JPH0710628A - Mixture for producing heavy concrete - Google Patents

Abstract

PURPOSE:To obtain a mixture for producing heavy concrete having high specific gravity and excellent chemical characteristics and mechanical characteristics. CONSTITUTION:15-30wt.% of a cement paste having 0.4-0.6 of water cement ratio is mixed with 70-85wt.% of total amount of coarse aggregate composed of hematite consisting essentially of ferric oxide and/or ground stone and fine aggregate composed of at least two kinds of hematite also consisting essentially of ferric oxide, sand iron and sand and 0.1-2wt.% based on the cement weight of a high-performance water reducing agent as an admixture. The added high- performance water-reducing agent improves fluidity of concrete by air entraining action like ball bearings, prevents separation of the aggregate having high specific gravity as much as possible and provides uniform high-strength heavy concrete.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for producing heavy concrete, which has a high specific gravity and excellent chemical and mechanical properties.

[0002]

2. Description of the Related Art In general, concrete made of a material having a high specific gravity, such as magnetite, titanium ore, barite, olivine, etc., is a heavy concrete or a shield concrete in addition to ordinary concrete. It is widely used as, for example, concrete for marine construction such as wave-dissipating blocks and seawalls, concrete for heavy machinery foundations, radiation shielding concrete, and the like.

Further, in a port structure or the like, there is an advantage that the stability increases as the weight increases,
In recent years, the demand for such heavy concrete is increasing year by year as the number of deep water structures tends to increase.

By the way, in the production of this kind of heavy concrete, since the specific gravity of the aggregate is large, the aggregate and the cement paste are easily separated at the time of transportation, placing, and hardening, and therefore, a uniform aggregate. There was a problem that it was difficult to obtain concrete. Because of this,
For example, measures such as reducing the water-cement ratio or increasing the separation resistance of aggregates by incorporating polymers etc. have been made, but on the other hand, the fluidity of concrete decreases and the workability deteriorates. A new problem has been pointed out that the chemical and mechanical properties of the product concrete are also reduced.

[0005]

In the present invention, therefore, the total amount is 70-
Hematite containing 85% by weight of ferric oxide as a main component and /
Alternatively, coarse aggregate composed of crushed stone and fine aggregate composed of at least two kinds of hematite, which mainly contains ferric oxide as a main component, iron sand, and sand, and a water-cement ratio of 0.4 to 0.6 are used. The high-performance water reducing agent as an admixture was added to the cement paste in an amount of 15 to 30% by weight, and the high performance water reducing agent was added to the cement in an amount of 0.
By adding 1% to 2%, it is intended to provide a homogeneous and high-strength mixture for producing heavy concrete, which can improve the fluidity of concrete and prevent the separation of high-density aggregate as much as possible. It is a thing.

In this case, the coarse aggregate such as hematite or crushed stone containing ferric oxide as a main component has a specific gravity of 2.4 to 5.
Those having a particle size of 0 and a particle size (particle size) of 5 mm to 50 mm are preferably used. Further, as the fine aggregate, there are hematite containing ferric oxide as a main component, iron sand, sand, and the like, like the coarse aggregate, and have a specific gravity of 2.5 to 5.0 and a particle diameter (particle size) of 5 mm or less. Those of are preferably used.

On the other hand, the fine aggregate ratio is 0.42 to 0.48, and if it is less than 0.4, the product concrete is roughened to reduce the strength and the specific gravity, and the cement paste and the coarse aggregate are used during the construction. The separation phenomenon occurs. If the fine aggregate ratio exceeds 0.5, the fluidity of the concrete mixture is lost and the workability deteriorates.

When the water-cement ratio is 0.3, not only the workability is deteriorated, but also the workability is extremely deteriorated.
If the water-cement ratio is 0.7, poor mixing results in material separation, resulting in reduced durability and strength. Furthermore, the weight% of the cement paste mixed with these aggregates is 15%.
When it is less than 30%, the fluidity is lowered, and when it is more than 30%, there are problems such as separation of material separation and reduction of specific gravity.

On the other hand, the total amount of aggregate is 70 to 85% of the product weight concrete. If it is less than 70%, the specific gravity of the product becomes low and it becomes uneconomical, and if it exceeds 85%, the workability deteriorates. .

Common cement such as Portland cement or blast furnace cement is used as the cement, and the compounding amount thereof is 1 m ³
About 325 kg to 463 kg is desirable. 325k
If it is less than g, the strength of the product weight concrete will decrease,
If it exceeds 465 kg, the specific gravity of the product becomes low, which is not preferable.

Furthermore, in the present invention, a high-performance water reducing agent composed of a complex compound mainly composed of modified lignin and an alkyl sulfonic acid is added as an admixture. Since it facilitates the movement of the aggregate, it is possible to reduce the unit amount of water, and therefore it is possible to prevent the separation of the material due to breathing. Further, not only the function of preventing the separation due to the difference in specific gravity between the high specific gravity aggregate and the cement paste can be fulfilled, but also the durability and freeze-fever heat resistance of the product weight concrete can be increased.

The amount of the high-performance water-reducing agent added is preferably 0.1% to 2% with respect to the weight of cement. If it is less than 0.1%, the durability of the product-weight concrete decreases, and if it exceeds 2%. The workability at the time of construction will deteriorate and it will be uneconomical.

In the present invention, it is needless to say that other well-known admixtures and the like can be added together as in the case of producing general heavy-duty concrete.

[0014]

EXAMPLES Next, the present invention will be specifically described with reference to examples. That is, heavy concrete was manufactured using the following materials. Coarse aggregate; South African hematite specific gravity 4.86 Crushed stone specific gravity 2.70 Fine aggregate; Brazilian hematite specific gravity 4.49 New Zealand sand iron Specific gravity 4.54 Sand specific gravity 2.60 Cement; Ordinary Portland cement Specific gravity 3.16 Admixture; High-performance water reducing agent (SP-9HS manufactured by Nisso Master Builder Co., Ltd.) Water reducing agent (Bozoris 70 manufactured by Nisso Master Builder Co., Ltd.) Air amount regulator (303A manufactured by Nisso Master Builder Co., Ltd.) Bridging water; The materials were mixed in the proportions shown in Table 1, all the materials were put into a forced brick mixer and stirred for 1 minute, and then the aggregate separability, slump, air content, etc. of the obtained concrete were measured. Then, this concrete was poured into a specimen frame, and after being demolded, it was cured in water for 1 week under the condition of 20 ° brass minus 2 °, and the 4-week strength and specific gravity of each cured specimen were measured.

[0015]

[Table 1]

[0016]

As is clear from Table 1, the heavy concrete obtained by the composition for producing heavy concrete according to the present invention has a high separability of bone during construction or hardening due to the small separability of the aggregate. It can be seen that not only can the material separation be effectively prevented, but also breathing can be suppressed and a heavy concrete with sufficient compressive strength can be obtained. Since this heavy concrete has a high specific gravity and a high strength, it can be suitably used as a concrete for a harbor structure, in particular, a wave-dissipating block on which an impact force acts.

The preferred embodiment of the composition for producing heavy concrete according to the present invention has been described above, but the present invention is not limited to this embodiment, and various modifications can be made without departing from the spirit of the present invention. Of course, changes can be made.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI technical display location C04B 24:22) B (72) Inventor Hiroyuki Kato 2-7-1, Nishishinjuku, Shinjuku-ku, Tokyo Japan Tetrapod Co., Ltd.

Claims (1)

[Claims] 1. A coarse aggregate composed of hematite and / or crushed stone containing ferric oxide as a main component in a total amount of 70 to 85% by weight, and hematite, sand iron and iron oxide similarly containing ferric oxide as a main component. Fine aggregate consisting of at least two kinds of sand is used as a cement paste 15 to 30 having a water cement ratio of 0.4 to 0.6.
A mixture for producing heavy concrete, characterized in that the high-performance water-reducing agent is added as an admixture in an amount of 0.1% to 2% with respect to the weight of cement, in addition to an amount of 0.1% by weight.