JPH059046A - Concrete composition - Google Patents

Abstract

PURPOSE:To improve the strength of concrete by compounding an aggregate consisting essentially of a gerenite compound to a specific cement conssisting essentially of plural compounds with a specific formula and gypsum. CONSTITUTION:A special cement is prepared by mixing 100pts.wt. of matrix powders containing 90-20 pts.wt. of 12CaO.7aL2O3 and 10-100 pts.wt. of at least one kind of gypsm dihyrate or hemihydrate gypsum with gamma-sCaO.SiO2 of a reduction slug derived from iron manufacturing, etc. Next, to 75-15 pts.wt. of this special cement, 25-85 pts.wt. of the aggregate consisting essentially of the gerenite compound having a composition of 2CaO.Al2O3.SiO2 of a blast furnace slug crushed stone, etc., and the proper quantity of water is added thereto and kneaded, and then by forming it in pressure, a concrete hardened body is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a concrete composition such as concrete or mortar containing cement and aggregate as main components, and more specifically, γ-2CaO.SiO ₂ and γ-2CaO. 12CaO / 7
The present invention relates to a concrete composition which is inexpensive and has excellent strength, which is made of a special cement containing Al ₂ O ₃ and gypsum as main components.

[0002]

2. Description of the Related Art A large amount of slag is produced in a steelmaking reduction period at a steelworks, and the waste material is used as a raw material for cement.

As a cement using the steelmaking reduction period slag, "cement" using the steelmaking reduction period slag and gypsum generated as a by-product for sulfur oxide pollution control treatment (Japanese Patent Publication No. 62-47827). , JP-B-62-50428) has been developed. This cement has physical properties (strength, etc.) comparable to ordinary cement, though its hardened body has the physical properties (strength, etc.) of ordinary cement, despite using waste materials such as steelmaking reduction slag and gypsum.
Furthermore, it has the characteristics of excellent early strength and no shrinkage, and is put to practical use as a useful cement.

The cement of Japanese Patent Publication No. 62-47827 is γ
-2CaO · SiO ₂ 10 to 80 parts by weight and 12CaO7
Substrate powder 10 containing 90 to 20 parts by weight of Al ₂ O ₃
0 weight part and 2 to 1000 weight parts of gypsum are the main components, and it is a fast, white and inexpensive cement.

The cement of Japanese Examined Patent Publication No. 62-50428 is γ
-2CaO ・ SiO ₂ and 3CaO ・ 2SiO ₂・ C
10 to 80 parts by weight of one or two kinds of aF ₂ and 12CaO
100 parts by weight of a substrate powder containing 7 to 20 parts by weight of a solid solution of 7Al ₂ O ₃ and CaF ₂ ;
An inexpensive cement that contains 1.0 to 1000 parts by weight of gypsum as a main component with respect to parts by weight and has a physical property (strength, etc.) similar to that of ordinary cement, and has excellent fastness and no shrinkage. is there.

[0006]

However, although the above-mentioned cement consisting of steelmaking reduction slag and gypsum is useful as an inexpensive cement having excellent early strength, no shrinkage, and a hardened body having an appropriate strength, When a concrete composition such as concrete or mortar is prepared by mixing water with aggregates such as commonly used sand such as silica sand and pebbles such as silica stone,
There is a problem in that the aggregate is not chemically or physically bonded to the special cement and the product thereof, the strength is remarkably lowered, and the strength required for the concrete composition cannot be obtained.

[0007] Therefore, the inventors of the present invention have earnestly studied to solve the problems of the prior art as described above, and as a result of various systematic experiments, the present invention has been accomplished.

An object of the present invention is to provide an inexpensive concrete composition having excellent strength.

The present inventors have focused on the following points with respect to the above-mentioned problems of the prior art. That is, the hydrate of the cement composed of steelmaking reduction phase slag and gypsum produces ettringite and a high-alumina gel and a high-alumina hydrate, which is a highly alkaline Ca (when a normal Portland cement is used). OH) ₂ is not generated.
For this reason, it is physically and chemically bonded to the aggregate used for general concrete, that is, Ca (OH) ₂ generated during hydration, and calcium silicate hydrate is generated to increase strength. Even if a commonly used aggregate based on natural silica such as silica sand or silica used for obtaining is used for the special cement, the strength is lowered and the strength required as a concrete composition cannot be obtained. .

Therefore, in order to improve the strength of concrete using the special cement, ettringite (3CaO.Al ₂ O ₃ ) which is a hydrated product of the special cement is used.
・ 3CaSO ₄ · 32H ₂ O) and a high-alumina gel, and an aggregate having a chemical-physical bond strength with a high-alumina hydrate.

Then, 2CaO.Al ₂ such as a gehlenite mineral which produces ettringite in the presence of water and gypsum.
The present invention has been accomplished by focusing on an aggregate containing O ₃ · SiO ₂ as a main component. In particular, the gehlenite mineral is a main component of blast furnace slag crushed stone and granulated sand, and is useful as an inexpensive and optimum aggregate.

[0012] Generally, the special cement contains 2CaO.Al ₂ O ₃ .SiO such as the above-mentioned grenite mineral.
_When a concrete composition is prepared by mixing an aggregate containing ₂ as a main component, Ca (O ₂₎ is added to the hydrate of the special cement.
Since H) ₂ does not exist, it has been considered that the strength of concrete does not sufficiently develop as in the case of using an ordinary aggregate containing silica as a main component.

[0013]

[Means for Solving the Problems] The concrete composition of the present invention comprises γ-2CaO.SiO ₂ and 12CaO.7Al.
Special cement mainly composed of ₂ O ₃ and gypsum, and ₂ Ca
It is characterized in that the main component is an aggregate containing O.Al ₂ O ₃ .SiO ₂ as a main component.

[0014]

The mechanism by which the concrete composition of the present invention exhibits excellent effects is not clear yet, but it is considered as follows.

The concrete composition of the present invention comprises γ-2C
aO ・ SiO ₂ , 12CaO ・ 7Al ₂ O ₃ and special cement mainly composed of gypsum, and 2CaO ・ Al ₂ O ₃・
The main component is an aggregate mainly composed of SiO ₂ .

This γ-2CaO · SiO ₂ and 12CaO
When a special cement containing 7Al ₂ O ₃ and gypsum as the main components and an aggregate containing 2CaO · Al ₂ O ₃ · SiO ₂ as the main components are mixed in the presence of water, 2CaO · Al ₂ such as a grenite solid solution is mixed. Aggregates mainly composed of O ₃ · SiO ₂ gradually form ettringite in the presence of gypsum contained in special cement.

The hydrated product of special cement, such as ettringite and high-alumina gel, and gypsum, which is one component of the special cement, are 2Ca such as grenite.
2CaO · A such as gerenicite, which is chemically and physically bound to ettringite and the like formed by reacting with the alumina component on the surface of the aggregate mainly composed of O · Al ₂ O ₃ · SiO _2.
It contributes as a paste component of an aggregate containing l ₂ O ₃ · SiO ₂ as a main component. Therefore, at the time of destruction of concrete, 2CaO.Al ₂ O ₃
When the crushing strength of the aggregate containing O ₂ as a main component is stronger than that of the paste component, breakage occurs in the portion related to the paste component. As a result, in the state where the aggregate is covered with the paste component, the strength of the concrete composition does not decrease, so that a concrete composition having excellent strength as a concrete composition can be obtained by using the special cement. it is conceivable that.

The special cement of the present invention is used as a waste material such as slag and gypsum during the steelmaking reduction period, and is also used as 2CaO.Al.
Aggregates mainly composed of ₂ O ₃ .SiO ₂ can be obtained as blast furnace slag crushed stone or blast furnace granulated sand at a low cost, and thus an inexpensive concrete composition can be obtained.

[0019]

The concrete composition of the present invention has excellent strength and is inexpensive.

[0020]

The invention (concrete example) which is more specific than the above invention will be described below.

The special cement is γ-2CaO · SiO ₂
And 12CaO · 7Al ₂ O ₃ and gypsum as main components. In addition, CaF ₂ and other components and impurities may be contained as long as the effects of the present invention are not impaired.

The special cement is γ-2CaO · S.
12CaO · 7Al ₂ O ₃ or 12C for iO ₂ .
90 to 20% solid solution of aO.7Al ₂ O ₃ and CaF ₂
It is preferable that the base powder is 100 parts by weight including 10 parts by weight, and at least one or more dihydrate gypsum or hemihydrate gypsum is 10 to 100 parts by weight. This special cement is characterized in that its hardened body has physical properties (strength, etc.) similar to those of ordinary cement, is excellent in early strength, and is a white cement with very little shrinkage.

Of these, the matrix powders other than gypsum are the main components of the slag during the steelmaking reduction period, and can be obtained at low cost as slag powder that is naturally destroyed by wind or slag powder that is obtained by arbitrarily crushing lumps.

It is preferable to use gypsum dihydrate or gypsum hemihydrate. Gypsum dihydrate is preferred because there are no hydrated compounds that change in volume upon transition. The dihydrate gypsum may be either a by-product such as desulfurized gypsum or natural gypsum. Further, hemihydrate gypsum is suitable because it immediately changes to dihydrate gypsum upon hydration, and therefore, as with the above, there is no hydrated compound that changes in volume upon transition. Anhydrous gypsum is CaO ・ Al ₂ O ₃・ 1, which has a large volume change during transition.
Since it is easy to form 0H ₂ O and the dimensional change of the hydrated cement component upon drying or water absorption is large on the order of 10 ^−3, it is necessary to consider the use.

The amount of gypsum mixed in the special cement should be at least 10 parts by weight per 100 parts by weight of the special cement. This is because a part of gypsum is γ-2CaO ・ SiO ₂ or / and 3CaO ・ 2S in special cement.
iO ₂ · CaF ₂ , and further reacts with 12CaO · 7Al ₂ O ₃ or 12CaO · 7Al ₂ O ₃ and a solid solution of CaF ₂ to form a cement hydration hardened material such as ettringite, and at the same time, the remaining gypsum contains gehlenite and the like. 2CaO
・ It is necessary to react with the alumina component on the surface of the aggregate containing Al ₂ O ₃・ SiO ₂ as a main component to form ettringite.
0 parts by weight or more is required.

The amount of gypsum mixed in the special cement is 5
If it exceeds 0% by weight, unreacted gypsum is increased, which causes deterioration of water resistance, which is not preferable.

As the aggregate containing 2CaO.Al ₂ O ₃ .SiO ₂ as a main component, any aggregate having this composition can be applied. Examples include blast furnace slag crushed stone, granulated blast furnace glass sand, and steelmaking oxidation slag.

Blast-furnace slag crushed stone is usually called melilite, which is a solid solution of gehlenite and akermanite (2CaO.
The main component is a solid solution such as MgO · 2SiO ₂ ).

Granulated sand is a glass-like grain that has been rapidly cooled.

The size of the aggregate may be the same as that of a usual silica-based aggregate. For example, in case of blast furnace slag crushed stone,
Size of fine or coarse aggregate (diameter: 0.1 to 5.0 cm)
In the case of water granulated sand, the size of river sand is about 0.1 to 1.0 mm.

The mixing amount of the aggregate may be the same as the mixing amount of the ordinary concrete composition such as Portland concrete, but when the mixing amount of the aggregate is 35 to 90% by weight, it is special. It is suitable because it can obtain the same strength as a hardened cement product. In addition, when the mixing amount is 25 to 85% by weight, it is possible to obtain a better effect of exhibiting properties such as high strength, early strength, and non-shrinkage, and thus it is more preferable.

The hardened body of the special cement is known as a hardened body whose dimensional change with time is smaller than that of ordinary concrete. Concrete using this special cement and the special aggregate according to the present invention is used. By using the composition, it is possible to obtain a composition having less dimensional change over time or a non-shrinking composition. Further, the hardened body of the above-mentioned special cement is known to have an early-strength property, but by using a concrete composition using this special cement and the special aggregate according to the present invention, similarly, the early-strength property is improved. May be included.

Therefore, in the case of urgent civil engineering and construction work, by using the ordinary cement admixture in the concrete composition of the present invention, the concrete of the present invention can be utilized by utilizing the early strength of the present invention. In addition to being able to apply the composition, the resulting concrete can also have excellent strength.

Examples of the present invention will be described below.

First embodiment

A concrete composition was prepared using a special cement consisting of slag for steelmaking reduction period and desulfurization gypsum and a grenite aggregate, and a performance evaluation test of the composition was carried out.

100 parts by weight of reducing slag, 15 parts by weight of gypsum, 15 parts by weight of water, and FM as a gehlenite aggregate
-2.5 Granulated sand was added and kneaded, and the mixture was pressure-molded at 100 kgf / cm ² to obtain a concrete hardened body of this example according to the present invention (Sample No. 1).

The compressive strength of the obtained concrete composition after one day was measured and found to be 520 kgf / cm ² .

For the purpose of comparison, a concrete for comparison was prepared in the same manner as in the first embodiment except that 300 parts by weight of silica sand, which is usually used as an aggregate, was used in place of the gerhenite aggregate (Sample No. C1). ), And the compression strength was similarly measured. As a result, the compressive strength was 200 kgf / cm ² .
When the concrete for comparison was rubbed with a fingernail, silica sand was easily peeled off. On the other hand, in the hardened concrete of the present example, the aggregate did not easily come off even if it was rubbed with the nail.

Second embodiment

100 parts by weight of the reducing phase slag and the amount of desulfurized gypsum shown in Table 1 were mixed, and 40 parts by weight of water and 300 parts by weight of gerenic aggregate were mixed with 100 parts by weight of the mixture to obtain 40 × as a mortar. It was poured into a mold of 40 × 160 mm and the compressive strength was measured after 10 days (sample number: 2 to
4). The results are shown in Table 1.

[0042]

[Table 1]

For comparison, the mixing amount of gypsum was 5 parts by weight (sample number: C2) and 200 parts by weight (sample number: C).
A mortar was produced in the same manner as in the second embodiment except that the above 3) was performed, and the performance evaluation test was conducted in the same manner. The result is
It is also shown in Table 1.

As is clear from Table 1, in the case of this example, a hardened mortar having a high strength was obtained when the amount of gypsum mixed was in the range of 10 to 100 parts by weight with respect to 100 parts by weight of special cement. I understand that.

Third embodiment

A mortar (W / C =) was prepared by adding water and the amount of the grenite aggregate shown in Table 2 to a special cement in which the mixing ratio of the reducing phase slag and the desulfurization gypsum was 75:25 by weight.
0.40), a plate material of 200 × 100 × 10 mm was prepared, and bending strength was measured as a performance evaluation test (sample number: 5 to 5).
7). The results are shown in Table 2.

[0047]

[Table 2]

For comparison, the same procedure as in the third embodiment was carried out except that the grenenite aggregate was not mixed (sample number: C4) or 100 parts by weight of special cement was added to 100 parts by weight of silica sand (sample number: C5). A mortar was produced by using the same, and a performance evaluation test was conducted in the same manner. The results are also shown in Table 2.

As is clear from Table 2, the mortar of the third embodiment according to the present invention does not decrease in strength below the strength of the special cement hardened product even when the aggregate is mixed. That is,
It can be seen that even if the special cement is used, the use of the special aggregate according to the present invention makes it possible to obtain an inexpensive and high-strength mortar without lowering the strength.

Fourth Embodiment

To a special cement in which the mixing ratio of reducing slag and desulfurization gypsum was 75:25 by weight, the amount of water and the amount of gerenic aggregate shown in Table 3 were added (W / C is shown in Table 3).
A 100φ × 200 mm concrete hardened body was obtained (sample number: 8 to 18). A performance evaluation test was conducted on the obtained hardened concrete, and air-dry strength (kgf / cm ² ) and saturated water strength (kgf / cm ² ).
cm ² ) and density (g / cm ³ ) were measured. The results obtained are shown in Table 3.

[0052]

[Table 3]

For comparison, no Gehrenite aggregate was mixed (Sample No. C6 to C8) or special cement 1
100 parts by weight of silica sand to 100 parts by weight (sample number: C9 to C1
1), and a hardened concrete body was prepared in the same manner as in the fourth example except that the mixing amount shown in Table 4 was used, and the performance evaluation test was conducted in the same manner. The results are shown in Table 4.

[0054]

[Table 4]

As is clear from Tables 3 and 4, it can be seen that the hardened concrete of the fourth embodiment according to the present invention does not fall below the strength of the hardened special cement even when the aggregate is mixed. That is, it can be seen that even if the special cement is used as the main raw material of the concrete, an inexpensive and high-strength concrete hardened body can be obtained by using the special aggregate according to the present invention without lowering the strength.

Fifth embodiment

A special cement having a mixing ratio of the reducing phase slag and the desulfurized gypsum in a weight ratio of 75:25 was added with 4 parts of gehlenite aggregate.
Mixing was carried out at a ratio of 0:60, and mortar was made in the water-cement ratio shown in Table 4, a plate material of 200 × 100 × 10 mm was prepared (sample number: 19 to 21), and a performance evaluation test was conducted by bending strength measurement. The results are shown in Table 5.

[0058]

[Table 5]

As is clear from Table 5, in the case of the mortar of the fifth embodiment according to the present invention, the strength is higher as the water cement ratio is smaller.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location C04B 14:04) 2102-4G (C04B 7/21 14:04) 2102-4G (C04B 11/28 14:04) 2102-4G (72) No. 1 Wanowari, Arao-cho, Tokai-shi, Aichi Prefecture, Inventor, Miyashita Kenji, Aichi Steel Co., Ltd. (72) Haruyasu Ishizu, Wano-wari, Arao-cho, Tokai City, Aichi Prefecture, Aichi Within Steel Co., Ltd.

Claims (4)

[Claims] 1. γ-2CaO.SiO ₂ and 12CaO.
Special cement containing 7Al ₂ O ₃ and gypsum as main components,
Concrete composition characterized by comprising an aggregate consisting mainly of _{2CaO · Al 2 O 3 · SiO} 2 as a main component. 2. The concrete composition according to claim 1, wherein the aggregate is at least one or more types of glass grains based on gehlenite or gehlenite. 3. The mixing ratio of the special cement and the aggregate is 2CaO.Al ₂ O with respect to 75 to 15 parts by weight of the special cement.
The concrete composition according to claim 1, wherein the amount of ₃ · SiO _{2 is} 25 to 85 parts by weight. 4. The special cement is γ-2CaO · SiO.
Substrate powder 10 consisting of ₂ and 12CaO.7Al ₂ O ₃
4. The concrete composition according to claim 3, which comprises 0 part by weight and 10 to 100 parts by weight of at least one dihydrate gypsum or hemihydrate gypsum.