4. Upgrading coal shale by treatment with road binder

Pre-project recommendations

The following solutions were planned at the preliminary design stage of the earthworks for the Dourges multimodal platform, based on the authorized operation on the "116/117" slag heap:

• use of raw shale for backfill (criterion AR1) and railway subgrades;

• production of formoschist by screening, for use in road sub-base (PF2 criteria) and railway sub-base.

Conclusions of the market's geotechnical campaign

Project studies prior to the start of work led to the following findings, based on a representative sample of boreholes drilled in the slag heap:

• a 0/150 grading curve, with 45% passing 20...