JPH02172846A - Heavy-weight concrete - Google Patents

Abstract

PURPOSE:To obtain heavy-weight concrete which is good in quality and stable and easy in procurement and purchasing by performing grain size regulation of fine steel grain for shot blasting which has specified nominal size and utilizing it as fine aggregate of heavy-weight concrete. CONSTITUTION:Heavy-weight concrete is obtained by performing grain size regulation of fine steel grain for shot blasting which has 2.5-0.15-mm nominal sieve size and utilizing it as fine aggregate. As the fine steel grain for shot blasting, the fine grain wherein grain regulation is performed respectively at sieve size of 2.5mm, 1.2mm, 0.6mm, 0.3mm and 0.15mm is preferably regulated to 100% sieve passing rate (similarly shown hereunder) at 5 mm sieve, 80-100% at 2.5mm sieve, 50-90% at 1.2mm sieve, 25-65% at 0.6mm sieve, 10-35% at 0.3mm sieve and 0-10% at 0.15mm sieve. In this heavy-weight concrete, unit water amount is made little to obtain prescribed workability at the same strength in comparison with the case of utilizing iron powder and scrap iron, etc., which have sp.gr. larger than magnetite and are used as material having large sp.gr. instead of magnetite difficult to be procured. Therefore drying shrinkage and a crack are made little and concrete large in air-dry sp.gr. is obtained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to heavy-duty concrete that has an enhanced radiation shielding effect by using fine steel particles for shot blasting, which is easy to handle, as a fine aggregate for heavy-duty concrete. ,
Concerns heavy concrete such as ballast concrete for increasing weight and vibration prevention.

[Prior Art] Generally, heavy concrete, which has a higher specific gravity than ordinary concrete, is used to shield from radiation.

Facilities that require this heavy concrete are for nuclear power use and research, such as nuclear reactors and facilities that handle radioisotopes.In recent years, the widespread use of radioisotopes and irradiation treatments in hospitals have become commonplace. Demand for heavy concrete, which has a high specific gravity and is used as ship ballast and machine foundations, has gradually increased.

Ordinary concrete can also be used for the above purpose, but since the shielding effect is proportional to the specific gravity x thickness of the concrete, ordinary concrete is better than heavy concrete for the same intensity of radiation. In some cases, it requires several times the thickness and is accompanied by design difficulties. Therefore, among natural ores, magnetite, which has a relatively high specific gravity, is hard, and has a low content of impurities, has been widely used as an aggregate for heavy concrete.

[Problem to be solved by the invention]

However, recently, the above-mentioned high-quality domestically produced magnetite ore has been depleted, and it has become extremely difficult to obtain foreign-produced magnetite ore in recent years. In addition, since the available iron ore is for steel manufacturing, it is difficult to obtain the required quality (Ir) as aggregate for concrete due to large variations in aggregate specific gravity, 2 particle size, contained impurities, chlorides, etc. In particular, regarding particle size distribution, JASS5 (Architectural Institute of Japan Standard Specifications for Building Works 5 Reinforced Concrete Works)
It is almost impossible to obtain aggregate that satisfies the particle size distribution specified in .

The present invention has been made in view of these conventional problems, and aims to solve the above problems by using fine steel particles for shot blasting as fine aggregate.

[Means to solve the problem]

This invention can be used as fine aggregate for heavy concrete with a nominal sieve size of 2.5 mm to 0.5 mm. -15 NVN steel fine grains for shot blasting are used with adjusted particle size. The steel fine particles for shot blasting have nominal sieve dimensions of 2.5+nm and 1.2mm, respectively.
0.6 m+n, 0.3 mm, O, 15 mm
The fine particles whose size was adjusted to
00%, ], 2Peng sieve 50-90%, 0.6mm sieve 25-65%, 0.3M sieve 10-35%, 0.1
It is preferable to use a 5 mm sieve at 0 to 10%.

[Effect]

When fine grain size-adjusted steel particles for shot blasting are used as fine aggregate for heavy concrete, the quality of concrete can be improved because the grain size distribution specified in JASS5 can be ensured for a given nominal sieve size. In addition, it has a higher specific gravity than magnetite, and it is easier to obtain the specified construction softness with the same strength than when using iron powder, iron scrap, etc., which are used as materials with a high specific gravity instead of magnetite, which is difficult to obtain. As a result, the unit amount of water and therefore the unit amount of cement 1-1 is also small, resulting in concrete with less drying shrinkage, cracking, etc., and a high air-dry specific gravity.

Furthermore, by adjusting the particle size of the fine steel particles for shot blasting as described in claim (2), it has the highest specific gravity compared to other particle size adjustments, and has low drying shrinkage and cracking, and is easy to work with. You can get good weight concrete.

〔Example〕

This invention will be explained below with reference to each table.

Figure 1 shows the particle size distribution of fine aggregate using fine steel particles for shot blasting used in the present invention, where the vertical axis shows the sieve permeability in weight percent, and the horizontal axis shows the sieve permeability. This is a diagram showing the opening of the temple. The particle size distribution of fine aggregate is defined by JASS5 (Architectural Institute of Japan Standard Specifications for Building Works 5 Reinforced Concrete Works) for quality assurance of concrete. In other words, it is an aggregate that passes 85% or more by weight of a 5M mesh sieve according to the concrete sieve standard, but fine steel particles for shot blasting with a nominal sieve size of 2.5 mm to 0.15 + nm, which is limited in the present invention. As shown by the dotted line in the figure, it clearly complies with the JASS5 regulations.

Figure 2 shows an example of the particle size of the fine steel particles for shot blasting as described above.
) of 2.5. 1.2.0.6.0.3°0.15 was adjusted to have a particle size of 10, 20, 25, 25, and 20% by weight, respectively, to obtain fine aggregate.

Figures 4 and 5 show an example (A) in which fine steel grains for shot blasting, which have been adjusted in particle size according to the present invention, are used when iron is used as the fine aggregate, and a similar method in which iron powder 2 is used. iron(
This is a comparison with example (B) in which a piece of steel was used, and as the coarse aggregate in both examples (A) and CB), a cut piece of round steel was used as the coarse aggregate; In both examples (A) and (B), heavy concrete using crushed stone is compared.

Iron powder, iron scrap, etc. are inherently extremely irregular in shape, so it is extremely difficult to secure a desired particle size distribution, and when these are used, the aggregate surface is rough and uneven. many,
Compared to using fine steel particles for shot blasting,
In order to obtain a predetermined construction softness with the same strength, as shown in Figure 4.5, the unit amount of water increases, and as the unit amount of water increases, the unit amount of cement increases. As a result, the heavy concrete of (A) has less breathing and drying shrinkage than that of (B), and has a higher air-dry specific gravity.

In addition, when comparing (A) in Figure 4 and (A) in Figure 5, there is a large difference in air-dry specific gravity when using cut pieces of round steel as the coarse aggregate and when using crushed stone. I understand that.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to obtain fine aggregate that does not contain chlorides or impurities and has no variation in specific gravity particle size, and by appropriately blending products with various particle sizes, it is possible to obtain It is possible to produce high-quality and stable concrete due to its adaptability to various conditions.Furthermore, it is very easy to obtain and procure aggregate.

[Brief explanation of the drawing]

Figure 1 is a diagram showing an example of the particle size distribution of fine aggregate using fine steel grains for shot blasting, Figure 2 is a table showing an example of the grain size of fine steel grains for shot blasting, and Figure 3 is a diagram showing an example of the particle size distribution of fine aggregate using fine steel grains for shot blasting. A table showing the particle size adjustment ratio of the fine aggregate according to the invention, FIG. 4 is a mixing example of heavy concrete using steel aggregates for both fine aggregate and coarse aggregate, and a table comparing the present invention and the conventional example. , FIG. 5 is a table comparing the present invention and a conventional example, showing an example of the preparation of heavy-duty concrete using steel as a fine aggregate and crushed stone as a coarse aggregate. Figure Figure Figure Figure Figure

Claims (2)

[Claims] (1) Heavy duty concrete characterized in that shot blasting fine steel particles with a nominal sieve size of 2.5 mm to 0.15 mm are used as fine aggregate for heavy duty concrete, with particle size adjusted. (2) Steel fine particles for shot blasting have nominal sieve sizes of 2.5 mm, 1.2 mm, 0.6 mm, and 0.5 mm, respectively.
The fine particles whose particle sizes were adjusted to 3mm and 0.15mm were passed through the 5mm sieve at 100% and 2.5% respectively.
mm, sieve 80~100%, 1.2mm sieve 50~
The heavy concrete according to claim (1), wherein 90% is sieved by 0.6 mm, 25 to 65% is sieved by 0.6 mm, 10 to 35% is sieved by 0.3 mm, and 0 to 10% is sieved by 0.15 mm.