JP2018083719A - Quick hardening material and quick hardening cement composition using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a quick hardening material excellent in stability of dimension with less length change in both of in-air curing and in-water curing, and excellent in quick hardening property, and a quick hardening cement composition.SOLUTION: There are provided (1) a quick hardening material containing an amorphous calcium aluminate clinker ground article with Blaine specific surface area of 4000 to 8500 cm/g, alumina cement with Blaine specific surface area of 3000 to 6500 cm/g, and gypsum, in which Blaine specific surface area of the alumina cement is smaller than that of the amorphous calcium aluminate clinker ground article, (2) a quick hardening material having content molar ratio of CaO and AlOin the amorphous calcium aluminate clinker of 1.3 to 2.5, (3) a quick hardening material containing the alumina cement of 5 to 20 pts.mass based on 100 pts.mass of the amorphous calcium aluminate clinker ground article, and (4) a quick hardening cement composition containing cement and any of quick hardening material (1) to (3).SELECTED DRAWING: None

Description

The present invention relates to a rapid hardening material for accelerating the hardening of hydraulic materials such as cement concrete and a rapid hardening cement composition using the same.

Concrete and mortar are hydrated and hardened by adding water to a hydraulic composition such as cement and aggregates such as gravel and sand, and the volume of crystals decreases before and after the hydration reaction. It is also known that shrinkage occurs due to drying due to evaporation of excess water (free water). If a large length change occurs in the concrete which is restrained by the structure itself or the reinforcing bars, it will crack. In addition, if the mortar used for finishing and repairing concrete changes greatly in length, adhesion may be lost or cracks may occur. Cracks reduce the waterproofness of the structure as a performance, and lead to the invasion of carbon dioxide, water, oxygen and salt, which are deterioration factors of reinforced concrete. Moreover, the yield strength of the structure is also reduced. Therefore, it is important from the viewpoint of durability to make the length change of the hydraulic composition used for concrete and mortar smaller and to suppress the occurrence of cracks.

As a means of suppressing changes in the length of concrete and mortar, the expansion of the bulk volume of crystals such as the hydration of quicklime and the reaction to form needle-shaped ettringite crystals compensates for drying shrinkage. Is known (Patent Documents 1 and 2). In addition, a fast-setting hydraulic composition that generates ettringite at an early stage using calcium aluminate and gypsum, or Auin and gypsum, and cures and develops strength in a short time has been proposed (Patent Documents 3 and 4). It has also been proposed that it is possible to compensate for drying shrinkage (Patent Document 5). Furthermore, a curing agent applied to the surface after curing has also been proposed (Patent Document 6).

Rapid hardened material, which generates ettringite early and imparts rapid hardening to cement concrete, hardens in several minutes to several tens of minutes after placing cement concrete on a mold, and exhibits practical strength that can be removed after several hours. It is widely used for emergency construction such as paving concrete on expressways, emergency repair mortars, grout mortars, etc. mainly for the purpose of opening road traffic for a short time.

Japanese Patent No. 4244261 JP-A-7-232944 Japanese Patent Publication No.49-30683 JP 2002-68795 A JP 7-215745 A JP 2009-149476 A

However, in emergency construction and emergency repairs that are opened for a short time, the curing conditions after curing change depending on the climate, the water supply is not constant, and the effect of compensating for shrinkage by the hydration reaction after curing may become unstable. It was a challenge. Further, there is a case where the adhesion strength with an existing structure is lowered due to expansion after curing, and there is a need for a hardened material that does not cause expansion.

Therefore, the present invention provides a quick-hardening material that has little change in length in both air curing and underwater curing, is excellent in dimensional stability, and is excellent in rapid hardening, and a rapid-hardening cement composition using the same.

That is, the present invention is (1) amorphous calcium aluminate clinker ground product Blaine specific surface area is 4000~8500cm ² / g, the Blaine specific surface area and contains alumina cement, gypsum is 3000~6500cm ² / g (2) Amorphous calcium aluminate clinker containing moles of CaO and Al ₂ O ₃ in which the branes specific surface area of the alumina cement is smaller than that of the pulverized amorphous calcium aluminate clinker (1) or (2) where the ratio of the hard cement is 1.3 to 2.5 and (3) the alumina cement is 5 to 20 parts by mass with respect to 100 parts by mass of the pulverized amorphous calcium aluminate clinker (4) Cement and a quick-hardening cement composition containing any one of (1) to (3).

When using the quick-hardening material of the present invention and the quick-hardening cement composition using the same, there is little change in length in both air curing and underwater curing, and it has excellent dimensional stability and rapid hardening. A material and a cement composition using the same can be provided.

Hereinafter, the present invention will be described in detail.
Unless otherwise specified, parts and% in the present invention are shown on a mass basis.
The cement concrete referred to in the present invention is a general term for mortar and concrete.

The amorphous calcium aluminate (hereinafter referred to as amorphous CA) clinker used in the present invention is obtained by mixing a raw material containing calcia and a raw material containing alumina, melting and heating, and rapidly cooling this. It is a general term for amorphous materials having hydration activity mainly composed of CaO and Al ₂ O ₃ . For example, CA clinker melted in an electric furnace is brought into contact with compressed air or water and rapidly cooled.

The content molar ratio of CaO and Al ₂ O _{3 in} the amorphous CA clinker used in the present invention is preferably 1.3 to 2.5, and more preferably 1.5 to 2.0 from the viewpoint of hydration activity and strength expression. preferable. If it exceeds 2.5, vitrification requires an extremely high melting point and a rapid cooling operation from this temperature, which makes manufacturing difficult and uneconomical. Hydration activity and initial strength may be reduced.

The vitrification rate of the amorphous CA clinker used in the present invention is preferably 90% or more, and more preferably 95% or more. If it is less than 90%, the rapid hardening property and initial strength development of cement concrete may decrease. The crystalline part of the amorphous CA clinker is not particularly limited. Specific examples of minerals to be generated include calcium aluminate such as 3CaO · Al ₂ O ₃ and 12CaO · 7Al ₂ O ₃ , gehlenite, calcium aluminoferrite, calcium ferrite, etc. due to secondary components and unavoidable impurities. It is done.

The vitrification rate of the amorphous CA clinker can be determined by powder X-ray diffraction / Rietveld analysis. That is, a predetermined amount of an internal standard substance such as aluminum oxide or magnesium oxide is added to the sample, and after sufficiently mixing with an agate mortar or the like, powder X-ray diffraction measurement is performed. By analyzing the measurement results with quantitative software, the amount of mineral composition produced is determined, and the balance is the vitrification rate of the clinker. As the quantitative software, “SIROQUANT” manufactured by Sietronics can be used.

The fineness of the pulverized amorphous CA clinker used in the present invention is preferably 4000 to 8500 cm ² / g, more preferably 5000 to 6500 cm ² / g in terms of the specific surface area of brain (hereinafter referred to as “brain value”). If the brane value is less than 4000 cm ² / g, the rapid hardening property and initial strength development of cement concrete may decrease. On the other hand, even if the brain value exceeds 8500 cm ² / g, further enhancement of the effect cannot be expected, and workability may deteriorate. In addition, it takes time to grind and is uneconomical.

The alumina cement used in the present invention uses bauxite, high alumina, refined alumina, etc. as an alumina source, and limestone, quick lime, etc. as a calcia source. It is obtained by melting or baking in a flat furnace, a rotary kiln or the like. Several types of alumina cements with different mineral compositions are known and commercially available, but their main component is monocalcium aluminate (CA). A commercial product having a CA content of 50% or more can be used in the present invention regardless of its type.

The CA content in the alumina cement can be determined by powder X-ray diffraction / Rietveld analysis. That is, a predetermined amount of an internal standard substance such as aluminum oxide or magnesium oxide is added to the sample, and after sufficiently mixing with an agate mortar or the like, powder X-ray diffraction measurement is performed. The CA content can be obtained by analyzing the measurement result with quantitative software. As the quantitative software, “SIROQUANT” manufactured by Sietronics can be used.

When an alumina cement is obtained industrially, impurities may be contained. Specific examples thereof include SiO ₂ , Fe ₂ O ₃ , MgO, TiO ₂ , MnO, Na ₂ O, K ₂ O, Li ₂ O, S, P ₂ O ₅ , and F. The presence of these impurities is not particularly problematic as long as the object of the present invention is not substantially impaired. Specifically, there is no particular problem if the total of these impurities is in the range of 10% or less.

The fineness of the alumina cement used in the present invention is preferably 3000 to 6500 cm ² / g, more preferably 4000 to 5500 cm ² / g in terms of Blaine value. If the brane value is less than 3000 cm ² / g, the rapid hardening property and initial strength development of cement concrete may decrease. On the other hand, even if the brain value exceeds 6500 cm ² / g, further enhancement of the effect cannot be expected, and workability may deteriorate. In addition, it takes time to grind and is uneconomical.

Amorphous CA clinker pulverized product and alumina cement used in the present invention, CaO and Al ₂ O ₃ partly alkali metal oxide, alkaline earth metal oxide, silicon oxide, titanium oxide, iron oxide, alkali A small amount of these are solidified to those substituted with metal halides, alkaline earth metal halides, alkali metal sulfates, alkaline earth metal sulfates, or the like, or containing CaO and Al ₂ O ₃ as main components. A melted one can also be used.

The brane value of the alumina cement used in the present invention is preferably lower than the brane value of the pulverized amorphous CA clinker, and more specifically, it is more preferably 500 to 1500 cm ² / g lower. When the brane value of the alumina cement is greater than or equal to the brane value of the pulverized amorphous CA clinker, the effect of improving the dimensional stability may not be obtained, and the initial strength development may be reduced.

In the present invention, the alumina cement is preferably 5 to 20 parts by mass, more preferably 7 to 12 parts by mass with respect to 100 parts of the pulverized amorphous CA clinker. If it is less than 5 parts, the effect of improving the dimensional stability may not be obtained, and if it exceeds 20 parts, the initial strength development may be reduced.

As the gypsum used in the present invention, anhydrous gypsum, hemihydrate gypsum, and dihydrate gypsum can be used. Among these, anhydrous gypsum is preferable in terms of setting properties and strength development.

The particle size of gypsum may be the level usually used for cement and the like, but a brane value of 3000 cm ² / g or more is preferable from the viewpoint of initial strength development of cement concrete. If the brane value is smaller than 3000 cm ² / g, the setting property and strength development of cement concrete may be lowered.

Although the usage-amount of gypsum is not specifically limited, 20-150 parts are preferable with respect to 100 parts of amorphous CA clinker ground materials, and 50-120 parts are more preferable. If the amount of gypsum used is less than 20 parts, the setting property of cement concrete may be reduced, and it may be difficult to promote long-term strength development. On the other hand, if the amount of gypsum used is more than 150 parts, initial setting is delayed, The initial strength development may be reduced.

  Any setting retarder used in the rapid-hardening material of the present invention may be used as long as it has a retarding action on the setting of the hydraulic cement. For example, citric acid, gluconic acid, tartaric acid, malic acid or salts thereof, boric acid salts such as boric acid and sodium borate, phosphates, alkali metal carbonates, inorganic salts such as alkali metal bicarbonates, saccharides, etc. One or two or more selected from the group of can be used. Among these, one or two or more selected from the group of citric acid, citrate, tartaric acid, tartrate, and alkali metal carbonate are preferable from the viewpoint of adjusting the curing time and developing the initial strength.

  The amount of the setting retarder used varies depending on the working (working) time, and it is difficult to determine uniquely. In the present invention, the addition amount is adjusted so that the cement concrete is hardened in accordance with the work (usable) time of 15 to 40 minutes, but usually comprises cement, amorphous CA clinker pulverized product, alumina cement and gypsum. 0.1-4 parts are preferable with respect to 100 parts of the rapid-hardening cement composition, 0.2-3 parts are more preferable, and 0.3-2 parts are the most preferable. Outside these ranges, sufficient work (usable) time may not be secured or strength development may be reduced.

  The use amount of the rapid-hardening material of the present invention is not particularly limited and is determined depending on the use, but 5-35 parts are preferable in the total of 100 parts of cement and quick-hardening material, and 10-30 parts Is more preferable, and 15 to 25 parts is most preferable. If it is less than 5 parts, the initial strength development may be small, whereas if it exceeds 35 parts, the long-term strength may be reduced.

As the cement used in the present invention, various portland cements such as normal, early strength, super early strength, low heat, and moderate heat, various mixed cements obtained by mixing these portland cements with blast furnace slag, fly ash, or silica, Examples include filler cement mixed with limestone powder, blast furnace slow-cooled slag fine powder, etc., and environmentally friendly cement (eco-cement) manufactured from municipal waste incineration ash and sewage sludge incineration ash. One kind or two or more kinds can be used.

  In the present invention, in addition to fine aggregates such as cement, cement rapid hardener, setting retarder and sand, and coarse aggregates such as gravel, expansion material, 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, setting agent, clay mineral such as bentonite, anion exchanger such as hydrotalcite, granulated blast furnace slag fine powder and blast furnace gradual It is possible to use one or two or more of the group consisting of admixtures such as slag such as cold slag fine powder and limestone fine powder as long as the object of the present invention is not substantially inhibited.

  Hereinafter, although an example and a comparative example are given and the contents are explained in detail, the present invention is not limited to these.

(Experimental example 1)
Amorphous CA clinker, Blaine each alumina cement clinker in a ball mill 6000 cm ² / g, was ground to 5000 cm ² / g. The obtained amorphous CA clinker pulverized product, alumina cement and gypsum were blended in the proportions shown in Table 1 to obtain a hardened material.
Using this rapid-hardening material, 20 parts of rapid-hardening material is used in 100 parts of rapid-hardening cement composition composed of cement and rapid-hardening material, and 150 parts of fine aggregate and water are added to this rapid-hardening cement composition. Was prepared in a room at 20 ° C., and the compressive strength and the rate of change in length were measured. For comparison, mortar prepared without using a hardened material was also demolded and measured for the base length 24 hours after molding, and the rate of change in length was measured (Experiment No. 1-1).

<Materials used>
Cement: Ordinary Portland cement, Blaine value 3200 cm ² / g, Specific gravity 3.15
Amorphous CA clinker: A molar ratio of CaO and Al ₂ O ₃ of 1.7 (amorphous clinker corresponding to the C ₁₂ A ₇ composition). Synthesized by using limestone as calcia source and bauxite as alumina source and rapidly cooling after melting at 1650 ° C. Vitrification rate 98%.
Alumina cement clinker: CaO and Al ₂ O ₃ content molar ratio 1 (crystalline clinker corresponding to CA composition). Using bauxite as the calcia source and limestone as the alumina source, sinter at 1450 ° C and then slowly cool to synthesize. CA content 67%.
Limestone: CaO content of 57 wt%, Al ₂ O ₃ content of 1.1 wt%, MgO content of 0.35 mass%, SiO ₂ content of 0.67 wt%
Bauxite: CaO content 0.75% by mass, Al ₂ O ₃ content 72% by mass, MgO content 0.31% by mass, SiO ₂ content 4.7% by mass Gypsum: commercial anhydrous gypsum pulverized product, brain value 6000 cm ² / g
Gypsum: commercially available anhydrous gypsum pulverized product, brain value 6000 cm ² / g
Fine aggregate: JIS standard sand, commercial product.
Setting retarder: Citric acid (commercially available)

<Measurement method>
Compressive strength: A 4 × 4 × 16 cm specimen was prepared according to JIS R 5201, and the compressive strength after 3 hours was measured.
Length change rate: Free shrinkage strain “JIS A 1129-3 Measurement method for length change of mortar and concrete-Part 3: Dial gauge method Annex A (reference) Free shrinkage strain test method by drying mortar and concrete” Measured according to. After 3 hours of molding, demolding and measuring the base length. The length change rate was measured after curing in water (20 ° C.) and in the air (20 ° C., 60 RH%) until the age of 28 days.

According to the present invention, it is understood that there is little change in length in either air curing or water curing, and a hardened material excellent in dimensional stability and quick hardening can be obtained. When the amount of alumina cement is 5 parts by mass or more with respect to 100 parts by mass of the amorphous calcium aluminate clinker pulverized product, the effect of the present invention is large. On the other hand, when it exceeds 20 parts by mass, the compressive strength is reduced for 3 hours. It can be seen that the performance decreases.

(Experimental example 2)
Amorphous CA clinker and alumina cement clinker were ground with a ball mill to the brain values shown in Table 2. Gypsum was added to the obtained amorphous CA clinker pulverized product and alumina cement clinker pulverized product to prepare a hardened material. The blend was 10 parts alumina cement and 110 parts gypsum with respect to 100 parts of the amorphous CA clinker pulverized product.
A rapid-hardening cement composition is prepared by making 20 parts of quick-hardening material out of a total of 100 parts of cement and quick-hardening material. Further, in a room at 20 ° C., 150 parts of fine aggregate and 50 parts of water are added to the quick-setting cement composition. A mortar was prepared by mixing 0.4 part of citric acid as a setting retarder, and the compressive strength and the rate of change in length were measured.

From Table 2, it can be seen that there is little change in length in either air curing or water curing, and a hardened material excellent in dimensional stability and quick hardening can be obtained. Amorphous CA clinker ground product, 4000 cm Blaine value of alumina cement, respectively ² / g, when 3000 cm ² / g less, it can be seen that 3 hours compressive strength is lowered the performance of the small Kyukata material. Also, amorphous CA clinker ground product, the Blaine value of the alumina cement, that each 8500cm ² / g, improvement in performance further be greater than 6500 cm ² / g is not uneconomical seen. When the brane value of the alumina cement is smaller than the brane value of the pulverized amorphous CA clinker, a rapid hardened material with little change in length in both air curing and underwater curing can be obtained. I understand.

(Experimental example 3)
Amorphous CA clinker having a molar ratio of CaO to Al ₂ O ₃ shown in Table 3 was produced. The alumina cement clinker and gypsum used were those of Experimental Example 1. Amorphous CA clinker and alumina cement clinker were ground to a brain value of 6000 cm ² / g and 5000 cm ² / g, respectively, and gypsum was added to the obtained amorphous CA clinker ground material and alumina cement clinker ground material. A hard material was produced. The blend was 10 parts alumina cement and 110 parts gypsum with respect to 100 parts of the amorphous CA clinker pulverized product.
A rapid-hardening cement composition is prepared by making 20 parts of quick-hardening material out of a total of 100 parts of cement and quick-hardening material. Further, in a room at 20 ° C., 150 parts of fine aggregate and 50 parts of water are added to the quick-setting cement composition. A mortar was prepared by mixing 0.4 part of citric acid as a setting retarder, and the compressive strength and the rate of change in length were measured.

From Table 3, it can be seen that when the content molar ratio of CaO and Al ₂ O ₃ is less than 1.3, the expression of the initial strength is lowered, and on the other hand, even if it exceeds 2.5, further effects cannot be obtained.

When using the quick-hardening material and the quick-hardening cement composition of the present invention, there is no change in length in both the air curing and the underwater curing, the dimensional stability is excellent, and the quick-hardening material excellent in rapid hardening is used. The used cement composition can be provided and can be suitably used in the civil engineering and construction fields.

Claims (4)

Amorphous calcium aluminate clinker ground product Blaine specific surface area is 4000~8500cm ² / g, the Blaine specific surface area and also contains an alumina cement, gypsum is 3000~6500cm ² / g, the Blaine specific surface area of the alumina cement A hardened material having a surface area smaller than the Blaine specific surface area of the pulverized amorphous calcium aluminate clinker. The rapid hardening material according to claim 1, wherein the amorphous calcium aluminate clinker contains CaO and Al ₂ O _{3 in} a molar ratio of 1.3 to 2.5. The rapid hardening material according to claim 1 or 2, wherein the alumina cement is 5 to 20 parts by mass with respect to 100 parts by mass of the pulverized amorphous calcium aluminate clinker. A quick-hardening cement composition comprising cement and the quick-hardening material according to any one of claims 1 to 3.