Anchoring material

Abstract

To provide an anchor fixing material capable of suppressing insertion resistance when installing an anchor and exhibiting high adhesion strength.SOLUTION: An anchor fixing material includes cement, a hardening accelerator, and a heavyweight aggregate, wherein a solid volume ratio of the heavyweight aggregate is 45 to 65%, and a content of the heavyweight aggregate with respect to 100 parts by mass of the cement is preferably 50 to 200 parts by mass.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an anchoring material. [Background technology]

[0002] In recent years, in addition to the addition of shear reinforcement steel bars to concrete structures, the installation of bridge fall prevention devices, and post-installed anchor construction methods, emphasis has been placed on the integration and durability of the inserted steel bars with the base concrete in slope reinforcement and rock fall prevention construction.The method used to fix the reinforcing steel bars involves drilling holes in the concrete, inserting filler materials containing inorganic hydraulic substances or organic resins into the holes, and then driving in anchors to fix them in place.

[0003] Materials containing cement are common inorganic hydraulic substances. For example, several methods have been proposed: a capsule-type anchoring material containing cement and a quick-setting agent in a container made of a water-absorbing material such as paper is immersed in water, inserted into a drilled hole, and a bolt is then inserted; a capsule is inserted into a drilled hole, water is poured in, and a bolt is inserted; and a rapid-setting cement is enclosed in an anchor fixing capsule that has an inner container made of a waterproof material and an outer container made of a water-absorbing material (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 3-225000 [Patent Document 2] Japanese Patent Application Publication No. 58-156698 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, from the viewpoint of workability, there has been a demand for not only adhesive strength after bolt insertion, but also good insertability, maintaining appropriate viscosity during anchor insertion to ensure smooth installation. In anchoring materials such as those described in Patent Documents 1 and 2, the rapid-hardening components consisting of cement and an accelerator exhibited rapid hardening upon water absorption, sometimes hardening during the bolt insertion work. This resulted in increased insertion resistance during anchor installation, making it difficult to perform the work reliably, and as a result, the required adhesive strength (anchoring strength) was not obtained in some cases.

[0006] An object of the present invention is to provide an anchor fixing material that can reduce insertion resistance during anchor installation and exhibit high adhesion during anchor fixing work. [Means for solving the problem]

[0007] The present invention has been made to solve the above-mentioned problems, and as a result of various efforts to solve the above-mentioned problems, the inventors have found that the above-mentioned problems can be solved by using heavy aggregate as the aggregate contained in the anchor fixing material, focusing on the volume fraction of this heavy aggregate, and setting the volume fraction within a predetermined range, and have thus completed the present invention. That is, the present invention is as follows.

[0008] [1] An anchor fixing material containing cement, a rapid hardening material, and a heavy aggregate, the volume ratio of which is 45 to 65%. [2] The anchor fixing material according to [1], wherein the content of the heavy aggregate per 100 parts by mass of the cement is 50 to 2000 parts by mass. [3] The density of the heavy aggregate is 3.2 g / cm 3 The anchor fixing material according to [1] or [2] above. [4] The anchor fixing material according to any one of [1] to [3], wherein the 2.5 mm sieve residue of the heavy aggregate is 1% by mass or less. [5] The anchor fixing material according to any one of [1] to [4], wherein the rapid hardening agent contains calcium aluminate powder and gypsum powder. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide an anchor fixing material that can reduce insertion resistance when installing an anchor and exhibit high adhesive strength. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, one embodiment of the present invention (the present embodiment) will be described in detail. [Anchor fixing material] The anchor fixing material according to this embodiment contains cement, a rapid hardening material, and a heavy aggregate.

[0011] (heavy aggregate) In this embodiment, heavy aggregate is contained from the viewpoint of ensuring the development of strength. Here, the heavy-weight aggregate has a volume fraction of 45 to 65%. The volume fraction refers to the ratio of the volume actually occupied by aggregate particles to the total bulk volume. In typical concrete, considering that the voids between aggregate particles are filled with cement paste, using aggregate with a high volume fraction (specifically, rounded aggregate) reduces the amount of cement paste required, making it economical and advantageous in terms of quality. In fact, the volume fraction of typical fine aggregate is approximately 65%. In contrast, in this embodiment, we have found that fine aggregate with some angularity, rather than rounded fine aggregate, is effective as an anchor fixing material. Previous research by the inventors has shown that the adhesive properties of inorganic anchors are maintained by the adhesion between the drilled concrete and the injection material. When bonding existing concrete to the anchoring material, angular aggregate (heavy-weight aggregate) fractures at a more curved interface than rounded aggregate (silica sand), resulting in higher bond strength (pull-out strength).

[0012] That is, if the actual area ratio is less than 45%, the insertion resistance when inserting reinforcing bars, etc. will increase. Also, if the actual area ratio exceeds 65%, the adhesive strength will decrease. The actual area ratio is preferably 48 to 63%, more preferably 50 to 60%, and even more preferably 55 to 59%.

[0013] The volume ratio of heavy aggregate can be adjusted by crushing it with an impact crusher such as a rod mill. This is because the impact crusher instantly reduces the particles, leaving the broken surfaces of the powder as new corners. The actual volume ratio can be calculated using the method specified in JIS A 1104:2006 "Test method for unit volume mass and actual volume ratio of aggregates," but specifically, it can be measured using the method described in the examples.

[0014] Examples of materials for heavy aggregate include crushed sand such as magnetite, hematite, peridotite, ferrochrome slag, ferronickel slag, copper slag, and electric furnace oxidizing slag, and electric furnace oxidizing slag is preferred from the viewpoint of suppressing alkali-aggregate reaction.

[0015] Here, electric furnace oxidizing slag refers to electric furnace slag produced during the melting and refining of iron scrap, and is a slag produced by oxidative refining. The fine aggregate for electric furnace oxidizing slag preferably satisfies the requirements set forth in, for example, JISA 5011-4:2018, "Slag aggregate for concrete - Part 4: Electric furnace oxidizing slag aggregate."

[0016] The density of heavy aggregate is 3.2 g / cm3 from the viewpoint of strength development. 3 It is preferable that the concentration is 3.5 to 4.5 g / cm or more. 3 It is more preferable that:

[0017] From the viewpoint of ease of inserting reinforcing bars, the 2.5 mm sieve residue of the heavy aggregate is preferably 1 mass % or less, and more preferably 0.5 mass % or less. From the same viewpoint, the 1.2 mm sieve residue is preferably 20% by mass or less, and more preferably 15% by mass or less.

[0018] (cement) The cement used in this embodiment is not particularly limited, and examples include various cements such as normal, early-strength, ultra-early-strength, low-heat, and moderate-heat cements; various blended cements obtained by mixing these cements with blast furnace slag, fly ash, silica fume, etc.; environmentally friendly cements (ecocements) produced using municipal waste incineration ash or sewage sludge incineration ash as raw materials; commercially available fine particle cements; and white cements. Various cements and blended cements can also be finely powdered and used. Furthermore, cements prepared by increasing or decreasing the amount of components (e.g., gypsum) normally used in cements can also be used. Furthermore, combinations of two or more of these can also be used. In the present invention, it is preferable to select ordinary Portland cement or high-early-strength Portland cement from the viewpoint of high strength development and increased bond strength.

[0019] The cement used in the present invention has a Blaine specific surface area (hereinafter also referred to as the Blaine value) of 2,500 cm from the viewpoint of production cost and strength development. 2 / g~7,000cm 2 / g, and 2,750 cm 2 / g~6,000cm 2 / g is more preferred. The Blaine specific surface area value is determined in accordance with JIS R 5201 (physical testing method for cement).

[0020] (Sudden hardwood) The hardening agent used in this embodiment is specifically calcium aluminate, calcium fluoroaluminate (C 11 Examples of suitable powders include powders containing calcium aluminate (3CaO·3Al2O3·CaSO4), calcium sulfoaluminate (3CaO·3Al2O3·CaSO4), etc. However, from the viewpoint of high early strength development and better adhesive strength due to expandability, it is preferable to use powders containing calcium aluminate and gypsum powder.

[0021] Calcium aluminate powder The calcium aluminate powder is a general term for a substance having hydration activity and containing CaO and Al2O3 as its main components, which is obtained by mixing a calcia raw material, an alumina raw material, or the like, and firing it in a kiln or by melting it in an electric furnace and cooling it. Either crystalline or amorphous calcium aluminate powder can be used.

[0022] The calcium aluminate powder may contain SO3 as a chemical component, and the content of SO3 in the calcium aluminate powder is preferably 1.0 mass % or less, and more preferably 0.01 to 0.9 mass %.

[0023] The molar ratio of CaO to Al2O3 (CaO / Al2O3 molar ratio) in the calcium aluminate powder is preferably 0.5 to 2.5, and more preferably 0.7 to 2. When the molar ratio is within the above range, early strength development can be further improved. The molar ratio of CaO to Al2O3 can be adjusted to fall within the above range, for example, by adjusting the blending of raw materials during production.

[0024] The particle size of calcium aluminate powder is set to a Blaine specific surface area of ​​3000 to 9000 cm from the viewpoint of strength development and ease of handling. 2 / g, and 4000 to 8000 cm 2 / g is more preferred.

[0025] ·Gypsum powder The gypsum powder used in this embodiment is a general term for anhydrous, hemihydrate, or dihydrate gypsum and is not particularly limited, but from the viewpoint of strength development, anhydrous gypsum or hemihydrate gypsum is preferred, and anhydrous gypsum is more preferred.

[0026] The particle size of the gypsum powder is not particularly limited, but from the viewpoint of ensuring the fluidity retention effect, the Blaine specific surface area is 3,000 to 9,000 cm 2 / g, and 4,000 to 8,000 cm 2 / g is more preferred.

[0027] The content of the gypsum powder is preferably 20 to 120 parts by mass, and more preferably 30 to 110 parts by mass, per 100 parts by mass of the calcium aluminate powder, from the viewpoints of achieving a good fluidity-retaining effect, reducing insertion resistance when installing the anchor, and achieving more reliable strength development.

[0028] In order to ensure the effect more reliably, the total amount of calcium aluminate powder and gypsum powder in the hardening accelerator according to this embodiment is preferably 80 mass % or more, and more preferably 90 mass % or more.

[0029] In this embodiment, the content of heavy aggregate is preferably 50 to 200 parts by mass, and more preferably 70 to 185 parts by mass, per 100 parts by mass of cement, from the viewpoint of reducing insertion resistance when installing the anchor and obtaining better adhesion strength.

[0030] The content of calcium aluminate powder is preferably 30 to 100 parts by mass, and more preferably 50 to 90 parts by mass, per 100 parts by mass of cement, from the viewpoints of achieving a high fluidity retention effect, reducing insertion resistance when driving the anchor, and achieving more reliable strength development.

[0031] In addition, the total proportion of cement, heavy aggregate, and quick-hardening material in the anchor fixing material of this embodiment is preferably 80 mass% or more, and more preferably 90 mass% or more, to more reliably achieve its effect.

[0032] Other ingredients In this embodiment, other components than the cement, the rapid hardening agent, and the heavy aggregate may include, for example, an alkali metal carbonate. By including an alkali metal carbonate, the fluidity retention effect is enhanced, and strength development can be further improved. Examples of alkali metal carbonates include sodium carbonate, potassium carbonate, lithium carbonate, sodium bicarbonate, potassium bicarbonate, and lithium bicarbonate, and combinations of these are also possible. In particular, the use of lithium carbonate is preferred from the viewpoint of strength development.

[0033] The content of the alkali metal carbonate is preferably 1 to 6 parts by mass, more preferably 2 to 5 parts by mass, in terms of solid content, relative to 100 parts by mass of cement.

[0034] Furthermore, from the viewpoint of further enhancing the effect of maintaining fluidity and reducing the insertion resistance when installing the anchor, it is possible to include silica fine powder.

[0035] Examples of the siliceous fine powder include pozzolanic substances such as fly ash and silica fume, with fly ash being preferred.

[0036] The fineness of the silica fine powder is not particularly limited, but the fineness of fly ash is 3,000 cm in Blaine value. 2 / g or more 9,000cm 2 / g or less, and silica fume has a BET specific surface area of ​​20,000 cm 2 / g or more 300,000 cm 2 It is preferable that the range is 1 / g or less.

[0037] The content of the siliceous fine powder is preferably 1 to 20 parts by mass, more preferably 2 to 15 parts by mass, relative to 100 parts by mass of cement.

[0038] In the present invention, it is possible to use an antifoaming agent within a range that does not adversely affect the performance. The antifoaming agent is used for the purpose of suppressing the amount of air entrained during kneading. The type of defoaming agent is not particularly limited as long as it does not significantly adversely affect the strength properties of the hardened mortar, and either liquid or powder form can be used. Examples include polyether-based defoaming agents, polyhydric alcohol-based defoaming agents such as polyhydric alcohol esters and alkyl ethers, alkyl phosphate-based defoaming agents, and silicone-based defoaming agents.

[0039] The content of the antifoaming agent is preferably 0.002 to 0.5 parts by mass, and more preferably 0.005 to 0.45 parts by mass, relative to 100 parts by mass of cement.

[0040] In this embodiment, at least one of the following may be used as needed: a setting retarder, a foaming agent, a water reducing agent, a setting adjuster, an air-entraining agent, an anti-rust agent, a water repellent, an antibacterial agent, a colorant, an antifreeze agent, admixtures such as limestone fine powder, slowly cooled blast furnace slag fine powder, sewage sludge incineration ash and its molten slag, municipal waste incineration ash and its molten slag, and pulp sludge incineration ash; a thickener; a shrinkage reducing agent; a polymer; clay minerals such as bentonite and sepiolite; and an anion exchanger such as hydrotalcite.

[0041] The anchor fixing material of this embodiment can be prepared by mixing the respective materials and, if necessary, pulverizing them. The method for mixing the respective materials is not particularly limited, and the respective materials may be mixed at the time of construction, or some or all of them may be mixed in advance. As the mixing device, any existing device such as a tilting mixer, an omni mixer, a Henschel mixer, a V-type mixer, a Plosser mixer, and a Nauta mixer can be used.

[0042] [Anchor fixing method] The anchor fixing method of this embodiment is a method for fixing an anchor to an object to be fixed using the anchor fixing material of the present invention. Specifically, examples of such methods include mixing (kneading) the anchor fixing material with water to form an anchor fixing composition, filling this into a hole using a pump or the like, and then inserting the anchor into the hole; or immersing the anchor fixing material in a container such as a cartridge or bag in water, inserting it into the hole in an absorbed state, and then pushing the anchor into the hole. Examples of the object to be fixed include a concrete structure, a brick structure, and the like. [Example]

[0043] The present invention will be further explained below based on experimental examples of the present invention, but the present invention is not limited to these.

[0044] [Experimental Example] For 100 parts by mass of cement, fly ash (commercially available, Blaine value: 3,500 cm 2 A mixture of 4 parts by mass of cement paste (100g / g), 0.9 parts by mass of a setting regulator (commercially available product, Denka Setter D-300), 0.3 parts by mass of a thickener (commercially available product, methyl cellulose), and 0.14 parts by mass of an antifoaming agent (commercially available product, oxyalkylene-based) was mixed, and then rapid hardening material and aggregate were added to obtain the parts by mass shown in Table 1 to obtain an anchor fixing material. 100 parts by mass of the resulting anchor fixing material was kneaded with 18 parts by mass of water to prepare an anchor fixing material composition. The prepared anchor fixing material compositions were measured for anchor insertion resistance and anchor adhesion strength. The results are shown in Table 1.

[0045] <Materials used> Cement: High-early-strength Portland cement (manufactured by Denka Co., Ltd.) - Hardening agent: A mixture of equal parts of calcium aluminate powder and gypsum powder. Calcium aluminate was made by blending CaO raw material (calcium carbonate), Al2O3 raw material (aluminum oxide), and SiO2 raw material (silicon dioxide), and then firing at 1,500°C to synthesize clinker. The chemical composition of the clinker was 43% by mass of CaO, 44% by mass of Al2O3, 10% by mass of SiO2, and 3% by mass of others. The clinker was milled using a ball mill to obtain a Blaine specific surface area of ​​5,000 cm 2 The gypsum powder was commercially available anhydrous gypsum powder (Blaine specific surface area: 5,000 cm). 2 / g) was used. Water: Tap water Aggregate A: Commercially available heavy aggregate (electric furnace oxidized slag, size 0.6-1.2 mm, bone dry density 3.91 g / cm 3 , actual floor rate 56%) Aggregate B: Commercially available heavy aggregate (electric furnace oxidized slag, size 0.3-0.6 mm, bone dry density 3.91 g / cm 3 , actual area rate 55%) Aggregate C: Aggregate A and Aggregate B mixed in a mass ratio of 60:40 (full volume ratio 59%) Aggregate D: Lightweight aggregate (commercially available silica sand, size 1.2 mm or less, bone dry density 2.6 g / cm 3, actual floor rate 56%) Aggregate E: Commercially available heavy aggregate (electric furnace oxidized slag, size 0.6-1.2 mm, bone dry density 3.91 g / cm 3 , actual floor rate 44%) Aggregate F: Commercially available heavy aggregate (electric furnace oxidized slag, size 0.6-1.2 mm, bone dry density 3.91 g / cm 3 , actual floor rate 66%)

[0046] The actual volume ratio of the aggregate was calculated as follows: a) Calculation of unit volume mass The aggregate sample was kept in an absolute dry state. A container with a volume of 495.7 ml was used. A metal round rod with a diameter of 16 mm and a length of 550 mm and a hemispherical tip was used as the poker. The sample was placed into the container up to 1 / 3 of the way, the top surface was smoothed with a finger, and the poker was used to poke it evenly 20 times. Next, the container was filled up to 2 / 3 of the way, and the poker was repeated the same number of times as above. Finally, the container was filled with sample until it overflowed, and the poker was repeated the same number of times as above. The excess sample was scraped off using a spatula as a ruler, and smoothed along the top surface of the container. After smoothing the surface of the aggregate, the mass of the sample in the container was measured, and the unit volume mass was calculated using the following formula. Unit volume mass = mass of sample in container ÷ volume of container

[0047] b) Calculation of performance rate The performance rate was calculated using the following formula: Actual rate = unit volume mass / bone dry density

[0048] <Evaluation items> (insertion resistance) The test conditions for insertion resistance are shown below. Anchor bars: D13 ·Material: SD295A ·Drilling diameter: φ18mm Embedded length: 91mm Nominal strength of base concrete: 21N / mm 2 After forming a hole in the concrete, an anchoring material was injected, and the length to which the reinforcing bar could be inserted was measured to determine the insertion resistance. Anchor insertion resistance (%) = length of rebar inserted / 91 mm x 100

[0049] (adhesion strength) A bond strength test was conducted in accordance with the JCAA's "Post-Installed Anchor Test." The conditions for the bond strength test were as follows: The anchor bars were pulled out with a jack after one day of age, and the bond strength per surface area of ​​the rebar was measured. Anchor bars: D13 ·Material: SD295A ·Drilling diameter: φ18mm Embedded length: 91mm Nominal strength of base concrete: 21N / mm 2

[0050] [Table 1] [Industrial Applicability]

[0051] The anchor fixing material of the present invention can be widely applied in the fields of civil engineering and construction, such as fixing reinforcing steel bars to concrete structures and brick structures used in water supply and sewage systems, agriculture and water supply, railways, electricity, roads, and construction.

Claims

1. An anchor fixing material comprising cement, a rapid hardening material, and a heavy aggregate, the heavy aggregate having a volumetric ratio of 45 to 65%.

2. 2. The anchor fixing material according to claim 1, wherein the content of the heavy aggregate relative to 100 parts by mass of the cement is 50 to 200 parts by mass.

3. The density of the heavy aggregate is 3.2 g / cm ３ The anchor fixing material according to claim 1, wherein the anchor fixing material is as described above.

4. 2. The anchor fixing material according to claim 1, wherein the 2.5 mm sieve residue of the heavy aggregate is 1% by mass or less.

5. 2. The anchor fixing material according to claim 1, wherein the hardening agent comprises calcium aluminate powder and gypsum powder.

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