JP3452228B2 - Stimulant for mixed cement and mixed cement composition - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a stimulant for mixed cement used in the civil engineering / construction industry and a mixed cement composition using the same.

[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 manufacturing cement clinker leads to global warming and causes a great deterioration in the balance of the natural environment.

In the cement field, since the amount of cement clinker produced can be suppressed in the cement field, attention is paid to a mixed cement prepared by mixing industrial waste such as blast furnace slag, fly ash, and silica fume. There is. Industrial wastes such as blast furnace slag, fly ash, and silica fume have latent hydraulic properties,
It is known that it reacts with calcium hydroxide produced during the hydration process of cement and contributes to strength development and densification of hardened cement. Here, the hardened cement is a general term for hardened cement paste, mortar, or concrete. However, the mixed cement mixed with these latent hydraulic substances has a problem that the strength development in the initial stage is poor as compared with ordinary Portland cement, and since the cement hardened body structure is difficult to densify, the carbonation reaction is extremely fast. there were.

In order to solve the problem of such mixed cement, a method has been proposed for enhancing the strength of blast furnace cement type B by using early strong Portland cement, which produces a large amount of calcium hydroxide, as a stimulating material (Yasunaga, Nakamura, Hoezaki, 49th
Annual Conference of Cement Technology Conference, p108-113 1995). However, in this method, the effect of strength development and the densification of the hardened cement are not sufficient, and the content of blast furnace slag is
Since it can only be increased to about 50% by weight,
There is a problem that the amount of cement clinker cannot be reduced, and if the content exceeds 55% by weight, the strength developability deteriorates.

The present inventor has made diligent efforts to solve these problems, and as a result, not only the initial strength development was improved by using a stimulant of a specific mixed cement, but also The present invention has been completed based on the finding that the structure of the hardened cement product can be densified and the carbonation reaction can be significantly suppressed.

[0006]

[Means for Solving the Problems] That is, the present invention is to produce a mixture containing a CaO raw material and a CaF ₂ raw material by heat treatment, and a group of minerals containing free lime and calcium fluoride as active ingredients. And has a Blaine value of 3,000 cm ² / g or more,
An average particle diameter is 20 μm or less, and calcium fluoride is contained in the stimulant of the mixed cement in an amount of 5 to 40% by weight, and further contains an inorganic sulfate. And a stimulant for the mixed cement, the mixture containing the cement and the stimulant for the mixed cement.

The present invention will be described in more detail below.

Mixed cement stimulant used in the present invention
(Hereinafter, referred to as the present stimulant) is produced by heat-treating a mixture containing a CaO raw material and a CaF ₂ raw material, and is a heat-treated product consisting of mineral groups containing free lime and calcium fluoride as active ingredients. Yes, it is different from a simple mixture of lime and calcium fluoride. The effect of the present invention cannot be obtained with a simple mixture. The raw material of this stimulant can be arbitrarily selected depending on the purity and cost, and is not particularly limited, but for example, CaO ₃ quality such as limestone and slaked lime as CaO raw material and Ca (OH) ₂ quality etc. Examples of the CaF ₂ raw material include fluorite and calcium fluoride produced as an industrial by-product. Al ₂ O ₃ and SiO present in each raw material
The presence of impurities such as ₂ , Fe ₂ O ₃ , MgO, TiO ₂ , and SO ₃ is not particularly limited as long as the object of the present invention is not substantially impaired.

The raw material in the present invention is preferably blended so that calcium fluffide as an active ingredient is 5 to 40% by weight, and 10 to 30% by weight in the heat-treated product. Is more preferable. Outside this range, a sufficient neutralization suppressing effect may not be obtained.

In the present invention, the heat treatment temperature is not particularly limited, but is usually preferably about 1,000 to 1,500 ° C. The method of mixing the raw materials is not particularly limited, and an ordinary method can be used. The heat treatment method for manufacturing the present stimulant is not particularly limited, and examples thereof include a firing method using a rotary kiln.

The grain size of the stimulant is usually a Blaine value of 3,000.
Above 0 cm ² / g, average particle size below 20 μm, Blaine value
The average particle size is preferably 4,000 cm ² / g or more and the average particle size is 15 μm or less, more preferably the Blaine value is 5,000 cm ² / g or more and the average particle size is 10 μm or less. Blaine value less than 3,000 cm ² / g, average particle size 20μ
If it exceeds m, the cement hardened product using the present stimulant may exhibit expandability, and sufficient strength development and neutralization suppressing effect may not be obtained.

The amount of the stimulant used is preferably 1 to 7 parts by weight, more preferably 2 to 5 parts by weight, based on 100 parts by weight of the binder composed of cement and the stimulant. When the amount is less than 1 part by weight, the effect of use is not sufficient, and when the amount is more than 7 parts by weight, the cement hardened product using this stimulant exhibits expansiveness, and sufficient strength expression and neutralization suppression effect cannot be obtained. There is.

In the present invention, the effect of the present invention can be made more remarkable by using the present stimulant in combination with an inorganic sulfate.

Here, the inorganic sulfate is not particularly limited, but for example, anhydrous gypsum, hemihydrate gypsum,
And gypsums such as gypsum dihydrate, alkali metal sulfates such as sodium sulfate and potassium sulfate, aluminum sulfate, magnesium sulfate, and alum, and the like, because the effect of the present invention is remarkable, also economical. From the viewpoint of, it is preferable to use gypsum, and it is particularly preferable to use anhydrous gypsum. The particle size of the inorganic sulfate is usually preferably a Blaine value of 3,000 cm ² / g or more.
More preferably 5,000 cm ² / g or more. If it is less than 3,000 cm ² / g, sufficient strength development may not be obtained. The amount of the inorganic sulfate used is not particularly limited, but is preferably 5 to 80 parts by weight, more preferably 10 to 60 parts by weight, in 100 parts by weight of the mixture of the stimulant and the inorganic sulfate. If it is less than 5 parts by weight, the strength enhancing effect may not be obtained, and if it exceeds 80 parts by weight, a sufficient neutralizing effect may not be obtained or long-term durability may be deteriorated.

The amount of the mixture of the present stimulant and inorganic sulfate to be used is preferably 1 to 10 parts by weight, more preferably 3 to 7 parts by weight, based on 100 parts by weight of the binder made of cement and this mixture. When the amount is less than 1 part by weight, the effect of use is not sufficient, and when the amount is more than 10 parts by weight, the hardened cement using the stimulant exhibits expansiveness, and sufficient strength development and neutralization suppression effect cannot be obtained. There is.

In the present invention, water is mixed with cement, the present stimulant, and, if necessary, inorganic sulfate to prepare a cement kneaded product. Any existing stirring device can be used as the mixing device used when producing the cement kneaded product of the present invention, and examples thereof include a tilting mixer, an omni mixer, a V-type mixer, a Henschel mixer, and a Nauta mixer. It can be used. As a mixing method, the respective materials may be mixed at the time of construction, or a part or all of them may be mixed in advance.

The amount of water used in the present invention is not particularly limited, and it is usually used, for example, in the range of about 25 to 100% in water / binder ratio, and about 30 to 60%. Preferably, about 40 to 50% is more preferable. If it is less than about 25%, workability may decrease, and if it exceeds about 100%, sufficient strength development and neutralization suppressing effect may not be obtained.

In the present invention, in addition to the stimulant and the mixed cement composition of the present invention, a water reducing agent, AE agent, A
E water-reducing agent, high-performance water-reducing agent, high-performance AE water-reducing agent, setting regulator, cement rapid hardening material, aggregate such as sand and gravel, alkaline substances such as calcium hydroxide, inorganic powder such as calcium carbonate, etc. The purpose of the present invention can be used in combination within a range that does not substantially impair the object.

[0019]

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

Example 1 C so that the heat-treated product has a CaO / CaF ₂ weight ratio of 80/20.
The clinker obtained by mixing the aO raw material and the CaF ₂ raw material and heat-treating at a maximum temperature of 1,300 ° C. using a rotary kiln was crushed as shown in Table 1 to obtain various stimulants. The stimulant was identified by a powder X-ray diffraction method, and it was confirmed that it was composed of a group of minerals containing free lime and calcium fluoride as active ingredients. The composition of this stimulant is JI
According SR 5202, it analyzes the CaO and F ₂ amount was further determined by converting the F ₂ amount to CaF _2. Various stimulants, cement α
3 parts by weight of 100 parts by weight of the binder consisting of the stimulant and the stimulant were mixed to prepare concrete with a binder unit amount of 380 kg / m ³ , a water / binder ratio of 50%, and a fine aggregate ratio of 45%. Strength measurements and accelerated neutralization tests were conducted. The results are also shown in Table 1.

<Materials used> CaO raw material: Limestone powder from Omi mine, Denki Kagaku Kogyo CaF ₂ raw material: Natural fluorite powder, commercial cement α: Denki Kagaku blast furnace cement B class fine aggregate: Niigata prefecture Himekawa , Specific gravity 2.63 Coarse aggregate: Made in Himekawa, Niigata, Specific gravity 2.67, Gmax = 20mm Water: Tap water

<Measurement method> Compressive strength: A test piece of 10φ × 20 cm was prepared and JIS A 1108
Measurement acceleration neutralization test according to the above: Prepare a specimen of 10φ × 20cm for 7 days
After curing in water at 20 ℃, cure for 3 months in an environment test room at 30 ℃, humidity 60%, carbon dioxide concentration 7%, and measure the neutralization depth inside the test piece by applying phenolphthalein to the cross section of the test piece.

[0023]

[Table 1]

Example 2 A CaO raw material and a CaF ₂ raw material were blended so as to obtain the present stimulant shown in Table 2, and a maximum temperature of 1,30 was used using a rotary kiln.
The clinker obtained by heat treatment at 0 ° C. is crushed,
The same procedure as in Example 1 was carried out except that the Blaine value was adjusted to 4,000 ± 200 cm ² / g and the average particle size was adjusted to 10 μm or less to obtain various stimulants. The results are also shown in Table 2.

<Materials used> Main stimulant a: CaO / CaF ₂ weight ratio = 100/0 Main stimulant b: CaO / CaF ₂ weight ratio = 95/5 Main stimulant c: CaO / CaF ₂ weight ratio = 90 / 10 Main stimulant d: CaO / CaF ₂ weight ratio = 80/20 Main stimulant e: CaO / CaF ₂ weight ratio = 70/30 Main stimulant f: CaO / CaF ₂ weight ratio = 60/40

[0026]

[Table 2]

Example 3 The same procedure as in Example 2 was carried out except that 100 parts by weight of the binder was mixed with the stimulating material d as shown in Table 3. The results are also shown in Table 3.

[0028]

[Table 3]

Example 4 3 parts by weight of cement and 100 parts by weight of a binder, the stimulant d
Was carried out in the same manner as in Example 2 except that the type of cement was changed. The results are shown in Table 4. For comparison, lime and calcium fluoride were separately fired and pulverized, and the stimulant was prepared by mixing the lime and calcium fluoride so that the CaO / CaF ₂ weight ratio after mixing was 80/20, and the same experiment was conducted. The results are also shown in Table 4.

<Material used> Cement β: fly ash paste made by Chichibu Onoda Cement
Ment type B Free lime: Baked reagent grade calcium carbonate at 1,000 ℃
Made, Blaine value 4,000 cm ²crushed to / g Calcium Fluoride: Natural Fluorite Powder Blaine 4,000c
m²crushed to / g

[0031]

[Table 4]

Example 5 In 100 parts by weight of a mixture consisting of the stimulant d and an inorganic sulfate,
Example 2 was carried out in the same manner as in Example 2 except that the amount of the inorganic sulfate salt shown in Table 5 was used and 5 parts by weight of the mixture was mixed in 100 parts by weight of the binder comprising cement α and the mixture. The results are also shown in Table 5.

<Materials used> Inorganic sulfate: Natural anhydrous gypsum, Blaine value 5,530 cm ² / g

[0034]

[Table 5]

Example 6 Using 100 parts by weight of a mixture of the present stimulant d and inorganic sulfate, a mixture of 30 parts by weight of inorganic sulfate was used, and the mixture was used in 100 parts by weight of a binder composed of cement and the mixture. Example 5 was repeated except that the amount was changed as shown in Table 6. The results are also shown in Table 6.

[0036]

[Table 6]

Example 7 Example 7 was repeated except that the type of cement was changed. The results are shown in Table 7.

[0038]

[Table 7]

[0039]

EFFECTS OF THE INVENTION By using the stimulant for mixed cement of the present invention, it is possible to obtain a mixed cement composition having a good initial strength development and a large effect of suppressing neutralization.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References Japanese Patent Publication Sho 48-9448 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) C04B 2/00-32/02

Claims (4)

(57) [Claims] 1. A product produced by heat-treating a mixture containing a CaO raw material and a CaF ₂ raw material, comprising a group of minerals containing free lime and calcium fluoride as active ingredients, and having a Blaine value of 3,000 cm ^2. A stimulant for mixed cement, which is characterized by having an average particle size of 20 μm or less at / g or more. 2. Calcium fluoride is 5-40% by weight in the stimulant of the mixed cement.
A stimulant for the described mixed cement. 3. The stimulant for mixed cement according to claim 1, which contains an inorganic sulfate. 4. A mixed cement composition comprising cement and a stimulant for the mixed cement according to claim 1.