Sand and gravel aggregates are one of the indispensable raw materials in infrastructure construction. They can be found in projects such as housing construction, road and bridge engineering construction, and water conservancy and hydropower facilities construction. Do you know about coarse sand, fine sand, 1-2 stone, 1-3 stone in industries related to sand and gravel aggregates? Today, Xiao Kai will take everyone to learn more.

Coarse aggregate

Coarse aggregate refers to aggregate with a particle size greater than 4.75 mm, also known as stone. The coarse aggregate can be further divided into 5-1 stones, 1-2 stones, 1-3 stones, 2-4 stones, and 4-6 stones.

Coarse aggregate - particle size of stones:

5-1 stone: represents crushed stone with a particle size of 5-10mm.

1-2 stones: represent crushed stones with a particle size of 10-20mm.

1-3 stones: represent crushed stones with a particle size of 16-31.5mm.

2-4 stones: represent two or four parts, with an international standard of 1/4-1/2 inch and a particle size of 10-15mm.

4-6 stones: represent four or six parts, with an international standard of 1/2-3/4 inches and a particle size of 15-20mm.

Fine aggregate

Fine aggregate refers to aggregates with a particle size less than 4.75 mm, also known as sand. Fine aggregate can also be divided into coarse sand, medium sand, fine sand, and ultra-fine sand.

The particle size and fineness modulus of fine aggregate sand:

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

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 below 0.25mm.

Stone powder, stone powder content

Stone powder refers to the particle size less than 75 in machine-made sand μ The composition of m is the same as that of the processed parent rock particles. Generally, ordinary concrete requires a stone powder content of less than 10%, and high-strength concrete requires a content of less than 5%;

There are differences in the definition of the content and particle size of machine-made sand and stone powder in foreign standards. In terms of defining the particle size of stone powder, countries such as the United States, Japan, and Australia define the particle size as 0.075 millimeters, while countries such as the United Kingdom and France define it as 0.063 millimeters; In terms of stone powder content, the US standard stipulates a maximum limit of 5-7% for stone powder content; In Japan, it is 7%; Australia has 25%; In the UK, it is 15%; France is 12-18%.

Natural sand, artificial sand, machine made sand, mixed sand

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

Artificial sand: including machine made sand and mixed sand.

Mechanized sand: Rock particles with a particle size less than 4.75mm, made from rocks, pebbles, and untreated mine tailings through processes such as soil removal, mechanical crushing, shaping, screening, and powder control.

Mixed sand: Sand made by mixing natural sand and machine made sand in a certain proportion.

"Machine made sand Methylene blue value (MB value)"

An indicator used to determine whether the content of particles with a particle size less than 0.075mm in machine made sand is mainly soil or stone powder with the same chemical composition as the processed parent rock; The Methylene blue value of machine-made sand is required to be MB ≤ 1.4, and should be controlled below 1.0.

The relationship between stone powder content and fineness modulus

The smaller the fineness modulus of machine-made sand, the finer the overall particles, and the more the content of stone powder, which is inversely proportional to the fineness modulus.

Needle, flake like particles

Needle shaped particles are those with a length greater than 2.4 times the average particle size of the particle size to which they belong; A particle with a thickness less than 0.4 times the average particle size is considered a flaky particle. The average particle size refers to the average value of the upper and lower particle sizes of the particle size.