JP5026928B2 - Quick set and spray material - Google Patents

Description

  The present invention relates to a quick setting agent and a spraying material used in a spraying method suitable for construction work such as tunnels, underground spaces, and slopes, and in particular, a quick setting agent and a high initial strength spraying that can obtain a spraying material having a high initial strength. Regarding materials.

In construction works such as tunnels, underground spaces, and slopes, spraying methods using spraying materials such as shotcrete are used. The general spraying method is to send cement kneaded material such as base concrete and quick setting agent through different transport pipes in different paths, and after merging and mixing in the middle of the pumping, it is sprayed on the ground from the tip of the spray nozzle It is done.
In recent years, spray materials have high initial strength in order to improve economic efficiency and work efficiency by shortening the construction cycle, and to improve safety without increasing the spray thickness. Is required. As an example, a spray material containing a cement mortar mainly composed of cement and gypsum and a quick setting agent mainly composed of calcium aluminates is known (for example, see Patent Document 1).
However, there is a need for a spray material that has a higher initial strength than conventional ones.
Japanese Patent No. 3421794

  An object of this invention is to provide the quick setting agent from which high initial intensity | strength is obtained, and the spraying material which can obtain high initial intensity | strength including this.

As a result of intensive studies for solving the above problems, the present inventors have found that a high initial strength can be obtained by incorporating specific calcium aluminates into the quick setting agent, and have completed the present invention.
That is, the present invention is a quick setting agent characterized by containing amorphous calcium aluminates and crystalline calcium aluminates.
Moreover, this invention is a spraying material formed by adding the said quick setting agent to the cement kneaded material containing water, cement, and gypsum.

  According to the present invention, a spray material having a high initial strength can be obtained. When the spray material of the present invention is sprayed on a natural ground or the like, it is possible to shorten the construction cycle and to obtain a highly safe spray material. Moreover, since the construction cycle can be shortened, the construction cost can also be suppressed.

The amorphous calcium aluminates and crystalline calcium aluminates used in the present invention can be obtained by heat-treating a CaO raw material and an Al ₂ O ₃ raw material. Calcium aluminates include calcium aluminate, calcium haloaluminate, calcium sodium aluminate, calcium sulfoaluminate, and those in which SiO ₂ , K ₂ O, Fe ₂ O ₃ , TiO _2, etc. are dissolved or combined. One kind or two or more kinds selected from the group can be used.

Amorphous calcium aluminates used in the present invention can be obtained by melting a CaO raw material and an Al ₂ O ₃ raw material and quenching them with water, air or the like. The molar ratio of CaO to Al ₂ O ₃ in the amorphous calcium aluminates is preferably 1.5 to 2.3, more preferably 1.6 to 2.2. If the molar ratio is less than 1.5, the strength is lowered for 10 minutes, and if it exceeds 2.3, the melting temperature of calcium aluminates is increased, so that the production becomes difficult.
Fineness of the amorphous calcium aluminates used in the present invention, from the viewpoint of enhancing the initial intensity of the spray material, preferably 3000 cm ² / g or more in Blaine specific surface area, 5000 cm ² / g or more is more preferable.

Crystalline calcium aluminates used in the present invention are those obtained by heat treating the CaO material and Al ₂ O ₃ raw material, a method for producing firing the CaO material and Al ₂ O ₃ raw material in kiln or the like, the molten It can be obtained by, for example, a method of removing the heat from the furnace.
The crystalline calcium aluminates preferably have a molar ratio of CaO to Al ₂ O ₃ of 0.5 to 1.5, more preferably 0.8 to 1.4. When the molar ratio is less than 0.5, the initial strength is lowered, and when it exceeds 1.5, the strength for 1 to 3 hours is lowered.
Crystalline calcium fineness of aluminates used, from the viewpoint of enhancing the initial intensity of the spray material, preferably 3000 cm ² / g or more in Blaine specific surface area, 5000 cm ² / g or more is more preferable.

  The blending ratio of the amorphous calcium aluminate and the crystalline calcium aluminate is preferably 5 to 500 parts by weight of the crystalline calcium aluminate with respect to 100 parts by weight of the amorphous calcium aluminate. Part by weight is more preferred. If the amount is less than 5 parts by weight, it is difficult to obtain the effect of the present invention. If the amount exceeds 500 parts by weight, the quick setting necessary for required spraying may not be obtained.

  It is preferable that the quick setting agent of the present invention contains an alkali carbonate in addition to amorphous calcium aluminates and crystalline calcium aluminates since the strength of the initial age can be further increased. Examples of the alkali carbonate used include sodium carbonate, potassium carbonate, and lithium carbonate. The amount of alkali carbonate used is preferably 0.1 to 30 parts by weight, more preferably 0.5 to 20 parts by weight, based on 100 parts by weight of calcium aluminates. If it is less than 0.1 part by weight, the effect cannot be expected, and if it is 30 parts by weight or more, the long-term strength may be lowered.

  If the quick setting agent of the present invention further contains alkali sulfate, it is preferable because the strength until the age of 1 day is increased. Examples of the alkali sulfate include sodium sulfate, potassium sulfate, and lithium sulfate. The amount of alkali sulfate used is preferably 1 to 30 parts by weight, more preferably 5 to 20 parts by weight, per 100 parts by weight of calcium aluminates. If it is less than 1 part by weight, the daily strength does not increase, and if it is 30 parts by weight or more, the long-term strength may decrease.

Furthermore, an alkali aluminate may be added to the quick setting agent of the present invention in order to improve quick setting at low temperatures. The amount of alkali aluminate used is preferably 0.5 to 20 parts by weight, more preferably 1.0 to 10 parts by weight, per 100 parts by weight of calcium aluminates. If it is less than 0.5 part by weight, quick setting may not be obtained at low temperatures, and if it is 10 parts by weight or more, long-term strength may be reduced.
In addition to the above materials, materials such as aluminum sulfate, gypsum and lime may be used for the quick setting agent of the present invention.

The spraying material of the present invention is obtained by adding the rapid setting agent to a cement kneaded material containing water, cement and gypsum. In this spray material, it is preferable that SO ₃ contained in the cement kneaded material is used in a state exceeding 3.5 parts by weight with respect to 100 parts by weight of cement and gypsum.

The gypsum used here is not particularly limited, and one kind or two or more kinds selected from anhydrous gypsum, hemihydrate gypsum, and dihydrate gypsum can be used. Anhydrous gypsum can be used for both type III anhydrous gypsum and type II anhydrous gypsum, but in order to improve the fluidity of the cement kneaded material before addition of the quick setting agent when reducing the water-cement ratio, II Gypsum containing type anhydrous gypsum is preferred, and gypsum containing 70-100% by weight of type II anhydrous gypsum is more preferred.
Further, the powder of the gypsum, in order to obtain a high initial strength using a smaller amount of gypsum, preferably 5000 cm ² / g or more in Blaine specific surface area, 5000~15000cm ² / g is more preferable.

  The method of adding and mixing gypsum into the cement kneaded material is not particularly limited. For example, it can be added and mixed in cement, added and mixed in an admixture excluding the quick setting agent, or separately mixed with gypsum alone. Well, you may combine these.

The amount of gypsum used in the spray material of the present invention is preferably such that the SO ₃ contained in the cement kneaded material exceeds 5 parts by weight with respect to 100 parts by weight of the total of cement and gypsum. If the SO ₃ contained in the cement kneaded material is 5 parts by weight or less, the initial strength of the spray material may be insufficient. In order to increase the long-term strength of the spray material, this amount is preferably more than 5 parts by weight and 20 parts by weight or less, more preferably more than 5 parts by weight and 15 parts by weight or less, most preferably more than 5 parts by weight and more than 10 parts by weight. Or less.

  The cement used in the present invention is normal, early strength, very early strength, moderate heat, low heat Portland cement such as Portland cement, mixed cement such as blast furnace cement and fly ash cement, municipal waste incineration ash and sewage sludge incineration Examples include eco-cement using waste such as ash as raw material, and one or more of these can be used. To obtain high initial strength, ordinary Portland cement, early-strength Portland cement, It is preferable to use one or more selected from ultra-early strong Portland cement or eco-cement.

  The cement kneaded material used in the present invention contains at least water, cement and gypsum, and in the range not impairing the effects of the present invention, if necessary, further add aggregates and admixtures that can be used in mortar and concrete. Also good.

Examples of the aggregate include river sand, land sand, sea sand, crushed sand, quartz sand, river gravel, land gravel, crushed stone, and artificial aggregate, and one or more of these can be used.
Examples of admixtures include high performance water reducing agents, high performance AE water reducing agents, water reducing agents including AE water reducing agents and fluidizing agents, pozzolans such as silica fume, latent hydraulic materials such as blast furnace slag, stone powder, and resin emulsions. , Expansion agent, foaming agent, foaming agent, rust preventive agent, pigment, fiber, water repellent, waterproofing material, antifoaming agent, setting retarder, curing accelerator, dust reducing agent, shrinkage reducing agent, thickening agent, Examples thereof include a non-separable admixture in water, and one or more of these can be used as long as the effects of the present invention are not impaired.

The above-mentioned cement kneaded material is obtained by kneading water, cement and gypsum and, if necessary, an aggregate and an admixture with a mixer such as a mortar mixer or a concrete mixer.
The order of adding each material is not particularly limited. One by one may be added, or part or all may be added simultaneously.

  The method for producing and using the spray material of the present invention is not particularly limited. For example, the cement kneaded material and the quick-setting agent can be produced by pumping in separate paths through separate transport pipes, and mixing and mixing in a Y-shaped pipe or the like during the pumping. At this time, a liquid such as water and the quick setting agent of the present invention can be mixed and mixed with the cement kneaded material before the cement kneaded material is added.

Example 1
[Strength test with mortar]
In a thermostatic chamber at 10 ° C., 1090 g of powder obtained by mixing 90 g of gypsum with 1000 g of ordinary Portland cement and 1000 g of fine aggregate were placed in a polyliter having a capacity of 2 liters. Further, 15 g of a high-performance water reducing agent and 385 g of water were added and mixed for 2 minutes at a rotation speed of 1250 rpm using a hand mixer equipped with a stirring blade (diameter 10 cm) to produce a base mortar. The produced mortar is allowed to stand for 30 minutes and then kneaded again for 55 seconds. Then, a predetermined amount of quick setting agent (Tables 1 and 2) is added for 5 seconds and further kneaded for 5 seconds to produce a quick-setting cement kneaded product did. The produced quick-hardening mortar is immediately filled into a simple metal mold (trade name “Summit Mold”) having an inner diameter of 5 cm and a length of 10 cm, and then stored under conditions of room temperature 20 ° C. and relative humidity 100% until the test material age. The mold was removed immediately before the compressive strength test, and the compressive strength test was performed. In addition, the strength test was performed at each material age with 0 minute immediately after the addition of the quick setting agent. The results are shown in Table 3.

From Table 3, from the quick setting agent No. corresponding to the examples of the present invention. 4-No. 10 is given, both the compressive strength at the age of 10 minutes 5N / mm ² or more, and the strength at the age of 3 hours 18N / mm ² or more, it is understood that the compressive strength at early ages is excellent.

Example 2
Effect of Lithium Carbonate The test was conducted in the same manner as in Example 1 using the rapid setting agent shown in Table 4. The results are shown in Table 5.

  From Table 5, it can be seen that by combining amorphous calcium aluminates, crystalline calcium aluminates and lithium carbonate, higher 1 hour strength and 3 hours strength can be obtained.

Example 3
Effect of sodium sulfate The test was conducted in the same manner as in Example 1 using the rapid setting agent shown in Table 6. The results are shown in Table 7.

  From Table 7, when alkali sulfate is added to amorphous calcium aluminates and crystalline calcium aluminates, when the setting rate of the quick-setting agent is increased, a higher material age of 5 minutes strength, material age of 1 hour strength, material age It can be seen that a 3 hour strength and a 24 hour strength are obtained.

Example 4
Effect of sodium aluminate The following test was conducted using the quick setting agent having the composition shown in Table 8 below.

Rapid setting test using cement paste In a constant temperature room at various temperatures, 545 g of powder obtained by mixing 45 g of gypsum with 500 g of ordinary Portland cement is put into a cylindrical plastic container having an inner diameter of 12 cm and a depth of 16 cm. 8 g of the agent was added and mixed for 1 minute at a rotation speed of 1,000 rpm using a hand mixer with a stirring wing having a diameter of 4 cm to produce a cement paste corresponding to the base concrete, and then kneaded for 30 minutes. The cement paste kneaded for 30 minutes was further mixed for 1 minute, added in the amount shown in the table to 100 parts by weight of cement, and stirred for 5 seconds to prepare a quick setting cement paste corresponding to the spray material. The resistance value when the penetration needle made of a round steel with a diameter of 5 mm with a flat tip was penetrated into the produced quick setting cement paste for 1 inch, that is, a proctor penetration resistance value was measured. In addition, the tester penetration resistance value was set to 0 seconds immediately after the addition of the quick setting agent, and the test was performed at each material age. The results are shown in Table 9.

  From Table 9, it can be seen that the rapid setting property at low temperatures is good when the quick setting agent of the present invention further containing sodium aluminate is used.

[Concrete spray test]
Base concrete corresponding to the cement kneaded material having the composition shown in Tables 10 and 11 was kneaded with a pan-type mixer having a capacity of 100 liters. The mixing method is to put coarse aggregate, a part of fine aggregate, cement, gypsum, and fine aggregate in the remaining order into the mixer, mix for 15 seconds, and then add separately mixed water and high-performance water reducing agent. It put in the mixer and kneaded for a predetermined time.
The manufactured base concrete was transferred to a tilting-type mixer having a capacity of 100 liters, allowed to stand for 30 minutes, and then kneaded again with the tilting-type mixer for 1 minute. The base concrete kneaded again is pumped using a spraying device (trade name “Aliba 260”), and pumped separately using a quick-setting agent supply device (trade name “Q Gun” manufactured by Nihon Pribrico Co., Ltd.). The quick setting agent (formulation No. 14 in Table 8, 12 parts by weight with respect to 100 parts by weight of cement) and Y-tube were mixed and mixed to produce quick-hardening concrete, that is, quick-hardening cement kneaded material.

In order to evaluate the workability of the spray material, the initial strength of the spray material is measured according to JSCE-G 561-1999 “Testing method of initial strength of sprayed concrete by drawing method”. The compressive strength was determined by multiplying the value by 4.
In addition, after the first day of age, specimens were collected from the concrete sprayed according to JIS A-F 561-2005 “How to make specimens for compressive strength test of shotcrete (mortar)” (draft). JIS A 1107: 2002 The test was conducted according to “2. Method for collecting core from concrete and test method for compressive strength”. The results are shown in Table 12.

  From Table 12, it can be seen that the concrete using the quick setting agent of the present invention (formulation No. 14 in Table 8) further containing sodium aluminate has excellent long-term strength.

Claims (4)

Amorphous calcium aluminates and crystalline calcium aluminates are contained, the molar ratio of CaO to Al ₂ O ₃ in the amorphous calcium aluminates is 1.6 to 2.2, and crystalline calcium aluminate the molar ratio of CaO with respect to Al ₂ O ₃ in the aluminates is Ri der 0.8 to 1.4, the content ratio of the amorphous calcium aluminates and crystalline calcium aluminates are, by weight, 100: 5-100: quick-setting admixture according to claim 500 der Rukoto.   The quick setting agent according to claim 1, further comprising an alkali carbonate.   The quick setting agent according to claim 1 or 2, further comprising alkali sulfate. The spraying material formed by adding the quick setting agent in any one of Claims 1-3 to the cement kneaded material containing water, cement, and gypsum.