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How to express the particle size of stone and sand used in construction?

Asker: Ali
Ask date: 7/23/2020 05:37:15PM
Question: How to express the particle size of stone and sand used in construction?

Reply：

Dear Ali,

The particle size of stones is usually between 5mm-31.5mm, and the specific classifications are as follows:

5-1 stones represent 5-10mm gravel;

1-2 stones represent 10-20mm gravel;

1-3 stones represent 16-31.5mm gravel;

2-4 stones represent two or four points, the international standard is 1/4-1/2 inches, which means 10-15mm gravel;

4-6 stones represent four or six points. The international standard is 1/2-3/4 inch, which means 15-20mm gravel.

Let’s take a look at the grain shape standard of sand (mechanism sand).

Refer to China's standards for construction sand: sand refers to rock debris formed and accumulated in natural conditions such as lakes, seas, rivers and mountains with a particle size of less than 5mm. It can also be processed by mining machinery with a particle size of less than 4.75 mm of construction particles. The thickness of sand is divided into 4 levels according to the fineness modulus:

Coarse sand: The fineness modulus is 3.7-3.1, and the average particle size is 0.5mm or more.

Medium sand: The fineness modulus is 3.0-2.3, and the average particle size is 0.5-0.35mm.

Fine sand: The fineness modulus is 2.2-1.6, and the average particle size is 0.35-0.25mm.

Extra-fine sand: The fineness modulus is 1.5-0.7, and the average particle size is less than 0.25mm.

In addition to particle size and particle size specifications, various construction projects also have corresponding requirements for the needle-like particles, mud content, stone powder content and firmness of sand and gravel materials. Therefore, the requirements must be specified in advance when configuring the production line to avoid affect the quality and sales of finished materials.