Ground grouting material and ground improvement method

Abstract

To provide a grouting material that achieves improved soil with high durability, without the need for adding colloidal silicas.SOLUTION: A grouting material includes the combination of a basis containing water glass and a curing agent. The basis and the curing agent are mixed and gelled. One hour after, the flock of the gelled body has a porod volume of 4000 nm3 or less, the floc having a radius of gyration of 9.5 nm or less.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a ground grouting material and a ground improvement method. [Background technology]

[0002] A chemical injection method in which a chemical solution is injected into the ground is used to improve soft ground and stop water leakage (see, for example, Patent Document 1). This method achieves an improvement effect by solidifying the ground by gelling in the ground containing silica, so the strength and long-term durability of the improved body are affected by the physical properties of the gel.

[0003] It is said that in order to obtain a highly durable gel, it is necessary to either suppress the amount of silica eluted from the gel (silica leaching rate) or suppress the shrinkage of the gel. Previous technology had been able to obtain a gel with no silica leaching and little shrinkage by adding colloidal silica particles, but this required the addition of colloidal silica to the water glass and hardener. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4517050 Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, compared to a combination of only water glass and a hardener, more installation space is required, and an additional process of adding colloidal silica is required, which increases the amount of work and further leads to increased costs.

[0006] The present invention has been made to solve the above problems, and an object of the present invention is to provide a ground grouting material which can provide an improved ground with good durability without the addition of colloidal silica. [Means for solving the problem]

[0007] The present inventors have conducted intensive research to solve the above problems, and by performing small-angle X-ray scattering measurement and analysis of the gel, they have calculated the porod volume, which corresponds to the volume of the aggregates that constitute the gel, and the radius of gyration of the particles formed by the aggregation of primary particles, and have investigated how these affect the leaching of silica and the shrinkage of the gel, and have investigated the radius of gyration at which the amount of leaching of silica is small and the porod volume at which the shrinkage of the gel is small.Then, they found that the above problems can be solved by controlling the radius of gyration and the porod volume of the gel without adding colloidal silica, and have completed the present invention.That is, the present invention is as follows.

[0008] [1] A ground grouting material consisting of a combination of a base agent containing water glass and a hardener, The base material and the curing agent are mixed, and one hour after gelation, the porosity of the aggregated particles constituting the gel is 4000 nm 3 The grouting material has a radius of gyration of 9.5 nm or less and the agglomerated particles have a radius of gyration of 9.5 nm or less. A ground injection material consisting of a combination of a base agent containing water glass and a hardener, The base material and the curing agent are mixed, and one hour after gelation, the porosity of the aggregated particles constituting the gel is 4000 nm 3 The grouting material has a radius of gyration of the aggregate particles of 9.5 nm or less. A ground injection material consisting of a combination of a base agent containing water glass and a hardener, The base material and the curing agent are mixed, and one hour after gelation, the porosity of the aggregated particles constituting the gel is 4000 nm 3 The grouting material has a radius of gyration of the aggregate particles of 9.5 nm or less. A ground injection material consisting of a combination of a base agent containing water glass and a hardener, The base material and the curing agent are mixed, and one hour after gelation, the porosity of the aggregated particles constituting the gel is 4000 nm 3 The grouting material has a radius of gyration of the aggregate particles of 9.5 nm or less. [2] The molar ratio of sodium oxide to silicon dioxide in the water glass (SiO 2 / Na 2 The ground grouting material according to [1], wherein O) is 2.6 to 5. [3] A ground grouting material according to [1] or [2], in which the amount of water immediately after mixing the base agent and the hardener and gelling is 55 mass% or more. [4] The ground grouting material according to any one of [1] to [3], wherein the silica concentration immediately after mixing the base agent and the hardener and gelling is 5 to 25 mass %. Effect of the Invention

[0009] According to the present invention, it is possible to provide a ground grouting material which can provide an improved ground having good durability without the addition of colloidal silica. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The ground grouting material according to one embodiment of the present invention (this embodiment) is a combination of a base agent containing water glass and a hardening agent. These are separated so as not to be mixed together until they are used as a ground grouting material.

[0011] The base material and the hardener were mixed, and one hour after gelation, the porosity of the aggregated particles constituting the gel was 4000 nm 3 The radius of gyration of the aggregated particles is 9.5 nm or less. In this specification, "gelation" refers to a state in which the fluidity is lost and the material becomes solid enough that it does not collapse under its own weight.

[0012] Porod volume is 4000nm 3 If the volume exceeds 100, the amount of water released due to the shrinkage of the gel, i.e., the amount of water released becomes large, and it becomes difficult to obtain an improved ground with good durability. 3 It is preferable that the wavelength is 600 to 3900 nm. 3 It is more preferable that:

[0013] If the radius of gyration of the aggregated particles exceeds 9.5 nm, the leaching rate of silica increases, making it impossible to obtain an improved ground with good durability.The radius of gyration is preferably 7.0 to 9.5 nm, and more preferably 8.0 to 9.3 nm.

[0014] The porod volume and radius of gyration can be controlled by adjusting the amount of water after mixing the base agent and hardener. For example, the porod volume and radius of gyration tend to decrease as the amount of water increases. In addition to the above, the molar ratio of sodium oxide to silicon dioxide in the water glass (SiO 2 / Na 2 O) can also be appropriately adjusted to control the Porod volume and radius of gyration.

[0015] The Porod volume and radius of gyration can be found as follows: A base agent containing water glass is mixed with a hardener to prepare a ground grouting material, and small-angle X-ray scattering (SAXS) measurements are performed one hour after gelation. For small-angle X-ray scattering measurements, for example, an X-ray diffraction device SmartLab manufactured by Rigaku Corporation can be used. The X-ray source used here is CuKα radiation (λ = 0.15418 nm), and the radius of gyration (Guinier radius) and Porod volume are calculated from the measured SAXS profile. The radius of gyration is the radius of the rotation of a particle obtained by applying the following formula (1) to the scattering profile in the low angle region, and is also called the Guinier radius.

[0016]

number

[0017] In the region where the scattering vector q = 4πsinθ / λ is sufficiently small, it can be applied regardless of the shape of the scatterer as long as the particle is uniform. Here, θ is the scattering angle, λ is the wavelength of the X-ray, I(q) is the scattering intensity at q, and I(0) is q = 0 nm. -1 The extrapolated value of the scattering intensity at g : is the radius of gyration of the particle.

[0018] Porod volume V p is the volume of the scatterer obtained by applying the following equation (2) to the scattering profile in a wide angle region.

[0019]

number

[0020] For actual analysis, programs such as AUTORG, DATPOROD, Dammif, or SasView and SASfit of the analysis software ATSAS can be used. The analysis range is radius of rotation q = 0.1 to 0.4 nm. -1 and the Porod volume is q = 0.1 to 4.8 nm -1 Let us assume that.

[0021] The amount of water immediately after the base agent and the hardener are mixed and gelled is preferably 55% by mass or more. When the amount of water is 55% by mass or more, it becomes easier to control the poroden volume and the radius of rotation within a predetermined range. The amount of water is more preferably 55 to 90% by mass. The amount of water can be determined by the method described in the Examples.

[0022] The silica concentration immediately after mixing the base agent and the curing agent and gelling is preferably 5 to 25% by mass, more preferably 6 to 24% by mass. By having a silica concentration of 5 to 25% by mass, water-stopping properties and practical strength as a ground improvement material can be obtained. The silica concentration can be determined by the method described in the examples.

[0023] The base resin and the curing agent will be described below. (Main ingredient) The base agent contains water glass, and from the viewpoints of preventing overflow in the ground and providing good permeability, it is preferable that the viscosity at 20° C. is 40 to 2000 mPa·s. The water glass according to this embodiment is an aqueous solution of an alkali silicate, specifically, an aqueous solution of sodium silicate or potassium silicate, and is preferably an aqueous solution of sodium silicate.

[0024] The viscosity of the base resin at 20°C is more preferably 40 to 1000 mPa·s, and even more preferably 50 to 500 mPa·s. The viscosity at 20°C can be measured with a tuning fork type vibration viscometer or a rotational viscometer (B type viscometer). The above viscosity is determined based on the molar ratio (SiO 2 / Na 2 O) or by diluting with water or the like. The viscosity can be adjusted to a desired range by adjusting the heating temperature and heating time when the silica source and the sodium source are finally heated and dissolved and reacted. For example, the viscosity increases as the heating temperature increases and the heating time increases.

[0025] When the water glass is sodium silicate, the molar ratio of sodium oxide to silicon dioxide (SiO 2 / Na 2 O) is preferably 2.6 to 5, and more preferably 2.9 to 4. When the molar ratio is 2.6 to 5, the initial strength can be further improved. As such water glass, No. 3 sodium silicate (No. 3 water glass) specified in the JIS standard (JIS-K-1408) or blended in accordance with the JIS standard, or sodium silicate having a molar ratio exceeding that is preferred, and for example, No. 4 sodium silicate (No. 4 water glass) and No. 5 sodium silicate (No. 5 water glass) sold by Fuji Chemical Co., Ltd. are preferred. The molar ratio of sodium oxide to silicon dioxide may be expressed as MR.

[0026] In particular, in this embodiment, the above molar ratio (SiO 2 / Na 2 When the porod volume is 2.6-5 and the amount of water is in the range of 55-90 mass%, the porod volume of the aggregated particles does not become too large and the radius of rotation of the aggregated particles can be made small. In other words, a highly durable grouting material with little silica leaching and little shrinkage is obtained. If the porod volume is too large, the primary particles of silica are densely packed in the aggregated particles, so although the aggregated particles themselves are dense, the overall state is sparse. For this reason, it is thought that when the porod volume is large, the volume shrinkage is large.

[0027] The solid content of the water glass is preferably 20 to 60 mass%, and more preferably 25 to 50 mass%. A solid content of 20 to 60 mass% allows high strength to be obtained. The solid content of the water glass is the solid content (solid component) remaining after removing volatile substances such as water and solvents from the water glass in the form of an aqueous solution, and this solid component substantially corresponds to a silicate compound such as sodium silicate, and can be calculated by the formula: solid content (%) = [mass after drying (g) / mass before drying (g)] x 100.

[0028] (hardening agent) The hardener includes at least one of an inorganic salt and an acid-releasing organic compound. These are preferably combined with the base agent in the form of an aqueous solution or in the form of an aqueous solution mixed with a thickener, for example. Examples of inorganic salts include carbonates such as sodium hydrogen carbonate, sodium carbonate, and potassium carbonate, and sulfates such as sodium sulfate and aluminum sulfate, with sodium hydrogen carbonate being preferred.

[0029] Examples of the acid-releasing organic compound include alkylene carbonates such as ethylene carbonate and propylene carbonate, water-soluble aldehyde compounds such as glyoxal, cyclic lactones such as γ-butyrolactone, dicarboxylic acid alkyl esters such as dimethyl succinate, and acetylated alkylene glycols such as ethylene glycol diacetate, with alkylene carbonates and water-soluble aldehyde compounds being preferred.

[0030] For example, ethylene carbonate, an alkylene carbonate, is converted to ethylene glycol and carbonic acid (H 2 CO 3 ) and the carbon dioxide (CO 3 2- ) and Na in the base water glass +It is believed that the reaction of the silica with the water glass causes the silica to polymerize, resulting in better strength. In addition, it is believed that high-concentration (high-silica concentration) water glass has a large amount of silica, and therefore the skeletal structure grows relatively when gelled, resulting in high strength. From this viewpoint, the acid-releasing organic compound is preferably an alkylene carbonate, and more preferably ethylene carbonate.

[0031] The content of the inorganic salt or the acid-releasing organic compound in the hardener is preferably from 1 to 99% by mass, and more preferably from 10 to 30% by mass, from the viewpoints of setting speed and strength.

[0032] It is preferable that the curing agent does not contain an isocyanate compound. The isocyanate compound is an isocyanate used in an injection material using an isocyanate, such as diphenylmethane-4,4'-diisocyanate (MDI), polymeric MDI (C-MDI), tolylene diisocyanate (TDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), xylylene diisocyanate (XDI), etc. Not containing an isocyanate compound can improve the safety of handling.

[0033] As described above, the aqueous solution of the curing agent preferably further contains a thickener. By containing the thickener, the viscosity at 20°C is preferably in the range of 40 to 2000 mPa·s, and more preferably 50 to 500 mPa·s. The viscosity at 20°C can be measured with a tuning fork type vibration viscometer. Examples of thickeners include acrylic-based thickeners, starch-based thickeners, vinyl-based thickeners, cellulose-based thickeners, gum-based thickeners, and inorganic-based thickeners. At least one of cellulose-based thickeners, gum-based thickeners, and inorganic-based thickeners is preferable, and cellulose-based thickeners are more preferable.

[0034] Examples of the cellulose-based thickener include carboxymethyl cellulose, methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl methyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and cellulose nanofiber. Examples of gum thickeners include guar gum and leucanthemum gum. Examples of inorganic thickeners include bentonite, kaolinite, sepiolite, talc, and silica fume.

[0035] The ground grouting material according to this embodiment is preferably combined so that the ratio of the viscosity of the base agent to the viscosity of the hardener (viscosity of the hardener / viscosity of the base agent) is 0.1 to 10, and more preferably 0.1 to 3. By combining the base agent and hardener in such a ratio of 0.1 to 10, the respective effects are easily exerted, and a practical gel time and high initial strength can be more efficiently obtained.

[0036] The base agent and the hardener are mixed when used and introduced into the ground, bedrock, etc. by injection or pouring, etc., to cause a good reaction and hardening. From the viewpoint of a good reaction and hardening, the mixing mass ratio of these is preferably base agent:hardener=1:0.5 to 1:3, and more preferably 1:0.5 to 1:1.

[0037] The ground improvement method using the ground grouting material according to this embodiment can employ, for example, a method in which the ground grouting material (i.e., the base agent and hardener) is injected into the ground using a 1.5 shot method or a 2 shot method.

[0038] The 1.5 shot method is a method in which the base agent and hardener are mixed by collision near the entrance of the injection tube and the mixture is injected, while the 2 shot method is a method in which the base agent and hardener are fed separately through an injection tube consisting of a double tube, mixed by collision at the tip of the injection tube, and then discharged. Compared to the 1 shot method in which the base agent and hardener are mixed in advance and the mixture is injected, this method allows for faster hardening and higher strength. EXAMPLES

[0039] The present invention will be described in more detail below using examples and comparative examples. However, the present invention is not limited to the following examples as long as it does not deviate from the gist of the present invention.

[0040] [Materials used] Water glass: Water glass manufactured by Fuji Chemical Co., Ltd. Acid-releasing organic compound: Ethylene carbonate manufactured by Toagosei Co., Ltd. Sodium bicarbonate: Reagent manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Water: Tap water

[0041] [Preparation of base agent] The molar ratio of sodium oxide to silicon dioxide in water glass (SiO 2 / Na 2 The viscosity at 20°C was adjusted by adjusting the raw material composition and the heating temperature and heating time when the raw materials were heated and dissolved to prepare a base material containing water glass with MR = 1.4 (viscosity at 20°C: 280 mPa s), a base material containing water glass with MR = 2.1 (viscosity at 20°C: 460 mPa s), and a base material containing water glass with MR = 3.1 (viscosity at 20°C: 190 mPa s). The viscosity of the base resin (20° C.) was measured using a tuning fork type vibration viscometer.

[0042] [Preparation of hardener] (1) Sodium bicarbonate hardener Sodium bicarbonate was mixed with water to create a sodium bicarbonate-based hardener. (2) Ethylene carbonate-based hardener Ethylene carbonate was mixed with water to prepare an ethylene carbonate-based hardener.

[0043] [Preparation of ground grouting material] The base agent and hardener were mixed to obtain the composition (by mass) shown in Table 1 below, and a ground grouting material was prepared with the amount of water and silica concentration immediately after gelation shown in Table 2 below.

[0044] [Table 1]

[0045] The amount of water and the silica concentration were determined as follows. (amount of water) The amount of water was calculated by dividing the amount of water in the ground injection material (the amount of water contained in the water glass plus the amount of water added) by the total weight of the ground injection material. [Amount of water in water glass (mass%) / 100 x amount of water glass (g) + amount of added water (g)] / [Mass of ground grouting material (g)] x 100 = [Amount of water (mass%)]

[0046] (Silica concentration) The silica concentration was determined by calculating the silica concentration in the ground grout material after mixing with the hardener from the silica concentration contained in the water glass. [Silica concentration in water glass (mass%) / 100 × water glass weight (g)] / [Weight of ground grouting material (g)] × 100 = [Silica concentration in ground grouting material (mass%)]

[0047] For each grouting material, the amount of water released, the silica leaching rate, the porosity volume of the aggregated particles that constituted the gel-like body one hour after gelation, and the radius of rotation of the aggregated particles were determined as follows. The results are shown in Table 1. (Water volume removed) The amount of water released was determined by measuring the weight of water released from the gel after one day of sealed curing. (Silica leaching rate) The silica leaching rate was calculated by suction filtering the above-mentioned degassed water through a 0.45 μm membrane filter, measuring it using ICP-AES to determine the silica concentration in the degassed water, and calculating the silica concentration in the ground injection material and the silica concentration in the degassed water from the formula [silica concentration in degassed water / silica concentration in ground injection material]. (Porod volume and radius of gyration) The poroduction volume of the aggregated particles constituting the gel-like material one hour after gelation and the radius of gyration of the aggregated particles were determined by the method described above using an X-ray diffractometer SmartLab manufactured by Rigaku Corporation.

[0048] The durability of each prepared grouting material was tested as follows. The results are shown in Table 1. (Durability test) The volume of the gel at 28 days after sealing and curing was measured and compared with the volume immediately after gelation to calculate the volume reduction rate ((1 - gel volume at 28 days / volume immediately after gelation) x 100 (volume)).

[0049] [Table 2] [Industrial Applicability]

[0050] INDUSTRIAL APPLICABILITY The present invention can be suitably used in the fields of civil engineering and construction, in particular for filling cavities at the back of various tunnels, backfilling such as filling cavities in civil engineering structures, lightweight embankments, landfills, and the like.

Claims

1. A method for improving ground using a ground injection material comprising a combination of a base agent containing water glass and a hardener, The curing agent includes at least one of an inorganic salt and an acid-releasing organic compound, The base material and the curing agent are mixed, and one hour after the gelation, the porod volume of the aggregated particles constituting the gel-like body and the radius of gyration of the aggregated particles are measured; The method for improving ground comprises mixing the base agent and the hardener, and adjusting the poroduction volume of the aggregated particles constituting the gel-like body one hour after gelation to 4000 nm 3 or less and the radius of gyration of the aggregated particles to 9.5 nm or less.

2. The molar ratio of sodium oxide to silicon dioxide in the water glass (SiO ２ / Na ２ The ground improvement method according to claim 1, wherein O) is 2.6 to 5.

3. 3. The method for improving ground according to claim 1, wherein the amount of water immediately after mixing the base agent and the hardener and gelling is 55 mass % or more.

4. The ground improvement method according to any one of claims 1 to 3, wherein the silica concentration immediately after mixing and gelling the base agent and the hardener is 5 to 25 mass%.

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