The raw materials of graded crushed stone, the content of needle-like particles.
1. The material of rolled crushed stone can be various types of rock (except soft rock), cobblestone or slag. The particle size of the cobblestone should be more than 3 times the maximum particle size of the crushed stone; the slag should be disintegrated and stable, and its dry density and quality should be relatively uniform, and the dry density should not be less than 960kg/m3.
2. The total content of needle flake particles in the crushed stone should not exceed 20%. There should be no harmful substances such as clay blocks and plants in the gravel.
3. Stone chips or other fine aggregates can use the fine sieving material of general crushing yard, or the fine sieving material of rolling asphalt surface treatment and penetrating stone, or specially rolled fine gravel Aggregate. Natural gravel or coarse sand can also be used instead of stone chips. The particle size of natural gravel should be appropriate, and if necessary, oversize particles should be screened out. Natural gravel or coarse sand should have a better gradation.
4. In the case that the plasticity index is too large, the product of the plasticity index and the content of fine soil below 0.5mm should meet the following requirements:
(1) In areas where the annual rainfall is less than 600mm, when the groundwater level has no effect on the soil foundation, the product should not exceed 120;
(2) In humid and rainy areas, the product should not be greater than 100.
5. The crushing value of the graded crushed stone or the stone used for the graded crushed gravel shall meet the following requirements:
The base layer of the third-level highway: not more than 35%