Accelerator and fast-hardening concrete

Abstract

To provide calcium aluminate having a quick setting property and emitting only an allowable small amount of odor, and a quick setting agent and quick setting concrete using the same.SOLUTION: Calcium aluminate includes CaO, Al2O3, and P2O5 as chemical components, in which the P2O5 is contained 0.01-0.8 mass% relative to the total mass of the calcium aluminate.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a calcium aluminate, and to an accelerator and rapid-hardening concrete using the same. [Background technology]

[0002] Fast-hardening materials that are often used for emergency repairs in concrete product manufacturing, construction work, and civil engineering work are mainly composed of calcium aluminate. Examples of such materials include the quick-setting agent for sprayed concrete used in tunnel excavation using the NATM method.

[0003] For example, Patent Document 1 describes SiO 2 , B 2 O 3 , P 2 O 5 A calcium aluminate-based cement quick-setting admixture containing such components is disclosed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 8-104556 Summary of the Invention [Problem to be solved by the invention]

[0005] Shotcrete materials are required to have excellent hardening properties such as rapid hardening, but in recent years, there has also been a demand for improvements in the working environment for workers who perform the spraying work. In closed spaces such as tunnels, the dust and odors generated during spraying are a problem for workers. Various methods for reducing dust have been considered up to now, but sufficient consideration has not been given to the odor.

[0006] Therefore, an object of the present invention is to provide a calcium aluminate having rapid setting properties and sufficiently little odor, and a quick-setting admixture and rapid-hardening concrete using the same. [Means for solving the problem]

[0007] As a result of extensive research into the above-mentioned problems, the present inventors have found that P contained in calcium aluminate 2 O 5 It has been found that by setting the content of within a specific range, it is possible to ensure rapid setting while sufficiently suppressing odor.

[0008] That is, the present invention is as follows. [1] Chemical components: CaO, Al 2 O 3 , P 2 O 5 A calcium aluminate containing P based on the total mass of the calcium aluminate. 2 O 5 The calcium aluminate has a content of 0.01 to 0.8 mass%. [2] CaO and Al 2 O 3 The molar ratio of CaO / Al 2 O 3 ) is 1.8 to 2.7. [3] A quick-setting admixture comprising the calcium aluminate according to [1] or [2]. [4] A fast-hardening concrete comprising cement and the accelerator described in [3]. Effect of the Invention

[0009] According to the present invention, it is possible to provide calcium aluminate having rapid setting properties and sufficiently little odor, as well as a quick-setting admixture and rapid-hardening concrete using the same. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, one embodiment of the present invention will be described in detail.

[0011] The calcium aluminate of this embodiment contains CaO, Al as chemical components. 2 O 3 , P 2 O 5 A calcium aluminate containing P based on the total mass of the calcium aluminate. 2 O 5 The content is 0.01 to 0.8 mass %.

[0012] Calcium aluminate is composed of CaO and Al 2 O 3 It is an inorganic hydrated active substance whose main chemical component is calcium aluminate. The mineral composition of calcium aluminate is not particularly limited, and it is CaO·2Al 2 O 3 , CaO 6Al 2 O 3 , CaO·Al 2 O 3 , 12CaO 7Al 2 O 3 , 3CaO·Al 2 O 3 In addition, examples include minerals and amorphous materials containing elements such as Na, Li, K, and S.

[0013] Calcium aluminate P 2 O 5 The content of P is 0.01 to 0.8 mass% based on the total mass of calcium aluminate. 2 O 5 If the content is outside the above range, it becomes difficult to suppress odor while maintaining quick setting properties. 2 O 5 From the viewpoint of further suppressing odor, the content of is preferably 0.01 to 0.7 mass %, and more preferably 0.02 to 0.5 mass %, relative to the total mass of calcium aluminate.

[0014] CaO and Al 2 O 3 The molar ratio of CaO / Al 2 O 3) is preferably 1.8 to 2.7, more preferably 2.0 to 2.65, and even more preferably 2.2 to 2.6. 2 O 3 If the molar ratio of the calcium aluminate is within the above range, the rapid setting property is further improved. 2 O 3 Other components such as impurities may also be contained within a range that does not impair the effects of the present invention, regardless of the form in which they are present.

[0015] CaO and Al 2 O 3 The total content of CaO and Al is preferably 75 to 99.9 mass%, more preferably 80 to 99.5 mass%, and even more preferably 85 to 99 mass%, based on the total mass of calcium aluminate. 2 O 3 When the total content is within the above range, the quick setting property tends to be improved.

[0016] Calcium aluminate may be crystalline, amorphous, or a mixture thereof. From the viewpoint of obtaining a better quick-setting property, calcium aluminate preferably has a vitrification rate, which is the degree of amorphization, of 60% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. The fineness of calcium aluminate is not particularly limited, but since it is easy to obtain an appropriate reaction activity when used as a quick-setting admixture for concrete, it is preferable that the fineness is the same as or higher than that of cement in the hydraulic composition to be mixed, and for example, a Blaine specific surface area of ​​3000 to 6500 cm 2 The powder size is 0.1 to 1.0 μm / g.

[0017] The calcium aluminate of the present embodiment may contain components other than those described above, provided that the effects of the present invention are not impaired. Examples of such components include SiO 2 , which does not significantly contribute to odor generation. 2 , TiO 2 , MgO, etc.

[0018] Calcium aluminate is, for example, a raw material that serves as a CaO source, Al 2 O 3 Source of raw materials and P 2 O 5 The raw materials are mixed so that the desired content of chemical components is obtained, and the mixture is heated until melted. In addition, since the structural state of calcium aluminate after cooling varies depending on the cooling process after heating during production, the vitrification rate, which is the degree of amorphization, can be adjusted depending on the cooling conditions such as the cooling rate. For heating, any method using a melting furnace such as a rotary kiln, an electric furnace or a reverberatory furnace can be suitably used.

[0019] The quick-setting admixture according to the present embodiment may contain, in addition to calcium aluminate, an alkali metal sulfate, an alkaline earth metal sulfate, aluminum sulfate, an alkali metal carbonate, an alkali metal silicate, or the like.

[0020] The content of calcium aluminate is preferably 40 to 90 mass%, more preferably 50 to 85 mass%, further preferably 70 to 83 mass%, and particularly preferably 75 to 82 mass%, based on the total mass of the quick-setting admixture. If the content of calcium aluminate is within the above range, the quick-setting property, workability, and strength development will be further improved.

[0021] The alkaline earth metal sulfate is not particularly limited and any of them can be used, and it is preferable to use an anhydride from the viewpoint of more excellent strength development. Examples of alkaline earth metals include magnesium and calcium, and among them, calcium is preferable. The alkaline earth metal sulfate may be used alone or in combination of two or more kinds. The particle size and grain size of the alkaline earth metal sulfate are also not particularly limited, and for example, an anhydride having a Blaine specific surface area of ​​3000 to 10000 cm is preferable. 2 / g. The content of the alkaline earth metal sulfate is preferably 5 to 55 mass%, more preferably 7 to 40 mass%, further preferably 8 to 25 mass%, and particularly preferably 9 to 15 mass parts, calculated as an anhydride based on the total mass of the quick-setting admixture. If the content of the alkaline earth metal sulfate is within the above range, it is likely to exhibit excellent long-term strength development.

[0022] Aluminum sulfate may be in any form, for example, 16-hydrate, anhydrous, etc., among which 16-hydrate is preferred. The content of aluminum sulfate is preferably 5-25 mass% in anhydrous equivalent to the total mass of the quick-setting admixture, more preferably 7-20 mass%, and even more preferably 9-15 mass%. If the content of aluminum sulfate is within the above range, it is easy to ensure long-term strength development even when the quick-setting property is increased in a low-temperature environment.

[0023] The quick-setting admixture according to the present embodiment is produced by mixing the above-mentioned components. The mixing method is not particularly limited, and for example, a general-purpose mixer such as a tilting mixer, a pan mixer, a two-shaft mixer, a grout mixer, a Hobart mixer, or an Omni mixer can be used.

[0024] The quick-setting admixture of the present embodiment can be mixed with cement, aggregate, water, etc. to prepare rapid-hardening concrete. The content of the quick-setting admixture is preferably 6 to 14 parts by mass, more preferably 6.5 to 12 parts by mass, and even more preferably 7 to 10 parts by mass, relative to 100 parts by mass of cement. If the content of the quick-setting admixture is within the above range, it is easy to achieve both rapid setting and workability.

[0025] The cement is preferably Portland cement, and any type of Portland cement may be used, for example, various types of Portland cement such as normal, early strength, super early strength, moderate heat, low heat, and sulfate resistant Portland cement. As the cement, a mixed cement containing Portland cement, such as blast furnace cement or fly ash cement, may also be used. One type of cement may be used alone, or two or more types may be used in combination. When using Portland cement, the particle size is not particularly limited, and for example, the 2500 cm 2 / g or more.

[0026] Examples of aggregates include fine aggregate and coarse aggregate. The fine aggregate is not particularly limited as long as it is a fine aggregate that can be used in mortar or concrete. The coarse aggregate is not particularly limited as long as it is a coarse aggregate that can be used in concrete. Both fine aggregate and coarse aggregate are suitable for use in concrete because they can easily ensure a predetermined aggregate strength and have a small difference in specific gravity with other contained components, making them less likely to cause material separation, and therefore have a surface dry density of 2.3 to 2.9 g / cm. 3 It is preferable to use aggregates such as those mentioned above. Specific examples of such aggregates include fine aggregates such as natural aggregates, such as river sand and sea sand, and crushed sands, such as silica stone, limestone, andesite, sandstone, and basalt, and coarse aggregates such as crushed stones, such as silica stone, limestone, andesite, sandstone, and basalt, and natural aggregates, such as river gravel. One type of aggregate may be used alone, or two or more types may be used in combination.

[0027] The content of aggregate in the rapid hardening concrete is not particularly limited, but from the viewpoint of excellent concrete pumpability during construction, the total of fine aggregate and coarse aggregate is preferably 300 to 600 parts by mass, more preferably 330 to 580 parts by mass, and even more preferably 360 to 570 parts by mass per 100 parts by mass of cement. When fine aggregate and coarse aggregate are used in combination, the mass ratio of fine aggregate to the total aggregate is preferably 50 to 69% by mass, more preferably 53 to 65% by mass, and even more preferably 56 to 63% by mass.

[0028] The rapid hardening concrete of the present embodiment may contain components other than those described above, provided that the effects of the present invention are not impaired. Examples of components that may be contained include accelerators, retarders, thickeners, dispersants, shrinkage reducing agents, defoamers, air-enhancing agents, expansive materials, fibers, water retention agents, pozzolanic reactive substances, ground granulated blast furnace slag, silica powder, limestone powder, alumina powder, and the like.

[0029] The amount of water in the rapid hardening concrete of this embodiment can be adjusted appropriately depending on factors such as the purpose and location of use. The water content is preferably 15 to 100 parts by mass, more preferably 20 to 90 parts by mass, and even more preferably 25 to 80 parts by mass, relative to 100 parts by mass of cement. If the water content is within the above range, the concrete is likely to have excellent fluidity and strength development.

[0030] The fast-setting concrete may be produced by mixing the above-mentioned components, or may be produced using a spraying device. When mixing, the mixing method is not particularly limited, and for example, a general-purpose mixer such as a tilting mixer, a pan mixer, a two-shaft mixer, a grout mixer, a Hobart mixer, or an omni mixer may be used. When using a spraying device, for example, each material except for the quick-setting admixture is mixed with water to form a base concrete, and the base concrete and the quick-setting admixture are mixed at the tip of a spray nozzle and sprayed by a wet spraying method, or each material including the quick-setting admixture is mixed to form a base composition, and the base composition and water are mixed at the tip of a spray nozzle and sprayed by a dry spraying method.

[0031] The calcium aluminate of the present embodiment and the quick-setting admixture and rapid-hardening concrete using the same have little odor while ensuring quick setting. Therefore, in addition to normal applications, they can be suitably used for spraying work in closed spaces, and the adverse effects on workers can be further reduced. EXAMPLES

[0032] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0033] The materials used in the examples are as follows: Calcium raw material: Calcium carbonate (industrial raw material) Aluminum raw material: Alumina (industrial raw material) Phosphorus raw material: Tricalcium phosphate (industrial raw material)

[0034] [Preparation of calcium aluminate clinker] Various raw materials were mixed and melted and fired in an electric furnace to prepare calcium aluminate clinker so as to obtain the chemical composition shown in Table 1. The firing temperature in the electric furnace was 1550±50°C, and the molten material was cooled in an air stream to obtain a clinker sample.

[0035] The vitrification rate of calcium aluminate clinker was determined by using a powder X-ray diffractometer to quantify the mass of each mineral contained in calcium aluminate clinker with mass M1 by an internal standard method or the like, calculating the total mass of the mineral phases that could be quantified; M2, and assuming the remainder to be a pure glass phase, using the following formula. Vitrification rate (mass%)={1-(M2 / M1)}×100

[0036] [Table 1]

[0037] [Preparation of Accelerator] Calcium aluminate clinkers A to F were pulverized in a ball mill to obtain a Blaine specific surface area of ​​5000±500cm. 2 The calcium aluminate powder was obtained by adjusting the grinding time so that the calcium aluminate powder had a particle size of 1 / g. 80 parts by mass of each calcium aluminate powder was mixed with 10 parts by mass of aluminum sulfate powder and 10 parts by mass of calcium sulfate powder, and mixed in a Henschel mixer to prepare quick-setting agents A to F.

[0038] [Various measurements] The methods for evaluating each performance are shown below, and the evaluation results are shown in Table 2. (1) Evaluation with fast-hardening concrete - Preparation of fast hardening concrete Cement 360kg / m 3 , fine aggregate 983kg / m 3 , coarse aggregate 700kg / m 3 , water 216kg / m 3 The mixture was mixed to prepare the base concrete. The base concrete was placed in a supply tank and pumped to the spraying device. The quick-setting agent was mixed near the spray nozzle at the tip of the spraying device and sprayed onto the mock tunnel. The amount of quick-setting agent added was 12 parts by mass per 100 parts by mass of cement. Odor evaluation The quick-hardening concrete was sprayed into the simulated tunnel. If the worker in the simulated tunnel noticed even the slightest odor, it was marked as "X", and if no odor was noticed, it was marked as "O". - Rapid hardening evaluation If even a small amount of the concrete sprayed onto the simulated tunnel wall spalled off, it was marked as "X", and if no spalling was observed, it was marked as "O".

[0039] (2) Evaluation with fast-hardening cement paste Preparation of fast hardening cement paste 400g of ordinary Portland cement and 200g of water were placed in a 500cc cylindrical container with a bottom, mixed with a hand mixer for about 1 minute, and then left to stand for about 30 minutes indoors at a temperature of 10°C. After standing, the cement paste was kneaded with the hand mixer for about 1 minute, to which 48g of an accelerator was added and stirred for 5 seconds to prepare a rapid-hardening cement paste. - Rapid hardening evaluation The rapid hardening property of the accelerator was evaluated by measuring the Proctor penetration resistance value at 10°C for the cement composition paste 30 seconds after the addition of the accelerator.

[0040] [Table 2]

Claims

1. Chemical composition: CaO, Al ２ O ３ , P ２ O ５ A calcium aluminate comprising: The P relative to the total mass of the calcium aluminate ２ O ５ The calcium aluminate has a content of 0.01 to 0.8 mass %; and aluminum sulfate, A setting accelerator that does not contain sodium aluminate.

2. In the chemical composition of the calcium aluminate, the CaO and the Al ２ O ３ The molar ratio of CaO / Al ２ O ３ 2. The quick-setting admixture according to claim 1, wherein the average molecular weight of the polymer is 1.8 to 2.

7.

3. The quick-setting admixture described in claim 1 or 2, further containing an alkali metal sulfate, an alkaline earth metal sulfate, an alkali metal carbonate, or an alkali metal silicate.

4. A fast-setting concrete comprising cement and the quick-setting admixture according to any one of claims 1 to 3.

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