JPH0243790B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a grouting material for the purpose of water stopping or ground reinforcement in soft ground or fractured zones of rock, and particularly to a grouting method using a suspension type grout consisting of a water glass liquid and a cement suspension. In general, chemical solutions based on water glass come in two types: solution type and suspension type. It is used for injection into large sand and gravel layers or the interface between horizontal structures and the ground. Unlike solution-type grouts, suspension-type grouts are mainly injected into clay soil in veins, or injected or filled into relatively large gaps, and are usually cement-based grouts with high consolidation strength. The most commonly used type of cement is LW, which is a combination of cement and water glass.Usually, the water glass liquid and cement suspension are mixed separately, and the water glass liquid and cement suspension are mixed using two pumps. The two liquids are pumped in small quantities, merged between the injection pump and the tip of the injection tube, and injected into the ground or into the void to form a gel. In general, cement-based injection materials are often required to have high initial strength in addition to gel time due to construction purposes and injection methods. For example, it is necessary to inject grout into very soft ground to improve the ground and excavate a tunnel etc. as early as possible.Also, in the case of continuous injection, it is necessary to harden the previously injected grout as soon as possible and then inject later. In order to prevent grout from entering and escaping and keeping it within a limited area, or in the case of backfilling, to solidify to a higher strength than the ground as soon as possible to prevent ground subsidence, etc. It is required that the expression of An object of the present invention is to overcome the above-mentioned drawbacks of LW and provide a grout material that exhibits high initial strength. According to the present invention, when mixing and injecting a suspension containing cement as a main component (liquid A) and an aqueous water glass solution (liquid B), liquids A and B are not mixed in equal amounts. By keeping the volumes of liquid A and liquid B in a proportionate proportion within a certain range, and by controlling the amount of added water glass within an appropriate range, it is possible to obtain a grout material that can increase initial strength. can. The present inventor has been conducting research on the component concentration and other aspects of the cement and water glass used to improve the drawbacks of the LW method described above, and the chemical solution that combines cement suspension and water glass is as follows. I learned that it has a singular characteristic. (1) Even if the total amount of water glass (SiO ₂ ) relative to the total amount of grout is the same, the initial strength of the chemical solution after mixing both A and B will be significantly different due to the difference in B solution, that is, water glass concentration. . In other words, when the total amount of water glass in a chemical solution is a certain constant value, compared to when a low concentration water glass solution is mixed with approximately the same amount of cement suspension, a high concentration of water glass The initial strength is more pronounced when a small amount of liquid is used. In addition, if a low concentration water glass liquid is used within the range described in (2) below, the amount of liquid A (water glass liquid) may be larger than that of liquid A (cement suspension). This is unfavorable, and the water glass concentration is
It is preferably 20% by weight or more in terms of SiO ₂ . (2) Furthermore, the amount of water glass added to the chemical solution is
Volume of liquid components contained in the mixture of both liquids A and B
For 100c.c., the weight of water glass is approximately as SiO ₂
The initial strength tends to be large in the ratio range of 3.5 to 9 g. The inventors of the present invention have studied the above-mentioned unique properties in more detail, found that these unique properties can be applied to actual drug injection, and have completed the invention described in the claims. That is, according to the present invention, a water glass solution (solution B) containing 20% by weight or more of SiO ₂ is used, and an injection chemical solution or grout is prepared by combining this with a cement suspension (solution A). In doing so, a grout with high early strength suitable for practical use can be obtained by proportionally mixing liquids A and B at a ratio within a certain range. Increase the amount of water glass added (a range in which the weight of water glass present is approximately 3.5 g or less as SiO ₂ with respect to the volume of the liquid component contained in the mixture of liquids A and B, 100 c.c.) If SiO ₂ is increased, the early strength decreases even though the SiO 2 content increases, and conversely, even if it is decreased, the early strength decreases, so it was excluded from the scope of the present invention. However, the formulation (type and amount of cement and additives),
Even if the scope of the present invention varies depending on the liquid temperature and other conditions, it can be considered that the scope of the present invention falls within the scope of the present invention if the early strength development is remarkable. In the present invention, early strength refers to within 24 hours after mixing liquids A and B, and the axial compressive strength after at least 2 hours is 0.5 kg or more, and the strength within 24 hours increases by 3 times or more. Refers to the case. The cement suspension used in the present invention includes not only a suspension of cement alone, but also additives that are sometimes added to ordinary grouting agents, such as water slag, fly ash, lime, gypsum, dispersants (retarders), etc. etc.), foaming agents, clay minerals such as bentonite, primary minerals such as finely powdered limestone and rocks, excavation levels and soil collected on site, and other bulking materials may be appropriately added. When the grout according to the present invention is used at a grouting site, a large amount of liquid A and a small amount of liquid B are mixed, so a proportional 1.5 shot method is used instead of the usual equal volume 1.5 shot method. The injection pump used is either a proportional pump (a pump made to have different discharge volumes for liquids A and B) or two pumps with different discharge capacities. Furthermore, the construction method of the present invention has the advantage that on-site mixing is very easy because the amount of the cement suspension in the A component is larger than the water glass aqueous solution in the B component. That is, with respect to the amount of grout (solutions A and B), in the proportional mixing of the present invention, the proportion of solution A is higher than in the conventional equal proportion mixing, so a large amount of cement can be used, and other aggregates can be used. etc. can also be mixed in. The purpose of use of the grout material of the present invention is not particularly limited, but it is mainly used for vein injection into soft ground such as clayey soil (silt, clay) and humus soil, and for ground with relatively many gaps such as sandy gravel layers. seepage injection, injection into fractured zones and cracks in hard ground such as bedrock, water stoppage and grounding in ground with particularly high levels of spring water, such as backfilling, targeting the interface between horizontal structures and the ground. Suitable for strengthening. The injection method of the present invention uses liquid A, which is a cement suspension, and liquid B, which is an aqueous water glass solution.
The water glass concentration in the liquid is 20% by weight or more based on SiO ₂ , and the amount of SiO ₂ is approximately 3.5 to 9 g per 100 c.c. of the volume occupied by the liquid components in the mixture of liquids A and B. Liquids A and B, which were prepared separately in Alternatively, it is an injection method characterized by stirring and mixing with the soil in the ground. The present invention will be explained in more detail below by giving Examples and Comparative Examples. The water glass used in the following examples is JIS No. 3.
_SiO2 : 28-30%, _Na2O : 9-10%), and the _SiO2 contained in the water glass stock solution 1 is about 400g. The cement is commercially available Portland cement. The water glass stock solution was diluted with water to prepare the water glass aqueous solutions used in the following Examples and Comparative Examples as shown in Table 1.

[Table] Next, as shown in Table 2, grout prepared by mixing a water glass aqueous solution as liquid B and a cement suspension as liquid A (Table 2 shows the amount of SiO ₂ in each grout and the gel time for its change). 2) and investigated the state of initial strength development.
Shown in 3.

【table】

【table】

【table】

[Table]
As is clear from the results in Table 3, Comparative Example 1
The conventional LW construction method involves mixing equal amounts of liquid A and liquid B (normally, the amount of water glass is 200 grout as in Comparative Example-1).
50 c.c. per cc) indicates that the initial strength is very weak. In addition, the water glass concentration is 20% by weight based on _SiO2 .
Even with the above, as shown in Comparative Example 2, when the weight of SiO ₂ is about 9 g or more per 100 c.c. of liquid in the blended liquid, early strength development is not observed, and conversely, Comparative Example 2
As shown in Figure 3, it can be seen that no early strength development is observed even when the weight of SiO ₂ is about 3.5 g or less. On the other hand, when the water glass concentration of liquid B is 20% by weight or more based on SiO ₂ as in Examples 1 to 6 of the present invention, liquid B is quantitatively smaller than liquid A; The _amount of SiO2 in the liquid is approximately 3.5 to 9 g per 100 c.c. of the volume occupied by the liquid components in the liquid mixture.
It can be seen that the early strength development is remarkable only in the range of . ``Effects of the Invention'' As described above, according to the present invention, grout with high initial strength can be used in water stopping, ground reinforcement, cavity filling, and other construction methods for soft ground and fractured zones that require high initial strength. This makes it possible to reliably obtain and achieve the desired construction method.

Claims (1)

[Claims] 1 A grout material used to strengthen water sealing in soft ground and fractured zones of rock, consisting of liquid A, which is a cement suspension, and liquid B, which is an aqueous water glass solution, and whose water glass concentration is based on _SiO2 . 20% by weight or more, and the amount of SiO ₂ in liquid B is approximately 3.5 to 9% per 100 c.c. of the volume occupied by the liquid components in the mixture of liquids A and B.
A grout injection method characterized by injecting grout that can obtain early strength development by proportionally mixing liquids A and B in a ratio such that g.