JPH0986976A - High fluidity cement composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce the cement composition exhibiting extremely high fluidity without causing separation of materials and fluidity decrease during the execution of the work, thus useful for production of a concrete manifesting high fluidity and high strength and as a self-leveling material. SOLUTION: This concrete composition consists of a clinker containing <=13wt.% of 4CaO.Al2 O3 .Fe2 O3 , <=5wt.% of 3CaO.Al2 O3 , the rest is 3CaO.SiO2 , 2CaO.SiO2 and 3-7wt.% of calcium sulfate and has 3000-4500cm<2> /g of Blaines specific surface area. The calcium sulfate consists of 10-35wt.% of gypsum hemihydrate, 20-45wt.% of insoluble calcium sulfate anhydrate and the rest is gypsum dihydrate, and high performance AE water reducing agent is added to this composition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high fluidity cement composition suitable for producing concrete which exhibits high fluidity and high strength and as a self-leveling material.

[0002]

2. Description of the Related Art In recent years, with the increase in the number of layers of concrete structures and the rationalization of construction methods and labor saving, high strength, without increasing the unit water volume, compaction work is unnecessary, and in densely arranged bar or narrow space. The development of concrete that goes into the details of the formwork that has Further, as a cement-based self-leveling material which is required to have self-fluidity, one having higher fluidity is required. As the cement used here, Portland cement is mixed with various admixtures such as blast furnace slag and fly ash, various high performance AE water reducing agents, cement with thickener added, cement with adjusted particle size distribution, and spheroidized cement particles. Cement and the like have been proposed.

However, the quality of the cement obtained by adding blast furnace slag, fly ash, etc. to Portland cement is difficult to control, and there is a problem that the hardening is delayed.
In addition, when a large amount of various high-performance AE water-reducing agents and thickening agents are added, there is a problem that the durability after curing is reduced. Cement with adjusted particle size distribution and cement with spheroidized cement particles are used for ordinary cement production. There is a problem that productivity is remarkably low because special equipment and processes are required in addition to the equipment and processes. Further, the conventional fluidity cement composition has a flow loss, and the fluidity decreases in a short time. Therefore, for example, the slump during transportation of green concrete, the amount of air, etc. are changed, and it is a target when actually working at a construction site. There were problems that fluidity could not be obtained, sufficient working time could not be taken, and that concrete pumps and piping were blocked during pumping.

As a method for improving the above-mentioned disadvantages, Japanese Patent Laid-Open No.
No. 6-80456 discloses 3CaO / Al.₂O_ThreeBut
5% by weight or less and 3CaO ・ Al₂O_ThreeAnd 4CaO ・ A
l₂O_Three・ Fe₂O_Three8-12% by weight of total solid solution
And the balance is 3CaO ・ SiO ₂And 2CaO / SiO₂
Blaine specific surface area consisting of 3300 to 4000 cm ²
/ G clinker powder and insoluble anhydrous gypsum 50% or more
SO in cement_ThreeIs 2-5% by weight
A fluid hydraulic composition prepared by adding a dispersant to a certain cement
Proposed. According to this proposed composition,
Although the points can be improved to some extent, especially regarding liquidity,
-There is still room for improvement, including loss
is there.

[0005]

An object of the present invention is to provide a cement composition which exhibits extremely high fluidity. Another object of the present invention is to provide a high fluidity cement composition which can improve the drawbacks of the above proposed high fluidity cement composition and has excellent fluidity including flow loss.

[0006]

The present inventors have found that high performance A
E Highly fluid cement composition that exhibits extremely high fluidity without using a large amount of water-reducing agent, does not cause material separation, has a small flow loss, and does not impair fluidity during construction work, etc. As a result, the fluidity is closely related to the mineral composition in the cement, the type and amount of gypsum, the Blaine specific surface area, etc. By adjusting these to a specific range, it is proposed in JP-A-6-80456. The high fluidity far exceeding that of the above composition, the fluidity is excellent even with the addition of a small amount of the high-performance AE water reducing agent, and the high strength can be solved to solve the above problems. The present inventors have found that the product can be used as a base cement of mixed cement and are effective in improving fluidity, and have arrived at the present invention.

The present invention relates to 4CaO.Al in clinker.
13% by weight or less of ₂ O ₃ · Fe ₂ O ₃ 3CaO · Al
A cement composition having ₂ O _{3 in an amount} of 5% by weight or less, the balance of 3CaO · SiO ₂ and 2CaO · SiO ₂ , and 3 to 7% by weight of gypsum and having a Blaine specific surface area of 3000 to 4500 cm ² / g. Is hemihydrate gypsum 10-35% by weight,
The present invention relates to a high fluidity cement composition having a proportion of 20 to 45% by weight of insoluble anhydrous gypsum and the balance consisting of gypsum dihydrate, in which a high performance AE water reducing agent is added to the composition.

In the present invention, 4CaO in clinker
・ Al₂O_Three・ Fe₂O_ThreeAnd 3CaO / Al₂O_ThreeIs
Closely related to liquidity. 4CaO / Al₂O_Three・ Fe
₂O _ThreeExceeds 13% by weight, 3CaO ・ Al again₂
O_ThreeIf it exceeds 5% by weight, the fluidity will be poor and
4CaO ・ Al₂O_Three・ Fe₂O
_ThreeIs 13% by weight or less, preferably 8% by weight or less, and 3
CaO / Al₂O_ThreeIs 5% by weight or less, preferably 4% by weight
% Or less. The remaining 3CaO / SiO₂There are many
In other words, 2CaO ・ SiO₂When there are few
Higher strength but lower fluidity and larger flow loss
Therefore, in order to enhance the fluidity, 2CaO ・ Si
O₂Is 45% by weight or more, preferably 50 to 60% by weight
It is desirable to do. 2CaO / SiO₂To increase
Low heat generation and high fluidity cement composition
Can be.

In the cement composition of the present invention, gypsum is contained in an amount of ₃ to 7% by weight (SO ₃ in the cement is about 1.5 to ₃ .
9 wt%), but this gypsum is hemihydrate gypsum 10-35
It is important that the ratio is 20% to 45% by weight of insoluble anhydrous gypsum and the balance is gypsum dihydrate. As will be apparent from the examples described below, the 0 stroke flow, which is an index of fluidity, is 260 mm or more and exceeds 300 mm, there is almost no flow loss, and material separation does not occur. If the amount of hemihydrate gypsum in gypsum is less than 10% by weight, the hydration reaction of 3CaO.Al ₂ O ₃ is fast and the effect of improving the fluidity cannot be expected. growing. If it exceeds 35% by weight, the 0 hit flow is 230
It becomes about mm, and stiffness occurs, resulting in a large flow loss. The amount of insoluble anhydrous gypsum in gypsum is required to be 20 to 45% by weight, preferably 25 to 35% by weight, but if the amount is too small or too large, 0 stroke flow is 200 to 240 mm.
The effect of improving the fluidity is small to some extent, and a flow loss of more than 10 mm occurs. The remaining dihydrate gypsum has a fluidity-improving effect, which is not so large as hemihydrate gypsum, and improves fluidity in combination with hemihydrate gypsum and insoluble anhydrous gypsum, and can reduce the worry of showing stiffness. . If the amount of gypsum in the cement composition is less than 3% by weight, the amount of gypsum is insufficient and the effect of improving fluidity is small, and there is a problem even when the cement is crushed or contracted after hydration. If it exceeds 7% by weight, stiffness will increase. Occurs and liquidity decreases.

In the present invention, the gypsum exhibits sufficient fluidity even if it is ground simultaneously with the clinker, or if it is added by mixing gypsum powder with a previously ground clinker, but it is higher when ground together with the clinker. It is preferable because it shows fluidity. When crushing clinker and gypsum at the same time, it is necessary to consider that gypsum dihydrate will not dehydrate into gypsum hemihydrate depending on the temperature of the crushing mill. If hemihydrate gypsum increases more than necessary due to dehydration, fluidity decreases and flow loss also increases.

In the cement composition of the present invention, the Blaine specific surface area is 3000 to 4500 cm ² / g, preferably 3800 to 4200 cm ² / g. The lower the Blaine specific surface area, the better the fluidity. However, when the Blaine specific surface area is less than 3000 cm ² / g, the viscosity becomes too low to cause material separation, and when it exceeds 4500 cm ² / g, the effect of the water reducing agent decreases. Since the dispersibility of cement particles is poor and the fluidity is poor, the above range is preferable.

The high-performance AE water reducing agent may be added to the cement composition in advance or may be added at the time of kneading with water. The amount added is 0.05 to 5 parts by weight, preferably 0.1 to 100 parts by weight of cement in the cement composition.
2 parts by weight. The high-performance AE water-reducing agent reduces the amount of water as the amount thereof increases, improves the dispersion of the cement particles, imparts fluidity, and reduces the drying shrinkage after curing, but if the amount is too small, the water-reducing agent decreases. The effect cannot be expected, and if it is too large, it does not contribute to the increase in fluidity and the durability after curing is reduced. As the high-performance AE water reducing agent, for example, naphthalene-based (naphthalene sulfonic acid formalin condensate etc.), melamine (melamine sulfonic acid formalin condensate etc.), amino sulfonic acid-based (aromatic amino) conventionally used for mortar or concrete Sulfonic acid polymer etc.), polycarboxylic acid type (polycarboxylic acid ether etc.)
Can be mentioned.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

EXAMPLES In each example, 0 hit flow, flow after 30 minutes (flow loss), and separation resistance were measured and evaluated using mortar kneaded by the following method. (1) Kneading of mortar This was carried out as follows using the device / apparatus described in JIS R5201 10.4.3 Mechanical kneading method. 800 g of cement and sand (Soma sand) 1120 in a mortar
g and mixed at low speed with a Hobart mixer for 30 seconds. The Hobart mixer was stopped, and 240 g of water to which a predetermined amount of a high-performance AE water reducing agent (polycarboxylic acid type: manufactured by NM, trade name Rheobirde SP-8S) was added was added and kneaded at a low speed for 2 minutes. Then stop the mixer and
The mortar adhering to the kneading bowl and the paddle was scraped off with a spoon for 2 seconds, and the mortar on the bottom of the kneading bowl was scraped up for 2 to 3 times. After that, at low speed again 2 minutes 4
Mix for 0 seconds. The water cement ratio is 0.3 and the sand cement ratio is 1.4. (2) Zero stroke flow The flow value at zero stroke was measured using a flow cone specified in JIS R5201 "Physical test method for cement". Those exhibiting a flow of 260 mm or more are preferable, and if the flow is less than 260 mm, the fluidity is poor and workability is difficult. (3) Flow after 30 minutes (flow loss) The kneaded mortar was wet-sealed, and the 0-stroke flow after 30 minutes was measured. Those showing a flow of 260 mm or more were considered good. (4) Separation resistance Visually, the mortar after 0 shot flow measurement, in which solid-liquid separation was not performed, was evaluated as good, and the solid-liquid separation was observed was evaluated as x. (5) Clinker composition (% by weight) used, Blaine specific surface area (cm ² / g), high performance AE added to cement
Tables 1 and 2 show the amount of water reducing agent (% by weight), the ratio of gypsum (% by weight), and the amount of SO _{3 in} the cement (% by weight). In Tables 1 and ₂ , C2S is 2CaO.SiO2, C
3A is 3CaO ・ Al ₂ O ₃ , C4 AF is 4CaO ・ A
It means l ₂ O ₃ .Fe ₂ O ₃ and the rest is omitted because almost all of it is 3CaO.SiO ₂ .

Examples 1 to 5 Table 1 so that the amount of SO _{3 in} cement was 3.0% by weight.
To the clinker shown in Fig. 1, dihydrate, semi-water and gypsum in the proportion shown in Table 1 were added, and the cement was crushed with a ball mill until the Blaine specific surface area reached 4100 cm ² / g. A mortar was prepared by adding a high-performance AE water reducing agent, and the flow for 0 hit, the flow after 30 minutes and the separation resistance were measured. Table 1 shows the results.

Comparative Examples 1 to 5 As shown in Table 1, when the amount of anhydrous gypsum in gypsum is small (Comparative Example 1), when the amount of hemihydrate gypsum is small (Comparative Example 2), and when the amount of hemihydrate gypsum is large (Comparative Example 3) ), when anhydrous gypsum is large (Comparative example _{4), 4CaO · Al 2 O} 3 · Fe 2 O in clinker
_When each of the cements containing a large amount of ₃ (Comparative Example 5) was used, the flow of 0 hitting, the flow after 30 minutes and the separation resistance were measured as in Examples 1 to 5. Table 1 shows the results.

[0016]

[Table 1]

As is clear from Table 1, in the case of the present invention, a zero hitting flow exceeding 300 mm is shown, and a zero hitting flow is 260 m even if the amount of the water reducing agent is small.
There is no flow loss and no material separation. On the other hand, 4CaO.Al ₂ O ₃ in the clinker
When the proportion of hemihydrate gypsum, gypsum anhydrate, and gypsum dihydrate in Fe ₂ O ₃ or gypsum is outside the range of the present invention, the zero-stroke flow is 190.
The flow loss is large at about 250.

Examples 6 to 10 The same cement (Examples 6 to 10) as in Example 4 was used, except that the Blaine specific surface area was changed as shown in Table 2.
In the same manner as in Examples 1 to 5, 0 hit flow, after 30 minutes flow and separation resistance were measured. In addition, in Examples 6 and 10, the clinker composition was changed as shown in Table 2. The measurement results are shown in Table 2.

Comparative Examples 6 to 10 As shown in Table 2, when the Blaine specific surface area is small (Comparative Example 6) and when the Blaine specific surface area is large (Comparative Example 7),
When 3CaO · Al ₂ O ₃ in the clinker is abundant (Comparative Example 8), anhydrous gypsum in gypsum is abundant (Comparative Example 9), and dihydrate gypsum is not used (Comparative Example 10) It was used and the flow of 0 hitting, the flow after 30 minutes and the separation resistance were measured in the same manner as in Examples 1 to 5. The results are shown in Table 2.

[0020]

[Table 2]

It can be seen from Table 2 that when the Blaine specific surface area is within the range of the present invention, there is almost no flow loss, and the zero hit flow is as large as 264 to 290 mm and the fluidity is good. It can be seen that when the Blaine specific surface area is small (Comparative Example 6), the fluidity is good, but material separation occurs, and when the Blaine specific surface area is large (Comparative Example 7), the fluidity is poor.
Further, it can be seen that the fluidity is poor even if the amount of 3CaO.Al ₂ O ₃ in the clinker is large and the amount of anhydrous gypsum in the gypsum is large.

[0022]

EFFECTS OF THE INVENTION The cement composition of the present invention has a remarkable effect that it exhibits extremely high fluidity without causing material separation, has a small flow loss, and does not lose fluidity during construction work.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location C04B 111: 62 (72) Inventor Satoru Asamoto 1-12-32 Nishimotomachi, Ube City, Yamaguchi Prefecture Ube Usan Head Office, Kosan Co., Ltd.

Claims (3)

[Claims] 1. CaO.Al ₂ O ₃ .F in clinker
13% by weight or less of e ₂ O _{3 and} 5 of 3CaO · Al ₂ O ₃
Weight% or less, balance 3CaO ・ SiO ₂ and 2CaO ・
In SiO _2, a cement composition of the Blaine specific surface area containing gypsum 3-7% by weight 3000~4500cm ² / g, 10~35 wt% the gypsum hemihydrate gypsum, insoluble anhydrite 20 to 45 wt% A high-fluidity cement composition in which the balance consists of gypsum dihydrate, and a high-performance AE water reducing agent is added to the composition. 2. The proportion of insoluble anhydrous gypsum in gypsum is 25 to 3
The high fluidity cement composition according to claim 1, which is 5% by weight. 3. The high fluidity cement composition according to claim 1, wherein the balance of 2CaO.SiO ₂ is 45% by weight or more.