JP6207992B2 - Cement admixture and cement composition-hardened cement using the same - Google Patents

Description

  The present invention relates to a method for producing a hardened cement body and a hardened cement body used in the field of civil engineering and architecture.

  Freezing and thawing resistance of hardened cement bodies such as concrete and slate is a problem in cold regions. In order to improve the freeze-thaw resistance, air is introduced into the cured body with AE agent, foaming agent, kneaded water containing microbubbles, etc. (Patent Documents 1 to 4). However, depending on the type of cement and the production conditions of the hardened cement body, there is a problem in the stability of the introduced air, and further improvement in freeze-thaw resistance is required.

  On the other hand, in the production of precast concrete subjected to steam curing, an admixture that promotes strength development and accelerates demolding from a mold has been developed (Patent Documents 5 to 9). However, further performance improvement is required for freeze-thaw resistance.

JP 2007-191358 A JP 2007-261242 A JP 2009-137025 A Special table 2008-502564 gazette JP 2000-301531 A JP 2001-294460 A JP 2011-153068 A JP 2000-233959 A Special table 2008-519752 gazette

  The present inventor provides a cement admixture excellent in initial strength development and freeze-thaw resistance.

  That is, the present invention includes (1) 10 to 70 parts by mass of free lime, 10 to 50 parts by mass of hydraulic compound, and 10 to 60 parts by mass of anhydrous gypsum in a total of 100 parts by mass of free lime, hydraulic compound and anhydrous gypsum. A cement admixture comprising a heat-treated product and a nitrogen gas foaming substance; (2) a cement admixture according to (1) further comprising glycerin; and (3) a fine quicklime and / or fine anhydrous gypsum. The cement admixture according to (1) or (2), (4) the cement admixture according to any one of (1) to (3), which is obtained by mixing and pulverizing a heat-treated product and a nitrogen gas foaming substance, (5) A cement composition comprising the cement and the cement admixture of any one of (1) to (4), and a hardened cement body produced using the cement composition according to (6) and (5).

  By using the cement admixture and the cement composition of the present invention, there is an effect that a hardened cement body excellent in initial strength development and excellent in freeze-thaw resistance can be obtained.

Hereinafter, the present invention will be described in detail.
Parts and% used in the present invention are based on mass unless otherwise specified.
The hardened cement of the present invention is a general term for hardened bodies of cement paste, cement mortar, and cement concrete.

Specific examples of the gas foaming material include aluminum powder, percarbonate, nitrogen gas foaming material, peroxygenated materials such as persulfate, perborate and permanganate.
In the present invention, it is preferable to use a nitrogen gas foaming material because the initial strength development and the freeze-thaw resistance are greatly improved. Here, the nitrogen gas foaming substance may be one or more selected from the group consisting of an azo compound, a nitroso compound, and a hydrazine derivative. Examples of the azo compound include azodicarbonamide and azobis. Isobutyl nitrile and the like are mentioned. Examples of the nitroso compound include N, N′-dinitropentamethylenetetramine. Examples of the hydrazine derivative include 4,4′-oxybis and hydrazine carbonamide. 1 type or 2 types or more can be used, and it is particularly preferable to use azodicarbonamide which is an azo compound. These nitrogen gas foaming substances generate nitrogen gas in an alkaline atmosphere when basic cement is mixed with water. Even if by-products such as carbon monoxide, carbon dioxide, and ammonia are produced as by-products. Good.

Although the usage-amount of a nitrogen gas foaming material is not specifically limited, Usually, 0.1-10 parts are preferable in 100 parts of cement admixtures, and 0.5-5 parts are more preferable. In each case, if it is less than the lower limit value of the preferred range, sufficient freeze-thaw resistance may not be imparted, and if it exceeds the upper limit value of the preferred range, strength development tends to decrease.
In addition, when blending the nitrogen gas foaming material into the cement admixture, it is preferable to mix and pulverize the heat-treated product with a ball mill, a vibration mill or the like because the freeze-thaw resistance is improved.

The heat-treated product used in the cement admixture of the present invention is a CaO raw material, a CaSO ₄ raw material, and at least one raw material selected from Al ₂ O ₃ raw material, Fe ₂ O ₃ raw material, and SiO ₂ raw material. It is obtained by heat treating the mixture.

The free lime referred to in the present invention is usually called f-CaO.
The hydraulic compound referred to in the present invention is yelimeite (also referred to as Auin) represented by 3CaO.3Al ₂ O ₃ .CaSO ₄ , 3CaO.SiO ₂ (abbreviated as C ₃ S) and 2CaO.SiO ₂ (C calcium silicate represented by ₂ S _{abbreviated), 4CaO · Al 2 O 3} · Fe 2 O 3 (C 4 AF for short) and _{6CaO · 2Al 2 O 3 · Fe} 2 O 3 (C 6 a 2 F abbreviated ), calcium aluminosilicate ferrite represented by _{6CaO · Al 2 O 3 · Fe} 2 O 3 (C 6 AF _{abbreviated), 2CaO · Fe 2 O 3} (C 2 F hereinafter) and the like calcium ferrite such, these It is preferable that 1 type or 2 types or more are included.
The anhydrous gypsum referred to in the present invention is represented as CaSO ₄ .

The CaO feed include such as limestone or slaked lime, as the _Al 2 _{O 3} raw material include such as bauxite and aluminum residual ash, as the _Fe 2 _{O 3} raw material include copper Karami and commercial iron oxide, SiO ₂ Examples of the raw material include silica stone, and examples of the CaSO ₄ raw material include dihydrate gypsum, hemihydrate gypsum, and anhydrous gypsum.
These raw materials may contain impurities, but this is not a problem as long as the effects of the present invention are not impaired. Examples of impurities include MgO, TiO ₂ , ZrO ₂ , MnO, P ₂ O ₅ , Na ₂ O, K ₂ O, Li ₂ O, sulfur, fluorine, and chlorine.

In the present invention, a method of heat-treating a mixture of a CaO raw material, a CaSO ₄ raw material, and at least one raw material selected from Al ₂ O ₃ raw material, Fe ₂ O ₃ raw material, and SiO ₂ raw material Although it does not specifically limit, it is preferable to bake at the temperature of 1000-1600 degreeC using an electric furnace, a kiln, etc., and 1200-1500 degreeC is more preferable. If the temperature is lower than 1000 ° C, it may be difficult to ensure the fluidity of the concrete immediately after mixing, or the initial strength may not be sufficiently developed. If the temperature exceeds 1600 ° C, anhydrous gypsum may decompose or the initial strength may not be sufficiently developed. It may be enough.

The proportion of each mineral in the heat-treated product is preferably in the following range.
The content of free lime is preferably 10 to 70 parts and more preferably 20 to 60 parts in a total of 100 parts of free lime, hydraulic compound and anhydrous gypsum. The content of the hydraulic compound is preferably 10 to 50 parts, more preferably 20 to 30 parts, out of a total of 100 parts of free lime, hydraulic compound and anhydrous gypsum. The content of anhydrous gypsum is preferably 10 to 60 parts, more preferably 20 to 50 parts, out of a total of 100 parts of free lime, hydraulic compound and anhydrous gypsum.

  The content of each mineral can be confirmed by a conventional general analysis method. For example, the pulverized sample can be applied to a powder X-ray diffractometer to confirm the produced mineral and analyze the data by the Rietveld method to quantify the mineral. Further, based on the identification result of chemical components and powder X-ray diffraction, the amount of minerals can also be obtained by calculation.

Fineness of the cement admixture comprising a heat-treated product of the present invention is preferably 2500~9000cm ² / g in Blaine specific surface area, 3500~9000cm ² / g is more preferable. If it is less than 2500 cm < ² > / g, the initial strength may be insufficiently increased, or it may be expanded after a long period of time to decrease the strength. Moreover, when it exceeds 9000 cm < ² > / g, the fluidity | liquidity of concrete may fall.

Glycerin used in the present invention is a compound represented by the chemical formula C ₃ H ₈ O ₃ , chemical name 1,2,3-propanetriol or glycerol.

  The proportion of glycerin added to the cement admixture is not particularly limited, but is preferably 0.1 to 10 parts, more preferably 1 in a total of 100 parts of the heat-treated product, the nitrogen gas foaming material and glycerin. ~ 5 parts. If it is less than 0.1 part, the effect of increasing the initial strength of the cured product may not be obtained, and if it exceeds 10 parts, the fluidity of the kneaded product may be deteriorated.

  Although the usage-amount of the cement admixture of this invention changes with mixing | blending, it is not specifically limited, Usually, 2-15 parts are preferable in 100 parts of cement compositions which consist of a cement and an early mold release material, 12 parts is more preferred. Outside the range, the effect of increasing the compressive strength may be small.

Fine particulate quicklime can be used by pulverizing limestone or slaked lime to obtain quicklime, and the average particle size is preferably 20 μm or less, more preferably 15 μm or less.
As the fine particle anhydrous gypsum, natural anhydrous gypsum, dihydrate gypsum, hemihydrate gypsum and the like can be used by pulverization, and the average particle diameter is preferably 20 μm or less, more preferably 15 μm or less.
The ratio of the fine calcium oxide and / or fine particle anhydrous gypsum to be substituted and blended is not particularly limited, but it is usually preferably 60 parts or less in a total of 100 parts of the heat-treated product and the fine particle calcium oxide and / or fine particle anhydrous gypsum. If the amount exceeds 60 parts, the fluidity of the kneaded product may be lowered, making it difficult to fill the mold, or the initial strength of the cured product may be lowered.
In addition, the average particle diameter of fine particle quick lime and fine particle anhydrous gypsum is measured in the state disperse | distributed using the ultrasonic diffraction apparatus using the laser diffraction type particle size distribution meter.

  In the present invention, a water reducing agent can be used in combination. Water-reducing agent is a generic name for those that have a dispersing action and air-entraining action on cement, improve fluidity and increase strength. Specifically, naphthalene sulfonic acid-based water reducing agent, melamine sulfonic acid-based water reducing agent, lignin sulfonic acid-based Although a water reducing agent, a polycarboxylic acid type water reducing agent, etc. are mentioned, it does not specifically limit. Among these, a lignin sulfonic acid-based water reducing agent is preferable because of its great effect.

As the cement used in the present invention, various portland cements such as normal, early strength, ultra-early strength, low heat, and moderate heat, and various portland cements mixed with blast furnace slag, fly ash, silica, limestone fine powder, etc. Examples include mixed cement, waste-use cement, so-called eco-cement, and the like. Among these, ordinary Portland cement or early-strength Portland cement is preferable in terms of kneadability and strength development.

  In the present invention, limestone fine powder, blast furnace slow-cooled slag fine powder, sewage sludge incineration ash and its molten slag, admixture materials such as municipal waste incineration ash and its molten slag, pulp sludge incineration ash, water reducing agent, AE water reducing agent, high Performance water reducing agent, high performance AE water reducing agent, antifoaming agent, thickening agent, rust preventive agent, antifreeze agent, shrinkage reducing agent, polymer, setting modifier, clay minerals such as bentonite, and anion exchange such as hydrotalcite One or more of the body and the like can be used as long as the object of the present invention is not substantially inhibited.

The amount of kneading water used in the present invention is not particularly limited, but is usually preferably 25 to 70%, more preferably 30 to 50% in terms of the water / cement composition ratio. Outside these ranges, workability may be greatly reduced or the strength may be reduced.

  The present invention will be described more specifically with reference to experimental examples below, but the present invention is not limited to these experimental examples.

"Experiment 1"
A CaO raw material, a CaSO ₄ raw material, and an Al ₂ O ₃ raw material are mixed, the raw materials are mixed so as to have a predetermined mineral composition as shown in the materials used, and heat-treated at 1350 ° C. using an electric furnace. Prepared. A cement admixture was prepared by mixing and pulverizing with a ball mill or mixing so that the heat-treated product, the nitrogen gas foaming material in the amount shown in Table 1, and glycerin totaled 100 parts. Further, a cement admixture containing fine lime and fine anhydrous gypsum was prepared.
The mixing and pulverization was performed simultaneously with the pulverization of the heat-treated product using a ball mill.
Further, the mixing was performed by a Laedige mixer, and the pulverized heat-treated product and the nitrogen gas foaming material were mixed.
With blast furnace cement B species in the cement, unit water content 145 kg / ^{m 3,} the unit amount of cement 440 kg / ^{m 3,} water reducing agent ^{2.5kg / m 3, s / a39.4} %, based on the air amount 4.5% of the concrete Formulated. The amount of air was adjusted by the amount of AE agent added. The cement admixture was blended with 20 kg / m ^{3 in such} a manner that the cement was replaced by an internal split, and those not blended were also tested for comparison. Tap water was used as the kneading water. The water reducing agent was previously added to the kneaded water.
This concrete is kneaded in an environment of 5 ° C., filled into a mold, and subjected to vibration molding using a table vibrator. After securing a pre-time of 1 hour at 20 ° C., the temperature is increased at 20 ° C./hr, Steam curing was carried out at 2 ° C. for 2 hours. Thereafter, the mold was demolded at a material age of 6 hours, and after water curing for 28 days, a compressive strength and freeze-thaw resistance test was performed.

<Materials used>
Water: tap water.
Dispersant: Naphthalenesulfonic acid, trade name “Mighty 150”, manufactured by Kao Corporation.
AE agent: Trade name “Master Air 303A”, manufactured by BASF Japan Ltd.
Nitrogen gas foaming material A: azodicarbonamide, commercial nitrogen gas foaming material A: benzenesulfonylhydrazide, commercial product CaO raw material: calcium carbonate (limestone fine powder), 100 mesh, commercial product Al ₂ O ₃ raw material: bauxite, 90 μm sieve Passage rate 100%, commercial product CaSO ₄ raw material: dihydrate gypsum, Blaine specific surface area 5000 cm ² / g, commercial product cement: blast furnace cement type B, commercial product fine lime: CaO content 97%, average particle size 10 μm, commercial product Fine particle anhydrous gypsum: natural anhydrous gypsum, average particle diameter 8 μm, commercial product A: 21 parts free lime, 32 parts Yelimite, 47 parts anhydrous gypsum, density 2.90 g / cm ³ , Blaine specific surface area 3500 cm ² / G.
Heat-treated product B: heat-treated product in a ratio of 30 parts of free lime, 20 parts of Yelite, 5 parts of C ₄ AF, 5 parts of C ₂ S, 35 parts of anhydrous gypsum, density 2.98 g / cm ³ , and Blaine specific surface area 3500 cm ² / g.
Heat-treated product C: heat-treated product having a ratio of 50 parts of free lime, 10 parts of Yelite, 5 parts of C ₄ AF, 5 parts of C ₂ S, 30 parts of anhydrous gypsum, density of 3.05 g / cm ³ , and Blaine specific surface area of 3500 cm ² / g.
Heat-treated product D: heat-treated product in a ratio of 70 parts free lime, 20 parts Yelimite, and 10 parts anhydrous gypsum, density 3.20 g / cm ³ , brain specific surface area 3500 cm ² / g.
Heat-treated product E: 21 parts of free lime, 32 parts of Yelimite, and 47 parts of anhydrous gypsum were separately synthesized and mixed. Density 2.90 g / cm ³ , Blaine specific surface area 3500 cm ² / g.
Heat-treated product F: 50 parts of heat-treated product with a ratio of 21 parts of free lime, 32 parts of Yelimeite, 47 parts of anhydrous gypsum, 23.5 parts of fine calcium oxide, 23.5 parts of fine anhydrous gypsum, 3 parts of glycerin, Prepared to have a Blaine specific surface area of 6000 cm ² / g.
Glycerin: Commercial product, purified glycerin.
Fine aggregate: from Himekawa, Niigata Prefecture, 5 mm below, density 2.62 g / cm ³
Coarse aggregate: from Himekawa, Niigata Prefecture, 25 mm below, density 2.64 g / cm ³

<Measurement method>
Compressive strength: measured in accordance with JIS A1108 (age 28 days).
Freeze-thaw resistance: In accordance with JIS A1148 (Method A), the test was carried out by freezing in water-thawing in water, and the relative kinematic modulus and mass reduction rate at 300 cycles were measured.

From Table 1, it can be seen that the freeze-thaw resistance of the concrete is greatly improved by combining the nitrogen gas foamed material with various heat-treated products. The effect is particularly great when nitrogen gas foam material is used. It can also be seen that the freeze-thaw resistance is improved by simply mixing and pulverizing the nitrogen gas foaming material together with the heat-treated product, rather than simply mixing. Furthermore, freeze-thaw resistance is also good when glycerin, fine lime and / or fine anhydrous gypsum are used in combination with the heat-treated product.

"Experimental example 2"
The same procedure as in Experimental Example 1 was conducted except that heat treated material A and nitrogen gas foaming substance A were used as the cement admixture, and the amount of nitrogen gas foaming substance A used was changed as shown in Table 2. The results are shown in Table 2.

From Table 2, increasing the blending ratio of nitrogen gas foaming material has little effect on compressive strength and improves the freeze-thaw resistance of concrete, but if it exceeds 10 parts, the compressive strength and freeze-thaw resistance are improved. Can be seen to decrease.

  By using the cement admixture and the cement composition of the present invention, a hardened cement body having excellent initial strength and freezing and thawing resistance can be obtained, so that it is widely used in the civil engineering and construction fields.

Claims (6)

A heat-treated product and a nitrogen gas foaming substance, which are 10 to 70 parts by weight of free lime, 10 to 50 parts by weight of hydraulic compound, and 10 to 60 parts by weight of anhydrous gypsum, in a total of 100 parts by weight of free lime, hydraulic compound and anhydrous gypsum. Contains cement admixture. The cement admixture according to claim 1, further comprising glycerin. The cement admixture according to claim 1 or 2, further comprising fine-grain quicklime and / or fine-particle anhydrous gypsum. The cement admixture according to any one of claims 1 to 3, wherein the heat treated product and a nitrogen gas foaming material are mixed and pulverized. A cement composition comprising cement and the cement admixture according to any one of claims 1 to 4. A hardened cement body produced using the cement composition according to claim 5.