GELSAP Technical Guide
TBM and EPB Tunnelling Spoil: A Practical SAP Solidification Trial
TBM and EPB Tunnelling Spoil requires a practical test with the actual liquid, process and handling target. This guide explains how industrial buyers can evaluate a suitable superabsorbent polymer with GELSAP.

Understand the spoil before dosing
Tunnel boring machine and earth-pressure-balance operations can produce spoil with high free-water content. Its consistency changes with geology, conditioning foam, fines and excavation conditions. A useful treatment target is defined by actual loading and transport requirements, not by a single generic absorption number.
Select an application point
A crosslinked sodium polyacrylate grade may be mixed with excavated spoil after the tunnel process when free liquid makes handling difficult. Trial locations include a dedicated mixer or controlled stockpile treatment area. Keep polymer addition away from equipment where unintended swelling could interfere with the operating process.
Measure the result
Test fresh and aged spoil separately. Document liquid chemistry, moisture, mixing energy, dose per cubic metre, waiting time, residual free liquid and excavator handling. If the waste destination imposes a paint-filter or leachability criterion, test to that requirement; visual solidity alone is insufficient.
Plan for site variation
Establish a dose range from repeated field samples rather than copying a laboratory result to every shift. Salinity, additives and groundwater conditions may change absorption. GELSAP can discuss particle size and a sample-testing plan once the spoil profile and required endpoint are provided.
Next step: request an application trial
Send the liquid type, approximate volume, pH, salinity or TDS, current process and desired handling result. See GELSAP’s natriumpolyakrylaatti yleiskatsaus ja sludge and slurry solidification page for related applications.
