JPH0641383B2 - Aggregate made of crushed sand - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing aggregate composed of crushed sand.

(Prior Art) Crushed sand is currently widely used as an aggregate used for manufacturing concrete and the like. This crushed sand is produced by crushing rocks and the like. Impurities such as dust contained in the crushed sand are removed by washing with water.

On the other hand, the aggregates actually used for concrete production must contain the particles of different sizes in an appropriate amount. The Japanese Industrial Standard (JIS) requires that the particle size distribution of crushed sand for concrete be distributed within an allowable range as shown in FIG.

FIG. 1 shows the particle size distribution obtained by crushing crushed sand. The horizontal axis is the aperture of the sieve, and the vertical axis is the amount passing through the sieve. According to Japanese Industrial Standards, only the particle size distribution in the range X shown in perspective in FIG. 1 is recognized.

(Problems to be Solved by the Invention) However, conventionally, when washing crushed sand with water, there is a risk that fine particles such as stone powder as well as impurities may be removed. In that case, for example, the particle size distribution is as shown by the Y line in FIG. In this Y-ray type, fine particles such as stone powder are almost lost. For this reason, conventionally, fine particles carried from other places such as sea sand are added to the washed sand to adjust the particle size.

(Object of the Invention) An object of the present invention is to produce an aggregate having a proper particle size distribution containing fine particles that have been lost during washing with water, without having to carry fine particles from another place as in the conventional case. To provide a method.

(Means for Solving the Problems) The method for producing an aggregate of the present invention is as follows.

A part of the raw crushed sand obtained by crushing the rough stone is unwashed, the remaining crushed sand in a larger amount than the unwashed crushed sand is washed, and the washed crushed sand and the unwashed crushed sand are mixed to be suitable. The particle size is adjusted to include fine particles in various proportions.

(Example) Next, an example of the present invention will be described with reference to FIGS. Crushed sand A is made by crushing rocks. If a part of the crushed sand A is C and the rest is B, only the crushed sand B is washed. The crushed sand C is preferably about 20% of the crushed sand A. The crushed sand C is left as it is without washing. Next, the washed crushed sand B ′ and the unwashed crushed sand C are mixed to obtain crushed sand D as an aggregate of the product.

In the washed crushed sand B ′, fine particles (stone powder) have been removed together with impurities, so that stone powder and the like necessary as an aggregate is eliminated. However, since the crushed sand C without washing contains the stone powder without loss, the particle size distribution of the crushed sand D obtained as a result of mixing the crushed sand B'and the crushed sand C is considered to be good including fine particles (stone powder). Become. Here, the stone powder refers to one having a plane value of about 1500 to 18,000 square centimeters / gram. In the present embodiment, about 3% of stone powder of crushed sand D is contained, and as indicated by the Z line in FIG.
It falls within the X range of IS.

It was confirmed that the amount of the crushed sand C without washing was about 20% of the crushed sand A. However, since the crushed sand C contains impurities, the quality of the crushed sand C as aggregate of the crushed sand D is not affected by the impurities. The proportion of crushed sand C should be selected. Crushed sand D
There is no problem even if stone powder is contained up to about 10%.

(Effect of the Invention) In contrast to the conventional method of adjusting the particle size by mixing fine sand such as sea sand, the present invention can produce a high-quality aggregate having a particle size distribution containing fine particles without carrying anything from another place. it can.

Further, in the present invention, since the crushed sand C is not washed, the water content of the aggregate (crushed sand D) can be remarkably lowered as compared with the conventional one in which all of the crushed sand is washed.

The amount of crushed sand to be washed decreases, and the amount of wastewater generated by washing decreases accordingly.

[Brief description of drawings]

FIG. 1 is a permissible range of the particle size distribution of crushed sand as aggregate for concrete production defined by Japanese Industrial Standards (JIS), and FIG. 2 is a diagram showing an embodiment of the present invention. A: raw crushed sand, B: crushed sand before washing, B ': crushed sand after washing, C: crushed sand without washing, D: crushed sand as aggregate.

Claims (1)

[Claims] 1. A part of raw crushed sand obtained by crushing a rough stone is unwashed, and the remaining crushed sand in a larger amount than the unwashed crushed sand is washed to obtain the washed crushed sand and the unwashed crushed sand. A method for producing an aggregate made of crushed sand, characterized in that the particles are mixed to adjust the particle size to contain an appropriate proportion of fine particles.