Ground grouting material and ground improvement method

Abstract

To provide a grouting material that achieves improved soil with high durability, even under contact with water.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 gelled body is subjected to FTIR / ATR measurement, in which the value of the strength around 3099 cm-1 divided by the strength around 3345 cm-1 is 0.55 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] Chemical grouting methods, in which chemical solutions are injected into the ground, are 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 it 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] In order to obtain a gel that is highly durable when in contact with water, such as in an underwater or groundwater environment, it is said that it is necessary to suppress the amount of silica eluted from the gel cured in water (silica leaching rate) or to suppress the shrinkage of the gel. [Prior art documents] [Patent documents]

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

[0005] If the water resistance of the gel is low, there is a concern that the strength will decrease due to silica elution from the gel, etc. Therefore, there is a need for a ground grouting material that will not deteriorate easily when in contact with water, that is, that will be able to create improved ground with good durability.

[0006] The present invention has been made to solve the above problems, and aims to provide a ground grouting material that can create improved ground that is durable even when in contact with water. [Means for solving the problem]

[0007] The present inventors have conducted extensive research to solve the above-mentioned problems. By measuring and analyzing the infrared absorption spectra of various gels using the total reflection method, they have investigated the correlation between specific spectral positions of the gel and the amount of silica eluted and volume shrinkage, and have found a configuration that can produce a highly water-resistant gel from the infrared absorption spectrum. Specifically, they have found that a highly water-resistant gel can be obtained when specific spectral conditions are met, and have thus completed the present invention. 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, wherein the base agent and the hardener are mixed, and the gel-like body is gelled for one hour. In the infrared absorption spectrum measurement using the total reflection measurement method, the wavelength of the infrared absorption spectrum is 3099 cm -1 The intensity (peak intensity) around 3345cm -1 A grouting material whose value when divided by the nearby strength (peak strength) is 0.55 or less. [2] The base agent and the curing agent were mixed, and after one hour of gelation, the gel was measured for infrared absorption spectrum using a total reflection measurement method. -1 The intensity (peak intensity) around 3345.5 cm -1 The grouting material according to [1], wherein the value obtained by dividing the strength (peak strength) in the vicinity of the grouting material by the grouting material is 0.3 or less. [3] The ground grouting material according to [1] or [2], wherein the silica concentration in the water glass is 6 to 24 mass %. [4] The ground grouting material according to any one of [1] to [3], wherein the pH after mixing the main agent and the hardener is 2.0 to 11.1. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a ground grouting material that can provide improved ground that has good durability even when in contact with water. [Brief explanation of the drawings]

[0010] [Figure 1]This is the infrared absorption spectrum measured by the total reflection method for a ground grouting material with a silica concentration of 16%, which is a combination of a base agent containing MR3.2 water glass and EC. DETAILED DESCRIPTION OF THE INVENTION

[0011] The grouting material according to one embodiment of the present invention (this embodiment) is a combination of a base agent containing water glass and a hardener, which are separated so as not to be mixed together until they are used as a grouting material.

[0012] The base resin and the curing agent were mixed, and after one hour of gelation, infrared absorption spectroscopy (FTIR / ATR) was performed on the gel using the total reflection method. -1 Nearby Intensity (I 3099 ) to 3345cm -1 Nearby Intensity (I 3345.5 ) divided by (I 3099 / I 3345 ) is below 0.55. In this specification, "gelation" refers to the state where the fluidity is lost and the material becomes solid to the extent that it does not collapse under its own weight. FTIR / ATR is a measurement method that can obtain an FT-IR spectrum of the sample surface (to a depth of about several μm) by detecting total reflected light. ATR stands for Attenuated Total Reflectance.

[0013] When the gel is measured by FTIR / ATR, infrared absorption spectra due to various silica structures are obtained. The various silica structures are characterized by their skeletal structure being Si(OH) 4-n (OSi) n Q n It can be expressed as a structure, Q n indicates a structure in which n Si atoms are bonded via an O atom, where n = 0, 1, 2, 3, or 4. Silica species that are cyclic are expressed as ring.

[0014] In the infrared absorption spectrum of the gel, -1 Near 1038cm -1 and 3099 cm -1 The peaks around 1 (monomer+dimer+trimer)+monomer, Q 2 (3R) rings, and H2O and OH - Clusters of (H3O2 - ) absorption due to OH vibration. -1 In the vicinity, a peak is observed that is the peak band of the OH stretching vibration of water, which shows the maximum value in the spectrum measured in this measurement. -1 Near 1038cm -1 and 3099 cm -1 The intensity of each peak in the vicinity (I 987 , I 1038 , I 3099 ) to 3345cm -1 The peak intensity (I 3345 The correlation between the standard value obtained by dividing the value by the water content and the gel having high water resistance was examined. Here, "near" the wavenumber means ±5cm of each wavenumber. -1 This refers to a state in which the peak top is between In this study, the main agent and hardener were mixed, and one hour after gelation, I 3099 / I 3345.5 It was found that when the ratio exceeds 0.55, the hydroxide ion content increases, and good durability in contact with water cannot be obtained. The reason why good durability cannot be obtained is not clear, but it is presumed that the amount of dissolved silica increases with the increase in hydroxide ion content. 3099 / I 3345.5 is preferably 0.1 to 0.55, and more preferably 0.45 to 0.53.

[0015] Linear Q 1 From the viewpoint of reducing the amount of I 987 / I 3345.5 is preferably 0.3 or less, and more preferably 0.1 to 0.3. 987 / I3345.5 It can be said that the term mainly refers to mobile silicic acid species that can flow out of the gel together with the solvent.

[0016] It is preferable to use the method described in the Examples for measuring the gel-like body by FTIR / ATR. 3099 / I 3345.5 and I 987 / I 3345.5 To achieve the desired conditions for each of the above, the silica concentration in the water glass is set to a range of 6 to 24 mass %, and the pH after mixing the base agent and the curing agent is controlled to be 2.0 to 11.1.

[0017] The main agent and curing agent will be described below. (Main ingredient) The main agent contains water glass, and from the viewpoint of preventing overflow in the ground and providing good permeability, the viscosity at 20°C is preferably 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.

[0018] The viscosity of the base agent 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 using a tuning-fork vibration viscometer. The viscosity can be adjusted by adjusting the molar ratio (SiO2 / Na2O) described below or by diluting with water or the like. The viscosity can also be adjusted to a desired range by adjusting the heating temperature and heating time during the final heating and dissolution reaction of the silica source and sodium source. For example, the viscosity increases as the heating temperature and heating time increase.

[0019] When the water glass is sodium silicate, the molar ratio of sodium oxide to silicon dioxide (SiO2 / Na2O) is preferably 2.6 to 5, more preferably 2.9 to 4. A molar ratio of 2.6 to 5 can further improve the early strength. As such water glass, No. 3 sodium silicate (No. 3 water glass) specified in JIS standard (JIS-K-1408) or formulated in accordance with the JIS standard, or sodium silicate with a molar ratio higher than that, is preferred, and for example, No. 4 sodium silicate (No. 4 water glass) or No. 5 sodium silicate (No. 5 water glass) sold by Fuji Chemical Co., Ltd. is preferred. The molar ratio of sodium oxide to silicon dioxide may be expressed as MR.

[0020] The silica concentration in water glass is I 3099 / I 3345.5 and I 987 / I 3345.5 From the viewpoint of easily achieving the desired conditions for each of the above and from the viewpoint of obtaining practical strength, the content is preferably 6 to 24 mass %, and more preferably 8 to 20 mass %.

[0021] The solid content of the water glass is preferably 20 to 60% by mass, and more preferably 25 to 50% by mass. A solid content of 20 to 60% by 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 water glass in the form of an aqueous solution. This solid component substantially corresponds to silicate compounds such as sodium silicate, and can be calculated by the formula: solid content (%) = [mass after drying (g) / mass before drying (g)] × 100.

[0022] (hardening agent) The curing agent includes at least one of an acid, 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 or the like. Examples of acids include inorganic acids such as sulfuric acid, nitric acid, and phosphoric acid, and organic acids such as citric acid, with sulfuric acid being preferred, and a concentration of sulfuric acid of 70% by mass or more being particularly preferred. 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.

[0023] Examples of the acid-releasing organic compound include alkylene carbonates such as ethylene carbonate (EC) and propylene carbonate (PC), 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.

[0024] For example, ethylene carbonate, an alkylene carbonate, decomposes into ethylene glycol and carbonic acid (H2CO3) in the presence of water, and the carbonic acid (CO3 2- ) and Na in the main ingredient, water glass + It is believed that the reaction of the two compounds results in polymerization of silica, resulting in better strength. Furthermore, if the water glass has a high concentration (high silica concentration), the amount of silica is large, so that the skeletal structure grows relatively when gelled, resulting in high strength. From this perspective, the acid-releasing organic compound is more preferably alkylene carbonate, and even more preferably ethylene carbonate.

[0025] The content of the acid, inorganic salt or acid-releasing organic compound in the curing agent is preferably 1 to 99 mass %, more preferably 10 to 30 mass %, from the viewpoint of setting speed and strength.

[0026] The curing agent preferably does not contain an isocyanate compound. Examples of the isocyanate compound include the isocyanates used in injection molding materials, such as diphenylmethane-4,4'-diisocyanate (MDI), polymeric MDI (C-MDI), tolylene diisocyanate (TDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and xylylene diisocyanate (XDI). The absence of an isocyanate compound enhances handling safety.

[0027] As mentioned above, the aqueous solution of the curing agent preferably further contains a thickener. By including a 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 using a tuning fork vibration viscometer. Examples of thickeners include acrylic thickeners, starch thickeners, vinyl thickeners, cellulose thickeners, gum thickeners, and inorganic thickeners. At least one of cellulose thickeners, gum thickeners, and inorganic thickeners is preferred, and cellulose thickeners are more preferred.

[0028] Examples of cellulose-based thickeners 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 leucantham gum. Examples of inorganic thickeners include bentonite, kaolinite, sepiolite, talc, and silica fume.

[0029] The ground grouting material according to this embodiment is preferably combined so that the ratio of the viscosity of the main agent to the viscosity of the hardener (viscosity of hardener / viscosity of main agent) is 0.1 to 10, more preferably 0.1 to 3. By combining them so that the ratio is 0.1 to 10, the respective effects are more easily exerted, and a practical gel time and high early strength can be more efficiently obtained.

[0030] In addition, the pH after mixing the base agent and hardener is I 3099 / I 3345.5 and I 987 / I 3345.5 From the viewpoint of easily achieving the desired conditions for each of the above, the pH is preferably 2.0 to 11.1, and more preferably 4.0 to 10.9. The pH can be measured by the method described in the Examples.

[0031] The base agent and hardener are mixed at the time of use and introduced into the ground, bedrock, etc. by injection or pouring, etc., to allow for good reaction hardening. From the viewpoint of achieving better reaction 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.

[0032] 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 main agent and hardener) is injected into the ground using a 1.5 shot method or a 2 shot method.

[0033] The 1.5 shot method is a method in which the base agent and hardener collide and mix near the entrance of the injection tube and then inject the mixture, while the 2 shot method is a method in which the base agent and hardener are supplied separately through a double-pipe injection tube, collide and mix at the tip of the injection tube, and then ejected.Compared to the 1 shot method in which the base agent and hardener are mixed in advance and then the mixture is injected, this method allows for faster solidification and higher strength. [Example]

[0034] The present invention will be explained in more detail below using examples and comparative examples, but the present invention is not limited to the following examples as long as it does not deviate from the gist of the invention.

[0035] [Materials used] Water glass: Water glass manufactured by Fuji Chemical Co., Ltd. Acid-releasing organic compounds: Ethylene carbonate manufactured by Toa Gosei Co., Ltd., or propylene carbonate manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Sodium bicarbonate: Reagent manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Sulfuric acid: industrial sulfuric acid manufactured by Fuji Chemical Co., Ltd. (concentration: 78% by mass) Thickener: Methylcellulose thickener manufactured by Shin-Etsu Chemical Co., Ltd. (Metolose SBQ-30000PE) Water: Tap water

[0036] [Preparation of main agent] The molar ratio of sodium oxide to silicon dioxide (SiO2 / Na2O) in the water glass was adjusted by adjusting the raw material composition. Furthermore, the viscosity at 20°C was adjusted by adjusting the heating temperature and heating time during the heating and dissolving reaction of the raw materials. To prepare a base material containing water glass with an MR of 1.4 (viscosity at 20°C: 280 mPa·s, silica concentration: 24.02% by mass), a base material containing water glass with an MR of 2.1 (viscosity at 20°C: 460 mPa·s, silica concentration: 29.93% by mass), and a base material containing water glass with an MR of 3.1 (viscosity at 20°C: 190 mPa·s, silica concentration: 29.15% by mass), respectively. The viscosity (at 20°C) was measured using a tuning-fork vibration viscometer.

[0037] [Preparation of hardener] (1) Sulfuric acid-based hardener A sulfuric acid-based hardener was prepared by mixing water with sulfuric acid. (2) Sodium bicarbonate hardener Sodium bicarbonate was mixed with water to prepare a sodium bicarbonate-based hardener. (3) Ethylene carbonate-based curing agent Ethylene carbonate was mixed with water to prepare an ethylene carbonate-based hardener. (4) Propylene carbonate-based hardener Propylene carbonate and ethylene carbonate were mixed with water to prepare an ethylene carbonate-based curing agent.

[0038] [Preparation of ground grouting material] The base agent, hardener, and thickener were mixed to obtain the formulation (by mass) shown in Table 1 below, to prepare the ground grouting materials shown in Table 2 below.

[0039] [Table 1]

[0040] For each of the ground grouting materials, pH and FTIR / ATR measurements of the gel-like material one hour after gelation (I 3099 / I 3345 , I 987 / I 3345 The silica leaching rate and volume change rate were determined as follows. The results are shown in Table 1.

[0041] (pH) The soil suspension pH test method JGS:0211-2009 was used as a reference. First, the test was conducted by converting the "dry soil" in the above test method into the "solid content of the gel." After preparing the ground grouting material and allowing it to gel, it was left to stand for 1 hour, and ion-exchanged water was added so that the gel solid content:water ratio was 1:10 by mass. After stirring with a stirring rod, it was left to stand for 30 minutes, and a pH electrode (HORIBA, 9625-10D) was inserted into this solution to measure the pH. 100 g of gel, including the syneresis water, was used for the test.

[0042] (FTIR / ATR measurement (I 3099 / I 3345 , I 987 / I 3345 )) The base agent and the curing agent were mixed, and the gel was left to stand for one hour. The infrared absorption spectrum of the gel was measured using an infrared absorption spectrometer (Spectrum Two, manufactured by PerkinElmer) with four accumulations. Figure 1 shows an example of the infrared absorption spectrum measured using the total reflection method for a ground grouting material (corresponding to number 7 in Table 2) that is a combination of a base agent containing MR3.2 water glass and EC and has a silica concentration of 16%. The ATR was performed using diamond, and the sample was measured using the ATR method. 987 , I 3099 , I 3345 Measure I 3099 / I 3345 , I 987 / I 3345 asked for.

[0043] (Volume change rate) 100g of the grouting material was added to a 200ml measuring flask. One day after the grouting material had gelled, water was added up to the mark and the material was cured in water. After one day, the water was replaced and the weight of the water was measured. The volume of the gel was calculated from the weight of the water. The volume change rate was calculated by dividing the volume of the gel cured for one day after injection by the volume of the gel before curing.

[0044] (Silica leaching rate) The volume change rate was determined by measuring the weight of the water replaced when measuring the volume change rate. The silica leaching rate was determined by measuring the silica concentration in the replaced water using ICP-AES after suction filtering the replaced water using a 0.45 μm membrane filter, and then calculating the silica concentration in the replaced water from the silica concentration in the ground injection material and the silica concentration in the replaced water, as follows: [silica concentration in replaced water / silica concentration in ground injection material].

[0045] Furthermore, the prepared grouting materials were tested for durability under contact with water as follows, and the results are shown in Table 1 below. (Durability test) Using the same test method as for the volume change rate, the volume change rate was calculated by dividing the volume of the gel that had been cured for 28 days after injection by the volume of the gel before curing.

[0046] [Table 2] [Industrial Applicability]

[0047] The present invention can be suitably used in the fields of civil engineering and construction, particularly for filling voids behind various tunnels, backfilling such as filling voids in civil engineering structures, lightweight embankments, landfills, etc.

Claims

[Claim 1] A ground grouting material consisting of a combination of a base agent containing water glass and a hardening agent, The base agent and the curing agent were mixed, and one hour after gelation, infrared absorption spectrum of the gel was measured using a total reflection measurement method. －１ The strength in the vicinity is 3345 cm －１ The value obtained by dividing the intensity by the intensity of the surrounding area is 0.55 or less, The molar ratio of sodium oxide to silicon dioxide in the water glass (SiO ２ / Na ２ O) is 2.6 to 5, the mixing mass ratio of the base agent to the curing agent (base agent:curing agent) is 1:0.5 to 1:79.95 / 20.05, the curing agent is an aqueous solution containing at least one of an acid, an inorganic salt, and an acid-releasing organic compound, the base agent and the curing agent are mixed, gelled, and an infrared absorption spectrum of the gel is measured using a total reflection method, and the value obtained by dividing the intensity near 987 cm −1 by the intensity near 3345.5 cm −1 is 0.3 or less; A ground grouting material having a pH of 2.0 to 11.1 after mixing the main agent and the hardener (excluding cases where the hardener is an aqueous propylene carbonate solution and the main agent:hardener ratio is 1:1.8 (mass ratio)).

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