What are the advantages and disadvantages of backfilling with graded sand?

Natural graded sand has good compactness, and the design characteristic value of compressive bearing capacity can reach 200~250Kpa, so it is a good material for backfilling artificial foundation. The disadvantage is that it is more expensive than ordinary sand.

Graded sand refers to a mixture of sand or stone with a certain particle size, which is used for foundation or other purposes. Its proportion varies according to the specific engineering design. If there is no provision in the design, you can refer to the quota.

Natural grading refers to continuous gravel.

The artificial gradation is gravel (20mm-40mm): natural sand: water =9. 1 1:4.97:3.

Graded macadam cushion should be dense and stable, and its particle size grading range should meet the following table:

The above two grayscales are both pad grayscales.

The first rule stipulates that the diameter of all particles should not be greater than 50 mm In order to better meet the compactness, the first rule is recommended! In addition, in order to prevent frost heaving and wet softness, attention should be paid to controlling the content of fine materials and plasticity index less than 0.5 mm When used as the cushion of asphalt pavement in moderate and wet sections, lime should be added to the gradation, and the fine materials can be appropriately increased. The addition of lime accounts for 8%- 12% of the fine material content, in order to increase the strength and stability of the cushion.

Graded macadam is sometimes called graded macadam cushion as cushion, and its particle size is required to be 5-40 mm, of which the content of 25-40 mm is not less than 50%.