JP2015086326A - Foundation injection material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a foundation injection material with high permeability hardly generating reduction of foundation modification effects by material separation without increasing the amount of a dispersant.SOLUTION: There is provided a foundation injection material consisting of an aqueous slurry of a hydraulic composition having a Blaine specific area of 5000 cm/g or more and containing (A) cement, (B) slag and (C) a dispersant with mass ratio of the cement and the slag (B/A)=1 to 100 and a ratio of total mass of the slag and the cement and mass of the dispersant (solid content conversion) (C/(A+B))=0.0001 to 0.1 where a rate of change of density just after manufacturing (ρ0) and density after 1 hour standing from manufacturing (ρf) by viscosity floating of slurry at 20°C manufactured by adding water to the hydraulic composition at 3.0 times amount, represented by the following formula of 50% or less (including 0). Rate of change (%)=(1-(ρf-1)/(ρO-1)×100.

Description

  The present invention relates to a cement-based ground injecting material used for reforming the ground, bedrock, or the like to be strong or for strengthening the foundation of a construction.

  In order to modify the ground and rocks to be impervious and strong, and to prevent liquefaction, a slurry-like ground injection material containing a hydraulic substance such as cement as a binding component is used. Cement-based ground injection material is a one-component type consisting of an aqueous slurry with all the ingredients added, and a two-component type that mixes a slurry containing cement as an active ingredient and a slurry containing a hardener as an active ingredient at the time of injection. There are things. As a one-agent type cement-based ground injection material, a so-called ultrafine particle-based injection material is known in which the cement and slag are pulverized to reduce the maximum particle size considerably to improve the permeability to the ground. (For example, refer to Patent Document 1.) In addition, in order to improve the permeability at the time of slurry injection, cement clinker pulverized material, slag, gypsum, soluble sulfate, etc. Also known are structured injection materials. (See Patent Document 2.)

  These cement-based soil injection materials can be easily penetrated by miniaturization of the components, but for example, material separation is likely to occur and progress with the elapse of the standing time due to, for example, laying, etc. In some cases, the strength of the injected ground was sluggish, which had an adverse effect on ground improvement. If a dispersant is used, solid particles can be prevented from aggregating, so that solid-liquid separation hardly occurs and material separation resistance can be improved. However, since the dispersed cement particles have a small particle size, the hydration reaction activity is very high, and it is easy to form hydrates at an early stage, solidify before sufficiently penetrating into the ground, etc. The Japanese lump is easily clogged, and conversely, the permeability is lowered. To prevent aggregation of the hydrate itself, if the amount of the dispersant is increased too much, the setting time of the hydraulic substance will be delayed, and it will not stay in the injected ground, but will be easily spilled by groundwater or spring water, etc. However, problems such as insufficient initial strength development occur.

Japanese Patent Laid-Open No. 9-255378 Japanese Patent Laid-Open No. 2004-231884

  In order to increase material separation resistance in a highly permeable cement-based ground injection material, it is effective to increase the blending amount of the dispersant, but there is a problem as described above. An object of the present invention is to solve such a problem, and is a cement-based ground injection material, which has good injection permeability and strength development, and increases the blending amount of the dispersant. Provided is a ground injecting material that does not cause degradation of ground reformability due to material separation.

  As a result of studying to solve the above problems, the present inventor is a hydraulic composition having a specific fineness containing cement, slag and a dispersant, and the density change of water having 3.0 times the mass added thereto. Found that a ground injection material made of an aqueous slurry containing a hydraulic composition that has a specific rate of change can have good injection permeability and strength development, and also has a hindrance to coagulation and curing properties. The present invention was completed because it was possible to prevent deterioration of the ground reforming property due to material separation without blending an amount of a dispersant sufficient to affect.

That is, the present invention relates to (A) cement, (B) slag, and (C) dispersant, mass ratio of cement to slag (B / A) = 1 to 100, and total mass of slag and cement and dispersant mass ( The ratio of the solid component) (C / (A + B)) = 0.0001 to 0.1 is a ground injection material made of an aqueous slurry of a hydraulic composition having a specific surface area of 5000 cm ² / g of branes, Density immediately after production by density levitation of a slurry at 20 ° C. produced by adding 3.0 times the mass (in terms of solid content) of water to the hydraulic composition, and density after standing for 1 hour from production The ground injection material is characterized in that the rate of change expressed by the following formula is 50% or less (including 0).
Rate of change (%) = (1− (ρf−1) / (ρ0−1)) × 100
Here, ρ0: an indication of density buoyancy immediately after slurry production, ρf: an indication of density buoyancy after standing for 1 hour in slurry production.

  Moreover, this invention consists of an aqueous | water-based slurry whose solid content concentration of a hydraulic composition is 3.2-40 mass%, It is the said ground injection material characterized by the above-mentioned.

  According to the present invention, it is possible to always stably obtain a ground injection material that has at least infusion permeability and strength development that are not inferior to those of conventional ones, and sufficiently prevents a decrease in ground modification effect due to material separation. Therefore, it can be easily modified to a solid ground or bedrock. Furthermore, since the ground injecting material of the present invention can suppress the water permeability of the injected ground and has a water-stopping action, it can be sufficiently applied to liquefaction countermeasures and water-stopping work.

The ground injection material of the present invention is an aqueous slurry of a hydraulic composition containing cement, slag, and a dispersant in a specific ratio. The cement used for the hydraulic composition may be any hydraulic cement. Specifically, there are various portland cements such as normal, early strength, super early strength, moderate heat, low heat, mixed cements such as fly ash cement and silica cement, white cement, special cements such as alumina cement and eco-cement. 2 or more may be used in combination. Preferably ordinary or early strength Portland cement is used. In addition, when using alumina cement, it is desirable to use it together with any Portland cement to adjust the rapid hardening. When using blast furnace cement, it is necessary to consider the amount of slag in the blast furnace cement as the amount of slag in the ground injection material. Further, in order to improve the injection permeability, a cement having a Blaine specific surface area of 5000 cm ² / g or more is preferably used. More preferably to use a cement of 7000cm ² / g~20000cm ² / g in Blaine specific surface area. The above is the recommended fineness of the cement used, and does not preclude the use or mixing of cement particles having a specific surface area of less than 5000 cm ² / g.

The slag used in the hydraulic composition specifically includes, for example, iron ore such as blast furnace slag, steelmaking slag, converter slag, desiliconized slag, etc. that is generated in the metal material manufacturing process. It is not limited to the posting example. It is desirable to avoid the use of molten slag, etc. originating from waste such as sewage sludge, municipal waste, and paper sludge, when the possibility of concentration of harmful substances cannot be eliminated. Preferably, slag with a high vitrification rate is good because initial strength development is high, and for example, blast furnace granulated slag is suitable. The ground can be strongly modified by the latent hydraulic behavior of the slag, and the injection material can be solidified early during injection to block the infiltration path and prevent the permeability from decreasing. The smaller the particle size of the slag, the easier it is to pass between the fine particles of the ground and the higher the reaction activity. The slag contained is preferably 5000 cm ² / g or more in terms of the specific surface area of Blaine. More preferably from 7000cm ² / g~20000cm ² / g in Blaine specific surface area. The above is the recommended fineness of the used slag, and does not prohibit the use or mixing of slag particles having a brain specific surface area of less than 5000 cm ² / g. When slag is contained and used, clogging due to consolidation in the slurry infiltration path in the ground or rock and clogging in the injection pipe and transport pipe can be suppressed without delaying the setting time. The slag content in the aqueous slurry is 1 to 100 parts by mass with respect to 1 part by mass of the cement content. Preferably it is 1.5-50 mass parts. If the amount is less than 1 part by mass, the permeability may be remarkably lowered, and if it exceeds 100 parts by mass, the initial strength is lowered, which is not preferred.

  Moreover, the dispersing agent contained and used in the hydraulic composition may be any as long as it can be used in a cement-based hydraulic composition such as mortar or concrete, and is not particularly limited. Moreover, what is called a water reducing agent, a high performance water reducing agent, a high performance AE water reducing agent, an AE water reducing agent, a fluidizing agent, or the like can also be used as a dispersant, and it may be liquid or powdered. By using a dispersant, aggregation of fine cement particles and slag particles can be suppressed, and clogging due to formation of aggregates does not occur even in fine ground or rock gaps. Content of a dispersing agent shall be 0.0001-0.1 mass part with respect to 1 mass part of total contents of cement and slag in conversion of a solid part. Preferably it is 0.001-0.05 mass part. If it is less than 0.0001 part by mass, the inclusion effect cannot be obtained and the permeability is lowered, which is not preferable. On the other hand, if the amount exceeds 0.1 parts by mass, there is a possibility of causing a setting delay or poor curing, which is not preferable because the cold of the injection material or sufficient reforming strength may not be obtained.

  In addition, the hydraulic composition may contain components other than cement, slag, and a dispersant, as long as the effects of the present invention are not substantially lost. In the case of solid particles in which such a component does not substantially dissolve in the aqueous slurry, it is easy to ensure high permeability by using a grain having a specific surface area that is approximately the same as or higher than that of the cement to be used. Examples of components that can be included include setting accelerators, thickeners, pozzolanic reactive materials, rapid hardening agents, gypsum, and bulking agents that can be used in cement-based hydraulic compositions such as mortar and concrete. It is not limited to the posting example.

The hydraulic composition has a specific surface area of 5000 cm ² / g or more for providing high injection permeability. Preferably the Blaine specific surface area of 7000cm ² / g~20000cm ² / g. When the hydraulic composition contains a liquid admixture such as particles or a liquid water reducing agent that are substantially dissolved during the preparation of the aqueous slurry, the hydraulic composition has a brain specific surface area with respect to the entire contained particles excluding these. Specific surface area. Therefore, it is not necessary that all the contained particles are particles having a Blaine specific surface area of 5000 cm ² / g or more. In the case of a hydraulic composition having a specific surface area of less than 5000 cm ² / g, the ground injection material obtained by forming an aqueous slurry is not preferable because it becomes difficult to inject into a low-permeability ground or rock having a narrow particle gap.

  The ground injection material of the present invention is an aqueous slurry of the hydraulic composition. The amount of water to be added to the hydraulic composition required for aqueous slurrying can be appropriately determined according to the construction conditions such as desired reforming properties and the state of the target ground. Preferably, 150 to 3000 parts by mass of water is added to 100 parts by mass of the hydraulic composition in order to easily obtain a workability suitable for injection into the ground or the like and good strength development. That is, it is set as the aqueous slurry whose slurry density | concentration of a hydraulic composition is 3.2-40 mass%. More preferably, an aqueous slurry having a slurry concentration of 4.7 to 33% by mass is used. Here, for example, when liquid admixtures are used for the hydraulic composition, the slurry concentration of the hydraulic composition is the concentration of the liquid admixture containing the solid component equivalent mass. Does not include the mass of the solvent after subtracting the mass equivalent mass. In addition, if the mass of the solvent component is approximately 1% or less of the mass of water to be added, the amount of added water is not substantially hindered even if the mass of the solvent component is not considered, but approximately 1%. When it exceeds, it is desirable to consider the mass of the solvent, and the mass of water added to the hydraulic composition is a value obtained by subtracting the mass of the solvent. An aqueous slurry in which the solid content concentration of the hydraulic composition exceeds 40% by mass is too low in fluidity, which may cause trouble in smoothly transporting the slurry to the injection apparatus, and may be difficult to inject uniformly. Therefore, an aqueous slurry having a solid content concentration of less than 3.2% by mass of the hydraulic composition has high ground permeability but may not have sufficient modified strength. is not.

In addition, the ground injection material of the present invention is a 20% hydrolyzed slurry immediately after slurry preparation, which is prepared by adding 3.0 times the mass (in terms of solid content) of water to the hydraulic composition. It is a ground injection material that requires that the change rate represented by the following formula of the density measured in step 1 and the density measured by density floating after standing for 1 hour after slurry preparation be 50% or less (including 0). . Preferably, the rate of change based on the following formula is 30% or less (including 0).
Rate of change (%) = (1− (ρf−1) / (ρ0−1)) × 100
Here, ρ0: an indication of density buoyancy immediately after slurry production, ρf: an indication of density buoyancy after standing for 1 hour in slurry production.

  The density float used is number 3 as defined in Table 3 of Annex 4 (normative) specific gravity float of JIS B 7525; 1997 density float. When the rate of change in density buoyancy based on the above formula is within 50%, material separation is difficult to proceed, and even if material separation occurs, ground improvement such as injection permeability and improved strength can be achieved. The ground injection material can be obtained without affecting the quality. In addition, if the rate of change exceeds 50%, material separation is likely to proceed, and it becomes a ground injecting agent with an uneven concentration in an inhomogeneous state, making it difficult to stably perform desired ground reforming. This is not preferable. Since this rate of change greatly depends on the component composition of the hydraulic composition, the selection of the effective component of the ground injection material and determination of the blending composition that can have high strength development and good permeability even when material separation occurs. Is necessary. In the present invention, in order to achieve the density change rate due to such floating, by adjusting the blending ratio of each component contained in the hydraulic composition within the above-mentioned content range, it has a more optimal ground reforming action. A ground injection material is obtained. Preferably, a ground injection material having a more optimal ground reforming action can be found for a ground injection material composed of an aqueous slurry having a slurry concentration of 3.2 to 40% by mass. Further, the ground injection material of the present invention is a one-agent type ground injection material, that is, a ground injection material suitable for a so-called one-shot type injection method, but a 1.5-shot or two-shot type method is used. It can also be used as a material.

  An example of a specific procedure for determining the rate of change in density buoyancy is as follows: the mass of the hydraulic composition used is measured, and the hydraulic composition is used as a liquid dispersant or other liquid formulation. When it contains, these mass correct | amends measured mass using the mass converted into the solid part. Next, water having a mass 3.0 times the mass of the hydraulic composition corrected as necessary is added and mixed using, for example, a commercially available high-speed grout mixer to prepare an aqueous slurry kept at a constant temperature of 20 ° C. . This slurry temperature is maintained until the subsequent density measurement. The allowable range of temperature error should be within ± 1 ° C as much as possible. Moreover, although mixing time is based on the amount of mixing and the capability of a mixing apparatus, it will be about 1-2 minutes in general. The obtained slurry is immediately put into about 2 liters of about 1000 ml graduated cylinders, and one of them immediately measures its reading (ρ0) using the recommended density float. The reading is the value of the density scale of the used hail. Moreover, the aqueous slurry put in another measuring cylinder is left still in the room | chamber temperature adjusted to 20 degreeC, and the reading ((rho) f) by density floating is similarly measured after 1 hour progress. The rate of change (%) is calculated from these two readings using the above formula. Although the above is a recommended example, it is not limited to this.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to the described Example.

[Preparation of hydraulic composition]
A material selected from A1 to D2 shown below was used to prepare a hydraulic composition having a blending amount shown in Table 1 (where C1 is a solid component equivalent mass). At the time of production, materials other than the liquid dispersant (C1) were put in a Henschel mixer and mixed together, and the liquid dispersant was added together with water when preparing an aqueous slurry to be described later. In addition, the specific surface area of the hydraulic composition excluding C1, C2, and D2, which are liquid materials and water-soluble materials, was measured using a brain air permeation device based on the provisions of JIS R5201. The results are also shown in Table 1.
A1: normal Portland cement (fineness: 3200 cm ² / g, manufactured by Taiheiyo Cement)
A2: Ordinary Portland cement (fineness: 7500 cm ² / g, manufactured by Taiheiyo Cement)
A3: Ordinary Portland cement (fineness: 9200 cm ² / g, manufactured by Taiheiyo Cement)
B1; granulated blast furnace slag (fineness: 4100 cm ² / g, commercially available)
B2: Granulated blast furnace slag (fineness: 7200 cm ² / g, commercially available)
B3; granulated blast furnace slag (fineness: 9000 cm ² / g, commercially available)
C1: Liquid dispersant containing naphthalenesulfonic acid formalin condensate as an active ingredient (solid component concentration 40% by mass, commercially available product)
C2: Powder dispersant containing polycarboxylic acid as an active ingredient ("Core Flow NF-100" manufactured by Taiheiyo Materials Co., Ltd.)
D1; type II anhydrous gypsum (fineness: 7200 cm ² / g, commercially available product)
D2; soluble sulfate (sodium sulfate; commercially available reagent)

[Measurement of slurry density of hydraulic composition by floating]
To 100 parts by mass of the hydraulic composition, 300 parts by mass of 20 ° C. water was added and mixed with a hand mixer for about 90 seconds to obtain a slurry. Immediately transfer 1 liter of the obtained slurry to a measuring cylinder of 1 liter in capacity, and JIS B 7525; 1997 density levitation appendix 4 (normative) specific gravity levitation range of 1.000 to 1.200 Was floated on the slurry in the graduated cylinder and the density was measured. The scale of levitation measured as this density was taken as an indication immediately after slurry production; ρ0. Similarly, 1 liter of the obtained slurry was immediately transferred to a graduated cylinder having a capacity of 1 liter, and allowed to stand in a constant temperature room at 20 ° C., and the slurry density after 1 hour was measured using the same float. . The scale of buoyancy measured as the density here was indicated as the reading after 1 hour of slurry preparation; ρf. From the value of each reading, the change rate of the slurry density at 20 ° C. in 1 hour was obtained by the following equation.
Rate of change (%) = (1− (ρf−1) / (ρ0−1)) × 100
Table 2 shows each reading and the calculated rate of change.

[Evaluation on the permeability of slurry and the strength of simulated ground]
A cylindrical polyethylene pipe having an inner diameter of 50 mm and a height of 500 mm having a bottom surface provided with about 100 random deaeration holes having a diameter of about 0.5 mm is vertically installed so that the bottom surface is in contact with the ground. No. 6 silica sand was poured into the tube to a height of 150 mm to prepare a simulated ground. On the simulated ground, 200 ml of the slurry in the graduated cylinder of the slurry whose density was measured after 1 hour from the preparation of the slurry was carefully collected from the upper surface, and this was gently poured into the simulated ground from the upper surface. After leaving it in a constant temperature room at 20 ° C. for 7 days, a cured portion (cured product) in the polyethylene pipe was taken out, and its length was measured to obtain a slurry penetration length. The cured product was processed into a cylindrical shape having a diameter of 50 mm and a length of 100 mm to obtain a specimen. The uniaxial compressive strength at the age of 28 days of this specimen was measured according to the “soil uniaxial compressive test method” defined in JIS A1216. Table 3 shows the slurry penetration length and the uniaxial compressive strength value of the cured product. Also, if the slurry penetration length is 100 mm or more and the uniaxial compressive strength is 1 N / mm ² or more, it is judged that the ground reforming effect is good. The quality effect was judged to be poor. Those evaluated as good are marked with ◯, particularly excellent among them are marked with ◎, and those judged as defective are marked with ×, and the evaluation results are also shown in Table 2.

[Evaluation of slurry concentration and permeability]
Hydraulic composition No. 1 in Table 1 1 and no. With respect to 9, water at 20 ° C. was added so as to achieve the slurry concentration shown in Table 3, and mixed with a hand mixer for about 90 seconds to prepare an aqueous slurry. 1 liter of the aqueous slurry obtained was immediately transferred to a graduated cylinder having a capacity of 1 liter, and allowed to stand in a constant temperature room at 20 ° C. for 1 hour. Next, the upper 200 ml of the slurry in the graduated cylinder was carefully collected from the upper surface, and this was gently poured into the simulated ground from the upper surface. After leaving it in a constant temperature room at 20 ° C. for 7 days, a cured portion (cured product) in the polyethylene pipe was taken out, and its length was measured to obtain a slurry penetration length. Further, the cured product was processed into a cylindrical shape having a diameter of 50 mm and a length of 100 mm to obtain a specimen, and the uniaxial compressive strength at the age of 28 days was measured by the same method as described above. Table 3 shows the above results and the evaluation results of the ground improvement effect determined based on the same criteria as described above.

  As a result of visual observation, after 1 hour of standing after slurry production, the slurry of any hydraulic composition (excluding No. 23) can be generally discriminated from the sediment and the supernatant liquid although there is a difference in degree, Some material separation was observed. However, it can be seen from the results in Table 2 that all of the ground injection material of the present invention penetrates to the simulated ground end (penetration length 15 cm) and easily penetrates to a deep place. Moreover, the uniaxial compressive strength of the hardened | cured material of the osmosis | permeation part is also comparatively high, and it turns out that a strong hardened | cured material is formed and it has the outstanding ground modification property. On the other hand, many ground injection materials made of an aqueous slurry of a hydraulic composition outside the present invention cannot penetrate to the end of the simulated ground. It became a thing. In addition, hydraulic composition No. Although the slurry of No. 23 could easily penetrate to the bottom of the simulated ground, it did not harden at all, so the simulated ground could not be hardened. Furthermore, it can be seen from the results in Table 3 that the ground injection material of the present invention can stably obtain good permeability and modified strength even when the slurry concentration is changed according to the construction environment of the target ground or the like.

Claims (2)

(A) Cement, (B) slag, and (C) dispersing agent, the mass ratio of cement and slag (B / A) = 1 to 100, and the total mass of slag and cement and the mass of dispersing agent (in terms of solid content) A ground injecting material comprising an aqueous slurry of a hydraulic composition having a specific surface area of 5000 cm ² / g of Blaine contained in a ratio (C / (A + B)) = 0.0001 to 0.1, The change expressed by the following equation of the density immediately after production by density levitation of the slurry at 20 ° C. produced by adding 3.0 times the amount of water (in terms of solid content) and the density after standing for 1 hour from production. A ground injection material characterized in that the rate is 50% or less (including 0).
Rate of change (%) = (1− (ρf−1) / (ρ0−1)) × 100
Here, ρ0: an indication of density buoyancy immediately after slurry production, ρf: an indication of density buoyancy after standing for 1 hour in slurry production. The ground injection material according to claim 1, wherein the hydraulic composition is an aqueous slurry having a solid component concentration of 3.2 to 40% by mass.