength increase (durability) is easily obtained. In particular, when water glass (the molar ratio may be higher than 2.5), pozzolan, lime, and an alkali agent are used, the molar ratio of 5iOt/MetO in the mixed solution is lower than that of water glass with a low molar ratio. Even if the molar ratio is the same as that in the case where alkali is used (without using an alkaline agent), a longer gelation time and long-term consolidation strength can be obtained.

〔Example〕

The present invention will be specifically explained below using experimental examples.

[Experiment-1] Commercially available No. 3 water glass (molar ratio 2.94, SiO□: 28
．． 29%, NazO: 9.94%, specific gravity 1.4 (manufactured by melting method) and slaked lime system, and the results are shown in Table 1.

Table-1 Si (h: 0.165 mol/mixed liquid 100cc table-
1, it can be seen that the gelation time is short for No. 3 water glass regardless of the amount of Ca(OH)z.

In addition, the strength is also small (for example, in the case of sample size 3, the consolidated standard sand is about 1.5 kg/cj after 30 days, and about 0.8 kg/cd after being cured in water for one month.

[Experiment-2] Table 2 shows the experimental results for the water glass-cement-alkali agent system.
Shown below.

The water glass used was that of Experiment 1, and caustic soda was used as the alkali agent. The mixing ratio of water glass and alkali agent was determined to be the molar ratio shown in Table-2. SiO□ content is 0.1 per 100cc of mixed liquid (liquid A and liquid B)
It is 65 moles.

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

[Experiment-3] Table 3 shows the experimental results for the water glass-cement or lime sludge-alkaline agent system.

Note that liquid A was a mixed liquid of 25 cc of water glass from Experiment 1, an alkaline agent (caustic soda), and water, and its molar ratio is shown in Table 3. For liquid B, 100 cc of water was mixed with 20 g each of cement or lime, and after standing still for 1 hour, 50 cc of the resulting liquid was taken.

Table-3 Unconfined compressive strength of consolidated standard sand in Table-3 (kg/C!
I+) was 0.8.0 after 3 days, respectively, in the order of sample inhibition.
．． 7, -10.5.1 month 0.5.0.4, -10.
3, which was found to be too weak for injection purposes.

[Experiment-4] Various pozzolans and commercially available water glass with Si, ox/NazO (molar ratio) 2.0 were mixed with slaked lime at Cab/Σ±b
(molar ratio) was added in an amount of 1.0, and the gelation time and consolidation strength of each blended solution were measured. The results are shown in Table 4.

Further, caustic soda was added and mixed to a commercially available water glass having a Sing/Nag◯ (molar ratio') of 2.94, and a gelation experiment was also conducted on a mixed liquid of water glass-pozzolan-slaked lime-caustic soda system. In this case, the molar ratio is 2.0, and SiO
□ is SjO□ caused by water glass, and Na2O is caused by the total amount of alkali and caustic soda in water glass. (Alkali caused by water glass is expressed as Nano, whereas alkali related to the sum of alkali caused by water glass and alkaline agents is expressed as Nano.

) Also, Ca○/SiO□ (molar ratio) was set to 1.0.

In this case, 3i0. is the silica content resulting from water glass and pozzolan. (The silica content caused by water glass is
In contrast, the silica content resulting from water glass and the silica content related to the total silica content resulting from pozzolan is expressed as 1±9. ) In Table 4, the numbers in the upper left column of each column for gelation time and unconfined compressive strength of consolidated standard sand are the measurement results when no alkaline agent is included, and the numbers in the lower right column are the measurement results when an alkali agent is included. shows.

The commercially available water glass with the above molar ratio of 2.94 used in the experiment had SiOx: 28.29%, Nag O: 9
．． 94%, specific gravity 1.4, and was produced by a melting method.

The content (weight %) and particle size of Sing contained in the pozzolan used in the following experiments are shown below.

Silica; 97% (5-10μ), Diatomaceous earth-8% (11μ)
) Fly ash = 55% [44μ or more (25% or less)
, 44 μ or less (75% or more)], acid clay: 69% (2
5μ) / / / , / / / / 2Q From Table 4, when increasing 5iO21 degrees, gelation time becomes shorter when relying only on 5i02 from water glass, but when relying also on SiO□ from pozzolan, It can be seen that a sufficiently long gelation time can be maintained.

Furthermore, it can be seen that in the case of only 5tot from water glass, gelation progresses quickly or is useful for increasing initial strength, while long-term strength increase depends on the Sin of pozzolan. In addition, if there is too much dependence on pozzolan and SiO□ in the water glass becomes too low, both initial strength and long-term strength tend to decrease. It can be seen that in the case of either one alone, a long gelation time, excellent initial strength, and long-term strength cannot be maintained.

In addition, in Table 4, the solidification strength and long-term solidification strength are both high for those whose silica content depends on both water glass and pozzolan. This is because the solidified material forms a stable structure because it maintains its diameter and is not an unstable and small molecule like Sin in water glass.

[Indeed *-53 S i at/ NazO (or S i (h/Naz
O) (molar ratio) was varied and the gelation time and consolidation strength were measured, and the results are shown in Table 5.

Fly ash was used as the pozzolan, and the silica content was 0.1 mol from water glass and 0.1 mol from pozzolan, making the total silica content 0.2 mol per lcc.

In addition, in a formulation with a molar ratio of 2.94.2.5.2.2, only commercially available water glass was used without using an alkaline agent, and in a formulation with a molar ratio of 2.0 to 0.5, the molar ratio was 2. .94 commercially available water glass mixed with caustic soda was used.

Table-5 From Table-5, 1 oz 2 0.2 mol/100 cc of mixed liquid,
It can be seen that long-term strength and long gelation time are obtained when the molar ratio of 5i02/Na2O is 2.5 or less.

[Experiment-6] In the same manner as in Experiment-5, the Cab/Sin (molar ratio) was varied and the consolidation strength was measured. The results are shown in Table-6.

Here, StO□/N a20 (molar ratio) is 1.5
And so.

Table-6 510! : 0.2 mol/100 cc of blended liquid From Table 6, it can be seen that a molar ratio of Cab/soil of 0.2 or more is desirable as it exhibits high consolidation strength.

[Experiment-7] In the same manner as Experiment-5, the molar ratio of CaO/SiO□ was set to 1.
0, S i ox / Na2O molar ratio 2.0, S
The gelation time and consolidation strength were measured by varying the iO2 concentration, and the results are shown in Table 7.

From Table 7, the SiO□ concentration is 0 per 100cc of blended liquid.
．． It can be seen that if the amount is 10 moles or more, high consolidation strength can be obtained, which is desirable.

The gelation time and consolidation strength of the various formulations shown in [Experiment-8] were measured, and the results are shown in Table-8.

Here, water glass with a molar ratio of 2.94 was used, and the molar ratio was adjusted to various molar ratios of 1.0.1.5.2.0 by adding caustic soda. (A? & Write in column) Also, SiO
2 indicates the number of moles in 100 cc of the blended liquid, and the ratio of SiQ□ caused by water glass to 3102 caused by pozzolan is 1:1 (mole ratio).

Table 8 shows that various reactants can be used in combination in the present invention, and that water-soluble polyvalent metal salts react with the water glass-pozzolan system and cause instant condensation, whereas limes are poorly soluble. Therefore, even if an equivalent amount of lime is mixed with the silica content, it does not react immediately, and even after gelation, calcium from the lime supplies Ca ions to the surrounding silica over a long period of time, and during gelation, unreacted silica It can be seen that the particles eventually form calcium silicate, which provides long-term strength.

[Experiment-9] Water glass - Pozzolan (Fryanche) - Alkaline agent (
Caustic soda) - A slaked lime-based liquid with a long gelation time is used as the basic material (liquid A), and a gelling accelerator, strength enhancer, etc. (liquid B) are combined or added to prepare any desired grout. The gelation time was measured for these and the results are shown in the table below.
9.

The basic material (listed in Experiment-2, Table-2) is S
i Ox: 0.2 mol (3i0. from water glass:
0.1 mol, 3i0z from fly ash: 0.1 mol), S i Ox/N a 20: 2.0,
CaO/Sioz: 1.0, gelation time 1
It is 30 minutes.

Table 9 The AB mixed liquid may be mixed in one mixer and injected during actual ground injection, or may be injected even if they are combined. In addition to the B liquid component shown in Table 9, the present invention can also be applied to any other suitable material, such as pozzolan, alkali metal salts, polyvalent metal salts, acidic water glass aqueous solutions, and water glass aqueous solutions with a high molar ratio (for example, 3 to 4 molar ratios). By using a reactant in combination, the gelation time can be adjusted from several seconds to several tens of minutes. Furthermore, the present invention can also be applied to a composite injection in which a rapid gelation accelerator (liquid B) is jointly injected into the basic material (liquid A), and then a basic material with a long gelation time is injected. The injection pipes used for injection are multiple pipes, single pipes, etc., and the present invention uses these injection pipes to perform the double pipe double bunker method, the double pipe Rondo composite injection method, the strainer injection method, and the double pipe instantaneous injection method. It is used in a wide range of injection methods, including construction methods. In addition to ground injection, the present invention also applies to
It is also used for ground improvement by injection mixing with soil, stirring and mixing, etc.

In this case, the consolidation material of the present invention has excellent workability because it starts consolidation after completing mixing with soil and compaction by adjusting the gelation time to be long. [Effects of the Invention] As shown, the consolidation material according to the present invention maintains consolidation strength even when the gelation time is prolonged, and has excellent long-term durability, making it an optimal consolidation material as a chemical solution for ground consolidation.

Claims (3)

[Claims] (1) A consolidation material containing water glass, pozzolan, and lime and having a molar ratio of SiO_2/Me_2O of a mixed system thereof of 2.5 or less. However, SiO_2 is a silica component resulting from water glass, and Me is an alkali metal. (2) The solidified material according to claim 1 further contains an alkaline agent, and a mixed system of SiO_
A consolidation material having a molar ratio of 2/Me_2O of 2.5 or less. (3) In the consolidation material according to claim 1 or 2, the content of lime is such that the molar ratio of lime/SiO_2 is 0.2 or more. , However, SiO_2 is the total amount of silica caused by water glass and pozzolan.