Polymer Slurry for Bored Piles: Mixing, Contamination and Bottom Cleanout
Polymer slurry is an engineered support-fluid system, not simply polymer added to water. Successful bored-pile use depends on repeatable preparation, suitable site water, controlled contamination and a bottom-cleaning method that reflects polymer sedimentation behaviour.
POLYWELL or DRILL-WELL?
POLYWELL is the powder route and requires controlled wetting and dispersion. DRILL-WELL is the liquid route and simplifies field metering, but every addition still needs to be recorded against actual treated volume.
Mixing
Use actual batch volume, not tank nameplate capacity. Introduce powder gradually into moving water and avoid fisheyes. For liquid polymer, meter into a moving fluid and allow adequate distribution before testing.
Density is a key contamination signal
Because fresh polymer systems contain little mineral solid, a rising density often shows that sand, silt, clay or rock fines are accumulating. High density + low sand should trigger a fine-solids check rather than an automatic polymer increase.
Do not keep sand suspended just to raise Marsh
Some polymer systems support the excavation while allowing coarse particles to settle. The operating sequence can be support → settle → clean. Bottom cleanout is therefore part of the system design, not evidence that polymer failed.
Reuse and replacement
Reuse while measured fluid condition remains within the approved operating window. Replace or exchange slurry when density/fines, cement contamination or repeated pre-concrete failure cannot be corrected economically.
For trial planning, see How to Run a Polymer Slurry Trial for Bored Piles.
Polymer support-fluid options
Choose powder or liquid delivery from site mixing capability and field-control needs.
Frequently asked questions
Should polymer be dosed to one universal kg/m³?
No. Starting treatment should be qualified with the product, water and soil.
Does low sand mean clean polymer slurry?
No. Fine silt or clay can raise density without appearing strongly in the sand test.
Can more polymer clean contaminated slurry?
No. Polymer does not physically remove existing solids.