JPH09110510A - Cement composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a cement composition enabling the increase of the content of a blast furnace slug and the reduction of the use of cement clinker by compounding the cement clinker, the blast furnace slug, anhydrous gypsum and a specific acid (base). SOLUTION: This composition is composed of preferably 10 90 pts.wt., especially preferably 20-70 pts.wt. of cement clinker (e.g. a quickly curing portland cement clinker), preferably 10-90 pts.wt., especially preferably 30-80 pts.wt. of blast furnace slug, preferably 1-10 pts.wt., especially preferably 3-7 pts.wt. of anhydrous gypsum, and preferably 0.05-3 pts.wt., especially preferably 0.1-2 pts.wt. of at least one (e.g. sodium formate) selected from formic acid, lactic acid and acetic acid and their salts based on 100 pts.wt. of the cement composition. The composition is excellent in the expression of initial strength and little in temperature dependency.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention mainly relates to a cement composition used in the field of civil engineering and construction.

[0002]

2. Description of the Related Art In recent years, the issue of global environmental protection has been greatly highlighted, and various attempts have been made in the cement field in connection with environmental protection. For example, it has been regarded as a problem that carbon dioxide gas exhausted in the process of producing cement clinker leads to global warming and causes a great deterioration in the balance of the natural environment. On the other hand, in the cement field, since it is possible to suppress the amount of cement clinker used, which also causes the generation of carbon dioxide, for example, blast furnace slag, which is industrial waste, such as blast furnace cement, fly ash cement, or silica cement. Attention has been paid to a mixed cement in which a pozzolanic material such as ash, fly ash, and silica fume is mixed. Among these, blast furnace cement is particularly noted because it can increase the content of industrial waste in the mixed cement as compared with fly ash cement or silica cement. For example, in JIS, the content of the pozzolanic substance in the mixed cement is up to 30% by weight for fly ash cement and silica cement when compared with various mixed cement type C, which has the highest content, whereas the blast furnace It is specified that up to 70% by weight can be mixed in cement. Industrial wastes such as blast furnace slag, fly ash, and silica fume have latent hydraulic properties and react with calcium hydroxide generated during the hydration process of cement, contributing to strength development and densification of hardened cement Is known to do.

Here, the hardened cement is a general term for hardened cement paste, mortar, or concrete. The mixed cement obtained by mixing these substances having latent hydraulic properties has a problem that the initial strength development is poor as compared with ordinary Portland cement. In order to solve the problem of such mixed cement, a method for improving the initial strength development property by pulverizing the blast furnace slag or pulverizing the blast furnace slag, and further adding anhydrous gypsum to develop the strength development property. A method for improving the above was proposed (Nakamoto et al., Annual Report on Concrete Engineering, Vol. 1
6, No. 1, 1994, JP-A-57-67051, JP-A 1-1
8956 publication). Generally, when blast furnace slag and cement clinker are mixed and pulverized, the cement clinker itself is also finely pulverized, and the workability of a cement kneaded product using the clinker may be deteriorated. Therefore, in these methods, the blast furnace slag and the cement clinker must be crushed separately, so that new manufacturing equipment must be added, and the crushing cost is high because of the fine powder, which is a fatal factor in manufacturing. However, even if anhydrous gypsum, whose strength is improved when added, is added, the blast furnace slag has a fineness of 6,
If it is not more than about 000 cm ² / g, on the contrary, the initial strength will decrease,
There is a problem that the temperature dependence becomes large and the initial strength development property is halved at low temperatures.

As a result of various studies to solve the above-mentioned problems, the present inventor can increase the content of blast furnace slag in cement by using a specific cement composition, and further, the initial strength. The present invention has been completed based on the finding that a cement composition having a good expression and a low temperature dependence can be obtained.

[0005]

That is, the present invention comprises cement clinker, blast furnace slag, anhydrous gypsum, and one or more selected from the group consisting of formic acid, lactic acid, and acetic acid or salts thereof. It is a cement composition obtained.

The present invention will be described in more detail below.

The cement clinker of the present invention (hereinafter referred to as the present clinker) is a generic name for Portland cement clinker, and the components are not particularly limited. For example, ordinary Portland cement clinker and early strength Portland cement Examples thereof include clinker and belite cement clinker. Among them, it is preferable to use early-strength Portland cement clinker from the viewpoint of strength development. The grain size of the clinker is preferably 2,500 to 7,000 cm ² / g in terms of Blaine value, and more preferably 3,500 to 5,000 cm ² / g. If it is less than 2,500 cm ² / g, sufficient initial strength may not be obtained, and if it exceeds 7,000 cm ² / g, slump loss of concrete may increase. The amount of the clinker used is not particularly limited, but is usually one or more selected from the group consisting of the clinker, blast furnace slag, anhydrous gypsum, and formic acid, lactic acid, and acetic acid or salts thereof. Cement composition containing 10
Of 0 parts by weight, 10 to 90 parts by weight is preferable, and 20 to 70 parts by weight is more preferable. If it is less than 10 parts by weight, the initial strength development is poor, and if it exceeds 90 parts by weight, the addition amount of blast furnace slag becomes extremely small, which is not preferable for the purpose of the present invention.

[0008] Blast furnace slag for use in the present invention but is not particularly limited, preferably 3,000 cm ² / g or more in Blaine value, 5,000 cm ² / g or more is more preferable. 3,000c
If it is less than m ² / g, the initial strength development may deteriorate. The amount of the blast furnace slag used is not particularly limited, but is usually preferably 10 to 90 parts by weight, more preferably 30 to 80 parts by weight, based on 100 parts by weight of the cement composition. If it is less than 10 parts by weight, the amount of blast furnace slag added is too small to meet the purpose of the present invention, and if it exceeds 90 parts by weight, the initial strength development may be poor. The cement composition of the present invention is excellent in initial strength development particularly in the range where the content of blast furnace slag in the cement composition is 50% by weight or more, especially in comparison with the conventional cement compositions.

The anhydrous gypsum used in the present invention is not particularly limited, and naturally-produced natural anhydrous gypsum, anhydrous gypsum obtained by heat treatment of hemi-water gypsum and dihydrate gypsum, and as an industrial by-product. It is possible to use anhydrous gypsum or the like generated. The grain size of anhydrous gypsum is preferably 2,500 cm ² / g or more in terms of Blaine value. 2,500 cm ²
If it is less than / g, it may expand and fracture due to unhydrated residual gypsum during long-term age. The amount of anhydrous gypsum used is preferably 1 to 10 parts by weight in 100 parts by weight of the cement composition.
-7 parts by weight is more preferred. If the amount is less than 1 part by weight, the initial strength may be deteriorated. If the amount exceeds 10 parts by weight, the unhydrated residual gypsum may cause expansion and fracture at a long-term age.

One or more selected from the group consisting of formic acid, lactic acid, acetic acid and salts thereof used in the present invention.
(Hereinafter, referred to as formic acids) generally belongs to organic compounds collectively referred to as oxycarboxylic acids, but, for example, like succinic acid, malic acid, tartaric acid, and gluconic acid or salts thereof, or salts thereof, the present invention can be used. It is not able to exert an effect, but rather has a different effect from other oxycarboxylic acids showing a strong setting retarding property. Formic acid of the present invention,
Specific examples include formic acid, lactic acid, acetic acid and the like, or their sodium salts, potassium salts, calcium salts, magnesium salts, barium salts, aluminum salts, zinc salts, ammonium salts and the like. The amount of formic acid used is preferably 0.05 to 3 parts by weight, and 0.1 to 3 parts by weight based on 100 parts by weight of the cement composition.
2 parts by weight is more preferred. If it is less than 0.05 parts by weight, the initial strength development may be insufficient, and if it exceeds 3 parts by weight, the enhancement of the effect cannot be expected.

Although the particle size of the cement composition of the present invention is not particularly limited, for example, the Blaine value is 3,000 to
It is preferably about 9,000 cm ² / g, more preferably about 4,000 to 6,000 cm ² / g. If it is less than 3,000 cm ² / g, the strength development may be deteriorated, and it is not preferable to grind it so as to exceed 9,000 cm ² / g because the cost will increase.

The amount of water used in the present invention is not uniquely determined depending on the type and composition of the materials used, but usually, the water / cement composition ratio is preferably 25 to 50% by weight, and 30 to 40% by weight is more preferred. If it is less than 25% by weight, sufficient workability may not be obtained, and if it exceeds 50% by weight, sufficient strength development may not be obtained.

In the present invention, it is of course possible to use a setting accelerator together with the cement composition of the present invention. Examples of the setting accelerator include alkali metal aluminates such as sodium aluminate and potassium aluminate, sodium carbonate, potassium carbonate, sodium bicarbonate, and alkali metal carbonates such as potassium bicarbonate, sodium nitrate, potassium nitrate, and nitric acid. Sulfates other than anhydrous gypsum such as calcium, sodium nitrite, potassium nitrite, calcium nitrite, sodium sulfate, potassium sulfate, gypsum dihydrate, gypsum dihydrate, and aluminum sulfate, calcium hydroxide, calcium oxide , Alums, thiocyanates, thiosulfates, and aminoalcohols such as triethanolamine, and the combination of one or more of them further promotes the effect of the present invention. It is preferable from the aspect. The amount of the setting accelerator used is preferably 3 parts by weight or less, and more preferably 0.05 to 1 part by weight, based on 100 parts by weight of the cement composition. If the amount exceeds 3 parts by weight, strength may decrease and workability may deteriorate due to an increase in kneading water.

In the present invention, in addition to the cement composition and the setting accelerator of the present invention, if necessary, aggregates such as sand and gravel, water reducing agents, high-performance water reducing agents, AE agents, AE water reducing agents, high performance agents AE
Water reducing agent, cement expander, thickener, rust preventive, antifreeze, polymer emulsion, clay minerals such as bentonite and montmorillonite, ion exchangers such as zeolite, hydrotalcite, and hydrocalumite, inorganic phosphate ,
In addition, one or more of boric acid and the like can be used in combination within a range that does not substantially impair the object of the present invention.

As the mixing device used in the production of the cement composition of the present invention, any existing stirring device can be used, for example, a tilting mixer, an omni mixer, a V mixer.
A mold mixer, a Henschel mixer, a Nauta mixer or the like can be used. In addition, the mixing may be carried out by mixing the respective materials at the time of construction, or part or all of them may be mixed in advance. In the present invention, the clinker, blast furnace slag, and anhydrous gypsum may be separately ground and mixed, or may be mixed and ground by mixing and grinding each material at the time of grinding, and a cheaper cement composition From the viewpoint of production, it is preferable to mix and grind.

[0016]

The present invention will be described in detail below with reference to examples.

Example 1 A test environment temperature such as room temperature and material temperature was set to 20 ° C., and the clinker, blast furnace slag, and anhydrous gypsum were crushed to have Blaine values of 3,120 cm ² / g, 3,970 cm ² / g, and 4,520, respectively. cm ²
/ g, the weight ratio of the present clinker / blast furnace slag is set to 40/60, and in 100 parts by weight of a cement composition comprising the present clinker, blast furnace slag, anhydrous gypsum, and formic acid a, the amount of anhydrous water shown in Table 1 is used. Gypsum and formic acid a are mixed,
A cement composition was prepared. To 100 parts by weight of this cement composition, 200 parts by weight of sand and 60 parts by weight of water were added to prepare a mortar, and its compressive strength was measured. Table 1 shows the results
It is described together.

<Materials used> Clinker: Normal Portland cement clinker manufactured by Denki Kagaku Kogyo Co., Ltd. Ground product Blast furnace slag: Commercially ground product Gypsum anhydrous: Natural anhydrous gypsum formic acid a: Kanto Chemical Reagent first grade calcium formate sand: Teura Standard sand water: Tap water

<Test method> Compressive strength: Measured according to JIS A 1108

[0020]

[Table 1]

Example 2 Using unmilled clinker, blast furnace slag, and anhydrous gypsum, 5 parts by weight of anhydrous gypsum in 100 parts by weight of a cement composition and 1 part by weight of formic acid a were used.
As in Example 1, except that the clinker and the blast furnace slag were mixed and ground as shown in FIG. The results are also shown in Table 2.

[0022]

[Table 2]

Example 3 The same procedure as in Example 1 was carried out except that formic acid of the type shown in Table 3 was used with 5 parts by weight of anhydrous gypsum in 100 parts by weight of the cement composition. The results are also shown in Table 3. For comparison, the same procedure was performed using citric acid instead of formic acids. The results are also shown in Table 3.

<Materials used> Formic acid b: Kanto Chemical Co., Ltd. reagent first-class formic acid Formic acid c: Kanto Chemical Co., Ltd. reagent first-class sodium formate d Formic acid d: Kanto Chemical Co., Ltd. reagent first-class potassium formate e: Kanto Chemical reagent 1st grade lactic acid formic acid f: Kanto chemical reagent 1st grade calcium lactate formate g: Kanto chemical reagent 1st grade sodium lactate formate h: Kanto chemical reagent 1st grade potassium lactate formate i: Reagents manufactured by Kanto Kagaku Co., Ltd. Primary calcium acetate Formic acid j: Equivalent mixture of formic acid a and formic acid f Formic acid k: Equivalent mixture of formic acid a, formic acid f and formic acid f Citric acid: Kanto Chemical Co., Inc. Manufacturing reagent first grade

[0025]

[Table 3]

Example 4 As in Example 1 except that 4 parts by weight of anhydrous gypsum and 1 part by weight of formic acid a were used in 100 parts by weight of the cement composition, and the amounts of the setting accelerator shown in Table 4 were used. I went the same way. Table 4 shows the results.

<Materials used> Agglomeration accelerator A: Powdered aluminum sulphate manufactured by Mizusawa Chemical Industry Co., 17% by weight of Al ₂ O ₃ , 43% water content Agglomeration accelerator B: Reagent 1st class sodium aluminate Agglomeration accelerator C: Reagent Primary calcium nitrate setting accelerator D: Reagent primary calcium thiocyanate Setting accelerator E: Reagent primary triethanolamine

[0028]

[Table 4]

Example 5 Example 5 was repeated except that the test environment temperature was 5 ° C. Table 5 shows the results.

[0030]

[Table 5]

Example 6 The procedure of Example 1 was repeated except that this clinker β was used. Table 6 shows the results.

[0032]

[Table 6]

[0033]

EFFECTS OF THE INVENTION By using the cement composition of the present invention, it is possible to increase the content of blast furnace slag, and further, it is possible to obtain effects such as good initial strength development and small temperature dependence.

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area C04B 24:04) 103: 14

Claims (1)

[Claims] 1. A cement composition containing cement clinker, blast furnace slag, anhydrous gypsum, and one or more selected from the group consisting of formic acid, lactic acid, acetic acid, and salts thereof.