JPH10226546A - Aggregate for concrete and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aggregate for concrete capable of producing a concrete having excellent performance and easily obtaining an ideal particle size distribution curve by mixing a natural sand with a crushed sand adequately niformized in particle size in a prescribed ratio. SOLUTION: The aggregate for concrete is constituted so that the particle size is controlled to be in a range of the standard (JIS-A-5308-APPENDIX 1) of the particle sized distribution of the aggregate for concrete by mixing the natural sand with the crushed sand in the prescribed ratio and the particle shape of the crushed sand is made uniform. As the natural sand, sea sand, river sand, land sand and the like can be used. The particle size of the crushed sand is made uniform by a method using a rotary disk, a method using a rotary table and a roller or the like. When a crushed sand of lime stone is used as the crushed sand, the production is facilitated since lime stone is soft and excellent in crushing property compared to the other kind of rocks. Then the productivity is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a concrete aggregate and a method for producing the same, and more particularly, to a concrete aggregate obtained by mixing natural sand and artificial sand and a method for producing the same.

[0002]

2. Description of the Related Art The use of fine aggregate in which fine grains and coarse grains are appropriately mixed makes it possible to produce concrete of a required quality compared to a case where the grains are uniform in size or a case where there are many fine grains. It can be produced economically with relatively small amounts of water and cement. In this sense, the particle size curve of the aggregate for concrete is defined in Japanese Industrial Standards JIS as shown in FIG.

As a conventional concrete aggregate, natural sand (sea sand, river sand, mountain sand, land sand) has been known. Also,
Crushed sand was also known as artificial sand. The crushed sand also compensates for the decrease in natural sand due to resource depletion.
The crushed sand used for the purpose of supplementing the shortage of the natural sand has been used after being adjusted in particle size and mixed with the natural sand. For example, a method of improving the workability of concrete by mixing fine particles with sea sand is disclosed in
No. 6342.

[0004]

However, in such an aggregate for concrete and a method for producing the same, there is a problem that crushed sand mixed with sea sand has a low production efficiency and is difficult to treat with dust. Had occurred. In addition, the crushed sand had a flat shape and the like and had irregular particle shapes, which had an adverse effect on particle size distribution, concrete properties, and the like.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a concrete aggregate capable of producing concrete having good properties. Another object of the present invention is to provide an aggregate for concrete capable of easily obtaining an ideal particle size curve. Another object of the present invention is to obtain an aggregate for concrete having an ideal particle size curve corresponding to the properties (coarse sand, fine sand, etc.) of natural sand.

[0006]

According to the first aspect of the present invention, a natural sand and a crushed sand are mixed at a predetermined ratio, and the particle size is adjusted to the standard (JIS A 5308) of a particle size curve of fine aggregate for concrete. An aggregate for concrete configured to fall within the range of Appendix 1), wherein the crushed sand is a concrete aggregate whose particle shape is adjusted. As the natural sand, sea sand, river sand, mountain sand, and land sand can be used. When using sea sand, it is necessary to remove salt. The crushed sand is sized by a method using a rotating disk, a method using a rotating table and rollers, or the like.

The invention according to claim 2 is the concrete aggregate according to claim 1, wherein the crushed sand is limestone crushed sand. Limestone is easy to manufacture because it is softer than other rock types and its friability is better than other rock types. Therefore, its productivity is excellent.

According to a third aspect of the present invention, there is provided a step of preparing natural sand, a step of measuring the particle size composition of the prepared natural sand, and a step of preparing limestone adjusted to a predetermined particle size corresponding to the particle size of the natural sand. The step of preparing crushed sand, the step of adjusting the particle shape of the limestone crushed sand, and the step of mixing the natural sand and the limestone crushed sand, the particle size of the mixed sand is the standard of the particle size curve of fine aggregate for concrete. (JIS A 5308
Comprising the steps of configuring the concrete aggregate to fall within the range of Appendix 1).

[0009]

According to the first and second aspects of the present invention, it is possible to easily obtain a particle size curve suitable as an aggregate for concrete. Moreover, concrete with good properties can be manufactured. In addition, crushed sand of limestone has good crushability, so that particles having different particle size distributions can be easily produced. Therefore, it is suitable for adjusting the particle size distribution of natural sand. Furthermore, in the case of limestone crushed sand, dust generated during crushing can be effectively used as an asphalt filler or the like. The reason for using the crushed sand having the grain shape thus prepared is as follows. In other words, when the grain shape of the crushed sand as the aggregate is square, or when it is elongated, or when it is flat, the use of such a fine aggregate is compared with the case of using a round fine aggregate. Then, the fluidity of the concrete deteriorates. In addition, when using fine aggregate having such a shape, in order to produce workable concrete, the unit water amount must be increased, which is contrary to minimizing the unit water amount, which is the basis of concrete mixing. . Concrete strength,
From the viewpoint of durability, the unit cement amount must be increased by increasing the unit water amount. In addition, the unit price of concrete increases due to the increase in the amount of cement, and the economic efficiency also deteriorates.

[0010] According to the third aspect of the present invention, natural sand and limestone crushed sand having a grain shape are blended. And the mixed sand which formed the appropriate particle size by this blend is made into the aggregate for concrete. That is, it is possible to provide an aggregate for concrete capable of producing concrete having good properties. Further, the production capacity of crushed sand can be increased. Further, dust generated at that time can be effectively used, and no waste is generated.

[0011]

Embodiments of the present invention will be described below. However, the present invention is not limited to these embodiments. First, limestone crushed sand is prepared as artificial sand. Limestone crushed sand is manufactured using the following equipment. For example, limestone is crushed by a crusher and stored in a crusher bunker. Then, a certain amount of crushed crushed stone is cut out from the crushed stone bunker, and crushed stones having different particle sizes are sieved by a sieving machine. And 5% of particle size in this crushed stone group
The following sharply ground crushed stone is supplied into a granulator. In this sizing machine, the corners of the crushed stone are removed and the particle shape is adjusted like natural sand. Alternatively, crushed sand of limestone is supplied to a vertical roller mill to be crushed. In the roller mill, the crushed sand of limestone is finely crushed by the compression and shearing action by the cooperation of the rotary table and the crushing roller. As a result, the crushed limestone sand is sharpened and the grain shape is further improved by the shearing action. Next, sea sand, river sand, land sand, or mountain sand is prepared as natural sand. Then, the particle size of the prepared natural sand (for example, sea sand) is measured. According to a sieving test (JIS A 1102). In FIG. 2, a curve x indicates a particle size curve of the natural sand. Also, the limestone crushed sand is prepared corresponding to the particle size curve of the natural sand. The sieving test result of the limestone crushed sand is shown by a curve y in FIG. Then, the natural sand and the limestone crushed sand are mixed at a weight ratio of 1: 1. As a result of this mixing, the particle size curve of the mixed sand is z in FIG. In FIGS. 2 and 3, curves a and b show the particle size curves of the fine aggregate for concrete shown in the above (Appendix 1 to JIS A 5308).

The mixed sand having a predetermined particle size obtained as described above was used, the mixture was designed and the following test was conducted. That is, a slump test. The test results are shown in Table 1 together with Comparative Examples. As a result, good slump performance was obtained.

[0013]

[Table 1]

[0014]

According to the present invention, it is possible to obtain an aggregate for concrete capable of producing concrete having good properties. Further, it is possible to very easily obtain an aggregate having an optimum particle size for concrete. In that case,
The grain shape of crushed sand is improved. Further, production capacity is increased. In addition, the workability of concrete using this is improved.

[Brief description of the drawings]

FIG. 1 shows a particle size curve of aggregate for concrete defined by Japanese Industrial Standards.

FIG. 2 shows respective particle size curves of sea sand and limestone crushed sand according to one embodiment of the present invention.

FIG. 3 shows a grain size curve of mixed sand of sea sand and limestone sand according to one embodiment of the present invention, together with a grain size curve of concrete aggregate specified by Japanese Industrial Standards.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Naoki Ono 750 Komori, Ogura Minami-ku, Kitakyushu-shi, Fukuoka Prefecture Mitsubishi Materials Corporation Higashiya Mine

Claims (3)

[Claims] 1. A natural sand and a crushed sand are mixed at a predetermined ratio so that the particle size is within a standard range of a particle size curve of fine aggregate for concrete (JIS A 5308 Appendix 1). An aggregate for concrete, wherein the crushed sand has a particle shape adjusted. 2. The crushed sand of limestone according to claim 1, wherein the crushed sand is limestone crushed sand.
3. Aggregate for concrete according to 1. 3. A step of preparing natural sand, a step of measuring a particle size composition of the prepared natural sand, a step of preparing limestone crushed sand adjusted to a predetermined particle size corresponding to the particle size of the natural sand, The step of adjusting the particle shape of the crushed sand of limestone and the mixing of the natural sand and the crushed sand of limestone allow the particle size of the mixed sand to be the standard of the particle size curve of fine aggregate for concrete (JIS A 5308 Appendix 1) ). A method for producing an aggregate for concrete, comprising the steps of: