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A few basic common sense about sand and gravel aggregates, if you don't understand it, you will suff

From： Hunan ZEGA Date：2021-12-10 09:40:07 Hits：1145 Belong to：Company News

sand and gravel aggregate is a collective term for sand, pebble (gravel), crushed stone, block stone, material stone and other materials in water conservancy projects, which are widely used in building construction, road and bridge engineering, hydropower facilities and other projects, and are one of the indispensable and important raw materials in infrastructure construction. In the industry, you must often hear others mention coarse sand, fine sand, 12 stone, 13 stone and other words, but what do you know what these specifically mean? Today we will learn together.

stones—coarse aggregates

aggregates with a particle size greater than 4.75 mm belong to coarse aggregates, also known as stones. It is commonly divided into 5-1 stones, 1-2 stones, 1-3 stones, 2-4 stones and 4-6 stones.

1, 5-1 stones

represents crushed stone with a particle size of 5-10mm, commonly known as guami stone.

2, 1-2 stones

stands for crushed stone with a particle size of 10-20mm, mostly used in surface roads and concrete.

3, 1-3 stones

represents crushed stone with a particle size of 16-31.5 mm.

4, 2-4 stones

stands for two and four points, the international standard is 1/4-1/2 inches, the particle size is 10-15mm of crushed stone.

5, 4-6 stones

stands for four or six points, the international standard is 1/2-3/4 inches, and the particle size is 15-20mm crushed stone.

two. There are four common finished materials in the production of sand and gravel aggregates

1, sand - fine aggregate

aggregates with a particle size of less than 4.75 mm, fine aggregates, also known as sand. Common fine aggregates are divided into coarse sand, medium sand, fine sand and extra fine sand. Coarse and medium sand are used for concrete, and fine sand is used for plastering and grouting. Ordinary concrete sand is suitable for medium sand.

Particle size and modulus of sand:

(1) coarse sand: fineness modulus is 3.7-3.1, average particle size is more than 0.5mm, also known as large sand, 05 sand.

(2) medium sand: fineness modulus is 3.0-2.3, average particle size is 0.5-0.35mm.

(3) Fine sand: fineness modulus is 2.2-1.6, average particle size is 0.35-0.25mm, also known as face sand.

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

2, stone powder

stone powder refers to particles in the machine sand with a particle size of less than 0.075 mm that are the same composition as the host rock being processed. Generally, ordinary concrete requires stone powder content less than 10%, and high-strength concrete requires less than 5%.

foreign standards have differences in the definition of mechanism sand powder content and particle size:

(1) Definition of stone powder particle size: the United States, Japan, Australia and other countries have a defined particle size of 0.075 mm, and the United Kingdom, France and other countries are 0.063 mm;

(2) Stone powder content: the US standard stipulates that the maximum limit of stone powder content is 5-7%; 7% in Japan; 25% in Australia; 15% in the UK; In France, it is 12-18%.

in China's actual construction site production, many places also refer to powder, sand, and stone mixtures within 10mm as stone powder, which is used for the laying of road hydrostatic layers.

3. Natural sand and machine-made sand

(1) Natural sand

naturally formed, artificially mined and screened rock particles with a particle size of less than 4.75mm, including river sand, lake sand, mountain sand, desalinated sea sand, but excluding soft, weathered rock particles.

(2) Machine-made sand

rocks, pebbles, unchemically treated mine tailings, made by soil removal, mechanical crushing, shaping, screening, powder control and other processes, with a particle size of less than 4.75mm.

(3) Mixed sand

sand made from a mixture of natural sand and machine-made sand in a certain proportion.

4, needle-like granules

machine sand particles whose length is greater than 2.4 times the average particle size of the particle level to which the particle belongs are needle-like particles; those whose thickness is less than 0.4 times the average particle size are flaky particles.

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