JP3460161B2 - Cement admixture and 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 cement admixture and a cement composition used in the civil engineering / construction industry.

[0002]

2. Description of the Related Art Conventional cement admixtures and compositions using calcium aluminates accelerate the setting and hardening of cement and have good initial strength development, so that they can be used for emergency construction or short work. It has been proposed as a so-called rapid hardening cement, which is applied to applications such as opening roads in time (JP-A-48-89222 and JP-A-4-6).
No. 133, etc.). However, these rapid hardening cements have a problem that it is difficult to satisfy both sufficient pot life and sufficient initial strength development.

Furthermore, in recent years, there has been an increasing demand for improvement in the performance of rapid hardening cements, and the use of calcium aluminate containing Na ₂ O has been proposed in order to improve the rapid hardening characteristics and strength development ( JP-A-4-55353). However, this calcium aluminate has a problem that it exhibits an alkali-aggregate reaction because it contains a large amount of Na ₂ O.

As a result of various efforts to solve the above problems, the present inventor has found that the above problems can be solved by using a specific cement admixture or cement composition. The invention was completed.

[0005]

That is, according to the present invention, the Li ₂ 0 content is 3 to 15% by weight, and the CaO / Al ₂ O ₃ molar ratio is 1.5 to.
A cement admixture containing a CaO-Al ₂ O ₃ -Li ₂ O-based substance of 3.0 , an inorganic sulfate, and a coagulation modifier, the cement being a cement composition comprising the cement admixture. is there.

The present invention will be described in more detail below.

CaO-Al ₂ O ₃ -Li ₂ O-based material used in the present invention
(Hereinafter referred to as CAL) has a Li ₂ 0 content of 1 to 15% by weight, and preferably a Li ₂ O content of 2 to 12% by weight.
9% by weight is more preferred. If it is less than 1% by weight, a sufficient effect of suppressing the alkali-aggregate reaction may not be obtained, and if it is used in excess of 15% by weight, further improvement of the effect may not be expected. The ratio of CaO and Al ₂ O ₃ in CAL is not particularly limited, but the CaO / Al ₂ O ₃ molar ratio is 1.5 to
3.0 is preferable and 2-2.8 is more preferable. When the CaO / Al ₂ O ₃ molar ratio is less than 1.5, the strength development in the middle to long-term age may deteriorate, and when it exceeds 3.0, the workability of the cement kneaded product using the same and the cement hardened product using the same The dimensional stability of may decrease.

The CAL of the present invention can be either crystalline or amorphous, and is a CaO raw material, an Al ₂ O ₃ raw material, or Li ₂ 0.
The raw materials are heat-treated, and each raw material is C
The components are not particularly limited as long as AL can be produced. For example, CaO raw materials include slaked lime and limestone powder, Al ₂ O ₃ raw materials include bauxite and aluminum residual ash, and Li ₂₀ raw materials include lithium salts such as Li ₂ CO ₃ and Li (OH) ₂ Can be used respectively. The heat treatment method is not particularly limited, but for example, a method using a rotary kiln, an electric furnace or the like can be mentioned, and the heat treatment time is not particularly limited. The heat treatment temperature is not particularly limited because it varies depending on the composition, but usually 1,
It is about 200-1,800 ℃. The method for cooling the heat-treated product is also not particularly limited, and for example, any method such as a rapid cooling method using water or high-pressure air or a gradual cooling method using natural cooling can be used. Moreover, the presence of other components or impurities is not particularly limited. For example, as other components, Na ₂ O, K ₂ O, MgO, TiO ₂ , Fe
_{2 O 3, B 2 O 3} , SiO 2, P 2 O 5, SO 3, and although contamination of F ₂ or the like is expected, their presence, during the heat treatment of the raw materials, the fired product or melt It has an effect of lowering the melting point of the compound, and also has an effect of enhancing the activity of the calcined product or the melt. Therefore, there is no problem if the amount of the compound does not substantially impair the object of the present invention.

The particle size of CAL is not particularly limited, but a Blaine value of about 1,500 to 8,000 cm ² / g is preferable. If it is less than 1,500 cm ² / g, sufficient strength development may not be obtained, and if it exceeds 8,000 cm ² / g, the fluidity of concrete using this may deteriorate.

The inorganic sulfate used in the present invention is a general term for gypsum, aluminum sulfate, alkali metal sulfate such as sodium sulfate, alkali metal sulfite, alkali metal bisulfite, etc., and is not particularly limited. Although not used, it is preferable to use gypsum from the viewpoint of great effect of the present invention and economy. The gypsum of the present invention is a generic term for anhydrous gypsum, hemihydrate gypsum, and dihydrate gypsum, and is not particularly limited, but the use of anhydrous gypsum has the greatest effect of the present invention. Is preferred. As the anhydrous gypsum, for example, natural anhydrous gypsum produced naturally, heat-dehydrated hemihydrate gypsum or dihydrate gypsum, and those produced as an industrial by-product can be used. The particle size of the inorganic sulfate is not particularly limited, but a Blaine value of 2,000 to 9,000 cm ² / g is preferable. 2,000
If it is less than cm ² / g, long-term durability may be deteriorated.
If it exceeds cm ² / g, the fluidity of the cement kneaded product may decrease. The amount of inorganic sulfate used is the cement admixture
In 100 parts by weight, 10 to 70 parts by weight is preferable, and 30 to 60 parts by weight is more preferable. If it is less than 10 parts by weight, sufficient strength enhancing effect may not be obtained, and if it exceeds 70 parts by weight, long-term durability may be deteriorated.

The setting regulator used in the present invention is, for example, an organic acid such as citric acid, tartaric acid, gluconic acid and malic acid or a salt thereof, phosphoric acid or a salt thereof, an alkali metal carbonate or an alkali metal heavy salt. Examples thereof include carbonates and boric acid, but are not particularly limited. However, the combined use of an organic acid and / or a salt thereof and an alkali metal carbonate provides good strength development. preferable. The amount of the coagulation modifier used cannot be uniquely determined because it depends on the purpose and application of use, but it is usually preferable to use it in the range of 0.5 to 5 parts by weight in 100 parts by weight of the cement admixture. , 1 to 3 parts by weight is more preferable. If it is less than 0.5 parts by weight, sufficient workability may not be obtained, and if it is used in excess of 5 parts by weight, strength development may be deteriorated.

The particle size of the cement admixture of the present invention is not particularly limited because it depends on the purpose and application to be used, but it is usually preferable that the Blaine value is about 1,500 to 8,000 cm ² / g. If it is less than 1,500 cm ² / g, sufficient strength development may not be obtained, and if it exceeds 8,000 cm ² / g, sufficient working time may not be obtained.

The amount of the cement admixture of the present invention used is 10 in 100 parts by weight of the binder composed of cement and the cement admixture.
˜50 parts by weight is preferred, and 20-30 parts by weight is more preferred.
If it is less than 10 parts by weight, the effect of strength development is not sufficient, and if it exceeds 50 parts by weight, long-term durability may deteriorate.

Examples of the cement include various types of portland cement such as normal, early strength, ultrafastness, and moderate heat, and various mixed cements obtained by mixing the portland cement with a pozzolanic substance such as silica or blast furnace slag. .

The amount of water used is not particularly limited and the usual range of use is used. Specifically, the water / binder ratio is preferably 25 to 50%, more preferably 30 to 45%.

The method for curing a cement kneaded product using the cement composition of the present invention is not particularly limited,
A commonly used curing method can be applied. The kneading method may be a commonly used method and is not particularly limited. As the mixing device used when producing the cement admixture or the cement composition of the present invention, any existing stirring device can be used, for example, a tilting barrel mixer,
Omni mixer, V type mixer, Henschel mixer,
And a Nauta mixer can be used. Further, the mixing may be carried out by mixing the respective materials at the time of construction, or by mixing a part or all of them in advance.

In the present invention, in addition to cement and cement admixtures, aggregates such as sand and gravel, reinforcing fiber materials, water reducing agents, high performance water reducing agents, AE agents, AE water reducing agents, high performance AE water reducing agents, Adhesives, cement expanders, antirust agents, antifreeze agents, soluble alkali salts such as sodium hydroxide, calcium compounds such as calcium oxide and calcium hydroxide, clay minerals such as bentonite and montmorillonite, zeolites, hydrotalcites, and hydro One or more of ion exchangers such as calmite and polymer emulsions can be used in combination within a range that does not substantially impair the object of the present invention.

[0018]

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

Example 1 CaO raw material, Al₂O₃Raw material and Li₂0 Mix the raw materials and put the electric furnace
Of the melt obtained at 1,600 ° C.
Grinding the linker, Blaine value 3,500 ± 200 cm ²Adjust to / g
The CAL was prepared and CAL having the composition shown in Table 1 was obtained. CAL's
The composition ratio was determined by chemical analysis. 50 parts by weight of this CAL,
50 parts by weight of inorganic sulfate and 2 parts by weight of coagulation modifier
As cement admixture, cement in 100 parts by weight of binder
25 parts by weight of admixture, 100 parts by weight of binder, water reducing agent
Binder / fine aggregate ratio using 1 part by weight and fine aggregate α
= 1/2, water / binder ratio = 40%, kneading temperature 20 ℃
The mortar is adjusted to
The compressive strength was measured. The results are also shown in Table 1. Also,
Using this binder and fine aggregate β, according to JIS A 5308
The amount of swelling was measured and a test of alkaline aggregate reaction was performed. Conclusion
The results are also shown in Table 1.

<Materials used> CaO raw material: Wako Pure Chemical Industries, Ltd. reagent primary calcium carbonate Al ₂ O ₃ raw material: Wako Pure Chemical Industries reagent, primary aluminum oxide Li ₂ 0 raw material: Wako Pure Chemical Industries reagent First-class lithium carbonate inorganic sulfate: Natural anhydrous gypsum coagulation regulator: Reagent first-grade mixture of 40 parts by weight citric acid and 60 parts by weight potassium carbonate Water-reducing agent: Polycarboxylic acid-based water-reducing agent cement: Denki Kagaku Kogyo common Portland cement fine aggregate α: Standard sand fine aggregate from Toyoura β: Sanukite pyroxene andesite, dissolved silica amount 75
0 mmol / l, decrease in alkali concentration 200 mmol / l, potentially harmful water: Tap water

<Measurement method> Compressive strength: A specimen of 4 × 4 × 16 cm was prepared, and after 1 day of age, it was aged in water at 20 ° C. and measured at a predetermined age.

[0022]

[Table 1]

Example 2 Example 2 was repeated except that the melted material melted at 1,600 ° C. was rapidly cooled by the high-pressure air method to crush the clinker obtained. The results are also shown in Table 2.

[0024]

[Table 2]

Example 3 CAL having a CaO / Al ₂ O ₃ ratio of 2.5 and a Li ₂ 0 content of 5% by weight was used, except that the amounts of CAL and inorganic sulfate used were changed as shown in Table 3. Was performed in the same manner as in Example 2. The results are shown in Table 3.

[0026]

[Table 3]

Example 4 CAL with a CaO / Al ₂ O ₃ ratio of 2.5 and a Li ₂ 0 content of 5% by weight was used, except that the amount of cement admixture used was changed as shown in Table 4. The procedure was as in Example 2. The results are shown in Table 4.
Shown in.

[0028]

[Table 4]

Example 5 CAL having a CaO / Al ₂ O ₃ ratio of 2.5 and a Li ₂ 0 content of 5 wt% was prepared by using industrial raw materials as the CaO raw material, the Al ₂ O ₃ raw material, and the Li ₂ 0 raw material. Use 50 parts by weight of this CAL, 50 parts by weight of inorganic sulfate, and 2 parts by weight of a coagulation modifier to prepare a cement admixture, and make 25 parts by weight of the cement admixture in 100 parts by weight of the binder, each unit amount , 450 kg / m ³ of binder, 1,066 kg / of coarse aggregate
Concrete with m ³ , fine aggregate γ 700 kg / m ³ , and water 144 kg / m ³ adjusted to a kneading temperature of 20 ° C. was measured for compressive strength at each age of the concrete. The results are shown in Table 5.
Also described in. Further, for comparison, the strength measurement results when a commercially available rapid hardening material is used are also shown.

<Materials used> CaO raw material: Limestone Al ₂ O ₃ raw material from Aomi Mine manufactured by Denki Kagaku Kogyo Co., Ltd .: Commercial bauxite Li ₂ 0 raw material: Commercial lithium carbonate fine aggregate γ: River sand from Himekawa, Niigata Prefecture, 5 mm lower coarse bone Wood: River gravel from Himekawa, Niigata Prefecture, Gmax = 25mm Commercially hardened material: Commercial product, main component calcium aluminate and gypsum

<Measurement method> Compressive strength: A test piece of 10φ × 20 cm was prepared and measured. After 1 day of age, the material was cured in water at 20 ° C.

[0032]

[Table 5]

[0033]

EFFECTS OF THE INVENTION By using the cement admixture of the present invention, it is possible to obtain a quick-hardening cement that exhibits good strength development and excellent alkali aggregate reaction resistance.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ identification code FI // C04B 103: 12 C04B 103: 12 103: 60 103: 60 (58) Fields investigated (Int.Cl. ⁷ , DB name) C04B 2/00-32/02

Claims (2)

(57) [Claims] 1. A Li ₂ 0 content of 3 to 15 wt% , CaO / Al ₂ O ₃
CaO-Al ₂ O ₃ -Li ₂ O-based material having a molar ratio of 1.5 to 3.0 ,
A cement admixture containing an inorganic sulfate and a setting modifier. 2. A cement composition comprising cement and the cement admixture according to claim 1.