Stockpile (Subgrade)

Stock pile is a large accumulated stock of goods or materials, especially one held in reserve for use at a time of shortage or other emergency.
A stockpile is a pile or storage location for bulk materials, forming part of the bulk material handling process. ... More controlled stockpiles are formed using stackers to form piles along the length of a conveyor, and reclaimers to retrieve the coal when required for product loading.
In this video you can see how to mixing the subgrade with dozer. Actually it's a process of mixing dry material or material preparation for laying.
Subgrade layers mostly 30 cm depth in two layers
Compaction required 98%
CBR 30 %
Don't hesitate to ask questions in comments

[@shahidkiani9170]

Subgrade stockpile, mixing by dozer