JP2015024947A - High-strength cement mortar composition and method for producing hardened high-strength cement mortar - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-strength cement mortar composition having high compressive strength without requiring a large-scale and special manufacturing facility.SOLUTION: A high-strength cement mortar composition comprises cement, an inorganic fine powder, water, a fine aggregate, a water reducing agent, an antifoaming agent, and a metal fine powder. The cement contains 10.0-70.0 mass% of CS and 10.0-70.0 mass% of CS, and the inorganic fine powder contains silica fume. A method for producing hardened high-strength cement mortar includes: a pre-curing step of curing the high-strength cement mortar composition in air at 15-25°C for 1-5 days; a first curing step of curing the high-strength cement mortar composition in water at 20-60°C for 1-7 days; a second curing step of curing the high-strength cement mortar composition in water at 80-100°C for 5-21 days; and a third curing step of curing the high-strength cement mortar composition in air at 80-200°C for 5-21 days.

Description

  The present invention relates to a high-strength cement mortar composition and a method for producing a high-strength cement mortar hardened body.

In recent years, an ultra-high-strength material capable of obtaining a compressive strength of about 200 N / mm ² has been proposed in accordance with demands for reducing the weight of structural members and reducing the amount of reinforcing bars used. In these materials, cement, pozzolanic fine powder, aggregate, and a high-performance water reducing agent are used, and ultrahigh strength is achieved by heat curing. In addition, it has been proposed to impart high toughness and crack suppression function by adding metal fibers and organic fibers to these (see Patent Documents 1 to 3).
For example, if a material having a higher compressive strength than the above-mentioned material is obtained, the load of the column member can be further increased, so that the number of columns in the structure can be reduced. It is conceivable that the living space can be further expanded and the degree of freedom in design and design is further increased.

  In order to increase the strength of a cement composition, a method of reducing the water / binder ratio is generally adopted. However, in order to further promote the chemical reaction of the binder, heat curing such as steam curing is required. May be. In order to further increase the strength, centrifugal molding or pressure molding may be performed for the purpose of reducing the voids in the cement mortar as much as possible. It has also been found that higher compressive strength can be obtained by combining these methods with autoclave curing and heat press curing.

JP 2001-181004 A JP 2006-298679 A JP 2007-126317 A

However, these manufacturing methods are not easy to implement because they require large-scale equipment.
Therefore, the present invention provides a high-strength cement mortar composition and a method for producing a hardened high-strength cement mortar body that are higher in strength and do not require large-scale and special manufacturing equipment as compared with the prior art. Objective.

  As a result of intensive studies to solve the above problems, the present inventors combined cement, an inorganic fine powder, a fine aggregate, a water reducing agent and an antifoaming agent, and further mixed a fine metal fine powder. As a result, it was found that high strength can be realized, and the present invention has been achieved.

That is, the present invention is a high-strength cement mortar composition comprising cement, inorganic fine powder, water, fine aggregate, water reducing agent, antifoaming agent, and metal fine powder, , C ₃ S 10.0% to 40.0% by mass and C ₂ S 40.0% to 70.0% by mass, and the inorganic fine powder contains silica fume. I will provide a. Such a high-strength cement mortar composition can exhibit an unprecedented very high compressive strength.
The inorganic fine powder may further contain fly ash. By adding fly ash, a higher strength cement mortar composition with higher fluidity can be obtained.
The present invention also provides a pre-curing step for curing the high-strength cement mortar composition in the air at 15 to 25 ° C. for 1 to 5 days, and curing for 1 to 7 days in water at 20 to 60 ° C. A method for producing a hardened cement mortar hardened body comprising a primary curing step and a secondary curing step of curing for 5 to 21 days in water or air at 80 ° C to 200 ° C.
The present invention also provides a pre-curing step for curing the high-strength cement mortar composition in the air at 15 to 25 ° C. for 1 to 5 days, and curing for 1 to 7 days in water at 20 to 60 ° C. Including a primary curing step, a secondary curing step of curing for 5 to 21 days in water at 80 ° C to 100 ° C, and a tertiary curing step of curing for 5 to 21 days in the air at 80 ° C to 200 ° C. A method for producing a high-strength cement mortar hardened body is provided.
According to such a method for producing a high-strength cement mortar hardened body, it is possible to produce a high-strength cement mortar hardened body that has an unprecedented high compressive strength.

  According to the present invention, a high-strength cement mortar composition having a high compressive strength and a method for producing a hardened high-strength cement mortar can be provided without taking a special curing method.

  Hereinafter, preferred embodiments of a method for producing a high-strength cement mortar composition and a cured high-strength cement mortar according to the present invention will be described, but the present invention is not limited to the following embodiments.

(High-strength cement mortar composition)
The high-strength cement mortar composition of the present embodiment includes cement, silica fume as inorganic fine powder, water, fine aggregate, water reducing agent, antifoaming agent, and metal fine powder. Further, fly ash may be further included as the inorganic fine powder.

As for the mineral composition of the cement, the amount of C ₃ S is 10.0 to 70.0% by mass, the amount of C ₂ S is 10.0 to 70.0% by mass, the amount of C ₃ A is 7.0% by mass or less, C ₄ The AF amount is 5.0 to 15.0% by mass. The amount of C ₃ S is preferably 15.0 to 68.0% by mass, more preferably 18.0 to 66.0% by mass, and further preferably 20.0 to 65.0% by mass. If the amount of C ₃ S is less than 10.0% by mass, the compressive strength tends to be low, and if it exceeds 70.0% by mass, the compressive strength after heat curing tends to be low. The amount of C ₂ S is preferably 12.0 to 65.0% by mass, more preferably 14.0 to 62.0% by mass, and further preferably 15.0 to 60.0% by mass. When the amount of C ₂ S is less than 10.0% by mass, the compressive strength particularly after heat curing tends to be low. The amount of C ₃ A is preferably 7.0% by mass or less, more preferably 4.5% by mass or less, and further preferably 4.0% by mass or less. When the amount of C ₃ A exceeds 5.0%, sufficient fluidity cannot be obtained. The amount of C ₄ AF is preferably 6.0 to 15.0% by mass, more preferably 7.0 to 15.0% by mass, and still more preferably 8.0 to 14.5% by mass. If it is the above range, high compressive strength and high fluidity | liquidity can fully be ensured.

The brane specific surface area of the cement is preferably 2500 to 4800 cm ² / g, more preferably 2800 to 4500 cm ² / g, still more preferably 3000 to 4200 cm ² / g, and particularly preferably 3200 to 3900 cm ² / g. When the brane specific surface area of the cement is less than 2500 cm ² / g, the strength of the high-strength cement mortar composition tends to be low, and when it exceeds 4800 cm ² / g, the fluidity at the low water cement ratio tends to decrease.

  In manufacturing the cement according to the present embodiment, it is not necessary to perform an operation different from that of normal cement. The cement is changed according to the target mineral composition such as limestone, silica, slag, coal ash, construction generated soil, blast furnace dust, etc., fired in the actual kiln, gypsum added And can be manufactured by pulverizing to a predetermined particle size. A general NSP kiln, SP kiln, or the like can be used for the kiln to be fired, and a general pulverizer such as a ball mill can be used for pulverization. Moreover, 2 or more types of cement can also be mixed as needed.

Silica fume is a by-product obtained by collecting dust in the exhaust gas generated when producing metal silicon, ferrosilicon, fused zirconia, etc., and the main component is amorphous SiO dissolved in an alkaline solution. ₂ . The average particle size of silica fume is preferably 0.05 to 2.0 μm, more preferably 0.10 to 1.5 μm, still more preferably 0.18 to 0.28 μm, and particularly preferably 0.20 to 0.28 μm. is there. By using such silica fume, it becomes easy to ensure high compressive strength and high fluidity of the high-strength cement mortar composition.

  In the high-strength cement mortar composition of the present embodiment, the silica fume is preferably 5-35% by mass, more preferably 7-30% by mass, and still more preferably 8-27%, based on the total amount of cement and inorganic fine powder. It is contained by mass%, particularly preferably 9-23 mass%. If it is the above range, high compressive strength and high fluidity | liquidity can fully be ensured.

Fly ash is a by-product obtained by burning finely pulverized coal in a coal-fired power plant and collecting the molten ash. The main components of fly ash are SiO ₂ and Al ₂ O ₃ . The brain specific surface area of fly ash is preferably 2500 to 7000 cm ² / g, more preferably 3000 to 6500 cm ² / g, still more preferably 3500 to 6000 cm ² / g, and particularly preferably 3500 to 6000 cm. ² / g. By using such fly ash, it becomes easy to ensure high compressive strength and high fluidity of the high-strength cement mortar composition.

  In the high-strength cement mortar composition of the present embodiment, fly ash is preferably 5 to 45% by mass, more preferably 8 to 40% by mass, and still more preferably 10 to 35%, based on the total amount of cement and inorganic fine powder. Mass%, particularly preferably 12 to 33% by mass. If it is the above range, high compressive strength and high fluidity | liquidity can fully be ensured.

The fine aggregate is not particularly limited, but river sand, land sand, sea sand, crushed sand, quartz sand, limestone aggregate, blast furnace slag fine aggregate, ferronickel slag fine aggregate, copper slag fine aggregate, electric furnace oxidation slag Fine aggregates can be used. The fine aggregate has a particle size of 5 mm through the 10 mm sieve.
It is preferable to pass through a mm sieve by 85% by mass or more.

  As the water reducing agent, lignin-based, naphthalenesulfonic acid-based, aminosulfonic acid-based, polycarboxylic acid-based water reducing agents, high-performance water reducing agents, high-performance AE water reducing agents, and the like can be used. From the viewpoint of ensuring fluidity at a low water cement ratio, it is preferable to use a polycarboxylic acid-based water reducing agent, a high-performance water reducing agent or a high-performance AE water reducing agent as the water reducing agent, and a polycarboxylic acid-based high performance water reducing agent. It is more preferable to use The high-strength cement mortar composition according to the present embodiment is preferably 1.0 to 6.0 parts by mass, more preferably 1.5 to 100 parts by mass of the water reducing agent with respect to 100 parts by mass of the total amount of cement and inorganic fine powder. 5.0 parts by mass, more preferably 1.8 to 4.5 parts by mass, particularly preferably 2.2 to 4.0 parts by mass. If it is the above range, high compressive strength and high fluidity | liquidity can fully be ensured.

  The amount of water is preferably 9 to 20 parts by weight, more preferably 9.5 to 18 parts by weight, still more preferably 10.0 to 16 parts by weight, especially 100 parts by weight of the total amount of cement and inorganic fine powder. Preferably it contains 10.5 to 14.0 parts by mass. If it is the above range, high compressive strength and high fluidity | liquidity can fully be ensured.

  Examples of antifoaming agents include special nonionic compounding surfactants, polyalkylene derivatives, hydrophobic silica, and polyethers. In this case, the defoamer is preferably 0.01 to 2.0 parts by weight, more preferably 0.1 to 1.0 parts by weight, and still more preferably, with respect to 100 parts by weight of the total amount of cement and inorganic fine powder. Including 0.2 to 0.5 parts by mass. If it is the above range, high compressive strength and high fluidity | liquidity can fully be ensured.

As the metal fine powder, cut steel wool and / or iron powder or the like can be used. Cut steel wool means steel wool cut into short pieces. Steel wool is a product in which very thin wires of iron are hardened in a cotton form, and is sometimes used as a scrubbing brush.
The shape of the metal fine powder is preferably 5 μm to 500 μm in diameter, more preferably 10 μm to 420 μm, still more preferably 15 μm to 400 μm, and particularly preferably 20 μm to 380 μm. The length is preferably 5 μm to 5.0 mm, more preferably 20 μm to 4.0 mm, still more preferably 30 μm to 3.8 mm, and particularly preferably 50 μm to 3.5 mm. If it is the above range, high compressive strength and high fluidity | liquidity can fully be ensured.

(Manufacturing method of hardened cement mortar)
The manufacturing method of the high-strength cement mortar hardened | cured material of this embodiment is the pre-curing process of curing the said high-strength cement mortar composition in the air of 15-25 degreeC for 1 day-5 days, A primary curing step of curing for 1 to 7 days in water and a secondary curing step of curing for 5 to 21 days in water or in the air at 80 ° C to 200 ° C.
The pre-curing step is preferably 16 to 24 ° C., more preferably 17 to 23 ° C., still more preferably 18 to 22 ° C., particularly preferably 19 to 21 ° C., preferably 1.5 to 4 days. The curing is preferably performed for 2.0 to 3.5 days, and more preferably for 2.5 to 3.3 days. If it is the above range, high compressive strength and high fluidity | liquidity can fully be ensured.

  The primary curing step is preferably 23 to 55 ° C, more preferably 25 to 50 ° C, still more preferably 28 to 48 ° C, particularly preferably 30 to 45 ° C in water, preferably 1 to 7 days, more preferably 1 Curing is carried out for 5 to 6 days, more preferably 1.8 to 5 days, particularly preferably 2.0 to 4.5 days. If it is the above range, high compressive strength and high fluidity | liquidity can fully be ensured.

  The secondary curing step is preferably 80 to 200 ° C, more preferably 83 to 190 ° C, still more preferably 85 to 185 ° C, particularly preferably 90 to 180 ° C in water or in the air, preferably 5 to 21 days. More preferably 5 to 19 days, still more preferably 6 to 17 days, particularly preferably 7 to 15 days. In water, warm water, in the air, steam curing devices, autoclaves, dryers, etc. can be used. If it is the above range, high compressive strength and high fluidity | liquidity can fully be ensured.

The manufacturing method of the high-strength cement mortar hardened | cured material of this embodiment is the pre-curing process of curing the said high-strength cement mortar composition in the air of 15-25 degreeC for 1 day-5 days, and 20-60 degreeC. Primary curing process for curing for 1 to 7 days in water, secondary curing process for curing for 5 to 21 days in water at 80 ° C. to 100 ° C., and 5 days to 21 in the atmosphere at 80 ° C. to 200 ° C. You may carry out in the tertiary curing process which performs daily curing.
The pre-curing step is preferably 16 to 24 ° C., more preferably 17 to 23 ° C., still more preferably 18 to 22 ° C., particularly preferably 19 to 21 ° C., preferably 1.5 to 4 days. The curing is preferably performed for 2.0 to 3.5 days, and more preferably for 2.5 to 3.3 days. If it is the above range, high compressive strength and high fluidity | liquidity can fully be ensured.

  The primary curing step is preferably 23 to 55 ° C, more preferably 25 to 50 ° C, still more preferably 28 to 48 ° C, particularly preferably 30 to 45 ° C in water, preferably 1 to 7 days, more preferably 1 Curing is carried out for 5 to 6 days, more preferably 1.8 to 5 days, particularly preferably 2.0 to 4.5 days. If it is the above range, high compressive strength and high fluidity | liquidity can fully be ensured.

The secondary curing step is preferably 80 to 100 ° C., more preferably 83 to 99 ° C., further preferably 85 to 99 ° C., particularly preferably 90 to 98 ° C., preferably 5 to 21 days, more preferably Curing is performed for 5 to 19 days, more preferably 6 to 17 days, particularly preferably 7 to 15 days.
The tertiary curing step is preferably 80 to 200 ° C, more preferably 83 to 190 ° C, still more preferably 85 to 185 ° C, particularly preferably 90 to 180 ° C, preferably 5 to 21 days, more preferably Curing is performed for 5 to 19 days, more preferably 6 to 17 days, particularly preferably 7 to 15 days.
In water, warm water, in the air, steam curing devices, autoclaves, dryers, etc. can be used. In the tertiary curing process, air curing is more preferable than water from the viewpoint of strength enhancement. If it is the above range, high compressive strength and high fluidity | liquidity can fully be ensured.

  Hereinafter, the contents of the present invention will be described more specifically with reference to examples and comparative examples. In addition, this invention is not limited to the following Example.

[Preparation of materials used]
In order to prepare the mortar compositions of Examples and Comparative Examples, the following materials were prepared.

(1) Cement:
The chemical components of the three types of cement used were measured according to JIS R 5202-2010 “Cement chemical analysis method”, and the mineral composition was calculated by the following Borg equation. The mineral composition of the obtained cement is shown in Table 1.

C ₃ S amount = (4.07 × CaO) − (7.60 × SiO ₂ ) − (6.72 × Al ₂ O ₃ ) − (1.43 × Fe ₂ O ₃ ) − (2.85 × SO ₃ )
C ₂ S amount = (2.87 × SiO ₂ ) − (0.754 × C ₃ S)
C ₃ A amount = (2.65 × Al ₂ O ₃ ) − (1.69 × Fe ₂ O ₃ )
C ₄ AF amount = 3.04 × Fe ₂ O ₃

(2) Silica fume The average particle diameter of silica fume is calculated from the particle diameter distribution measured using a laser diffraction / scattering particle size distribution measuring apparatus (trade name “LA-950V2” manufactured by Horiba, Ltd.). The% curve was calculated, and the particle diameter at which the accumulated volume was 50% by volume was determined from the particle diameter-% accumulated volume curve. A 0.2% sodium hexametaphosphate aqueous solution was used as a sample dispersion medium, and the sample was dispersed for 10 minutes with a homogenizer with an output of 600 W before measurement. The calculation of the particle size distribution followed Mie scattering theory. The particle refractive index was 1.45-0.00i, and the solvent refractive index was 1.333. Table 2 shows the accumulated amount (volume%) of each particle size.

(3) Fly ash: manufactured by Joban Thermal Power Industry Co., Ltd., density: 2.27 g / cm ³ , specific surface area: 4680 cm ² / g, 45 μm sieve residue: 11.0%

(4) Fine aggregate: Crushed sand: Density 2.62 g / cm ³ , coarse particle ratio 2.80

(5) Water reducing agent: polycarboxylic acid-based high-performance water reducing agent (solid content concentration 25% by mass)
(6) Antifoaming agent: Special nonionic compounding type surfactant (7) Fine metal powder:
Cut steel wool (A): Nippon Steel Wool, diameter 20-30 μm, length 0.1-3 mm, density 7.85 g / cm ³
(8) Steel fiber (B): manufactured by Tokyo Seizuna Co., Ltd., density: 7.87 g / cm ³ , fiber diameter 0.16 mm, fiber length 13 mm, aspect ratio 81.25, tensile strength 2200 N / mm ²
(9) Mixing water (W): Tap water

[Preparation of high-strength cement mortar composition]
A high-strength cement mortar composition was prepared as follows based on the composition shown in Table 3.

  Cement, silica fume, fly ash, and an antifoaming agent were added to the mortar mixer, and kneading water containing a water reducing agent was put into the mixer and stirred for 10 minutes to prepare a mortar composition. In Examples 1 and 2, the metal fine powder powder was further added to prepare a high-strength cement mortar composition.

[Curing method]
The high-strength cement mortar composition that has been kneaded is filled in the mold, then cured in the atmosphere of 20 ° C and humidity of about 70% for 3 days (pre-curing step), then demolded, and in water at 40 ° C for 3 days. The primary curing process was carried out. Then, as a secondary curing, curing was performed in 98 ° C. warm water for 7 days, and then as a tertiary curing, drying was performed with a 98 ° C. dryer for 7 days. These curings were carried out to produce a high-strength cement mortar hardened body.

[Evaluation of high-strength cement mortar composition]
(1) Fresh properties (test method)
The flow value was measured using the high-strength cement mortar compositions prepared by the blending of Comparative Examples 1-2 and Examples 1-2. The flow value was measured according to JIS R 5201-1997 “Cement physical test method” under the condition of no drop.

(2) Strength test According to JIS A 1132-2006 “How to make a specimen for concrete strength test”, a 5 cm × 10 cm cylindrical specimen is prepared and according to JIS A 1108-2006 “Concrete compressive strength test method”. The high strength cement mortar hardened body was subjected to a compressive strength test.

(Evaluation results)
Table 4 shows the flow values and the compressive strength test results.

In the case of Comparative Examples 1 and 2 without using cut steel wool, at the time of the secondary curing period 14 days, it became 289N / mm ² and 308N / mm ^2.
In the case of Examples 1 and 2 were mixed with cut steel wool 2% by volume, 7 days strength of 20-30 N / mm ² approximately, 14 days strength is increased by about 10 to 50 N / mm ^2, at 14 days 300N / A high compressive strength of mm ² or more was obtained.
When Example 1 is compared with Example 4, it turns out that fluidity | liquidity is increasing by the reduction | decrease of the amount of silica fume. In this case, the strength did not decrease, but rather tended to increase slightly. This is presumably because the fluidity increases due to the decrease in the amount of silica fume, which improves the filling properties of fresh mortar and reduces the entrapment air that becomes a defect.
Moreover, fluidity | liquidity was improved by reducing the amount of fine aggregates like the comparative example 3, the comparative example 4, and Example 4. FIG.
Even when the amount of silica fume was changed or the fine aggregate rate was changed as in Example 3 and Example 4, a high compressive strength of 300 N / mm ² or more was obtained at the end of curing.

When the mineral composition of the cement was changed as in Example 5 and Example 6, the flow value decreased as the amount of C ₃ A increased. Moreover, in the curing period of 14 days, a high compressive strength of about 300 N / mm ² was obtained.
In contrast to Example 4, when fly ash was substituted for part of the cement as in Example 7 and Example 8, the fluidity was slightly improved. When fly ash was up to about 15% by mass, the decrease in strength was small.

As in Example 9 and Example 10, high compression of about 300 N / mm ² even when the water content is increased to 13% by mass with respect to the total amount of cement and fine inorganic powder (silica fume + fly ash). Strength was obtained.
Moreover, as shown in Table 4, when the air curing of the tertiary curing was performed after the water curing of the secondary curing, a very high compressive strength was obtained. Cement curing is generally considered to be sufficiently hydrated in water, but the results of the examples suggest that it is better to cure in air after curing to some extent. ing. In cement mortar using silica fume at a low water cement ratio, it is important that silica fume be sufficiently hydrated. In the case of air curing, hydration is likely to occur due to the penetration of steam into fine voids in the cured product. It is inferred that there is a phenomenon that is going on.

Claims (10)

A high-strength cement mortar composition comprising cement, inorganic fine powder, water, fine aggregate, water reducing agent, antifoaming agent, and metal fine powder,
The cement contains 10.0% to 70.0% by mass of C ₃ S and 10.0% to 70.0% by mass of C ₂ S, and the inorganic fine powder contains silica fume. A high-strength cement mortar composition.   The high-strength cement mortar composition according to claim 1, wherein the metal fine powder is cut steel wool.   The metal fine powder has a diameter of 5 μm to 500 μm and a length of 5 μm to 5.0 mm, and includes 1.0% by volume to 5.0% by volume with respect to the high-strength cement mortar composition. 2. The high-strength cement mortar composition according to 2.   The high-strength cement mortar composition according to any one of claims 1 to 3, wherein an average particle size of the silica fume is 0.05 µm to 2.0 µm.   The high-strength cement mortar composition according to any one of claims 1 to 4, wherein the silica fume is contained in an amount of 5 to 35% by mass in a total amount of 100% by mass of the cement and the inorganic fine powder. The inorganic fine powder further comprises fly ash, Blaine specific surface area of the fly ash is 2500cm ² / g~7000cm ² / g, the high strength cement mortar composition according to any one of claims 1 to 5, object.   7. The high-strength cement mortar composition according to claim 6, wherein the fly ash is included in an amount of 5% by mass to 45% by mass in 100% by mass of the total amount of the cement and the inorganic fine powder.   Any one of Claims 1-7 which contains 9 mass parts-20 mass parts of water and 1.0 mass part-6.0 mass parts of water reducing agents with respect to 100 mass parts of total amounts of the said cement and the said inorganic fine powder. The high-strength cement mortar composition according to claim 1.   A pre-curing step in which the high-strength cement mortar composition according to any one of claims 1 to 8 is cured in the air at 15 to 25 ° C for 1 to 5 days, and 1 in water at 20 to 60 ° C. A method for producing a hardened high-strength cement mortar comprising a primary curing step of curing for 7 days to 7 days and a secondary curing step of curing for 5 to 21 days in water or in the air at 80 ° C to 200 ° C.   A pre-curing step in which the high-strength cement mortar composition according to any one of claims 1 to 8 is cured in the air at 15 to 25 ° C for 1 to 5 days, and 1 in water at 20 to 60 ° C. A primary curing process for curing for 7 days to 7 days, a secondary curing process for curing for 5 to 21 days in water at 80 ° C to 100 ° C, and curing for 5 to 21 days in the air at 80 ° C to 200 ° C. A method for producing a hardened high-strength cement mortar comprising a tertiary curing step.