JP4982332B2 - Quick-hardening cement composition admixture, quick-hardening cement composition containing the same, quick-hardening cement kneaded material and spraying material - Google Patents

Description

  The present invention relates to an admixture for a quick-setting cement composition, a quick-setting cement composition containing the admixture and having a high initial strength, a quick-setting cement kneaded material, and a spray material.

In construction work such as machine foundations, bridges, tunnels, underground spaces, and slopes, cement paste, mortar or concrete cement composition kneaded material (cement kneaded material), quick setting agent, hardening accelerator, rapid hardening material A kneaded material (quickly cemented kneaded material) of a quick-hardening cement composition such as shotcrete, quick-setting mortar, and quick-hardening concrete produced by adding the above is widely used.
In particular, in construction works such as tunnels, underground spaces, and slopes, spraying methods using spraying materials such as spray concrete and spray mortar are widely used. The general spraying method is a method in which cement kneaded material such as base concrete and rapid setting agent are pumped by separate routes through separate transport pipes, mixed and mixed in the middle of pumping, and then sprayed from the tip of the spray nozzle onto the ground. is there.

In recent years, spray materials are required to have high initial strength for the purpose of shortening construction cycles and improving safety. 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 aluminate is known (for example, see Patent Document 1).
Japanese Patent No. 3421794

However, a quick-hardening cement composition, a quick-hardening cement kneaded material, and a spray material having higher initial strength have been desired.
Accordingly, an object of the present invention is to provide an admixture for a quick setting cement composition, a quick setting cement composition, a quick setting cement kneaded material, and a spraying material that can obtain high initial strength.

As a result of diligent investigations to solve the above problems, the present inventors have added an admixture containing type II anhydrous gypsum having a specific surface area of 8000 cm ² / g or more obtained by heat-treating gypsum waste to a cement kneaded product. Thus, it was found that high initial strength can be obtained despite the small amount of gypsum added, and the present invention was completed.
That is, the present invention is an admixture for rapid hardening cement composition characterized by containing type II anhydrous gypsum having a specific surface area of 8000 cm ² / g or more obtained by heat-treating gypsum waste.

  Moreover, this invention is a quick-hardening cement composition containing an ettringite-type quick-hardening material and said admixture for quick-hardening cement compositions.

  Furthermore, the present invention is a rapid-hardening cement kneaded material obtained by mixing an admixture for rapid-hardening cement composition, water and cement, and then adding an ettringite-based rapid hardener.

  Furthermore, this invention is a spraying material which consists of said rapid hardening cement kneaded material.

  According to the admixture for a quick-setting cement composition of the present invention, the quick-setting cement composition and the quick-setting cement kneading, which have high initial strength even when the ratio of water cement is high, even though the addition amount of gypsum is small. In particular, the initial strength after 10 minutes from the addition of the ettringite-based hardener to the cement kneaded material is also high. Thus, since the initial strength of the rapid-hardening cement kneaded material and the spray material of the present invention is high, the construction cycle can be shortened and the safety of construction can be improved. In addition, since the construction cycle can be shortened, the construction cost can be suppressed.

The quick-hardening cement composition admixture of the present invention contains type II anhydrous gypsum regenerated from gypsum waste, which has a brain surface area of 8000 cm ² / g or more.

As a method for obtaining type II anhydrous gypsum from gypsum waste, it is preferable to crush or grind the gypsum waste and calcin it at a temperature of 350 ° C. or higher to obtain powder. When firing without crushing or crushing gypsum waste, moisture, paper components, etc. contained in the gypsum waste are likely to remain. It is difficult to adjust to 8000 cm ² / g or more. A preferable example of the gypsum waste material is gypsum board waste material.

In addition, the fineness of the gypsum used in the present invention is preferably 8000 cm ² / g or more, more preferably 10000 to 30000 cm ² / g in terms of the specific surface area of branes, from the viewpoint of obtaining high initial strength with a smaller amount of gypsum used.

  The method for incorporating the gypsum used in the present invention into the cement kneaded product is not particularly limited. For example, it may be incorporated in cement, in an admixture excluding an accelerating agent, or separately mixed with gypsum alone. These may be combined.

The amount of gypsum used in the present invention is preferably such that SO ₃ contained in the cement kneaded product 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 high initial strength required for the rapid-hardening cement kneaded material may be insufficient. Furthermore, from the viewpoint of increasing the long-term strength of the rapid-curing cement kneaded material, the SO ₃ contained in the cement kneaded material is more preferably more than 5 parts by weight and 20 parts by weight or less, and more preferably more than 5 parts by weight and 10 parts by weight. Most preferably, it is at most parts by weight.

  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 a raw material, and one or more of these can be used. Among these, one or two or more kinds selected from ordinary Portland cement, early-strength Portland cement, ultra-early-strength Portland cement or eco-cement are preferable because high initial strength can be obtained.

  The cement kneaded material used in the present invention contains at least water, cement, and gypsum, and further adds aggregates and other admixtures that can be used in mortar and concrete, as long as the effects of the present invention are not impaired. You may do it.

  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.

  Other admixture materials include, for example, high-performance water-reducing agents, high-performance AE water-reducing agents, water-reducing agents containing AE water-reducing agents and fluidizing agents, pozzolans such as silica fume, latent hydraulic substances such as blast furnace slag, stone powder, Resin emulsion, expansion material, 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 Agents, non-separable admixtures in water, and the like, and one or more of these can be used as long as the effects of the present invention are not impaired.

The cement kneaded material is obtained by kneading water, cement and gypsum, and an aggregate and an admixture to be added if necessary, using a mixer such as a mortar mixer or a concrete mixer. The order of addition of each material is not particularly limited, and may be added one by one, or a part or all of them may be added simultaneously.
The cement kneaded product may be allowed to stand after the kneading is completed after the three types of water, cement and gypsum come into contact with each other, but it is preferably stirred at a low speed with an agitator or the like.
Furthermore, it is preferable that the time from when the three kinds of water, cement and gypsum come into contact with each other until the ettringite-based hardener is added is 10 minutes or more, and the initial strength and ettringite-based rapidness are preferably 10 to 120 minutes. It is more preferable because the mixing of the hardener and the cement kneaded material can be improved. If it is less than 10 minutes, the initial strength may be insufficient. In addition, if it exceeds 120 minutes, the consistency of the cement kneaded product is lowered, and there is a possibility that the mixing of the ettringite-type hardener and the cement kneaded product may be insufficient, and the fluctuation of the initial strength of the quick-hardening cement kneaded product becomes large. There is a fear.

  The ettringite-based rapid curing agent used in the present invention is a rapid setting agent (material) or a rapid curing agent (material) that produces ettringite. For example, quick setting agents (materials) / quick hardeners (materials) based on calcined alunite, quick setting agents (materials) / quick hardening agents (materials) based on sodium aluminate, calcium aluminates Examples thereof include rapid setting agents (materials) and rapid hardening agents (materials) containing as a main component. Among these, from the viewpoint of increasing the long-term strength of the rapid-curing cement kneaded material, a rapid setting agent (material) / hardening agent (material) mainly composed of calcium aluminates is preferable.

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 type or two or more types selected from the group can be mentioned. These calcium aluminates may be compounds, solid solutions, vitreous, or those in which two or more of these coexist.

Examples of the state of the ettringite-based hardener include powders, slurry forms obtained by mixing liquids with powders, and liquids. While also be used in any state, fineness when used as a powder, from the viewpoint of initial strength and long-term strength of the rapid hardening cement kneaded product is high, 3000 cm ² / g or more in Blaine specific surface area is preferably, 5000 cm ² / G or more is more preferable.
In addition to the substances that generate ettringite, such as calcium aluminates, the ettringite-based hardener may contain various carbonates, sulfates, nitrates, hydroxides, oxides, and the like.

  The method for producing and using the rapid-hardening cement kneaded product of the present invention is not particularly limited. For example, the cement kneaded material and the ettringite-based rapid hardener may be pumped by separate paths through separate transport pipes, and may be manufactured by merging and mixing with a Y-shaped pipe or the like during the pumping.

  Moreover, the spray material of this invention is a spray material which consists of the said rapid-hardening cement kneaded material.

Hereinafter, the present invention will be described by way of examples.
[Materials used]
Cement: Ordinary Portland cement (SO ₃ content: 2.5% by weight)
High-performance water reducing agent: Polycarboxylic acid-based high-performance water reducing agent (trade name; NT-1000H, Pozzolith product sales)
Fine aggregate: land sand (density: 2.60 g / cm ³ , coarse grain ratio: 2.77)
Coarse aggregate: crushed stone (density: 2.64 g / cm ³ , maximum dimension: 12 mm)
Gypsum: Gypsum 1-3
Gypsum 1: Type ^II anhydrous gypsum regenerated by pulverizing gypsum board waste material at a temperature of 350 ° C. or higher (SO ₃ content: 56.8% by weight, Blaine specific surface area: 12200 cm ² / g)
Gypsum 2: hemihydrate gypsum (SO ₃ content: 55.2% by weight, Blaine specific surface area: 7000 cm ² / g)
Gypsum 3: Fluoric acid gypsum (SO ₃ content: 54.3% by weight, type II anhydrous gypsum, Blaine specific surface area: 7500 cm ² / g)
Gypsum 4: Fluoric acid gypsum (SO ₃ amount: 54.3% by weight, type II anhydrous gypsum, Blaine specific surface area: 12800 cm ² / g)
Ettringite-based quick-hardening material 1: Mixture of amorphous calcium aluminate powder and sodium aluminate powder having a composition of 12:12 CaO · 7Al ₂ O ₃ in a weight ratio of 9: 1 (quick setting agent 1)
Ettlingite-based rapid hardener 2: Mixture of amorphous calcium aluminate powder of 12CaO · 7Al ₂ O ₃ composition and alumina cement in a weight ratio of 7: 3 (quick setting agent 2)

[Initial strength confirmation test with cement paste]
In a 1-liter polycup, 540 g of powder obtained by mixing 40 g of gypsum with 500 g of ordinary Portland cement was added. Further, a total of 250 g of water and a high-performance water reducing agent were added and mixed for 3 minutes at a rotation speed of 1250 rpm using a hand mixer equipped with a stirring blade (diameter 4 cm) to produce a cement paste. The produced cement paste is allowed to stand for 30 minutes, and then kneaded again for 55 seconds. Then, a predetermined amount of the quick-setting agent 1 (ettringite-based hardened material 1) is added for 5 seconds and further kneaded for 5 seconds. A cement kneaded product (rapidly hardened cement paste) was produced.
The resistance value when a penetrating needle made of a round steel with a diameter of 2 mm having a flat tip is inserted into this quick-hardening cement paste for 1 inch, that is, the proctor penetration resistance value, is added for 10 minutes ( Measurement was made after 10 minutes). This Procter penetration resistance value indicates the initial strength characteristics of the rapid-hardening cement paste. Higher proctor penetration resistance values at the same age indicate higher strength.

  Table 1 shows the types of gypsum used, the quick setting agent (ettringite-based rapid hardwood) addition rate, and the proctor penetration resistance value of each age in each cement paste. The test was conducted in a constant temperature room at 10 ° C and 20 ° C.

 All of the rapid hardening cement pastes at the test level corresponding to the examples of the rapid hardening cement kneaded product of the present invention showed a high value of the penetration of Procter after adding the ettringite type hardener to the cement kneaded material.

[Strength test with mortar 1]
In a thermostatic chamber at 10 ° C., 1080 g of powder obtained by mixing 80 g of gypsum with 1000 g of ordinary Portland cement and 1000 g of fine aggregate were placed in a 2 liter plastic cup. 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 the quick-setting agent 1 (ettringite-based quick-hardening material 1) is added for 5 seconds, and further kneaded for 5 seconds. A product (quick mortar) was produced. 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.

  Table 2 shows the types of gypsum used, the ettringite-based quick-hardening material addition rate, and the Procter penetration resistance values for each age in each quick-hardening cement kneaded product.

[Strength test with mortar 2]
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 2 liter plastic cup. Furthermore, the amount of water and high-performance water-reducing material in the table were added, and the mixture was 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 manufactured mortar was allowed to stand for 30 minutes, then kneaded again for 55 seconds, and then 100 g of quick-setting agent 2 (ettringite-based quick hardener 2) was added for 5 seconds, followed by further kneading for 5 seconds. (Rapid mortar) was produced. 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.

  Table 3 shows the types of gypsum used, the amount of water, the amount of high-performance water reducing agent added (SP amount), and the compressive strength of each material age in each rapid-hardening cement kneaded product.

  Each of the test-level rapid mortars corresponding to the examples of the rapid-hardening cement kneaded material of the present invention is the condition that the compressive strength of the same material age is the same water cement ratio after adding the ettringite-based rapid hardener to the cement kneaded material. A high value was shown below, indicating that the water-cement ratio required to obtain the same initial strength can be increased. Further, even when gypsum 1 with a high water-cement ratio was used, a higher initial strength was exhibited than when gypsum 3 or 4 with a lower water-cement ratio was used.

[Concrete spray test]
The base concrete having the composition shown in Table 4 was kneaded with a 100-liter pan mixer to produce. 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 1 (C × 9% by weight) was mixed and mixed in a Y-shaped tube to produce a quick setting concrete, that is, a quick setting cement kneaded product.
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. The results are shown in Table 5 together with the base concrete slump and whether or not spraying is possible.

  Gypsum 2 had a small base concrete slump and could not be sprayed. Shotcrete using gypsum 1 showed very high initial strength.

The quick-hardening cement composition, the quick-hardening cement kneaded material and the spraying material containing the admixture for the quick-hardening cement composition of the present invention have a high initial strength and should be used particularly preferably for emergency work and spraying work. Can do.
Moreover, since the spraying material of the present invention has a high initial strength after spraying on natural ground, it can be suitably used for construction work for spraying concrete such as tunnels or mortar.
Furthermore, since the spray material of the present invention after spraying has a high initial strength, it can be particularly suitably used for construction work that requires a shorter construction period.

Claims (6)

An admixture for a quick-hardening cement composition, comprising II-type anhydrous gypsum having a Blaine specific surface area of 8000 cm ² / g or more obtained by heat-treating gypsum waste. A rapid-hardening cement composition comprising an ettringite-based quick-hardening material and the admixture for rapid-hardening cement composition according to claim 1 . The total 100 parts by weight of the cement contained in the type II anhydrous and gypsum sudden hydraulic cement composition, according to claim 2 SO ₃ contained in the cement kneaded product is less than 20 parts by weight more than 5 parts by weight Quick-hardening cement composition. A rapid-hardening cement kneaded material obtained by adding an ettringite-based rapid hardener after mixing the admixture for rapid-hardening cement composition according to claim 1 , water and cement. The total 100 parts by weight of the cement contained in the type II anhydrous and gypsum rapid hardening cement kneaded product, according to claim 4 SO ₃ contained in the cement kneaded product is less than 20 parts by weight more than 5 parts by weight Quick-hardening cement kneaded material. The spraying material which consists of the quick-hardening cement kneaded material of Claim 4 or 5 .