Particulate object, cement-based mixture, improving method of bedrock or subsoil, lining method, filling method, production method of particulate object, and production method of cement-based mixture

Abstract

To provide a material in order to repair a concrete structure and the surroundings thereof self-therapeutically over a long term.SOLUTION: A particulate object is formed by mixing an ion emissive compound containing at least one of sodium carbonate and sodium hydrogen carbonate and capable of emitting a positive ion or a negative ion and a hardening resin or a polyethylene terephthalate resin, and is mixed into cement and water. The particulate object has 5 mm or less of a maximum size defined by a nominal size of minimum size among sieves through which at least 90% of mass of the particulate object passes in a test conducted on the basis of JIS A 1102(2014) "Method of test for sieve analysis of aggregates".SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a powder or granular material, a cement-based admixture, a method for improving rock or ground, a lining method, a filling method, a method for producing a powder or granular material, and a method for producing a cement-based admixture. [Background technology]

[0002] Patent Document 1 discloses a construction method for repairing water leakage from cracks that have occurred in underground structures such as concrete structures, in which a water-stopping agent is injected into the cracks to stop water leakage. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 4-1365 Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 discloses the use of cement-based or water glass-based waterproofing agents. However, when repairs are made with these materials, there is a risk that they will deteriorate over a long period of time due to contact with groundwater, etc., and water leakage will occur.

[0005] Therefore, it is desirable to be able to repair concrete structures and their surroundings in a self-healing manner over a long period of time.

[0006] An object of the present invention is to repair a concrete structure and its surroundings in a self-healing manner over a long period of time. [Means for solving the problem]

[0007] The present invention relates to a powder or granular material which is formed by mixing an ion-releasing compound capable of releasing cations or anions, containing at least one of sodium carbonate and sodium bicarbonate, with a curable resin or a polyethylene terephthalate resin, and is then mixed with cement and water, and the powder or granular material has a maximum dimension, defined as the nominal dimension of the smallest dimension of a sieve through which at least 90% of the powder by mass passes, of 5 mm or less in a test conducted based on JIS A 1102 (2014) "Sieving test for aggregates."

[0008] The present invention also relates to a powder or granular material which is prepared by mixing and molding an ion-releasing compound capable of releasing cations or anions, containing at least one of sodium carbonate and sodium bicarbonate, with a curable resin or a polyethylene terephthalate resin, and then mixing the mixture with cement and water, and which has an average particle diameter defined by "arithmetic mean value of particle diameter" in JIS Z 8901 (2006) "Test powders and test granules" of 30 μm or less. Effect of the Invention

[0009] According to the present invention, the surroundings of a concrete structure can be repaired in a self-healing manner over a long period of time. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a flow chart for explaining the flow of a method for producing powder or granular material according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a flow chart for explaining the flow of the method for producing a cement-based admixture according to the embodiment of the present invention. [Diagram 3] FIG. 3 is a table showing examples of blending of cement-based admixtures according to the embodiment of the present invention. [Figure 4] FIG. 4 is an example of an application of a cement-based mixture, showing a cross section of a tunnel constructed using the rock bolt reinforcement method. [Diagram 5]FIG. 5 is an example of an application of the cement-based mixture, showing a cross section of a tunnel being excavated by a shield method using a shield machine. [Figure 6] FIG. 6 is an example of an application of a cement-based mixture, showing a cross section of ground with a number of boreholes provided in the vicinity of a planned position for excavating a tunnel. [Figure 7] FIG. 7 is an example of an application of a cement-based admixture, showing a cross section of a borehole formed vertically in the ground. [Figure 8] FIG. 8 is a graph showing the change in groundwater level when a cement-based admixture containing powder and granular material and a cement-based admixture not containing granular material are injected. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, the powder and granular material and the cement-based admixture C according to the embodiment of the present invention will be described.

[0012] The cement-based admixture C according to this embodiment is used, for example, as a filler to be filled in the space between a concrete structure such as a tunnel and the ground or rock mass, or in gaps in the ground or rock mass, an improvement material to be injected into the ground or rock mass, a lining concrete to line the inner surface of a tunnel or a pit, a filler to fill a pit, etc. The cement-based admixture C contains cement, water, and powdered or granular material.

[0013] The cement used in this embodiment may be a type of cement or a mixture of multiple types of cement from the group consisting of portland cement, blast furnace cement (including blast furnace slag), silica cement, fly ash cement, fine particle cement, ultrafine particle cement, and ultra-fine particle cement.

[0014] The powder contains an ion-releasing compound capable of releasing cations or anions, and a curable resin or a PET resin (polyethylene terephthalate resin). The ion-releasing compound is, for example, sodium carbonate or sodium bicarbonate, and the powder in this embodiment contains at least one of sodium carbonate and sodium bicarbonate. The powder may contain other ion-releasing compounds.

[0015] The curable resin may be a thermosetting resin, a photocurable resin, a moisture curable resin, or the like.

[0016] Examples of the thermosetting resin include epoxy resin, phenol resin, (meth)acrylic resin, unsaturated polyester resin, vinyl ester resin, polyimide resin, urethane resin, polyurea resin, etc. The thermosetting resin may be used in combination with a thermosetting agent.

[0017] Examples of the photocurable resin include acrylic (methacrylic) resin, acrylic urethane resin, epoxy resin, silicone resin, etc. The photocurable resin may be used in combination with a photopolymerization initiator.

[0018] Examples of the moisture-curable resin include moisture-curable urethane resins and hydrolyzable silyl group-containing resins.

[0019] In addition, the curable resin may be a water-curable resin that cures by reacting with water, an air-curable resin that cures by reacting with oxygen in the air, an acid-curable resin that cures by reacting with acid, an amine-curable resin that cures by reacting with amine, or a curable acrylic resin that cures by heat or a catalyst.

[0020] The curable resin used in this embodiment is not limited to one of the above curable resins, and two or more of them may be used in combination.

[0021] Next, a method for producing powder or granular material will be described with reference to the flow chart shown in Fig. 1. In the following, a case where an ion-releasing compound capable of releasing cations or anions is mixed with a curable resin will be described.

[0022] First, the ion-releasing compound and the curable resin before curing are mixed and stirred (step S1). The mixing ratio of the curable resin and the ion-releasing compound is preferably in the range of 0.5 to 2.0 (mass of the curable resin: mass of the ion-releasing compound = 1: 0.5 to 2.0) such that the ratio of the mass of the ion-releasing compound to the mass of the curable resin is 0.5 to 2.0. When the ion-releasing compound and the curable resin before curing are sufficiently mixed, the process proceeds to step S2.

[0023] In step S2, the mixture mixed in step S1 is solidified. A method suitable for hardening the hardening resin used is adopted as the method for solidifying the mixture. Specifically, for example, when a thermosetting resin is used, the mixture is hardened by heating the mixture. When a photosetting resin is used, the mixture is hardened by irradiating it with ultraviolet light. When a moisture-hardening resin is used, the mixture is hardened by leaving it in air for a predetermined time. Whether the mixture has solidified may be determined based on the elapsed time, or may be determined by measuring the strength or elastic modulus of the mixture.

[0024] Next, the solidified mixture is pulverized (step S3). The pulverization method is not particularly limited, but may be dry pulverization, wet pulverization, low-temperature pulverization, dry pulverization, heated pulverization, frozen pulverization, or the like.

[0025] Next, it is determined whether the powder or granular material has the target particle size (step S4). Specifically, it is determined whether the maximum dimension of the powder or granular material generated in step S3 is 5 mm or less. In this embodiment, the maximum dimension of the powder or granular material is defined by the nominal dimension of the smallest dimension of a sieve through which at least 90% of the powder or granular material passes in a test based on JIS A 1102 (2014) "Sieving test of aggregates". If the maximum dimension of the powder or granular material is larger than 5 mm (NO in step S4), the process returns to step S3, where the powder or granular material is crushed again, and then the process returns to step S4, where a test based on JIS A 1102 (2014) "Sieving test of aggregates" is performed. It is more preferable to determine whether the maximum dimension of the powder or granular material is 2.5 mm or less, 1.2 mm or less, 0.6 mm or less, 0.3 mm or less, 0.15 mm or less, or 0.075 mm (75 μm) or less.

[0026] In addition, the determination of whether the powder or granular material has a target particle size (the determination in step S4) may be made based on the average particle diameter of the powder or granular material produced in step S3. Specifically, when the average particle diameter of the powder or granular material is measured as the average particle diameter defined by "arithmetic mean value of particle diameter" in JIS Z 8901 (2006) "Test powders and test particles", it is determined whether the average particle diameter of the powder or granular material is 30 μm or less. At this time, if the average particle diameter is larger than 30 μm (NO in step S4), the process returns to step S3, and the powder or granular material is pulverized again, and the determination in step S4 is made again. It is more preferable to determine whether the average particle diameter of the powder or granular material is 20 μm or less, or 15 μm or less.

[0027] By mixing powder or granular material having such maximum dimensions or average particle diameter into, for example, an improvement material for improving the ground or bedrock, or a filler for filling holes drilled in the ground or bedrock, the fluidity of the improvement material or filler is improved, and the improvement material or filler can be injected over a longer distance.

[0028] In addition, when mixing an ion-releasing compound capable of releasing cations or anions with PET resin, in step S1, the PET resin is heated and melted, and then mixed with the ion-releasing compound and stirred.

[0029] Next, in step S2, the mixture mixed in step S1 is cooled and hardened. The cooling method may be to leave it in the air for a predetermined time, or to forcibly cool it using a cooling device or the like. The other steps are similar, so the explanation will be omitted.

[0030] Next, a method for producing the cement-based admixture C containing powdered granular material of this embodiment will be described with reference to the flow chart shown in FIG.

[0031] First, cement and water are mixed and stirred (step S11). When the cement and water are sufficiently mixed, the process proceeds to step S12.

[0032] In step S12, the powder / granules selected in step S4 are mixed into the mixed cement and water. At this time, it is preferable that the ratio of the mass of the powder / granules to the mass of the cement is within a range of 0.3 to 5.0 (mass of cement: mass of powder / granules = 1: 0.3 to 5.0). If the ratio of the mass of the powder / granules to the mass of the cement is greater than 5.0, sufficient initial strength cannot be obtained. Also, if the ratio of the mass of the powder / granules to the mass of cement is less than 0.3, the effect of the powder / granules cannot be obtained.

[0033] It is also preferable that the ratio of the mass of water to the total mass of cement and granular powder is within the range of 0.5 to 100 ([mass of cement + mass of granular powder]: mass of water = 1: 0.5-100). If the ratio of the mass of water to the total mass of cement and granular powder is less than 0.5, there is too little water, and the fluidity of the cement-based admixture C cannot be ensured. If the ratio of the mass of water to the total mass of cement and granular powder is greater than 100, there is too much water, and the cement cannot solidify.

[0034] Next, in step S13, it is determined whether the viscosity of the mixture (cement-based admixture C) generated in step S12 is a target viscosity. Specifically, it is determined whether the viscosity of the mixture generated in step S12 is within the range of 3 mPa·s to 200 mPa·s as measured by JIS Z 8803 (2011) "Method of measuring viscosity of liquids". If the viscosity is outside the range of 3 mPa·s to 200 mPa·s, the process proceeds to step S14, where a viscosity adjuster is added to adjust the viscosity. Specifically, the viscosity is adjusted by adding a flow agent (dispersant) or water to lower the viscosity, and by adding a thickener to increase the viscosity. In this way, by making the viscosity of the cement-based admixture C appropriate, it is possible to suppress separation of the cement and the powder particles. In other words, it is possible to maintain a state in which the powder particles are appropriately dispersed in the cement. Note that FIG. 3 shows a specific example of the mix ratio (mass ratio) and viscosity of the cement-based admixture C.

[0035] Next, specific examples of uses of the cement-based admixture C thus produced will be described with reference to Figs.

[0036] Fig. 4 shows a cross section of a tunnel T (concrete structure) excavated by the rock bolt reinforcement method. In the method shown in Fig. 4, a plurality of holes 2 are drilled at a predetermined interval in the circumferential direction on the inner surface of the tunnel T, and a rock bolt 1 and a cement-based mixed material C are inserted into each of the drilled holes 2, thereby reinforcing the ground M. Although not shown in the figure, the rock bolts 1 are provided at predetermined intervals along the axis of the tunnel T.

[0037] In the example shown in Fig. 4, the cement-based mixture C is used as a filler for filling the gap between the rock bolt 1 and the ground M. In the example shown in Fig. 4, the cement-based mixture C filled in the hole drilled in the ground M is solidified, so that the rock bolt 1 and the ground M can be integrated together. This can improve the strength of the ground M.

[0038] Furthermore, in the example shown in FIG. 4, the cement-based mixture C is used as a material for constructing the lining concrete 3 that covers the inner surface of the tunnel T.

[0039] Next, another application will be described with reference to Fig. 5. Fig. 5 shows a cross section of a tunnel T being excavated by a shield method using a shield machine 10. In the method shown in Fig. 5, a cement-based mixture C is injected as a backfill material into a gap generated between the inner peripheral surface of an excavated hole 11 and the outer peripheral surface of a segment ring 12.

[0040] In the example shown in Fig. 5, the cement-based mixed material C is used as a filler (backfilling material) for filling the gap between the segment ring 12 and the ground M. In the example shown in Fig. 5, the cement-based mixed material C filled in the gap between the segment ring 12 and the ground M is solidified, whereby the segment ring 12 filled with the solidified cement-based mixed material C and the ground M are firmly bonded together, and the strength of the gap between the segment ring 12 and the ground M can be improved.

[0041] Next, still another application will be described with reference to Fig. 6. Fig. 6 shows a cross section of the ground M in which a plurality of boreholes 20 are provided near a planned excavation position R of the tunnel T before the tunnel T is excavated. In the example shown in Fig. 6, four boreholes 20 are drilled around the planned excavation position R of the tunnel T along the tunnel T. The four boreholes 20 are filled with a cement-based mixture C.

[0042] In the example shown in FIG. 6, the cement-based mixture C is used as a filler to be filled in the borehole 20, and is also used as a water-stopping material to stop groundwater in the area around the borehole 20. In this embodiment, the cement-based mixture C is filled into the borehole 20 under pressure. As a result, the cement-based mixture C penetrates into cracks and voids present in the ground M around the borehole 20. The cement-based mixture C in the borehole 20 and the cement-based mixture C that penetrates into the cracks and voids in the ground M solidify, thereby improving the strength of the cracks and voids in the ground M around the borehole 20, and forming a sealing zone Z around the borehole 20 that suppresses the penetration of groundwater. This ensures the strength of the ground M around the tunnel T, and suppresses the intrusion of groundwater into the tunnel T when the tunnel T is excavated.

[0043] Next, still another application will be described with reference to Fig. 7. Fig. 7 shows a cross section of a borehole 30 formed vertically in the ground M. In the example shown in Fig. 7, a cement-based mixture C is injected into a space 30a defined by an expandable and contractible packer 31 in the borehole 30.

[0044] In the example shown in FIG. 7, the cementitious mixture C is used as a filler to be filled in the borehole 30. In the example shown in FIG. 7, there are cracks in the ground M around the borehole 30. Therefore, by injecting the cementitious mixture C into the space 30a under pressure, the cementitious mixture C permeates from the borehole 30 into the cracks 32. The cementitious mixture C that has permeated into the cracks 32 solidifies, thereby sealing the cracks 32. This makes it possible to improve the water impermeability of the ground M.

[0045] Over a long period of time, the cementitious mixture C that has solidified due to the hardening of the cement components may develop cracks in the cementitious mixture C due to groundwater or other water seeping into the cementitious mixture C, earthquakes, expansion and contraction of the cementitious mixture C, etc., or the cementitious mixture C may melt, causing gaps to form between the cementitious mixture C and the ground M.

[0046] Usually, when the cement-based mixture C cracks or melts, the strength of the ground M or the cement-based mixture C itself decreases. However, in this embodiment, an ion-releasing compound is eluted from the powder in the cement-based mixture C, and carbonate is generated. Specifically, sodium of sodium carbonate or sodium bicarbonate contained in the powder is replaced with calcium in the cement contained in the ground M or the cement-based mixture C, and this calcium carbonate precipitates and accumulates in the gap between the cement-based mixture C and the ground M or in the cracks in the cement-based mixture C. In this way, the calcium carbonate precipitated in the cracks in the cement-based mixture C or the gap between the cement-based mixture C and the ground is accumulated, filling these parts. In other words, by using the cement-based mixture C mixed with the powder, the cement-based mixture C and its surroundings become denser than at the initial stage of construction.

[0047] In this way, by mixing the powder into the cementitious mixture C, the cementitious mixture C will self-heal and repair over a long period of time even if cracks occur in the cementitious mixture C or gaps occur between the cementitious mixture C and the ground M. This maintains the ground improvement effect over a long period of time and prevents groundwater from seeping into the concrete structure (tunnel T).

[0048] Here, the effect of mixing powdered granular material into the cement-based admixture C will be described with reference to Fig. 8. Fig. 8 is a graph showing the change in groundwater level when the cement-based admixture C containing the powdered granular material of this embodiment is injected into a borehole 30 formed vertically in the ground M as shown in Fig. 7, and when the cement-based admixture C1 not containing the powdered granular material is injected. Fig. 8 also shows the change in water level in the borehole 30 when no cement-based admixture is injected into the borehole 30.

[0049] As shown in Fig. 8, when no cement-based admixture is injected, groundwater flows into the borehole 30 over time, causing the water level to rise. When the cement-based admixture C1 is injected into the borehole 30, the effect of suppressing the inflow of groundwater into the borehole 30 is observed, but the groundwater level rises over time.

[0050] In contrast, the cement-based admixture C containing the powdered granules of this embodiment shows no significant change in the groundwater level even after 90 days. This is believed to be because, as described above, the ion-releasing compound is eluted from the powdered granules in the cement-based admixture C, calcium carbonate is generated, and the calcium carbonate is deposited in the cracks in the cement-based admixture C and in the gaps between the cement-based admixture C and the ground M, so that the water-blocking effect continues.

[0051] The uses of the cementitious mixture C are not limited to those shown in Figures 4 to 7 above, and it may be used, for example, as a material for sprayed concrete to be sprayed onto supports or the inner walls of tunnel T, or for filling (backfilling) a hole.

[0052] In addition, in the above embodiment, the explanation is given for the ground M, but the present invention can also be applied to a bedrock or a gap between a bedrock and a concrete structure constructed on the bedrock.

[0053] In the above embodiment, sand or the like is not added to the cement-based admixture C, but sand, fine aggregate, or the like may be added if necessary.

[0054] According to the above embodiment, the following advantageous effects are achieved.

[0055] The powdered material of this embodiment is formed by mixing an ion-releasing compound capable of releasing cations or anions, including at least one of sodium carbonate and sodium bicarbonate, with a hardening resin or polyethylene terephthalate resin (PET resin). By filling the cement-based admixture C containing such powdered material into the space between the concrete structure and the ground or rock, or into gaps and cracks in the ground M, even if the cement-based admixture C cracks or the cement-based admixture C dissolves and a gap is formed between the cement-based admixture C and the ground M, the ion-releasing compound is eluted from the powdered material to generate carbonate, so that the cement-based admixture C can be repaired in a self-healing manner for a long period of time. Therefore, it is possible to suppress the penetration of groundwater into the concrete structure for a long period of time and ensure its strength.

[0056] Furthermore, in the above embodiment, the maximum dimension of the powder or granule is set to 5 mm or less, or the average particle diameter of the powder or granule is set to 30 μm or less. The smaller the particle diameter of the powder or granule, the easier it is to fill every corner of the space between the concrete structure and the ground or rock, and the voids in the ground or rock. The maximum dimension of the powder or granule is more preferably 2.5 mm or less, 1.2 mm or less, 0.6 mm or less, 0.3 mm or less, 0.15 mm or less, or 0.075 mm (75 μm) or less. The average particle diameter of the powder or granule is more preferably 20 μm or less, or 15 μm or less.

[0057] In addition, by setting the ratio of the mass of the powder to the mass of the cement within the range of 0.3 to 5.0, the sodium contained in the ion-releasing compound can be reliably replaced with the calcium contained in the cement. In other words, there is no excess of powder, so that an increase in costs can be suppressed.

[0058] Furthermore, the fluidity of the cementitious mixture can be ensured by setting the ratio of the mass of water to the total mass of the cement and granular material within the range of 0.5 to 100, and by setting the viscosity of the cementitious mixture measured according to JIS Z 8803 (2011) "Method of measuring viscosity of liquids" within the range of 3 mPa·s to 200 mPa·s. More preferably, the upper limit of the viscosity is 100 mPa·s or less, and the lower limit of the viscosity is 5 mPa·s or more. Also, it is not necessary to set a lower limit of the viscosity (it may be less than 3 mPa·s) due to the error of the measurement method.

[0059] Although the embodiments of the present invention have been described above, the above-mentioned embodiments merely show some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above-mentioned embodiments.

[0060] For example, when filling the space between a concrete structure and the ground or rock mass, or voids in the ground or rock mass, the mixture of the cementitious admixture C may be different between the beginning and end of the filling work. Specifically, the viscosity may be low in the beginning of the filling work, and high in the end. In this way, the cementitious admixture C can be spread to the innermost part of the space to be filled in the beginning of the filling work.

[0061] For example, it is preferable to make the density of the powder greater than that of water, so that the powder can be more easily mixed with cement.

[0062] Furthermore, in the above embodiment, the cement-based admixture C is described as being used to fill cracks or spaces present in the ground M, or to fill gaps between the ground M and a concrete structure constructed on the ground M, but the cement-based admixture C may also be used to construct the concrete structure itself. [Explanation of symbols]

[0063] C···Cement-based mixture 1. Rock bolt 10. Shield tunneling machine, 11. Drilling hole 20. Borehole 30. Borehole 30a...Space 31. Packer 32. Crack M...Ground R: Planned excavation location T...Tunnel Z...Sealing Zone

Claims

1. A powdery or granular material which is made by mixing and molding an ion releasing compound capable of releasing cations or anions, containing at least one of sodium carbonate and sodium bicarbonate, and a hardening resin or a polyethylene terephthalate resin, and is mixed with cement and water, A powder or granular material whose maximum dimension, defined as the nominal dimension of the smallest dimension of a sieve through which at least 90% of the mass passes, is within the range of 5 mm or less in a test based on JIS A 1102 (2014) "Sieve separation test for aggregates."

2. A powdery or granular material which is made by mixing and molding an ion releasing compound capable of releasing cations or anions, containing at least one of sodium carbonate and sodium bicarbonate, and a hardening resin or a polyethylene terephthalate resin, and is mixed with cement and water, A powder or granule having an average particle size defined by the "arithmetic mean value of particle diameter" in JIS Z 8901 (2006) "Test powders and test granules" of 30 μm or less.

3. A cement-based admixture comprising the powder or granular material according to claim 1 or 2, cement, and water.

4. The cementitious admixture according to claim 3, A cement-based admixture, wherein the ratio of the mass of the powder to the mass of the cement is within the range of 0.3 to 5.

0.

5. The cementitious admixture according to claim 3, A cement-based admixture, wherein a ratio of the mass of the water to the total mass of the cement and the powder / granular material is within a range of 0.5 or more and 100 or less.

6. The cementitious admixture according to claim 3, A cement-based admixture having a viscosity measured according to JIS Z 8803 (2011) "Method for measuring viscosity of liquids" of 200 mPa·s or less.

7. A method for improving rock or ground, which comprises injecting the cementitious admixture according to claim 3 into the rock or ground.

8. A lining method for lining the inner surface of a hole drilled in bedrock or ground with the cementitious mixture according to claim 3.

9. A method for filling a tunnel formed in a rock mass or ground with the cementitious mixture according to claim 3.

10. A method for producing powdered material to be mixed with cement and water, A method for producing powdered or granular material, comprising mixing an ion-releasing compound capable of releasing cations or anions, the compound containing at least one of sodium carbonate and sodium bicarbonate, with a curable resin or a polyethylene terephthalate resin, and solidifying the mixture, and pulverizing the mixture to produce a powdered or granular material.

11. 3. A method for producing a cement-based admixture, comprising mixing cement with water and then mixing the powder or granular material according to claim 1 or 2 with the mixture.

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